Model Engine Maker

Engines => From Kits/Castings => Topic started by: deltatango on January 29, 2020, 01:46:20 AM

Title: A Tandem Compound Mill Engine
Post by: deltatango on January 29, 2020, 01:46:20 AM
In my former world of w##k the saying was "if it hasn't been written up, it hasn't happened" so I guess it's time that I started a build log for the current engine.

The choice of engine for this project is the result of my interactions with MEM so I hope you all like it, particularly Tug and Bob Potter who have played their parts in getting this one started. Tug has written of the origins of the Arnold Throp/Peter Southworth compound mill engine model in "Tug's Corliss Tandem Compound Project" build log so I won't duplicate too much of that here, just enough to set the scene.

Arnold Throp, who was an apprentice with Cole Marchent & Morley, engine builders in Bradford (Yorkshire, UK) described a model of a typical small-to-medium sized mill engine in "Model Engineer" in 1982 but didn't give any construction details and as far as I know no such details have been published. The design was worked on by Peter Southworth and he evolved five basic versions and made (or modified) patterns and was the original supplier of castings. Since then the availability of castings has been patchy. At the Forncett day out two years ago I saw Tug's progress with his all-Corliss valved tandem compound version and was impressed with it (both the design and the workmanship!). At that time Bob Potter was running "Southworth Engines" and supplying drawings and castings for boiler feed pumps and for the mill engine and he sent me a set of drawings.  The engine was, just, within what my machines could deal with and I was very taken with the idea of building one so parted with the money. Bob had given up on sending castings via the post/couriers but he, very kindly, delivered the 23 kg of metal to friends of ours "to await collection". Customer service indeed! Since then the Southworth range has been taken over by Blackgates Engineering and their 2019 catalogue only lists the feed pumps, I really hope that Arnold and Peter's legacy isn't going to be forgotten!

Of the five versions shown on the drawings my choice was the tandem compound with Corliss valve HP and slide valve LP cylinders and an "air pump" (spray condenser, really). The cross-compound versions were attractive but too bulky for easy storage, transport or display. The tandem is long but will at least fit on a shelf.

As I've done with previous projects I re-drew the design using the "Alibre" CAD package and here are three screen dumps of the results:

(https://sat02pap002files.storage.live.com/y4ml2Xh_tWXREjfXp2tu5iXNTK4Hhhpki7GzxWRiDJOhej78snBJ0jOAvceBeNUE5u7JAFu3RVdu5wrIFq-5Q5IR86mia4Iwl-2v-qgsQzoU--5NHjHPysZoLCO6zyM1dSli5yE-gkAsjoB84ZfYg10rnXz97vH5tJGxHIFvDHvpT_kP0CQn5pi9qIFf2X5T6On?width=640&height=437&cropmode=none)

(https://sat02pap002files.storage.live.com/y4mwQlQnxus6p8-uN9BFICswnCDndfNoLBun_7-JZzKtR9OjU6mrENiUa5RYe58B4ymBL26Zx-Zj5l6e9FyLYO3g-pu-xDnQNRF-GhWWjJVe9n15JYdMJ4xnyFoorR5qAv1wjQIgDBBQmou3CjnKoj4bVsL4Emi6XuWawjEoVym2VaW944EKe6wiOLKxCsWcrUd?width=640&height=356&cropmode=none)

(https://sat02pap002files.storage.live.com/y4m_Mlwth7Fqqd8QwIVt6-z9g0znuQ-D1u3n4AGU-PTa4C7F8vOydvXnTLwGGm_BEQJ-KSQvcLELCkYvMpDdgQel-vqClxshAD41DviQl7mlCyqs-wlPOAMu8wnLSDWdYNZP36dXDN754BIG11jbgZ7JXnN-gA0nrhFn9DRrOQ-3KJY1dZbgHVs-ReGcscuFXtl?width=640&height=437&cropmode=none)

Next post I'll put in a drawing and make a start on the big bits i.e. the flywheel and crankshaft.

David
Title: Re: A Tandem Compound Mill Engine
Post by: crueby on January 29, 2020, 01:59:10 AM
Oh, now that is a real beauty of a design!!  How big will the model be?


Hey, shop elves, break out the popcorn!!   :popcorn: :popcorn: :popcorn:
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 29, 2020, 02:44:29 AM
Great to have you watching and commenting Chris!

The baseboard as drawn is just over 1 m long and the flywheel is 250 mm OD. The Hercus "260" lathe swings, not too surprisingly, 260 mm. As you will see soon this is a tight fit.

Hope you have lots of popcorn on hand as this won't be a quick build!!

David
Title: Re: A Tandem Compound Mill Engine
Post by: Larry on January 29, 2020, 03:13:49 AM
Great looking design. Anxious to follow your MEM Corliss build.
Title: Re: A Tandem Compound Mill Engine
Post by: cnr6400 on January 29, 2020, 03:30:52 AM
"OK Chris, I'll back the dump truck full of   :popcorn:  into your cellarway now, and then go get another load for  me"    :Lol:

CAD looks great David, look forward to watching the build. Have you checked the workshop door to be sure you can get it out when finished?  :shrug: :Lol:
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 29, 2020, 03:40:04 AM
Thanks, good to have you along Larry and cnr!

It will go through the door - endways on. I just hope I get it finished before I'm too old and feeble to lift the damn thing.

There is also the important question from the "local authorities" as to "where do you think you're going to put this one?".

David
Title: Re: A Tandem Compound Mill Engine
Post by: JackPick on January 29, 2020, 05:12:14 AM
Wow, there's some work in that one David. Nice CAD model too.
Best of luck.
John
Title: Re: A Tandem Compound Mill Engine
Post by: MJM460 on January 29, 2020, 05:30:14 AM
Hi David,

Looking forward to following along.  It will be an interesting build.

MJM460

Title: Re: A Tandem Compound Mill Engine
Post by: john mills on January 29, 2020, 06:52:30 AM
Hi David

  I  too will follow your build  it will be an interesting model in full size these engines must have been impressive machines to watch working and i am sure your model will be too.
     
       John






Title: Re: A Tandem Compound Mill Engine
Post by: Jo on January 29, 2020, 07:40:46 AM
Nice to see the construction of another of Arnold's engines David.  :)

I am building his Cross Compound version ... its rather huge  ::)

Jo
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 29, 2020, 07:50:48 AM
John, MJM, John and Jo, it's good to have you following.

Jo, what progress have you made with the cross-compound? It would be huge bordering on humongous...

John M these machines are indeed very impressive to watch and many of them ran for a century or more with only replacement of normal wearing bits.

OK, just been called for a meal, more later.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Jo on January 29, 2020, 08:28:42 AM
Jo, what progress have you made with the cross-compound? It would be huge bordering on humongous...

I didn't get very far as having finally found a big enough board to sit it on I decided I needed to find a display/storage arrangement for it first. It is too wide to sit on a side board or in a display cabinet so I toyed with the idea of converting a coffee table to mount it in but got no where so there it sits  :disappointed:

Jo
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 29, 2020, 10:25:55 AM
Jo, thanks for the picture. I've seen some pictures of completed cross-compounds and it was thinking about those, and where we could put them that convinced me to go for a tandem. However, it would be great to see yours restarted, could my efforts inspire you??

It wasn't just seeing Tug's model that set me off, I have family connections to NW England so a representation of an important part of the history of Lancashire has meaning for me.

The model is based on a design by Arnold Throp, published in Model Engineer, 20th August and 17th September 1982. Arnold T described it in general as “… representative of the smaller types which were made in great numbers from about 1860 onwards in this country for driving textile mills, …”.

As the model is not intended to represent any particular full size engine it can have an invented back-story. My mother’s family were all from Burnley (Lancashire, England) with her father’s family (Read) being road and general contractors (“Paviors and Contractors” in the trade directories of the time) and her mother’s (Easton) were brush makers. The Eastons made every sort of brush from ladies hair brushes to the rotary brushes for road sweeping machines but their main source of income was sweeping and specialised brushes for the cotton industry.

Based on that background I have invented the engine building firm of “Easton and Read, Engineers, Burnley”. As these engines were often given female names this one can be “Mary” for my maternal grandmother. An engine this size was quite likely to have driven a weaving mill in the Burnley area, spinning mills used much larger engines. All I have to do is get the model to the stage where a makers plate and name plate are needed...


After collecting the castings I re-packed them into a small trolley case and spread the smaller ones out among our other bags (the maximum weight for any single item of luggage is 23 kg, same as the total of the castings so we had to keep the case weight down). I don't think the person on the check-in desk had ever had a case that small that weighed so much but she accepted my explanation of the contents - without much idea of what they were, I suspect.

After unpacking the set looked like:

(https://8lktra.sn.files.1drv.com/y4mPaPsB2VPvBZ0_35nw_97k-bp8kfRyqDrj1MbVekh-WJbc8fvGZvY0WJm4Mhm52xVouJioKtjlGioHspubvWLh3DAFJSKVo6dY9lB-PWQdGO88h3cL1QnLbyB6on4wO1GXO-ebe0enciivXffGcClfclZi7gVzb1YbSft_y0SCl-FWmN7Vn6AanXKnjClAjAuyaX1oky6h-toGvIQ--eiNw?width=800&height=600&cropmode=none)

and, with an embryo crankshaft included:

(https://7vktra.sn.files.1drv.com/y4mt0VksMRCcTBJYx1mv2FyVlTAF_kKuF3CVa3aCz1yU1h0QLWRtpHqeVglA1YMehcKj9U7PPD2ih_ytxBkklmSxg3eXnOmodQlcrpL7sgXbnGTJRC_dc0utMtkDBcopMFPvad-lgz6vwLW0veKeQTrx3qbykDYhngoGscQquJ3jRKHkl8vIhKDzorQwyO6qMEnBulZI1jNj91BBOjvgJ035A?width=800&height=600&cropmode=none)

Enough background, time to get on with cutting metal, there's a heck of a long way to go!

David
Title: Re: A Tandem Compound Mill Engine
Post by: scc on January 29, 2020, 09:06:05 PM
Great stuff.........I'm in  :popcorn: :popcorn: :popcorn:   Terry
Title: Re: A Tandem Compound Mill Engine
Post by: jadge on January 29, 2020, 10:24:12 PM
Should be an interesting build. Wow, one metre, that's a pretty big model. The castings look rather nice with good definition.

Andrew
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on January 31, 2020, 02:18:04 PM
Hello David,

Good to see you are about to start  :) I'll try to remember to look in from time to time but been a bit noticeable by abscence lately due to other distractions. Love those drawings - were that I could do likewise - super job indeed  :ThumbsUp:

Hope your castings prove as easy to machine as mine were - good luck with the build.

Who knows - it might even have the effect of getting mine back on the agenda (let alone the top) ::)

Best Regards - Tug



Title: Re: A Tandem Compound Mill Engine
Post by: Bobp on January 31, 2020, 06:38:43 PM
Thank you for your kind words David. I am pleased you managed to sort out the final part of the journey for them. What a marathon. My Corliss build has been very spasmodic but I am sure your posts will spur me on. The drawings are superb and are certainly helpful in trying to get you head around the Arnold Throp / Peter Southworth plans.

Blackgates have sorted the pumps now and I am encouraging them to get on with the Corliss. They certainly have some castings and I have offered to help them if they need it to get sets together. The engines are far too important to be lost to the likes of us and there is not much around that is so impressive and big! You can save a fortune on gym membership by just moving them around!

Bob
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 01, 2020, 02:34:45 AM
Terry and Andrew, it's good to have you along, thanks for looking in.

Bob, I'm pleased you like the drawings, thank you! I'll PM later.

OK, we have Jo, Tug and Bob (and maybe others yet to come out of the woodwork?)with part completed Throp-Southworth engines and me with one just started, some friendly competition might be just what I need in the future to keep me going.

I haven't made a full set of drawings as yet, just been creating them as needed. The CAD model is based on the original drawings that Bob emailed to me and I've just spotted one difference from the actual castings so there will be revisions. The first is for the crankshaft etc:

(https://sat02pap002files.storage.live.com/y4mDDTECOE_JzpwAO1HnZt7yUByWiSONJ4duEenFMTb69VEJQQ_C1eFL3IzuvngNP9skOnOMVNYFTopxsC3-FvQikZIXa5bAM6sqTMkcznvo9_zBtU4Os6XuYW_plnj7GgsCM4zO3uPeRULDvfQbxsv6B5c8oTzG3x6rieYjW2YmcgCeWhwfwLwzjy3cCdJ1C1S?width=1584&height=944&cropmode=none)

I started with the crankshaft because:
1) It looks to me to be the logical core of the engine

2) It can be used as a gauge for boring the flywheel and if I can machine that on the Hercus 260 then everything else is within the capacities of my machines.

The crankshaft started life as a shaft from an unknown gearbox that was left behind at our previous house so this bit of metal has been waiting for a need to pop up for over 40 years. Hoarding rules!!
A long time ago I put this into the wood heater when the fire was very hot and left it overnight in the hope of softening it but I don't think that worked. The outside still had a hard case on it that would have defeated HSS and made for some exciting hot chips down the front of the T-shirt:

(https://sat02pap002files.storage.live.com/y4mSs1er0wWG2aGbXpgjZ5kIGMPOzDKDv28byoMhSwfum8J9Evs4QqgpGPO0feCsAUWxGPpcwUGE27K46SaKLMV9UgKhM_LMu-1o9kEc1dKUR9rDYhtSee38EGKDFwGcAFflXcRHZJYOpA9RIKqh6Mb6JGT-hPS80SLnJrgt5ctHfxAPDKvcfDQcMlVv9NWdc6V?width=640&height=480&cropmode=none)

(https://sat02pap002files.storage.live.com/y4mEKH2mQRDH_LH97maw8GHWx5ObuiId1ANcg3-YnthGSseTEs6QxnGGN0COJ-ponJ-Ij-xy-GrbF2LBIiU1uBg5VNiF-U6zxEoPfmpUjAIapmhSAiqCDMHH35xdczEA80ckcB4tfp-jv7l9K2H1tJXSJyECUV-FDHc_a7f2JtT4ry2zo7gWx8CwrTaBByeXhkX?width=640&height=480&cropmode=none)

and some intriguing patterns where the splines had been:

(https://sat02pap002files.storage.live.com/y4mycYeZz0GqTW3IpjGAsYrzoXj8F7pJOPTZ5rw2goq_ysHmCD_GZJsXoENW-KMfOfloOWPhKgYhdzLRqrStotKiV0ZKuvg0Sj_bWRLh2KQeVJukjwQccCFcT5tWjwGbQZOLd0VQpV-7ZUtunMTfkk6Aqn0pe45EUD9Cu-uTA-wuxt_AItFOcYiyI_a3rSjSgxq?width=640&height=480&cropmode=none)

Once through the hard case the steel was tough but gave a reasonable finish even HSS worked well:

(https://sat02pap002files.storage.live.com/y4mW1ajnqipVydM8-pTAEcq3NEMgFk0-xVkv_RaL-fZ2RU1yKLuHCHyTW_VwJBQ3hkcLepmqtfUkwI6ecpridWqGRWiZJ7nFoAF1zdRCk3gbeaRUzDP7QUnPsd4VzQDzDtynUcf4bEod5xYy_UKXenG6qO2DURx7p0vs45curU3TcWbkyYpcXs29HkwhS4HgueA?width=640&height=480&cropmode=none)

Which all got it looking like:

(https://sat02pap002files.storage.live.com/y4m5-vS7adf1R4igEveL9z2nCOLOZQZHVtc06JtXf7B-mMEiOj7KkGNXr1wexDsgHQBe5Kr2lbTrBd_IgZh6Jnqv0G8a2zNnjGTmMKiPEST3S5GwckMvch1uyfLMTQ6-xp2lr4klO-6ZdG2YJal-gxNmpSqrAp-QLqdC-HWoGaWBIE66zssFMBrf4xkHukfpa14?width=640&height=480&cropmode=none)

All this happened just before we went away for Christmas and I'd also part-machined the flywheel, just failing to to achieve the slight interference I was aiming for on the crankshaft. Interestingly, when I got back to it in January the fit was rattling - shrinkage? Or just my failing memory?? Anyway the boss that carries the flywheel was machined off and a sleeve bored then fitted with Loctite 638. You'll have to take my word for it that the central part of the shaft here is 0.001" down to give the glue somewhere to live:

(https://sat02pap002files.storage.live.com/y4mZBmsl7KASVahTe7fJ2DFFoc4BVaTBFrTzi2WbA_YwuvT_yKvo_ctevwtV_iSQUNiWyLlk-9Ty_hxsOLjsWYVXHmAmtPpi-aGwgLdloRQ3KvJTrqDVQcAS3kh9vURbtJfsmSa_684FNhMf0T1gNSrJhoc9PUPHcoMIHfVPoUoeR4ZhYrSvvbUO-UqH4WVENsr?width=640&height=480&cropmode=none)

Just how successful this will be when the keyway is cut through it remains to be seen.

Next the flywheel.

David
Title: Re: A Tandem Compound Mill Engine
Post by: crueby on February 01, 2020, 03:01:26 AM
Watching along - really like the shape of those flywheel castings.  Those chips from the shaft look like they were HOT!
 :popcorn: :popcorn: :popcorn:
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 01, 2020, 03:18:04 AM
Chris, the rule-of-thumb for carbide tooling that I picked up somewhere is that if the chips aren't blue then you aren't driving the tools hard enough. The finish was "spikey" but usable:

(https://pfktra.sn.files.1drv.com/y4mBjhRr9flNF--j8vrKUntWHxLfujeHYOlLn1Y1qip2q1iIWumwST_Zkjfi_PHDbvU_y2sordmhy9OnKaV77ax1aOMp0gN_vKJPtlMz0B3bOz85EYRRuIUbaZ_Bd_9ECW1M2sdjtxyovUKNAXyCIamIR2uFh0tXdBYariKemrImlh_Uuo4aTC0aAeP_G96Oh5-R-x8NIgQ4zLAWG8vnvkUrg?width=800&height=600&cropmode=none)

The interrupted cut over the old splines really made the chips fly, full face shield worn for that one!

David
Title: Re: A Tandem Compound Mill Engine
Post by: sco on February 01, 2020, 08:44:16 AM
Watching along quietly David.  Impressed by the colour of those chips!

Simon.
Title: Re: A Tandem Compound Mill Engine
Post by: pgp001 on February 01, 2020, 09:27:36 AM
You can add me to the number of interested builders of Southworth engines.
Mine being a Pollit & Wigzel called "Agnes" is not quite the same, but it too was originally modelled by Peter Southworth.

Phil
Title: Re: A Tandem Compound Mill Engine
Post by: Jasonb on February 01, 2020, 10:08:20 AM
I've got a set of drawings that I was given so do I count?
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 01, 2020, 11:35:06 AM
Simon, I love the colours and textures in the chips image but I'll try not to use any more material that produces such colourful swarf, hopefully everything else will come out of kinder materials like CI, FCMS, GM etc.

Phil, How I wish my Lancastrian ancestors had names like Pollitt and Wigzell! (OK I know P&W were a Yorkshire firm). Building Agnes surely counts you in.

Jason, I think anyone with a set of drawings counts, although you probably should machine at least something from them to really qualify  :stickpoke:

Seriously, for Bob's purposes when he's talking to Blackgates then the more people he can cite as "building one" or "interested" the better. In fact anyone with a workshop and a copy of any of George Watkins' books could be included.

David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 02, 2020, 01:38:07 AM
The largest bits of the Corliss are the two halves of the flywheel. The nominal finished diameter of the wheel is 250 mm so that fits on the Hercus 260, just...

Before finding out how I was going to turn the outside of the flywheel the two halves had to be joined so the mating faces were cleaned up on the mill:

(https://sat02pap002files.storage.live.com/y4mjhtOQfPJB1-ppo8RgoMXCC-arReW6pMtFoUQRBlHSnKdwKs8k21_Npo20z2UdA7klBUwjmv4SIwzMLuyG_z10XR4HExBRU1ShtBYNh2Udbf7Q1Zdgymo8cep_u3e00yBTJa0i75o07pG6O5WWS9_SEfK2jBlOV1YfDKSALh_dTsCT2eiq0U0uvj3sZD7QdAX?width=640&height=480&cropmode=none)

The castings were made so that the finished diameter should pass through the centre of spaces between barring teeth so I aimed to get these right and get both pairs of bolting flanges to an even thickness. These looked OK when I first had them finished but all was not quite right and this caused a lot of extra work.
With the bolting faces cleaned up - and the iron was very nice to machine - I printed out two copies of the bolt-hole drawing 1:1 and used these as templates for the holes. Each flywheel half was set up by clamping to angle plates and setting horizontal to drill holes for the studs:

(https://sat02pap002files.storage.live.com/y4mq80Kik7EZeYEf_iBYP_bgBAmlh2MW5KAyK34K5rhiHep0AJK9HHVCs95b1zQC7DQ37HLBE9XXUL9OlT-LezPDb3y-gzgqorv9UToMuP4q4SOUrLno1iOnNg0kalgkF4yxHtdvyawQjbob9nCNt1Ti6wFspz5k_fxBwApNGynCJ6my6faz_SOTQ4l2lu82VpI?width=640&height=480&cropmode=none)

The outer bolting flanges were filed flat and the central boss "spot-faced" sideways on in the mill:

(https://sat02pap002files.storage.live.com/y4mmdRCBvyb30GQw4yd221JqfTzcUf_Rknhm8Plhi4ZA-WXNYLF3DJoMEknvhl41c2yRxWX9HEYzgZ2AdLasJLLyj2rXkrkQinhwndf1HgCMKdgUaUNZj5H036WJpFQ0_jwTQyPE_JYjb2f-FK-vmRAdJKrDGc8sYV5LqC1LYM93KKpwOa6qMdEfjklhP4ZuKT9?width=640&height=480&cropmode=none)

When fixed together the halves of the bolting flanges and the central boss all lined up very well and close to size and I was, prematurely, very pleased with the result. With the studs made (never made 1BA nuts before!) and the flywheel assembled I centered the wheel under the drill, again relying on the bolting flanges and boss, so the rough hole could be started with a 16 mm end mill, part of the plan to ease setting up on the faceplate later:

(https://sat02pap002files.storage.live.com/y4mv9_v456biGZJmkSNRrB8gmAkNjtFtgkGoANRT9_UaeN9bKZbmRrRGEEKMTmh7vhy-6JrBACb4pgLpO_rWNQwTO75xZ4ZynMPql5Z-57MtALC0vlg0lwRrOA9cId9C83sJHGztGJyqXzlfdLDrrJBA01o4Gu7k0pRDMkJRKAe35MQ1rtKyLR1Ki-5dqgCj6Km?width=640&height=480&cropmode=none)

and mounted in the lathe with the help of a centre for support:

(https://sat02pap002files.storage.live.com/y4mWr56P8voXvbg57JYuq6-OOJofpEkVsiELIYX8ryhMZL9a130ukvDZlKgwzC0PKWXuPNFjEzrRF2CgLrkPwEBQ2hChmjrA0OFrapx2UTHnlmSGK-LSdgMTGro37xH6qCiD6bPmfrdB0DoxLmvk1aXUsJ0L2F8Qez1d0vbfUhIqg350hMU7VonRsj00JgKv7Fh?width=640&height=480&cropmode=none)

A large tipped boring bar could just be made to reach across the outside of the rim but had to be upside-down and the lathe run in reverse, hence the threaded rod washers and nuts through the headstock to prevent the faceplate unscrewing - as I thought  :-[ :

(https://sat02pap002files.storage.live.com/y4mhVZlawjtUOlS9y_xMYSHHlrhpoSjVeY7UdwXHClZi4A9dAQmbt7ImD6ZoA_-_i31Mob6a95EJw6aG0TVqt7VR4EfFe8ruCr57uW-ngbgEXhxTtgV6oHo5uIj0L5-evSz94JNnWENv7Vxi3n_C-Llrf4UPy8T07Hc5bTy5WeuXSsJV-APYVvfsxe116v4XhOy?width=640&height=480&cropmode=none)

With perfect hindsight it's clear that this could fail, I should have put the securing rod through the faceplate before mounting the casting then it could have been tightened up hard. Having it over the boss and therefore transmitting the clamping forces via the spokes meant that it couldn't be as tight as was needed and the faceplate unscrewed just a fraction. As a consequence the faces weren't mutually at right angles and this had to be corrected later when the crankshaft was finished to the correct size and used as a mandrel:

(https://sat02pap002files.storage.live.com/y4mbkIAArXh3N9e0Amb1YKcqYYMn9i_kjUk9wmFnSTPfN_dNw2iPgUgzCSTN6-M8AUTM3AGqX-winTBsiealybJcQbchyYsjwrq4AfnET4VhPcqBnP3o3ahTc_6h_VWhWf7f6rkrzD7taYJvvHsiZU6-OitNAAsziSZ6C8cbEWLbHYAgfVm5LHcYVw7ZZN5Vgso?width=640&height=480&cropmode=none)

I'll come back to correcting more errors in the next post.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Johnmcc69 on February 02, 2020, 01:52:51 AM
Excellent work David!
 I love your drawings, very nice work!
 Going to be a big engine,  Bob did a really beautiful job with the MEM corliss design. I'll have to have a look at the others.

 Looking forward to this design take shape.

 John
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 02, 2020, 06:22:48 AM
Thanks John!

All and any nice comments and encouragement are very welcome, particularly at the start of what will be a long project. I enjoy the CAD modelling and drawing almost as much as the workshop stuff.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Jasonb on February 02, 2020, 07:15:07 AM
Looking good so far, I'm interested to see how concentric the barring teeth came out.

If you find you need to have the flywheel back on the faceplate for doing the grooves then you can run the lathe the normal way by making use of your rear toolpost with an upside down tool, may need to do that if it chatters mounted on the shaft.
Title: Re: A Tandem Compound Mill Engine
Post by: jadge on February 02, 2020, 10:51:03 AM
Definitely agree that if one doesn't get blue swarf when turning and milling steel then you're not pushing hard enough. I call it the oh beep test. If a chip lands on the back of the hand and you don't think, or say, oh beep then it's not hot enough.  :)

The close up of the finish on the crankshaft looks a bit odd. The pattern is quite uniform but there is evidence of tearing of the material. You could try upping the rpm and hence surface speed. The 'ridges' due to the feedrate look rather pronounced; what was the nose radius on the tool?

Andrew
Title: Re: A Tandem Compound Mill Engine
Post by: jadge on February 02, 2020, 11:09:57 AM
The flywheel looks like it machined nicely. There's an art to producing nice to machine cast iron. The castings for my traction engines look a bit rough, but they machine beautifully.

When bolting a flywheel to a faceplate it can be helpful to align the flywheel by looking at a tool tip against the inside edge of the rim. That way the rim should run reasonably true after machining. If the boss runs eccentric so be it, and it's much less obvious. I had similar reach problems with my flywheel. But I bought a cheap left hand boring bar so I could run the lathe in the normal direction. Gneerally it's a bad idea to clamp on spokes as there's a risk of breaking them. Here's how I mounted my flywheel:

(https://listerengine.com/coppermine/albums/userpics/10022/normal_Flywheel_Setup_MEM.JPG)

The two steel bosses bolted 1 and 7 o'clock locate the flywheel and also provide the drive. The clamps on the spokes are simply to stop the flywheel from falling off the faceplate. The clamps are nipped up, but by no means tight.

Andrew
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 02, 2020, 11:46:01 AM
You blokes are getting ahead of me here, slow down please ;D

Andrew, You're right about the finish. This was from a TCMT tip with 0.4 mm tip radius, the finishing cut (hard to get a meaningful picture of this, I'll have to play with the lighting and find something to show the scale) was from a DCGT also 0.4 tip. The DCGT was run fast with a shallow cut and fine feed and, what's more, it survived pretty well. I don't mind writing off a tip or two for jobs like this crankshaft. Gary Neasby suggests that his Eccentric tools can be turned through 90* and used for a shaving cut to give a very fine finish, haven't tried this yet. Following Eccentric Engineering on Facebook is very entertaining - worth a look. The tip re mounting a flywheel on the faceplate is timely, it is going to have to go back to cut the rope grooves - see later.

Jason, you must be psychic, the barring teeth were anything but concentric and the next set of words and pictures will deal with that. Also, I just came in from the workshop where I had the flywheel on the crankshaft between centres and the chatter drove me to pack up for the night, clearly it has to go back on the faceplate before the neighbours start throwing things! Before I started the grooves I made a boring bar to take a 4 mm square HSS bit and run at the front, didn't know that you could buy LH boring bars but the HSS form tool was easy enough to grind up using the Worden.

Thanks for all the advice!

David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 02, 2020, 12:33:55 PM
Now to deal with the current crop of stuff-ups. The intention was to fit the flywheel to the crankshaft with a few microns of interference to get it to stay where it was put. The old engine erectors used wedges for this but I didn't feel like trying to emulate them, they were in a totally different class. Before Christmas I just failed to achieve this and overshot boring the flywheel and got a nice sliding fit. Christmas intervened and when I got back to it three weeks later the fit was rattling, not sure if this could really be shrinkage, maybe just a poor memory of what was?? Anyway it had to be fixed and, as described in an earlier post, I turned down the crankshaft and Loctited on a sleeve. This was turned down with a flywheel half being used as a gauge for the final fit:

(https://sat02pap002files.storage.live.com/y4mLTlsBVU_gDVgBARXgihrYQqDjM1wld69pHR5IWu7sG9Le31QsHygj63RYMLZIk4Yic6zjerkWQwKb2fLCtI6_2zgRB9nCBNziiFwMNeUD7MUlrX7Ze2X1vgJU8eozDCCVPn_WxsQOFFnzQz8fQsWEvXD2Obt8e100Whl2Bu3TiMCqdK808RP6JfxdG-jnIh6?width=640&height=480&cropmode=none)

which has worked well with the flywheel gripping nicely:

(https://sat02pap002files.storage.live.com/y4mSzzQ9XzagrPYh4MA37YGmnc8kM6bb7FLnd8o67KnMU41Y-jC5n8WeOatbfnXx7vxXQT9T2q5eIWpxt4TVKxcvp-I6dSQtukWOKqGcLZ2l9c7IH0cS5pmCRb6zVzsoXAInIidgNu4Zop29j1iHkLXZvmnDf52rflA8wOILAHEyUgssT4BlEzJ7HSnOPTooNbG?width=640&height=480&cropmode=none)

Following on from Jason's earlier query, the barring teeth definitely didn't come out concentric and in addition almost all of them were partially filled in where sand had fallen off in the mold. I'd concentrated on getting the bolting flanges lined up and to drawing size which also had the two halves of the outer surface nicely aligned as well.  If I had another set of castings to work on I might be tempted to go back and have another go at getting the barring teeth concentric - but I think I'd be able to resist the temptation! As it was the casting machined very well but the teeth were a couple of mm eccentric. I came up with two plans to fix this:

1) The elegant but very time consuming one - machine the tooth ring off, cut a new ring of teeth on a piece of plate and attach

or 2) turn the tops down to be concentric then approximate the tooth shape by milling on the rotary table.

No. 2 won, at least I can go back to 1 if the result isn't good enough.

Of course things are never that simple and I had to make an auxiliary table for the 6" RT to take the flywheel:

(https://sat02pap002files.storage.live.com/y4m9KZEAziVY8QiI5IYKfZQKBezuwHJDo_KFL6rMholH_WguHGpNF849YjFg3tCBJqJ1ZlC7Q-ZsRMpcEDnhlga8cxycpZtzEDC1dbFeSok97Gh3Z7mC7rqC-JM6so3SZgkfB5vw2Dxzwe7kQWtsvYO1ygMfYK8pzp-hoR-7Bq4bSA-o3vIz4b93fVYzZ186Zie?width=640&height=480&cropmode=none)

The flame-cut disc of 5/8" plate was another find from the hoard and drilling and tapping didn't take very long. It will surely come in handy again?

The starting point was having the centre of the flywheel under the axis of the spindle. The wheel was moved in X to bring a 3 mm cutter outside and then offset in Y by about 40 mm which brought the cutter to the position where it could generate one side of a set of straight-sided teeth. The stepper motor drive was set to give 96 divisions and one side of all the teeth cut. With a ~40 mm offset in the other Y direction the other flanks of the teeth were cut:

(https://sat02pap002files.storage.live.com/y4mkDFkbrWTqL0XYY3mr87jdvvwA8qxnlPjadve0bMrowF5D2BDfLdjzTCaNo9t2kPC0EfZ6EvOauUmf0jmNRbdtwA7iWHFPf9Q0pYOe17kIlBAX00mYHLFPZZi7CVxTMKzM0I4XF-95SME0t7CM3E43fNNgDjZyCpaMgZiiRfK3dlVy71CIDI1ddjQIhSGFWBr?width=640&height=480&cropmode=none)

The teeth definitely aren't the specified "10 DP" shape but at least they are near to uniform and they look a lot better. If I ever get really inspired a new ring can be made to drawing and fitted, right now I can't see this happening!

Now I have to cut the rope grooves without driving everyone nuts with the chatter.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on February 02, 2020, 01:19:38 PM
Hi David,

When I did my flywheel you may recall that originally it was for the Twin Tandem. The OD and grooves were the only machining I coudn't do at home so were done at work on a Colchester student on a mandrel. I gashed the grooves first before going in with a form tool for the final profile - that may help some. I spaced the grooves using a 'slip' and moving the dead stop up to the carriage after each groove.
Don't know if that will help curb the chatter for you a bit - it does make a bit of noise doesn't it - just think about the guys doing the fullsize - Throp in his book describes this process as going on for two weeks or so  :o - imagine the noise that had to be tolerated by all those around - no noise regulations in those days for sure!

Comiserations on the barring teeth - I did have better success in getting them to be uniform but as with yours some of the tooth form leaves a mite to be desired.

Good to see your progress and the excellent coverage of your pics

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: MJM460 on February 03, 2020, 09:39:54 AM
Hi David, you are off and running on those new castings.  The flywheel is looking good.  It will be an impressive looking engine.  Following along, even if I don’t have a copy of the drawings.

So long as the appearance is good those gear teeth should be fine.  The speed barring gear works at and the usual duration should mean the tooth form is not very critical.  Better to have them running true. 

I have been a bit slow to jump in, but my lathe has 12 inch swing and D-4 chuck attachment.  If you need access to the larger lathe to complete the flywheel, please give me a call.  I believe you have my number.

MJM460





Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 03, 2020, 11:36:09 AM
Thanks Tug and MJM!

Tug - after your message I ground up a 1 mm wide grooving tool in HSS and used it to gash the rope grooves. This is a great improvement with almost no chatter and that only at full depth when the form tool is cutting all round:

(https://sat02pap002files.storage.live.com/y4mTX0vBUSr7kYhF1Z9cxz2dohe4sHv2nLl6u1IN7ieLqxzV__5WqQeA7tD5SnBoL-rFVyvjluIMg_A84heP8u91y_asAZKDdIo8q4FVRpRPYGC0IQ_uAHVQ4FX5K6RME37iEVBsfNP2BgauEEM3Dq5Zuh1iHEKubkobffIjTvCTbu9EmgkbU0SotAuCrcXxlDU?width=640&height=480&cropmode=none)

Only another 11 grooves to go, maybe an hour's work, not another week or two. In the picture you can also just see the scrap of 1/8" gauge plate, used as a spacer, sitting on top of the carriage stop. The flywheel was centered on a piece of rod in the tail stock chuck and I left that there for location to reduce the need to over tighten the clamps. Interestingly, one half of the flywheel cuts very nicely whilst the other is harder and is where the chatter happens ( we are well under any skin here I would hope!).

MJM - many thanks for the generous offer! I may be out of the woods now with this one but there could be others! I'll call anyway.

I'm not actually sure why Arnold T specified "10 DP" for the teeth when he then drew the engine to use a manual barring lever. It isn't supposed to need a barring engine but AT may have had it in mind to design one as an alternative. Apparently the lack of a barring engine "encouraged" the driver to be careful where he stopped the engine, if this wasn't right and the engine wouldn't start under steam then he had to get out the lever and turn it by hand. AT shows several pictures of machining Corliss engine castings in his little book "Vertical Milling in the Home Workshop"(MAP, 1977) and Figs 38 & 39 show him making the ring of teeth to go on the pattern. "This is a gunmetal gear needed as part of a metal pattern {my emphasis} from which the flywheel of Fig. 18 was made" - p54.

As to the noise of machining, Tug, this should be compared with the noise level of a weaving shed where even a shouted conversation was impossible. My Mother had a story from pre-war Burnley where she'd seen weavers holding a conversation by lip reading - one on a passing tram and one on the footpath. Apparently this was the only way to communicate in the shed.

Thanks again guys!

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on February 03, 2020, 01:00:10 PM
Hello David, glad to hear that was of help, looks like you are well on the way now :ThumbsUp:

I just had another read of Throp's book 'The Last Days of Mill Engine Building' where he decribes this process in full size...

The wheel was buit up on a short shaft spanning a deep pit set on plummer blocks. This could take up to a 32 foot diameter flywheel  :o With it's centre line two feet above the pit the pit itself must have been very deep indeed (he doesn't say exactly) but he does say it had to be deep enough to contain the many tons (sic) of swarf generated as once turning began it had to be finished. A cross slide was set across the face that had two saddles on that were driven by a pinion meshing in the barring teeth. This was driven by line shafting through a worm gear. He makes the comment that the teeth had to be there for this turning operation whether for a barring engine or not in final application - interesting, hadn't realised that before.

He goes on to say that it took two turners, day and night, on twelve hour shifts with a large wheel taking over three minutes for one revolution - the teeth being preformed with a 'stepped tool' followed by a form tool manually operated - no carbides in those days, possibly not even HSS so lots of work for the tool makers I guess!.

It also took two men several days to dig out the swarf ready for the next wheel - that must have been a very unpleasant task, probably just a bit of rag over their mouths for protection.


The stories of the noise that factories produced and long term deafness of workers as a consequence has been well documented and recognised here.
When I began work at a company called Utilux in 1984 (an Aussie company actually) here in the UK they had three twenty ton presses without any form of sound protection and one fourteen ton press with a 'home made' booth running multi stage progression tools. The noise when all were working at the same time was unimaginable and extremely invasive - at it's worst it would run right through your body - despite ear defenders you simply couldn't get away from it. Fortunately Health and Safety finally ensured sound booths being installed and life was much better after that. Well I stayed there for fourteen years till made redundant!

Good luck with the rest of those grooves.

Tug
Title: Re: A Tandem Compound Mill Engine
Post by: pgp001 on February 03, 2020, 10:35:54 PM
I used a similar setup for grooving the 12" diameter flywheel on Agnes, I found that a couple of chunks of lead sat on the boring bar reduced the harmonic vibration and noise quite a bit.

(https://listerengine.com/coppermine/albums/userpics/10026/Flywheel_196_05-04-16.jpg)

I was running at approx 9 rpm for this and using a home made tool with the correct scale rope groove profile, that is not a plain vee groove but one with a radiused root and parallel sides for the outer half.

(https://listerengine.com/coppermine/albums/userpics/10026/Flywheel_197_05-04-16.jpg)

After a bit of a clean up it looked OK. I was glad to get that bit over with though.

(https://listerengine.com/coppermine/albums/userpics/10026/Flywheel_202_07-04-16.jpg)

Phil
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 05, 2020, 10:17:35 AM
My "shop elf" (4 y o grandson) was here last night for his first sleep-over with Grandma and Grandpa so I was late getting into the workshop. If a machine doesn't start I now know not to panic, just check the e-stop, he loves pressing them but never gives them a flick to release. One of these years I hope I can start teaching him, then he'll learn what those buttons do when a machine is running...

Tug, I didn't know of Throp's book 'The Last Days of Mill Engine Building' and there's a copy on order now - thanks! With the barring teeth being needed for driving the pulley for final machining then the 10 DP form make sense for a model. I've used a lot of Utilux connectors, 1/4" push-ons in particular over the years, didn't know they had a UK factory.

Phil, that flywheel for "Agnes" is a magnificent piece of work I really hope to see that model finished sometime, please! I didn't have lead hammer heads on the boring bar but if you look closely you can see the sheet of roofing lead wrapped around the bar with Blutak under it. With this precaution and the wheel on the faceplate the chatter went away.

After gashing the grooves on the Corliss flywheel took just over 4 minutes each to turn with the form tool, I almost managed a shadow picture of the tools:

(https://sat02pap002files.storage.live.com/y4meDGtIfzKhm5KZWoAoc3xzPOAiFWR1PkE7AkPKD8ZY_lEr3il_GsOsbhRtvzJj8DriytxA4T06AE-nUx8RRsQpBF83VmlHbuW5K7KNVRFoxpclh5g7l1OjR0OaoYvSxybAipvsUpOOmaYSUlbKYL6shKgzjaZaOw8LrehIPLIfMmVftTg8IHYyUA-sg19zCKT?width=640&height=480&cropmode=none)

The bump on the left side of the gashing tool is shadow, the tool was ~ 1 mm  wide and parallel sided. The drawings show a groove with a 40* included angle which seems to be a later "Improved English" form shown in figures from Fletcher "Rope Driving: a Treatise on the transmission of power by means of fibrous ropes", Wiley, NY 1900:

(https://sat02pap002files.storage.live.com/y4mxjGxjcLH14Xncaf8QGqz_wloEk0uYv2zsdid6miTwpRyYEsHA6OR8BuLwoj4HV3Cj65KeN3GMcDGD7DzEi6n_pqp86woMaW7O0xP5Aju7B3bWS0LHzT6vdgqbSzM3cH0RbEiP4w3kFqVWptYRWcPlUUZbpXb9tUkJvToaSTgL83SKZh5CEfryuvbCZjqmeXj?width=673&height=854&cropmode=none)

although the included angle there is 45* rather then 40. I guess that the section Phil is using is something like Fig 67?

After a lot of work and a major sigh of relief the flywheel looks like:

(https://sat02pap002files.storage.live.com/y4mKvSz3Mf-pYPBNM27U-lpJz3DUnf7OVk5YtV-wlat0cUvb6QjRiGKhYVGTHAP0TNLniTKCil6uwpUJSbZDmfs8ZH2glJN90D3DFSu--pURbKmKCkrARSG_9rlGMxn14tqVIK_MF_QebgOWew3lCI2vdBQidSE_XoQprBf_1-FjAt1dHvHV83q6qffOi42VsEn?width=640&height=480&cropmode=none)

so I can move on knowing that all the other bits are well within the capacity of my machines.

David

Title: Re: A Tandem Compound Mill Engine
Post by: cnr6400 on February 05, 2020, 12:19:29 PM
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
Title: Re: A Tandem Compound Mill Engine
Post by: scc on February 05, 2020, 10:49:17 PM
David,  You are making excellent progress.  I have a soft spot for mill engines, especially the big ones like this.  They were not well received at first..........our house, built in 1842 is situated opposite a row of handloom weavers houses, builtin 1802.  Soon after many big mills were built nearby, putting the hand men out of work.  Riots followed with many engines being damaged. In 1842 Chartists gangs dropped the boiler plugs at Farington Mill, about 2 miles up the road and all work stopped. As this was the biggest mill in the area there was much disruption. I often wonder if folk involved in the construction of my house were involved.  Anyway there are now several preserved engines in Lancashire to enjoy.
Apologies for the digression.....your build is great :ThumbsUp:            Terry
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 07, 2020, 12:32:27 AM
Terry, I think digressions a great! When we are building models of older engines there is always an historical context that I think is worth knowing. Part of the motivation for modelling old things is to preserve them and keep their history a little bit alive. From where you live it's a bit easier to tour the preserved engines, they are a bit further away from here  :(

David
Title: Re: A Tandem Compound Mill Engine
Post by: john mills on February 07, 2020, 11:25:09 AM
Hi David
you have done a great job on your fly wheel using your machines the hercus lathe looks like it must be one of the latter models mine is the 9".
I to are not keen on lead on skinny litte boring bars  i have usually used a much bigger bit of steel mild steel is as good as any thing .have used bars with a piece welded on the side that will fit in the tool holder 1 1/2 or 2" dia
will do wonders .
it is interesting to know what happened running the full size engines we don't know what regular jobs needed doing to keep them running or if they run with little problems.

  john
Title: Re: A Tandem Compound Mill Engine
Post by: Mcgyver on February 07, 2020, 08:07:31 PM
thats a great looking engine - thanks for posting the build..will be watching!
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 08, 2020, 02:59:14 AM
Thanks Mcgyver - I hope I can keep going and any encouragement is welcome and helpful!

John M, The lathe is a Hercus 260 from 1983. The bed and saddle are the same as the 9" machines but the headstock is new and has roller bearings. The tailstock and top slide look like Hercus just stuck blocks onto the old patterns to raise the centre height.

The books by George Watkins give a bit of information about the running of the engines and the very rare occasions when something broke. All the main bearings have adjustments for wear but with  speeds in the range 60 to 90 RPM wear was small. Some of these engines ran for many decades without failure. The mills ran 50 weeks in the year so any maintenance had to be well planned.

David
Title: Re: A Tandem Compound Mill Engine
Post by: john mills on February 08, 2020, 06:43:45 AM
HI David
my lathe was from the early 70's 72 and i did get tapered roller head stock bearings.

          John
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 11, 2020, 01:02:28 AM
The crankshaft needs keyways for the flywheel, governor pulley and the eccentrics although I'm still doubtful about the eccentrics. Those could be made in two pieces as drawn and located with a key or made in one piece and secured with hidden grub screws. Right now the 3D printer is making the two part versions in PLA so I have something to handle and work out how to get the studs and nuts in (or that it isn't possible). Tug has discussed this in his build and went for the solid version. The other reason for using grub screws is valve timing, if the keyway angles aren't right then you're stuck, I may well start with solid, get the timing right, then cut the keyways but all that is in the future.

The crankshaft was set up in v-blocks and brought true to the x-axis of the mill:

(https://sat02pap002files.storage.live.com/y4mApPYUiZcf82Uw1C8Ut9x8WP1CN7FV72koaCguLG0VZjgB-vgc7VELnF32Py1Pm9Y-mr4ZM5bXQvJFGY-fAtkHpoyfEOxi9h0svr8uEAPCKsXdDtVwDZxbuvOf1w4Xpu3YRMMmWZv9DusA9iNxAuoNHgTWCCnTd6AnkTq2CnJW_uJfkLEgLd0PKHFOYQBBtHe?width=640&height=480&cropmode=none)

Then the flywheel keyway cut:

(https://sat02pap002files.storage.live.com/y4mfADVnU-fV_8kyOoetNgPTC50-J83q-6HH7IwBeJUcuspOFSnpg5cOJuQORE22V9NERFzzbIJx5oFebBsrcSL6ZyUph9dOJJSU4u-5dlBjte5SowcTd4saMn4lgewElLU6CLix95nrUB3SsQHmE6Chw4ql14WOBlzfiM7mJCbyCELAJbioyYFUxfUmjSDeOi4?width=640&height=480&cropmode=none)

followed by that for the governor pulley ( angular position doesn't matter here so it might as well be done with this set up):

(https://sat02pap002files.storage.live.com/y4mMWX7aAzsbYmtGZy_H9Xh0OOGd4WkjFLoXeMQUAWdDWZxsGiz7fyQZA6EYv6SLwS5t5yB0iQE_xNS_LxJ7oS4vJCR0Xx35tYkBdFzIatYIgI355GoLotRkaT6AG_Og1jgM5HEwtKGbtwdMnfqzxlanjSYFxObKTFo4UISe0WfilwT2plN7tsK3-l6cRjtu3Ds?width=640&height=480&cropmode=none)

When I bought the Aciera mill it came with a lot of attachments and among these was a slotting head. At first I thought this was seized but on stripping it down it was just clogged solid with ancient grease. The complete lack of wear makes me think it has never been used and I have been waiting for a good reason to use it - the keyway in the flywheel was perfect for this:

(https://sat02pap002files.storage.live.com/y4m5APCh7Qjxt4719nES6xjiprYMGyF6y1pvJakbTsYkggxRlL0lfhA0vHjwzgNojrMb0xAXdYzTgjucZ-cbGNAlVobc49EOK3ulHcK3dOXFkg_ohQdBZgBBewG9XiWYnneQo2LpyiGmjWNxQP0BZfqSz9PWUsXNj0cZW2W-RUDdRcivU4QoQnU9DUyGU3O0xqO?width=640&height=480&cropmode=none)

The angle plate not only prevented lateral movement it was also a reference for a square that I used to align the flywheel split line with the machine axis. The simple, square-ended form tool cut well:

(https://sat02pap002files.storage.live.com/y4mHmz0pe1pr8RTbYH4tx9Q88xPLNKPxxAT-6TyuT9q7BUZsa6JamUaEsMVcSK-1TeE7-sga5EzX4B8BB8aHzi6fnf0tTjt4pm1MKrsz3OehFNw3ZWcFXQxxIHmi8g87aCTal2QrU3GDLar0YvvPQ1-wd9mOpnEHWhAxg3HchZXODUGsiBj360nwpPsAXnsGdw0?width=640&height=480&cropmode=none)

although I was probably over cautious with the feed. A little bit of fitting with a needle file was needed to get the key to go in but it all seems nice and firm now.

The family now looks like:

(https://sat02pap002files.storage.live.com/y4mKvSz3Mf-pYPBNM27U-lpJz3DUnf7OVk5YtV-wlat0cUvb6QjRiGKhYVGTHAP0TNLniTKCil6uwpUJSbZDmfs8ZH2glJN90D3DFSu--pURbKmKCkrARSG_9rlGMxn14tqVIK_MF_QebgOWew3lCI2vdBQidSE_XoQprBf_1-FjAt1dHvHV83q6qffOi42VsEn?width=640&height=480&cropmode=none)

In a couple of hours I should be able to play with the plastic eccentrics...

David
Title: Re: A Tandem Compound Mill Engine
Post by: Johnmcc69 on February 11, 2020, 02:04:18 AM
 :ThumbsUp:
 :popcorn:
Excellent work!
...wishing I had a Aciera...

 John
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 11, 2020, 03:09:20 AM
Thanks John,
What I bid for the F3 felt like a lot of money at the time but it doesn't seem that way now! A Schaublin lathe that takes W20 collets would be great but they are very very rare here Downunder.

David
Title: Re: A Tandem Compound Mill Engine
Post by: crueby on February 11, 2020, 05:04:38 AM
That flywheel assembly is a beauty!
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 11, 2020, 05:20:39 AM
Thanks Chris, just wish I could get somewhere near your levels of productivity!

As yet (tempting fate here) I don't have too many problems with shop elves, apart from the e-stop pusher, and I'm glad of that - just imagine your lot turning it into an elf unicycle and riding around the shop at 3am...
David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on February 11, 2020, 10:40:05 AM
Hi David,

Lovely result on the flywheel and shaft  :ThumbsUp: - you do have me inspired BTW got all the drawings out yesterday  ;)

I know it's looking ahead a bit for you but on my drawings there was a small annotation by Peter Southworth defining the angular positioning of the eccentrics. Do you have that on yours?

I decided I would stick with this and have marked the shaft accordingly (and the C/L of the eccentrics) to ensure this is as close to his recommendation as possible. My thinking was that even if this is out slightly there is enough variation in the linkage make up to make allowance for any discrepancy. Though mine aren't keyed I have the grub screws biting into deep centres for positive location. Unless Peter's anotation is out I'm fairly confident I won't have to remove the straps to adjust the eccentrics.

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 11, 2020, 12:15:27 PM
Hi Tug,
Thanks! Well, it would be great to see your build make progress again. Maybe we can restart, or even start, one or two others?

I know there's no need to look at fixing the eccentrics anytime soon but I do like to get each part finished in its turn, OK I try to ignore the OCD but that isn't always possible  :)

The drawings that Bob P sent me also have the extra sketches that help with the angular positions of the eccentrics but I still had a hell of a time interpreting them. Please take a look at the attached drawing and let me know if you think the keyway positions are correct. Just looked again myself and see I need to add an arrow for direction of rotation and a note to confirm that the crankshaft sections are viewed from the crank end. If Arnold T drew all this up and got it right then he was something special!

I've just been cleaning up the 3D prints of the two-part eccentrics, I'll play with these soon to work out if I want to make the real ones that way or follow you with solid and accept the possibility that the crank might have to come off sometime in the future.

Regards, David
Title: Re: A Tandem Compound Mill Engine
Post by: Jasonb on February 11, 2020, 04:59:57 PM
I wonder whether those angles are optimised for running on steam, if you are going to be running on air it may be worth going for something with a bit more adjustment.

Don't let Tug get distracted I'm waiting for him to get on with his "Twin Shaft"  ;)
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on February 11, 2020, 05:45:38 PM
Hello again David,

I gave quite a bit of thought as to whether to make the eccentrics more scale like and from two parts as they ideally should be. Came down in favour of impression rather than realism mainly due to the time I wanted to give to them. Also, in the way mine were made (from the drawing) there was little space to get a functioning nut in without a lot of secondary machining of the cut out and subsequent thinning (and likely potential for distortion) of the outer wall thickness.

I still feel comfortable with that decision but would encourage you to go the two part route if desired as it will certainly look much better.

Your angles match mine for the Corliss and exhaust but I do not have any indication for the slide valve ? Wonder why?

Ne'er fear Jason - Twin Shaft and Corliss intentions are 'on the bench' together - hopefully get a start on them by the end of the month :) possibly sooner  :) :)

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 11, 2020, 09:38:11 PM
Jason's point about running on air vs steam hadn't occurred to me - I doubt I'll be building a boiler big enough to run this engine on steam.

With that point, and Tug's experience, in mind the solid eccentrics with grub screws look like the way to go. Maybe a two stage process, solid first, then when the timing is optimised re-make with keys? I'll have to think about how best to secure the crank, maybe a taper pin left over long until the final fix?

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on February 12, 2020, 09:37:07 AM
Apart from the engine in the Wide a Wake and my first, a Stuart Twin Victoria, I've made the slide valves in other engines (destined to run on air only) with no lap, the length equalling the port spacing. Whether this gives any great advantage I'm not sure but the engines do run better - that is smoother - at slow speeds.  How this will translate to Corliss valves I'm not sure - it's been a bit too far ahead to really contemplate.

I've taken the angular location of the eccentrics as drawn at face value and fixed them as such. Thoughts so far are that any adjustment can be made either in the linkage or on the valve lever itself. My plan is to replace the square drive to the valve with a tapered seating so allowing variation - certainly on set up - possibly fixing with a drop of Loctite if required once settings are established. Thinking of course is only part of the equation  ::)

You have the nub David - once that crank is fixed those eccentrics are there to stay - well mine are for sure ;)

Best - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: gbritnell on February 12, 2020, 03:01:07 PM
What a gorgeous flywheel!
gbritnell
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 18, 2020, 06:07:52 AM
Thanks George - I'm pleased with it as well!

Still working on bits associated with the crankshaft, and before thinking any more about how to make the eccentrics, I made the governor pulley. This is a straight forward piece that started as a rather rough gunmetal casting. This had a cast-in line marking the diameter and I cut along this with a slitting saw:

(https://sat02pap002files.storage.live.com/y4moDSZ1jiGPbsahzTbm4DxOcEdGZL9seQSa_Yv7rzb3j5ihuZpEAwKvxA7ccZnJWvgIZ_hQ4zzaDATrlUr1Kq6s62bytF2uOsP5IvGwrIzF4K7nCp1HFbZSU3m10056zUTPcSz5Qa_CRly2vareM1Xg3mQqL76Edc4PB9LWVghW3YYllcjc2iLBOOUX6678h-m?width=640&height=480&cropmode=none)

Note the very carefully judged sliver of metal being left behind by the saw, this kept the top piece in place so it didn't fly off when the cut finished. Next time I do a job like this I'll know to set it up like this deliberately  :D .

The two halves were soft soldered back together. In this picture you can just see that I should have marked this out for myself and not relied on the cast in line:

(https://sat02pap002files.storage.live.com/y4mKbLgqIDoigQ9lAydoQm3t_7LfafK3cxVCzL8Sm7VMvWQjGRXNuqr5PuwfXR2S7j_1A_xzlOHKy0qDeCv_7AtwB-iJEDakj4wZ6u93IpDz3lKgo76a67lD-AsvisUjZXlnMyN0LjThomJWVDGlY1BSPD7CmZPug7r-HiyJXSbOsIQBQCWfMv-qjyflMfeT3cC?width=640&height=480&cropmode=none)

Set up in the 4-jaw the bore was finished to size and one face cleaned up:

(https://sat02pap002files.storage.live.com/y4mpbUUWxsz_l5zzmMGEyWce5kW7BgzWVuopeOYCLEislYKn-aqzyI9nQRsZ_PMIaqUF9zenGI3MP3WNQ7Ky_d0dYPLAB5uEg63Wjbbf37yCRMaIp-EQvHSEV7N8L_xoYxU_UgGjJNOz_-DCGJVUwsF0HFTcEXQFsU9mX61ZCyUH2H_bmsxkKAG5QIDP0UKPkZ1?width=640&height=480&cropmode=none)

This was then superglued to a mandrel turned in place on the 4-jaw SC chuck and the outside and other face finished:

(https://sat02pap002files.storage.live.com/y4mRg2Yx9BKWjw33ZTkRrYBwLEI4gKJpg-vY5DxG7ZiWk2GacN7nibKuq3SkFoSGaGE_Is_qMP78xLKwV2lLhhNxLM197bQKn3NAOygUGYDFCAS_Phtoq-tB7XGi1DWEdtBwR9E94ddmFpUeUqDQ3bjjStfpPfwzwsYcPTR-3YEkSB4U649sOEmxtFZyKQ2HOFj?width=640&height=480&cropmode=none)

The mandrel moved to the rotary table and a drawing made with the set of angles and offsets needed for machining the four cutouts:

(https://sat02pap002files.storage.live.com/y4m4xZTVvO7fZgIPWeBhEBi7Q6O6gv2KYyWNX61FQAlFIelOXOdz7HgJE_4ejV5kVuXr6xoGCPRaQQJJzhGGR80_h7fBnlg_q-dA7hdJ-TC0Kwajvg0Q4UqCAb6qNnveUeyhp5Z0jlkdEIbMjE0Qh1vMr9BBRt6xpKmo680dtKXTfqBH_Ob0pStOSkEHylPqoub?width=640&height=480&cropmode=none)

After heating the mandrel to both break the superglue bond and de-solder the joint two 7BA studs were made up using 2.4 mm stainless TIG welding rod and the whole lot fitted together:

(https://sat02pap002files.storage.live.com/y4mDxIYOssP6bZ-4sd5SwR2H0QLYhYStQDkntXKBxgdcU_d4JjqB3P781slBFt3UPF3Ne6Vh_guIjfNGsiFGAcRf7O5njFeWbD3aKSiFX0ctSCGcIbZfoZFdmv4xpzu-TtnAjDOrf1xoWyzlkQvCNzQ6QMwTfq0swUXYfWhREm__3tsw_SngpYzVkFGAyZkV8Mt?width=640&height=480&cropmode=none)

The slightly rough patches are the consequence of not quite getting the original split line across a diameter as there is very little metal to spare on this casting. As the part will eventually be painted the rough bits can be cleaned up later.

Now I have no more excuses for not getting on and working out how I'm going to make the eccentrics.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Flyboy Jim on February 18, 2020, 01:56:59 PM
Nice writeup on the machining process for this part.

I like those clamps on your rotary table.

Jim
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 19, 2020, 03:35:24 AM
Thanks Jim, I made five of the clamps to a design in either Model Engineer or Model Engineers Workshop, I've tried to track down the reference but so far it's eluded me. Hopefully someone else on the forum will recognise them.

A few days ago I 3D printed samples of the eccentrics for the tandem compound so I had some bits to handle whilst I made a decision about making them split (as drawn) or solid. In the picture the slide valve eccentric is on the right, Corliss valve eccentric (there will be two of these) on the left:

(https://tj4rog.sn.files.1drv.com/y4mfQahYcFSmskiVlMS8ns9VkL6a41cjpHVYcgkGi8w7PC5JRA7uIP500kZLlwuKDaOeEQ7IcTdb6H1YS5p2n6tIZXvsIg8LjN1NGON3qHSjJKW4UsuZVJ3h-3IZ_z4U_wA2phDWYb5qDRlnFQ78GusyASwlDgmfbh_VZNx_aGO14ITUs_7RhoFS4nOzjWYaPYhBhfExbzzCYMJkWQkRtYJFQ?width=800&height=600&cropmode=none)

The studs are 7BA and on the slide valve eccentric it is possible to fit standard 7BA nuts using tweezers and needle-nose pliers but it's awkward and getting a spanner on the nuts to tighten them properly just about impossible. The one nut I got on for the Corliss eccentric is an 8BA thin nut tapped out to 7. Getting it in there was tedious and tightening it impossible. I'd really like to hear from anyone whose has made the parts to the original drawings but, for me solid eccentrics will be the way to go. Tug has pointed out that even with everything fixed it will be possible to adjust the valve events so I'll get on and cut the keyways in the crankshaft and make the crank. Making the eccentrics will keep until I've made the straps, it will be easier to turn the eccentrics using the straps as gauges; the other way around isn't really possible.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on February 21, 2020, 04:56:59 PM
Nice work on that governor pulley David :ThumbsUp:

It was the likely hood of not being able to tighten the nuts inside the eccentric cut-out that was the real deciding factor for making them one piece. As someone pointed out on mine after fitting dummy bolts, once in situ they can hardly be seen anyway  ::)

Plus one on doing the straps first too :)

Regards - Tug


Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on March 09, 2020, 11:03:50 AM
Thanks Tug, it's good to have you following along.

This reply has taken longer than I'd expected, a week away in South Australia and a mini CNC machine project have got in the way. I'm back in the workshop now but with two projects on the go together. On the mill engine front the crank and crank pin were the next bits. The crank starting out as the end of a bit of flat steel bar that came in the kit for the Wyvern (think it was intended to become the con rod but I fabricated that instead of carving from the solid):

(https://sat02pap002files.storage.live.com/y4m7PQLWeqghtOyXy7sEk_Xt9JL9LwpV3IslGY00c4Y_OswMCFF-LOg51F5SNCfLcf7S3rUXW0-_TEp6diyphNwDMBtzEjd6_oaD_b2go9TlNhUuyXPanmLJi7sn88U_l2wR63IyVTOlGqTOc5VcaGRhIWkYyC3RdeaOmCo07IpafnuniuVkQb_P-95BU9YgexL?width=640&height=480&cropmode=none)

After the holes were drilled and reamed the blank was roughed out using the bandsaw:

(https://sat02pap002files.storage.live.com/y4mKh4PxA_e8PJxvhtg3r5jd6ZuUdZnpRhgQVDEZqzeu42oyyNeeuyQnRiQFKWUiFDemqHdXAUwBFtd7QT_baTJAddgIbnfCrGEa7zj9NJburRfWwiejHeXO7HTCORhQPs7tBGMYJX9G8wcXeKh73SPeem7YBRQZOlZVChMILaWklHdr1Kqy1rBMk8EswKWUWJb?width=640&height=480&cropmode=none)
(https://sat02pap002files.storage.live.com/y4mppTw3sLSZHvZGXvIyTw0_fWu-O2jiQcmUWuLq5s6c0zNLmgX6LK_l745Qt1eh8tReIQ3LRc5Zf-XY3slBGyvhU-HCMRJ9LMS3n6OA0MJhk9hOsP2x1ITnKeg8_Yf3_XuAW-s0JzamSeTdgK1pV1LbFI9Ca7aLEVOQgd1uDZKJL2YrEjCkuAHlSwry-nY_mIJ?width=640&height=480&cropmode=none)

A bit of tool making followed to make a centering pin to locate the part on the rotary table and to drill and thread a hole in the RT adaptor plate for a clamp screw:

(https://sat02pap002files.storage.live.com/y4mNsx0QCFP_Fx55DbnCYf1DaLxOwj7TL-HKSAX77mL6mbXpGlrKZbf0556A5Ej_X3F6Kn_d-2qKCRKlDcwEQpbzHUYWGowSGCIg94_P9VJ16ig7aD4ICMgxUXY5OZHExPwY-ZnxCoRFpzMt2CAqL_X8UZmOb84RJ5giEJHrs1bRx9enIf47Dd83GPW8x6yP4PI?width=640&height=480&cropmode=none)

the stepper motor drive for the RT handled the rounding of the ends and I'm pleased with the finish from a 10 mm carbide end mill:

(https://sat02pap002files.storage.live.com/y4mhZq45Bgkd-1CdQtX1e22PdaF35WuLNAsfn_QSoR2NHe315BtSBEIHHQWgSWk-M_5Q3avBZrW4KPgNMwodFqKnXzUe0nPIDR-eYSFSfUbIhKJI59T5IcYrMmUWbkIJqj37Ie1k85xMvry92ebEf-Pb3lVqrHg6uqeHsufhLQePbwx_7k0el_LO0shstIGZMDu?width=640&height=480&cropmode=none)

The same tool cleaned up the flat sides as well:

(https://sat02pap002files.storage.live.com/y4m3Wx0Cc94d4B_8WnYppj_XaPw48tWcsa11tnaX_5haEe_hTPl66GP9HqDFbFlRJzorYd9X-Q3Pb3f71sq91K_AdBQSNuM1f7WdFb4z0FbBSGveIpj1HtLRCDvtrNjJrTEiR6NitCNv396lU0fVFylotkUtLVOj3X43bgiQYd-I4OoJiokBxeld8cV1lh7dePb?width=640&height=480&cropmode=none)

The pin was turned on the end of a scrap shaft from a washing machine gearbox, which I hope will be a steel with good wear properties, and then the oil holes drilled:

(https://sat02pap002files.storage.live.com/y4m3yFG0CKb4U2za4Oi5pmkyPUl-G40Zpkr_FnRLfHzVVd4etvgsRvaqMmUHscUF5DVUHu0H1--h_nBFZAdzYauD36lsk_D3kQnP15VXaZUZjBiKWL-MqpExiPcxYXhGLrxRvBmrP1RUVTK_Gfm22fQEF1l7Tj4XxIbfG-54RIe7wDdlEFS-KWVFYyDDGrpBLXb?width=640&height=480&cropmode=none)
(https://sat02pap002files.storage.live.com/y4mO5hd358H4szQdD2_yVa_2TmjABvxp_hM-3LoDFdMWTUEFVR_fJXltehVdeV2AciyQqghYc-F8AQ2ZVLpNXelYCDQnCGWpbChfPrA8BYW4f7Ec_FdwqsizrwbC0fEslSWbYlj68F8Qri1_gZ9THmaVEC0qfJUeDgBHrXpUhiYoM51RDYr2NI0Zxj8fLeyP-dV?width=640&height=480&cropmode=none)

The two bits won't be fixed together for a long time yet but this is what they'll look like:

(https://sat02pap002files.storage.live.com/y4mGLkEXTxet7gEohlVAoZPuAhJnDUI3GGMgzBlBs3EbYGKEFnEjJPAXR6I0T6SzuROajt7b7LwUynF7yTnvkNwzzSnvM4kMyOKxGx7rTa8p0bj28lD8n7tCZUS-Erd5mN-1bxCHtxr0xeKQ7vohuzIkRysEOJd9gOV-Z9EL-A4Wn1dvZy8-VWyNsqYynXZTgpe?width=640&height=480&cropmode=none)

The two 8BA threaded holes are for fixing the bit that catches oil from the lubricator.

I feel the need to get the flywheel and crankshaft bits spinning so the main bearings and supporting cast iron will be next.

David
Title: Re: A Tandem Compound Mill Engine
Post by: J.L. on March 27, 2020, 08:23:57 PM
Beautiful photography as well as superb machining.  :ThumbsUp:
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on March 27, 2020, 11:18:25 PM
Thanks John, it's good to hear from you again.

Right now I'm trying to finish off another project that has been occupying desk and bench space for too long, I'll get back to the Compound "real soon now". The other project is a miniature CNC mill based on a scrapped microscope; this provided cross-roller linear rails for the XYZ guides and a stiff frame. Adding steppers and lead screws etc didn't look too hard but it would probably have been quicker to start over, ah well...

David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on May 02, 2020, 01:25:24 PM
The project that was holding up work on the tandem compound is showing promise of working and I'm getting back to machining. The pile of bits that might turn into a mini (micro?) CNC machine was clogging the desk and I either had to try to make something of them or chuck them out, which wasn't really an option. It's taken about six weeks to get the three axes working under the control of bCNC on an old laptop and GRBL in an Arduino Mega interpreting the G-Codes. The Dremel I tried out as a spindle proved to be useless and a real 500W spindle is currently tangled somewhere in the bowels of a very disrupted postal system. The little Frankenmachine looks like:

(https://sat02pap002files.storage.live.com/y4mVettaGen9NTmWYslJOQ7qcNK43rYEqqhZ6-NCmNPb02tLjnfr54OIhgCw6P9tzlJR7t0Ao6Pceorg6AawldqgaJLyFy3NhTXpw4TNks20RBdzZkhmcTcRUVXEiTsQEDdTU2HSpcQNT1ZWpUAwixo7a0WOBElrmDWjxp9GX6X9d9_2seyU3_bw9SwkWXv9Fxk?width=640&height=480&cropmode=none)

It may turn out to be useful but even if not I now think I understand the basics of CNC.

The flywheel and crankshaft for mill engine are sitting on the bench and I really want to see them spinning so some bearings and bed plates are needed. The bearings started as bits of some bronze flask clamps that came from my late father-in-law's dental practice. Careful marking out will allow the threaded holes to end up being machined away:

(https://sat02pap002files.storage.live.com/y4mIm3EOFBDe6B-MS8UKmLkGulx-iGp9ey7YuenzCxi6NYPd-SE7AS8Bbb8Bp6md7AaAoxk7Ay7gH1hwl6Ynt3snk74o2TMvjPaMTZ36F860F01Vtn65IqyLYvGBfdfrB1609Ixt2xSDB1iPGrI2SzGouPu11nTgUjWqNoWS66Jph1MRF4Qjz4Y3TP3okS_gB6B?width=640&height=480&cropmode=none)

which were reduced in stages using the bandsaw and mill:

(https://sat02pap002files.storage.live.com/y4muYStyJn-ITTqzwU463wNh1EtiOIdV7YtGdzrBsnaUlKm44FDOhL8tikT3BcGNZkM_40aVMb80nrD0hi24LGrgDecD3n36xzN1ZxZj7CIBNyZUQQykWMXEXV6lCMRQDOtCN2s84Tvo6iycVIeYQ1RvKQ3IUH1JIoBjMrNSHB1YSXTxvvWx41qBR8P9n0jjTcg?width=640&height=480&cropmode=none)

(https://sat02pap002files.storage.live.com/y4mpNTl1ZanB0kbsWb5X964O5Q9lguS0E0fLfXsPf_APZe40Y0yUgv32FAgUyPMPpr89FdPDznUdDcqc6RN_b_OsglEicFyRdfQbK4-52eFQK5_a5qmiyhGx-E-9umBB6DJkXaXhbhaS0wzRMTJuw_35eLZcRNwdZy8MhD_oP0lQ5slB7FoMT1kIeKMxeINa3rm?width=640&height=480&cropmode=none)

until there were two little piles of bronze blocks:

(https://sat02pap002files.storage.live.com/y4m93G30fQP-JHNqOlKE6tmaDukyHSr7-IVHYmgxKR8tgSe5bFNJEIhQf399ceyNLWdffVyCZMBWX4ROWKk785cPe-K_HgjQ9Jh6AXd100HJROQIAGrZ72WIXB59ADIisS0xIGoCGYd0s9qUnGzQ-3oLLyOZ2oka1PIV2fDvl_fApoPDOCMhnBleGJx8iyeqx2u?width=640&height=480&cropmode=none)

that were reduced to finished size in groups:

(https://sat02pap002files.storage.live.com/y4medjPEhXLuGI7uu-mlLhXYInp4eUZyym99HBK5Fo1ncRvsOomuS_1b5ujvM0VUjlj9mFsf-FzRpfy-kkrbV67guE5AAo1c3w45umnl28q9fQQVznNfDNNceiupNowpxklfQXPurZYFPjszIeGejTEh3zwamEsk4aI54tmNDBXxuthpBJ4XngkivAUPHcLj1rC?width=640&height=480&cropmode=none)

which hopefully leaves them all the same size. The little excursion over the marked line with the bandsaw will largely get  machined away:

(https://sat02pap002files.storage.live.com/y4mF-DzYzjALa0UhAH1cfPF5syQ46CrQGdRrP7AU636gXyhUxpvDxBiH5LU7E5Ok5HrkB9KaVEloTZgqJmfaznt9Gdq6bqrzm_BtOc1NnfDO0C0fLYhjAiIl-15Xf_zczKFaPPtjsPw4iH8i_R_GsA8G4HbBKZFCK5jM96CqKaN1uyo92VjdaeZWcNGgs1CiGwO?width=640&height=480&cropmode=none)

To make these stacks of bits easier to handle for setting up in the 4-jaw they were super-glued together in a lightly greased nest made from a glass plate and angle plate:

(https://sat02pap002files.storage.live.com/y4mtQlPpZ68lFgTmBph75p-_JM6NDvMduu36oZxazHlq6DexcDHegVOnwamDsoKojL18vww54FL4SJ33kIXjZO7N6qXc-Z6VdCfKk-uyuqXotvCm607NtrlzsD-qewbbiuLbJZyFBOvV6DzmSnTaqcz8AXV82TzHneM6_EjBnPEXE8HG6ys0iY2y8nzlsemD1kl?width=640&height=480&cropmode=none)

Once in the chuck and centered using a dial gauge the holes were piloted with slot drills and then bored out to size:

(https://sat02pap002files.storage.live.com/y4mMnzB5F1YAU-gCxjzXoF_Ycxh06_EbI8rRbKo3TcDsrbhN86VXJmss-3AmLLvL38RLfYM7rmqmj6XRriYNmRdjRgFzlNIpWV4-OLj1JwjYdmR9YGaqz_P0-ASBEzCw97doCNWHNSETpYEAiddjPbEDUIgcckc_jdyUM7eIKpT4BED5UZ1Fmwwd3_Bu4w_ozLu?width=640&height=480&cropmode=none)

(https://sat02pap002files.storage.live.com/y4mHkaYLwaMJI37ScImEN4Q7RrJY0sAEcA_CIcuQvY5TybSDzXGSERD-gyXTPqZnKAT8iE_LELms4bV81fIHn0_WOHA_pa6eFNy5uAmVTmMBwwmH76RkTwhnH1DJsy4R8NH9Rrp1CVnTZS53tltXcxHy_1Jgozo_KVvfK1ask4ByDk8TFe268ObSxnGruwzAnXY?width=640&height=480&cropmode=none)

Its good to have the engine and other workshop distractions with the world going crazy outside and I really feel for anyone who have suffered from the effects, direct or otherwise, of the pandemic. We've been keeping our heads down here along with a lot of the rest of Australia and are just starting to see some hope of positive change, we are thinking of everyone where things may be going less well - hang in there folks!

David
Title: Re: A Tandem Compound Mill Engine
Post by: Admiral_dk on May 02, 2020, 09:32:05 PM
Nice to see progress again David - though the CNC project can turn out to be very useful later  :ThumbsUp:

Best wishes

Per
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on May 04, 2020, 11:43:25 PM
Thanks Per it's good to know you're following along.
The new spindle came out of the dungeon dimensions on Sunday morning - full marks to Australia Post for getting things moving - and I've pulled the CNC machine apart again to fit it in so progress on the mill engine is slowed again. When I get the spindle working in the  machine I'll know how useful it is.

David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on August 18, 2020, 07:26:10 AM
It's time to go back to reporting progress with the mill engine.

There have been a number of distractions including the current Stage 4 lock-down in Melbourne. Most businesses are shut down, for most purposes we are confined to staying within a 5 km radius of home and there is a 8pm to 5am curfew. It is now said to be harder to get permission to leave Australia than it is to leave North Korea.

In the previous post there was a picture of starting the boring of a main bearing - in the end this didn't go well as the irregular existing hole deflected the boring bar enough to cause a dig-in that moved the bits in the 4-jaw chuck. You can see the evidence for this on the 2nd block from the right in the vice below. Plan B meant taking the parts back to the mill and using a 12 mm round-nosed cutter to rough out the hole:

(https://sat02pap002files.storage.live.com/y4mYY9CgaaBXFIXFdI2sB9NEbyHytW2e_z5KOd14n7PIIKUx-NYWJBUuaBjeNTDlRNjJ8Rwg2uTBjsolMEAzOk_UmvY1CofupTer4qP7NJLcTjJnof0uRwcBZeVF2kFuRktTaPEA5cdRrMFk0VX9lSU5WeZKe0CA9OmhlX-HSzUdFV3n-_mjVcSn15eTHu_r3n6?width=640&height=480&cropmode=none)

as it turned out the result from that wasn't at all rough:

(https://sat02pap002files.storage.live.com/y4mtjqwo5xNtkmBAsUmOQbtam3eHkgJqasSjMZ2u_Fw7zgxpFltJReru6_mFHie1oqTAnlqygbWJi14Hc5yhSnfyGo4mTktCHfo9i9viW2czYJ5yxr-pLXhkImW5m1uZxKTo_pWFJB2OuK3lEXJHEK8wwKkq82bD0U5tzx3HhCWxkzyhYS0yc-0209V7dOFF9_x?width=640&height=480&cropmode=none)

and the bearings went back to the 4-jaw and were bored to size without any more trouble. The upper halves of the bearings have a deep groove in which the oil distribution ring turns. I made a 4 mm square ended tool and mandrel to cut this (the cutting edge was very sharp - the picture didn't capture this) :

(https://sat02pap002files.storage.live.com/y4mlw61druhg_UDvKrHmMpMnxjPKAfbHFxADxaaV2kBRj2Fnf-3TUDR4skK3VllGwihUDRwp3dwPhopvt3Wu0PvAVbVdOQzXcEmBDjcPHV21bvN92uG7AdzbyolB_57V204bXBJWD2cM-Mn9A6DM3f7QkoEgo4Bdahanu0lAjfxv4e3J86y9WNSO8UMna3S6KLA?width=640&height=480&cropmode=none)

and approached the machining rather carefully as this was working something like form tool with all the cutting edge engaged at once. As it turned out I didn't need to stress about this as it went really well and produced a very satisfying finish:

(https://sat02pap002files.storage.live.com/y4mQpFX94VltednLaNiZUMIhTbh-y344Us3bW5rlZZZmtiuqUmd0MEGzbzAQ8YcMuyjQbZNw2ml0_fb_krFXyWoLyTyw9tUkouMc3paQfzzvZ0fYpguPtEBiuzFd-yEUHMOAggIomn9xoNKe5W7L1hZ-cQQvTbE-SuvUFBG9xn8we_t-NDY3liZtvm3IxNpadSK?width=640&height=480&cropmode=none)

The lower bearing halves are stepped to make a groove for the oil ring and this was straight forward turning in the 4-jaw, no dig ins this time round:

(https://sat02pap002files.storage.live.com/y4mXoLFZDHFaaGHs4d6-Q81S-maMmPEsY2gJfbjCYnbyCSoHrq5T0W4r-mn9rsQKZ6AMAZheM5StDh9gocsAf2EqtWLcKfpFPiwDEDMquVSxU3YlmEVEnJ7ovPx-Cx1tWmWrWzEMiudWsnGzi3uLVbMuKq9q7hHG47Dh2Wdw9vbQRzFaBQpqGUaoQY9QN5Go4m0?width=640&height=480&cropmode=none)

The oil rings themselves were turned and bored on a stub of MS and were about 35 thou thick. This was a lot less difficult to part off than I expected - the learning process keeps on going:

(https://sat02pap002files.storage.live.com/y4mrkEk8kVdv0RG6L3fRZ1-Xk9SOSKRKpzBPxpvHLY_TobEK9HzNcOtCqA2aT22HXRf4WR_fP2FhrCe_ZCes56ja_MThXelLJNHwnUv132nrXWSzrd-Hn5V1rh1egekWgcg_2Nk_eD532Vs2PzUfG0JpIDvWFkzp6Fl7CxvYJ_oPQ3WqKFuL_xf2TsaTYktxr7Z?width=640&height=480&cropmode=none)

Two little families of bits were the end result:

(https://sat02pap002files.storage.live.com/y4m5iOQWDrUAczZ34U66lywM_n907EB6BYWeLfe9dnyd5ZHJrbs6MGS2EkAOsXaUNyX6BTDnnRMzyu5t0HwZCr4v0x-yXhvhXrg4U8zeqEZBxI6W1Pye6fzXhsiBiji0tnl9Rkbj8WyOZGwZ1v_PTDwWMKcIK1f1eiAMn6N28sZ0TCsChzVdwubyfroo6vH1bq_?width=640&height=480&cropmode=none)

Making homes for these means a long session of milling cast iron, its a dirty job but I really like the metal.

David
Title: Re: A Tandem Compound Mill Engine
Post by: john mills on August 18, 2020, 08:05:06 AM
Hi David

good to see you making progress  the end result is looking great .
In melbourne we don't have much choice we have to fill in time so a good excuse to be working on these projects

I  feel for people how don't have hobbies living in apartments  it must be a long slow process to fill in the time
with this curfew and restrictions it must be hard to find what to do
               John
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on August 19, 2020, 10:08:49 AM
Hello David - it's been a while since I've looked in on MEM - just had a PM notification to bring me here.

Good to see you back on the Throp andf making some more progress. Strangely enough I picked up on mine again about a month ago.

Now have the valves etc made and the internals all up and running - packing in etc and the cross head built and Con Rod made, all turning over nice and smoothly.

Incidently - don't know what you use to break super glue but after making the big end bearing by the usual soldering together method I broke it apart (intentionally) before all the machining was done :facepalm2: Decided to super glue it together which was successful but messy with dried cyano on the bearing surface itself. Concerned that heating it to to break it apart might bake the glue on I tried dropping it in a small container of acetone and left it for a hour or so for lunch - came back to find it laying in two parts with all traces of cyano completely gone  :)

Working on the exhaust valve linkage at the moment - good luck with further progress on yours. I don't look in here much these days but will keep an eye out for further updates

Best Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on August 19, 2020, 01:22:01 PM
Hello John and Tug,
Thanks for the interest (and thanks to any and all who may be following along).

As John says we're very lucky to have full time, if unpaid, employment to keep us sane (or at least no less sane than we were pre-Covid-19). It's hard to imagine trying to work from home with a couple of small children when home is a 5th floor flat.

Tug, I'm pleased that you're back at work on the engine and following along here. It sounds like the mechanical bits of yours are just about finished and the timing must have worked out as we discussed earlier. My actual progress is a bit ahead of the description here on MEM and I bit the bullet and cut the timing keyways in the crankshaft last week; I'd simulated the valve motion in Alibre and convinced myself that it was at least close enough to work.

For breaking superglue I use heat, at around 200 C the stuff denatures and the bits fall apart. The residue has no strength or adhesion and usually flakes off, if it doesn't then it will scrape off a metal surface with a hard plastic scraper. There hasn't been any sign of "baking on". The only thing to be careful of is the fumes, I don't know if they are actually dangerous but it is a job that needs a well ventilated area. I've read about using acetone (or an acetone/water mix) but haven't tried it.

Regards, David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on August 20, 2020, 01:21:01 PM
The main bearings are mounted in CI housings, one is just a pillar with a slot in the top, the other a substantial baseplate. Whilst fondling these - with a steel rule - it became clear that there wasn't much, if any, machining allowance so there had to be some compromises made as to finished size. The story is that the aluminium  patterns for the current casting sets were cast from the original wooden masters without adding any more material for shrinkage allowance so the results are bound to be a bit on the small side. Fortunately the metal machines beautifully and there are only a few thin hard patches on the surface.

The first bit tackled was the main bedplate which had no smooth, flat or right-angled surfaces anywhere on it but a bit of filing on the top surfaces got some usable references. These allowed the casting to be mounted upside down to flatten the base. Getting at the whole surface required a lot of clamp juggling:

(https://sat02pap002files.storage.live.com/y4me48_RRHzleQdHEhF_m0YVmBOko-XGbeHt_yc1taIzNeXGNFxb96IJk5BntkR4tX9_9Yg45MvJ2vbX-ZQwBVsQS7x1qH3kTz5W43hL_odjPWxjAzrH7cUWb0ctD7l-3jvF0CB7ILjE5crZvUP79edP_kCBpuYfWkgPvUUolt-cQNi0dpg8f8xEiSK6pECR34c?width=640&height=480&cropmode=none)

Then the flange where the slide casting attaches was faced:

(https://sat02pap002files.storage.live.com/y4m8OlWLmMGt85Kz0KEY_sU6pGPB2YA-XsprGUsnBd1lqAmRGagGIAR3TgPJTxND1tJXpE3j41WpkvuKgRIv77VRpZZfOttfL7Rat6Me-iEB4bMzY3GUsP5vAmNn5CRwUoHEETc48lut-xEfwrL96sqP8mDvCQIEMiGoBu7XeZfu79eM2OF6knaCtAVCYAzFp8g?width=640&height=480&cropmode=none)

and one edge cleaned up as the other datum surface:

(https://sat02pap002files.storage.live.com/y4mY7s0tlBN7Pn5htqrFOzSNygUQWK01XfnvYuBqmXkIdrjxmU9mOvUEwONWo3WNVqaMGD65HZsUeUz692HbS8IhUOObaOq5hVGZUT0fUWv-Za6BddVnrDLziqS8e6Rvkj_siqH6WjpTAdV1ndBgXO9TFhfnS2TixgGrLpfX0KKJ3COqHKyErVeqZNvnZUauiIS?width=640&height=480&cropmode=none)

The final width is under size by the drawing but I'll have to live with that.
The outer end bearing was much simpler and I dealt with this the same way, first filing the top as flat and square as I could then machining the base:

(https://sat02pap002files.storage.live.com/y4m8yCbf5l9YCtix3CtWj9MjtmDbXbIbvybuq5DhCyao5qruhDANHFA5P7rMNkmXERW-GslE4RnitdGbFNCZH2wb74MMsCpbMQ_x7MEDsQ72ep9NOnPi7jmN1rXU2Zbpg9K0_H8kQDLzvP8NbuRcxXz7MhCdJQ-o-PfhInBPhsegf0W3ZJ_Wf4a30UYWDecloKG?width=640&height=480&cropmode=none)

With clean, square bottom surfaces clamping became easier and the two castings were mounted up together to machine out the bearing housings together:

(https://sat02pap002files.storage.live.com/y4mt7JJhZRc5p_SYwKdxI1fkNWmdWJKdC4EHFs0iwWf1y5LMHyHIWDRXXky6bnI2-gbxs97tV2QUKKllCOKQy5v3C1SWhN3mSSoAjYVfThRqyDrW6-NJRYOycgRQ5HZQ3Gh54UA1zvCfnO9w8GRkKWPNPDL10h5w5EgrN9gzCrEki1pR3jsGs60hgX8KLP_lfX4?width=640&height=480&cropmode=none)

By a fluke the nominal housing width was the same as that of my thick parallels, having one of these in a smooth, sliding and shake-free fit was very satisfying:

(https://sat02pap002files.storage.live.com/y4mPQ4bv8Gwj6Gf-mEvfevxJ5JndIjmz1I92ixxx6Z-LvyLWOR7HUVq-dJSm6bcAEbMCxQN9lhsVDILUjM9rIDqA0CsA8pcuT9n4VZnugxrdvuyo_cKR3Bpap7kPtJMtwHO39hfykJJySqyGp3blQcRDkr4_GKqukt-bf7Pf_dHv3oLjaVQmBHNB966eqj8U0SU?width=640&height=480&cropmode=none)

Each bearing needs an oil well beneath it where the oil ring picks up lubricant. The slot drill was just long enough to get to the bottom of this even if there wasn't all that much of it in the collet:

(https://sat02pap002files.storage.live.com/y4mlQ5eB5LDtK7xc2BwOMFTcf3wukrfAjYvW0JNXJj8FeHElwNMsx6RtkTR-VIBO-Z7CuQLCQdsqe_1vT4Lk-4emvDeWM6v0PDTabt28dqQYFdysmd1DVIuvygpUhQR9GtOn8fhPx3eq9in3en77T_o3E28FSAinKBgCS2Erwblsrm_b-L1GHR0waELcX72pdi_?width=640&height=480&cropmode=none)

Drilling the mounting holes and the holes for the handrail stanchions was easy with clean datum surfaces from which to set things up:

(https://sat02pap002files.storage.live.com/y4mKKrS6CLJgIwiXRT5NBxQV78SIfEE1M_4HIZUvaBG4_-0DVDDjh5hBqj-wEnx0CmrGXV_KMONl4tJ6upHYrU4sSXH5Qm2ZkpjbWW_4JGKMhPvlobnIOtwLKIxqoYTndUgONnHC6K_RZ42w8l70G_eilnSjraUqbVNy8_-3VtMrRXH9HjdvtgF-cXCIMX6t623?width=640&height=480&cropmode=none)

The set of 1/2" thick parallels is a recent purchase and they are so very useful I should have bought them long since.

David
Title: Re: A Tandem Compound Mill Engine
Post by: kvom on August 20, 2020, 02:35:47 PM
For me 1/8 and 1/32 parallels are lifesavers.   :)
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on August 25, 2020, 12:37:19 PM
Hi kvom, and anyone else who's reading,
I've had 1/8" parallels for along time and they've done some of what was needed, however they can be a right b@#$%r to keep standing upright in some situations. The 1/2" set don't have that problem. I haven't seen any at 1/32" thick but those would have been very useful on lots of occasions, must look out for some.

The bearing caps for the main bearings are also iron castings and were provided as a single casting for the two parts. Machining these went in stages, first to make a flat reference surface on the top of the stud bosses which is where the low-profile clamps came in again:

(https://sat02pap002files.storage.live.com/y4mj5RbslZck83JepFD41Zi8AvloeQ0vR_VmPgfiTMTjK4H0nYIQyUV6ZRzpyZk1hFvQi6AgSObz5VMHCu3nbG_6blX-rqHVaPLkM7MWBKR_QonoIA6rniuXEbFvsff87qes9UilZYQRZNvip-TMDry4lTVZLvn89kQc7Ib-OgZCbHGUbpaIEJHHysI56OxVHKn?width=640&height=480&cropmode=none)

Then the parts were turned over and the bosses supported on parallels (much easier on the 1/2" jobs) in order to flatted off the bottom surface:

(https://sat02pap002files.storage.live.com/y4mEXLvz6jv5XaStC4zPydFHXZL4IgJcQkNaZDdrol1kBI5HZ4020JPZ69navHWNT9c0uKkrAN0L8E7pYtzAAaUroH_6FXLH9P8FHKNksbOliPMfnLqB3dtZUKr94gHOsOTjqoq_OwHycG63iT9rWEYgz6ZzIvR5mhZCtckIp4NPNY_OzzvORI2KfDX1p0b9cW_?width=640&height=480&cropmode=none)

and clean up the oil pot tops to height:

(https://sat02pap002files.storage.live.com/y4mqGVVu7pTJm7kLzXA9EHLD2pPgtcQvkMX78c9GppbWnhdoaN93MxOIY7CcUhRalE2lK8pqwGAMe99N1n-Q7BR2uZacGS08IxRyr6bulONqoPuSjpr-5m6diuV8DGv3Ke8Xa8rogG36Il7VQtynUtyDcGof_OOKH5EHjF-Be1qHOl5-Pu6phSjXLHf6ZvBAHsP?width=640&height=480&cropmode=none)

After hack-sawing the two bits apart and machining them to width I used a small round-nosed end mill to tidy up the sides of the pots:

(https://sat02pap002files.storage.live.com/y4mHLJ00ZrVR82y64wsssAMvjZyr_IYCm-LCvmwb-i8Yt9DfMGoeapaHsFW0Ksy2Yze08v1ZJv31Zv_YsBqcgmNDq7Qe5zPbVl0nfDU4Rl7YsYM0gQHP-R6aU32KnLxzCpMGkWOZGgOSDxSyXMjCl75RfQ-Mcd7oH4wYz3-9vN2EnOeV_9UabNgId9VIYGAj7US?width=640&height=480&cropmode=none)

The stud holes were drilled 4BA tapping size at first and the caps used as drilling jigs for the tops of the bearing housings, afterwards opening out to clearing size:

(https://sat02pap002files.storage.live.com/y4mEKufGeHBf3qPgoepIaD0Lr-lmaQ_sv7utzivEnIbu3_axOuU8mwh_fLQJdEahZh1bg-APMEL-twavpbYXJxX76zFf-00U2kRC8bYaXfhNPqVAW-kfhbe2KXjSBZw2omielnH52uxwHl2heSmelcbgGlDPS79Be0cTRgnprUxfMC3_vuDdamypdOlepJNXYvx?width=640&height=480&cropmode=none)

Looking at that last picture reminds me to round over the ends of the caps some time soon.

Tug's progress on his version of Arnold T's engine reminds me of just how much work there is still to go. Tug's workmanship is also something else I can only aspire to matching!

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on August 30, 2020, 11:28:07 AM

Quote Tug's progress on his version of Arnold T's engine reminds me of just how much work there is still to go.

I guess you are not far off there David but every step eh? Although I have a lot of small items to get through I've only just realised that I am actually not that far off - surprising how it all comes together.

Not able to send you the details of the valve lever at the moment but will do soon

Keep that progress ticking along

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on September 12, 2020, 01:36:44 PM
Between the crankshaft and the high pressure cylinder is the base for the slide which guides the crosshead, this also supports the valve rockers and governor so alignment and squareness are necessary. As with the main bearing base the casting was filed close to flat on the underside then the top machined to make the first datum surface:

(https://sat02pap002files.storage.live.com/y4mUVQDPn4PebtsEAwG5CC2F9BqaHI68OOs0QZAlQ5Saxfz_gUkDazJH1Z5nAWGiNHRF-D2wSjwQKujiRt3JGx6mZmCeqZ8i5Us9trG3XxCJuerNIUf5_L1GWCze961uHTVE0obVgWI-qHx_yWCVTL3fqvTEs0id1b1S7oSHzMNlx4UUMi_c6MW_k8jR_5rR8kQ?width=640&height=480&cropmode=none)

I hope the world doesn't run out of 8" x 4" file cards (I'll explain what those are/were for younger people if necessary ;D) before I cease to need them!
The casting was turned over and the underside finished flat and to thickness:

(https://sat02pap002files.storage.live.com/y4mU_nNcld2-RDI3A8snNCobRLVYj2AoY8T8OLnd6MGWehBrd2EPNuiTZ8yc2e13pAuKjssEsBSS2lEeZDfHmCcdM94hHjXVp1L9V6jW7NS8AggdjnEIfSgXJsgoFBFSITw5MXJ8aFUSHZOf6g9lMfXutFwUZwKK9JU3-1nswK3rolq8aNsD8GjpXfLfd53-NiE?width=640&height=480&cropmode=none)

then flipped again to clean up the crankshaft end flange as the next datum:

(https://sat02pap002files.storage.live.com/y4mppJE0L3tZ5huluQ9ruJubSYkvwmAiiyx7E-7ZM63OTSxzhe0IUR7cT290PSWmSilBQ35UajLkzSfa89qZZp_qabR4GIzg5iBNn3E2E2VJM6_BydYkPyItMwRhBeMDD5x69lIS8RNkxSNKMlJUZsNl4ehTtA1qGywBl7R5plQEe54MDTL3EDdTyWwp3NBCuBQ?width=640&height=480&cropmode=none)

At the same setting the back edge was milled as the third reference face. It was clear from the casting fondling stage that there was very little, if any, metal to spare on the width so there would have to be compromises on the flange dimensions. The main bearing base was added to the set-up so at least the flanges would line up, even if they were under nominal size, and the longitudinal centre line could be aligned between the two parts:

(https://sat02pap002files.storage.live.com/y4mR-ZQKqo4g8whqPvuNb0Eqo52JqYW137iSpb6mW9rUH5nFOOw1Fz_CpK4h8r8BP6_oY4QF0nC6RKeIFRc4AHyKMxImVlCVXRDtxKEnopUkeW5B4OpY01ghiyNQiEsSQciV1Hp0sxldfFclTBtmUyBtrMnrdIEyvDGcokd38au9lgSuJ3giDtJQKtacQMuw984?width=640&height=480&cropmode=none)

Locating the centre line from the reference edge I dug out the slide way with an oil well at each end:

(https://sat02pap002files.storage.live.com/y4mNCp4yuid5R7JjJdbvK2BSAW6aUAXUo1HxBQXJFCAR7mLaJqHpUPuUM2izCoKCrAooGiecOE-zHXhYcaG0YeaXOEILagq5ZixD7SNprpEIkGD8b3KzjRmnpJN6osZARKwbN0FXa5PPacaIx545hyxCZE2IZ33N1i_Fsdwy1GFC9jtvNJrKaqE5O9yGs6oKr05?width=640&height=480&cropmode=none)

Some holes for handrail stanchions and holding-down bolts were next. The part-circular cut out to clear the HP cylinder flange was very rough as cast but cleaned up fine later with half-round files:

(https://sat02pap002files.storage.live.com/y4mjaDHTpdO4WgIh9d5IIrb4TUVuScYhZIXtPSchMyIHpa5xdOWjIpbV_Hsgc8cKS6DYYx4Ass2ldvEbap2AclpicGUgt3b79w4u-KGDI6okQ-fTTe2J4FPayBlgU97xRlL-WiclWgP4FdmwR9Jt3Tqf-I92uwTaueH-pp9VfKcWvxUMRfWWeJzUBzGddYVmem2?width=640&height=480&cropmode=none)

The mounting face for the governor was the final surface that needed machining and the bolt holes in the flange and that of the main bearing base were drilled in the same setup :

(https://sat02pap002files.storage.live.com/y4mjaDHTpdO4WgIh9d5IIrb4TUVuScYhZIXtPSchMyIHpa5xdOWjIpbV_Hsgc8cKS6DYYx4Ass2ldvEbap2AclpicGUgt3b79w4u-KGDI6okQ-fTTe2J4FPayBlgU97xRlL-WiclWgP4FdmwR9Jt3Tqf-I92uwTaueH-pp9VfKcWvxUMRfWWeJzUBzGddYVmem2?width=640&height=480&cropmode=none)

Just one more base casting to go then on to smaller, maybe more interesting, bits.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on September 12, 2020, 08:09:53 PM
Hello David - good to see you making more progress 👍 At this rate you'll soon be catching me up ;D

I sent you and Neil Lickfold a PM from my old laptop when I was on holiday - it shows as sent but he didn't get his, can I assume you didn't either?

Decided to carry on a bit further on mine, near finishing the governor parts at the mo

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on September 16, 2020, 01:06:38 PM
Tug: I've got a way to go yet to even see the dust you're making but I am moving (PM dealt with). I'm also really pleased to see you getting back to work on this engine - seeing yours was what started all this.

The base plate for the two cylinders was tackled much the same as the other base castings. Neither side was smooth and flat enough to leave as a reference so the top side was filed smooth(er) and set downwards on the mill table to take a skim from the bottom:

(https://sat02pap002files.storage.live.com/y4meqkg1yLDeYreZA3V-ubZoy_HlPFK42Lc75k_X-2hlF4fZVH4zswwy5TpZqc_OmV602Ni2L8yKYOBPaULQO2EchKciRCmbkW0EYdZgO9zBsqkQwxLZxWxP-sJAxj9hfBxp0EZ2zQxmZ4OHdj25G_s0UGqd22XiOe-_5ufFazdPfqfHrOx9y8VIDrJ2WCCEc2k?width=640&height=480&cropmode=none)

Lots of clamp juggling was involved as was the case for the top side after turning the part over. Also at this setting one long edge was milled (after changing the face mill for an endmill):

(https://sat02pap002files.storage.live.com/y4myt7f3hwRUoNW_ZqZFLDDsjXO9E61CU57ISv1FuJh2d7pFvfWKfYHgGKlJE8YuHDXZVGVNxSlJxX2Ges8-wwnFXbd96OjESsXOYNqip_OewG0EjnCKHrovSnDl2BgDbkVeQjRwViqNFk2-XmGnmOrHwWoALFFP94Z55OvRkyW7f2bH_YCgKgkAfOkC-3nJQqv?width=640&height=480&cropmode=none)

I don't have a picture of machining the crankshaft end flange but that was the second datum face to be cleaned up. After that the second edge was milled:

(https://sat02pap002files.storage.live.com/y4mRSFfr3QHy5_d_MyWD_cgrKN0lICf_UjwVB3jLVT4NPrD47_aX_0Tk4t68xy7kVrtXWv5uHM7al4vAjOjZQNqUTyfljChk0jE_6v4vOD78b_F4j8PY2UcbP--oN_6hCDXivs0R39NfohLVorXEcSpgh9nYevwwQQ30bK7aMtwG22Zlw6guweJX8H-k15JifJ4?width=640&height=480&cropmode=none)

The drawings show four cast-on bosses for holding down bolts but the end two were missing on this piece and were replaced with steel inserts:

(https://sat02pap002files.storage.live.com/y4mvu5cwOnCxJK20DCUw71X_WUxRudFjpciQkEBPrg-31OG15s1FYcJqVoKXQUNv6WrnPDVf8voKu0UlLN4yZnc3H70lFzZL-SkPn9dfZBN52aALB3FtpiFWXw_z0-7hraKsvLrt_mKDUv8bKD-ICzoktpif50JiuC7l8QxKcoLh-BynmS2ZSHhaLTLxYCt9m58?width=640&height=480&cropmode=none)

The blue line shows the nominal location by measurement from the flange but this isn't critical so I drilled the holes concentric with the casting's rounded corners and used JBWeld to fix the inserts in place.

I don't have any dislike of working with wood but the "marine grade" ply I bought to build up a core for the engine base is horribly splintery and the dust mask was essential, nothing like the marine grade material I've used in the past. Anyway, it is very stiff, and hopefully its stable, so there is something to rely on for long-term alignment. With the two pairs of flanges bolted up and the main bearings aligned using the crankshaft the holding down bolt holes were drilled and some of the studs made so the work so far could be put together:

(https://sat02pap002files.storage.live.com/y4ma8SWbamGqIDiUX0mlbyDIuSUei5DhErk69j6STPA586D2H1M2oNMKQBXoiXwHod-A25hhxT2gmvGQKYONAlmUr23TgzaeqpH0DgMzcrOiGORR1ZqTaoaHAPGF01P0iCgcVD-szpUdPWtFaj7WeXCU0uzCYpy5cV7LYDutfM9vCiP80DESxv0G4hc9qfHaF6T?width=640&height=480&cropmode=none)
(https://sat02pap002files.storage.live.com/y4m51jF9Pv5FhKqAf-k8slotSABt7avvVIMxbAgLLkJZGjEpEEdF51ixEgfT2F-a9QRPpf_qsFy-wAeORqngnI-wuiWRllY4LW35mNbSesBfa-HXVGmabfBl0hXDZrf5zPn9cZxHIvObZUwtWKr2pBwozjSdbwkuC4ca4t9TXYyVNRNpL_hNCI5C43LKb4ax50B?width=640&height=480&cropmode=none)

I've stocked up on BA fasteners with smaller heads and I think these really improve the appearance, hope so anyway because they're damned expensive!

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on September 16, 2020, 06:58:54 PM
All this work takes me back a bit David - glad all that CI dust is in your workshop and not mine again  :D

It's a big old base needed for sure - have you had any thoughts on filling that open area at the back? I'm at a bit of a loss on that - possibly a neatly printed description plate?

I had a new belt arrive today - much better, pulled flat the stretched out length was 166 260+ mm as ordered. I have to take the shaft out to fit it but can see that the tension will be much better - https://www.ebay.co.uk/itm/Turntable-Drive-Belt-166mm-record-player-belt/280828907661?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 (https://www.ebay.co.uk/itm/Turntable-Drive-Belt-166mm-record-player-belt/280828907661?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649)

You are right about the fasteners - pricey little devils and this engine just eats them ::)

Regards - Tug


Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on September 28, 2020, 01:32:17 PM
Tug, Thanks for the info on the governor belt, now I know what to look for but I'll wait until the actual bits are in place before measuring the length.

As for cast iron dust the Karcher industrial vacuum cleaner is probably the "tool" that gets turned on most often at any time. When I'm machining CI then it gets even more use.

That big empty space is an issue. I have thought about moving the steam stop valve into it and maybe adding some dummy small valve levers but that makes the piping messier. George Watkins' book "The Textile Mill Engine" shows pictures of a lot of engines and the engine house interiors, some of these have magnificent Victorian CI lamp standards in that space, fluted columns and elaborate lampshades, one of those would be fun to model. However, in Vol 2 of Watkins picture # 48 shows a large alternator in that area with a short rope drive from the flywheel. In between the introduction of electric motors for driving machines and the National Grid being able to provide all the power needed, some mills (maybe mostly weaving sheds) had both rope drive and electric power transmission. Drawings for a 1920s 500kW alternator would be very useful.

Back in the workshop I decided (hoped?) that I'd worked out the locations for the eccentric keyways - I'd found the original drawings difficult to interpret for certain. The positions I used are:

(https://sat02pap002files.storage.live.com/y4me-_FdxxO7jIsqTc19S7GRR9nsJiPqhxpbzB7Gk8_rSWDV6NbC4Nc1MWQws5Fn9dYXstTvQdC9L6WKHqZcnCOz1hp1TB3yIl2zwjVuzJBjT8Varv7uSjxOVJISeLiu8ZqnobTW_npUNrF_BDZwBT5QTeZlBMQZaCvRkBScumIIqO09Ub3UFXg_-ghyZBKmNaC?width=640&height=210&cropmode=none)

and the Arduino controlled dividing head made setting out the angles easy. There's a reference line scribed across the crank and the shaft end to align things, just have to remember to get the crank pointing the right way on final assembly:

(https://sat02pap002files.storage.live.com/y4mM4USyED3qsOqe7TkznRR3uZem0-ejmBdCGt98BP1JqlomdmItko9szuhMahbw55xYNHYdkLPoGcaN9SDwGZHbivCLDyGKzKfCzAzJfNneTnAn6n31xL_rxnFocodoWZk_7h50oAzsvRFFH8mE_jC_n2j6MFfqZAPIds26u7Tv62xtsGHM6IYCm0q_NbAlOaX?width=640&height=480&cropmode=none)

Next up are the eccentrics and straps.

David
Title: Re: A Tandem Compound Mill Engine
Post by: scc on September 28, 2020, 05:06:15 PM
 :popcorn: :popcorn: :ThumbsUp:
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on September 28, 2020, 10:47:29 PM
Hi David, I'm not sure what the actual 'diameter' of the belt is that I have currently fitted but though it does work it is a bit on the slack side. Of the two I bought the 166mm dia appears to be about right. I have yet to remove the flywheel in order to fit it though.

Like you I have several of Watkins books -  The kind of layout you refer to with central floor mounted stop valves, lights etc is usually  associated with twin layouts - single cylinder or tandem - but most inline plants appear (though not always) to have the stop valve on the hp cylinder. As you can imagine I scoured the ink off the pages looking for ideas and details and based mine on several images. Most of these in-line engines were erected in some pretty tight engine rooms as indicated by the angle of which most images of them are taken. Great books by GW, just a shame (from our perspective) that the individual engines are only covered by the one image.

I'm pretty certain the 45 and 42 degrees for the Corliss set up are the same as Peter Southworth had annotated (too late now to go and check).

Got the governor linked up today - looking good and works well but still more linkage to come. So far, overall, I have found the drawings to be fine to work too but the build up of the links to the cut off levers is quite misleading. The GA side view shows the drive lever to be on the outside of that top bracket (and outside of the governor lever too) though differs in the plan view. I don't  think its going to quite work out that way on mine ::)

Hope you get some more good progress in in coming days  - afraid I can't help with drawings for an alternator :D

Regards - Tug

Title: Re: A Tandem Compound Mill Engine
Post by: kvom on September 29, 2020, 02:46:01 AM
Would you be willing to share the Alibre part files?  I am wondering if they can be converted to Solidworks.
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on October 06, 2020, 06:29:25 AM
Tug, thanks for the comments, I've found some pictures of generators and alternators in 'Modern Power Generators" by James Weir French, Volume 2 of 1908 so they are more or less the correct period. There's a lot of work to draw something up from the pictures (and wonderful paper fold-out diagrams) but it would be possible, I wouldn't try to make a working version!

As I've modeled it the HP cylinder with the valve gear looks like:

(https://sat02pap002files.storage.live.com/y4mD6Xsp2EnSDvbs7ROK7ACf4SRKPgGfthrimSzzDquDygPYPWDUF-1SOiCZ_UcQZqeHHR5_UEDgrCa8ZtxoeAonj-lRLcv9MAAUZsm9V-Cx8IPkMEHDpdEt5F3VqXaZpwnDrT-rKMXok7zDhhqmwLxAlwt2audGY2Sop_hN2-LMJxGtigPdLmJSL-4xME3_17P?width=784&height=531&cropmode=none)

The link lengths aren't quite right yet, the "Trip Gear and Dashpot Arrangement" drawing isn't dimensioned so I'm having to scale from it, not good practice I know but I'm trying to get the Alibre assemblies to move as near to reality as possible. I don't think this is totally possible with the current set of motion constraints but I hope I can make a video of the valve motion without being able to simulate the trip action.

In his build log Tug also pointed out the problems with assembling the eccentrics so I 3D printed one of each type (Corliss valve and slide valve) as originally drawn so I could have a play with the pieces (Corliss on the left, 1/8" throw, slide valve on the right, 1/4" throw):

(https://sat02pap002files.storage.live.com/y4mNhbhhRSypW_1amHXRyLtUVRGf61HaZHJuVAs-Yif-p4hHkEkyyJoRpNzX5WH6OZ-S1L72NjDcd4CL_fpazMiu6RapKjfhdrkfsWI3-t46F-hM-iMw36Eu8Gevfw0uUXmYtCQtUnAaQcc3TZyWfxsgHsntWrNWEQ1qwaJFlP9XuItCXJNpVYEcxFyNjdhUBEC?width=640&height=480&cropmode=none)

It's just possible to get nuts on the studs for the slide valve eccentric but adequate spannering doesn't seem possible; on the Corliss side even getting a nut on was challenging. These will have to be solid and "decorated" somewhat to improve the appearance, although they aren't really all that visible.

Before starting on making the eccentrics it looked like a good idea to have the straps to hand to use as gauges so the three GM castings were fondled and found to have plenty of machining allowance, to have the core hole close to the centre and remarkably close to circular. They were mounted off this to start machining:

(https://sat02pap002files.storage.live.com/y4mjfjvGLD_ZYrd2PGeIY_D04Z4nzwbEK-AexAHoNFAov0IUsxzs93RqmLh5yalsj1jrTpD8pJO9QsscTOgmTJS2H4EIE_5uBH5T2PABjlsnCMYG5q7Nyi4FWQQsjRKPZ5U4DOqi9lbx6cH4SBKPBAdAVRsggirF5nlvvqNp9hw_dC7QXzlyjJT5IkrbBuvym28?width=640&height=480&cropmode=none)

with both sides smooth the external lumps and bumps were brought to size in sequence:

(https://sat02pap002files.storage.live.com/y4mX0gYd78qDEnxEanLnVjXyuBNlvhqlFOkELzqW6kfqP51D32ggWEBidhew8L75i1hxeI7NA6QYs2ZM9ie5J0yjXpbYSfxcAK1JvrfemidXGDt7GAq3ILB3cleQNDZWXBM4eO0coCa40LTOKni-xUvI1u7yVP84Jgku7qNr3BNahrzie2YgR5On-2mE-IO33d4?width=640&height=480&cropmode=none)
(https://sat02pap002files.storage.live.com/y4mtb5LfWSGzrPdr9g0vVZ-N-0bDSuPfwSu7zRxsOsqwXw-bWpMK5ByZ-1ZrhUMJ6rBTeMlm3jQSjeAbXL2E7HHjwiGASonAu-e7hF-dgXqj3giSqOdurF4iwsxtb8Syw4rV4Ubo5Tz-RyV7esDKQKUAgjuILPJ472vJ71SXF3duxPBJIxjm2zd9U04Jppu6TgB?width=640&height=480&cropmode=none)

the clamp stud holes drilled and the two halves slit apart:

(https://sat02pap002files.storage.live.com/y4mGb6WtJZ9OM7AB3uvWbEzCGC1Jyu_kts6K9UQC5pKqkyN6yp4xPHTpnSPXHd1SIcrkVU2MO7ZxhUVVQoHq_E1s54ensU4hJEPKwlMb_xndkk32yR0NhAJlJBpaIPl94BFrceMvIQ5qphUTXuObAO5ObYy6cGr7u7eOAtd-MJ1a1o1dBcOQQEB6hi3zbnQIJn7?width=640&height=480&cropmode=none)

then set up in the 4-jaw chuck for boring the hole to size and turning the internal groove:

(https://sat02pap002files.storage.live.com/y4mPmIs6Pc8R0qB85tfw9BW64BHUywTAx7BsYxX8X-FlUHAaBOiLrVF3OZSmzhith6UJNdF0QHKGTHBxpliWii_MROJEYvoJXtlp_CHyH_sRqMPVaBgquekgtEJuapO9Z6_Ohtg3_qHPBpeEmtR7s6lZi4sYpHqSBGYNobRzAFHuemOPLQjVvoaR6DmzV0U343Y?width=640&height=480&cropmode=none)

(https://sat02pap002files.storage.live.com/y4mglDb8KTiqN86N9wzwE5sFTmutNpn2st2z5Xqtj9ZNLZMHqqOq5Zr1lXo1yU5jxMvXY8M1ghS9nSYtF6M2HQwpvO8w5OzzBaTrSTT9xsfWupc_cKucX0EQG2LkY1ZdKN3sP0Cv2mZhtpwdKlRLu3cmASlHtd3VDdeZQqXnXAtem9G1TDyaiRmgldy_KcCocEz?width=640&height=480&cropmode=none)

Thanks for looking in!

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on October 06, 2020, 11:40:11 AM
Thanks for the drawings David - I do admire your ability to do such  :ThumbsUp:

I had come to the conclusion that the format was as you have it then 'found' the undimensioned trip gear drawing (twice scale) that shows it correctly. Hadn't paid too much attention to that whilst making the parts.

I have found that there has been one or two parts that required 'scaling' but as you say no alternative. So far though it appears to be working out. I think I will have to modify that top bracket slightly as mine is slightly wider than dimensioned - it will need a cut out to clear the drop links to the cut off arms.

The one thing I am wondering about is that the trip arms only engage the trip block by their own weight which isn't a lot - they will certainly have to have a very free pivot! Have to see how that works out in practice.

Keep up that great coverage  :ThumbsUp: :ThumbsUp:

Regards - Tug

Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on October 06, 2020, 12:01:25 PM
Tug,
Thanks for the kind comments re the drawings (screen dumps in this case), those are almost a given once you've built the CAD model, that's the trickier bit. You could always download the Alibre Atom3D 30 day free trial and I'll send you some files to look at & play with  :D

I was stressing about having missed something that would make the trip arms positive in their action but I really don't think that there is anything but gravity. Jeweled watch pivots come to mind as being necessary! People have built these engines and got them to work so it must be possible. Is their anyone on MEM who has finished one? Knows of a finished one?

Regards, David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on October 06, 2020, 01:14:29 PM
Yes David I've seen two run and one other turned over by hand.


The first was a twin tandem compound, corliss and slide valve but it did use a lot of air. The second, built by Terry Fleet who was the original instigater of the design, I've seen run several times at our local show. That is a cross compound (both corliss) I do remember Terry telling me he had to fiddle a lot with the valve setting before he got it running (don't think about it - think positive I tell myself :))

The other was a single corliss bought by a friend who brought it round to show. It was bought as a non running example but the reason was soon traced to a poorly made linkage on the trip blade. Haven't seen him since so don't know if he got it running - I'll ring him later to see.

Thanks for the offer but I think I'll forego the Alibre at this time  :old:  :)

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on October 19, 2020, 12:37:09 PM
With the straps available to use as gauges the eccentrics themselves were turned on a stub of FCMS bar:

(https://sat02pap002files.storage.live.com/y4m_h9ZxxIoNwHztwPEETzv0HQl1CPzAbZGEx_Ra7_ajPBgYE4xeo1lTqboSVXC25R8KTz7ljeGydvnLNMK1U7sL2MIkswHQAU0rhadGp_jNZGlzI6qBgN4QnmnlpYsGfxUgfXBOw4Aogt6D2ctLSBDEZEFrmiiqlbX1Zmoxw9MPT_-eFikRF5mu61xjaqu8Loz?width=640&height=480&cropmode=none)

and parted off using the rear tool post (best thing since sliced bread IMHO, particularly with a TC tipped tool):

(https://sat02pap002files.storage.live.com/y4ml2pxLA57d17zIX4cTFRArWA93ntlAG43ohF-EO1lG0NsOYz2xq60T4ZA-tvyMsPtjTdz45QcotLJLlN0EwMGoRnqNJFx5Ir_OeLoVKOKbmdsfPK8CnBhtdraNjiOyq3CR2T4NyWjV6ST8iysHHfe8gNZZmhpfM-pXHpo2TQTKvBQBvj7UwXeeHRecnpIrKoZ?width=640&height=480&cropmode=none)

The three thin slices of steel were tricky things to hold. Machining soft jaws to take them was the first thought but, just for once maybe, I stopped to think a bit further ahead and instead turned a mounting hole in a bit of Al bar:

(https://sat02pap002files.storage.live.com/y4mfv3HzEXszvJfCubeoZleQnMqvzdOK7BxEwkC-1QzO1EtScSoa_yJB4iRF8lW29aAahIMbLbYkRLFtTgkcObY7-Yiry8AdRnwD6IXu9zyi8F1T9LN7HyVE8B06dIfPf6cFnYa5DRczKJreT8ALkl1HdCx2nhb68GWbnm13zyK1zyC3xFN0yRYi29CnmIPqAvL?width=640&height=480&cropmode=none)

The first attempt to use hot-melt glue turned out to be a not-quite-good-enough idea and I went back to using cyanoacrylate to hold the eccentrics to finish the second sides and start the marking out for the crankshaft hole:

(https://sat02pap002files.storage.live.com/y4mkbNsuPCVjSGzA2ABvR1bMrEmeNfK0pq5xnuPZ1v29bjxbJdlthPIgE7QYH6XUUWTdwKq-r6JlJNFHqPoJKrlW5TOzV3ZFh0R_cU3Z1dFqBV6BfR6JFfZ1KsdFLucxbw5QSEjuQVLR5-fVLBlS9thEFjngc9Aeuc3XEoOlQtbrgIlnfe29Lq2d7SHYHDT26xP?width=640&height=480&cropmode=none)

Centre-punch dots are to keep each part associated with its fitted strap.

Transferred to the 4-jaw for boring and bored out to fit a plug gauge turned to the measured crankshaft diameter:

(https://sat02pap002files.storage.live.com/y4mYwEm_E_zWy7mADbgymVC3JUayGqM8LWB-PG0Wgc5tl1Vv7hPSnXWc71602s35AO7Qk0m6YZdTcJGGLC4W7v0IeRKRm_iO-9nZBM7qWNJCjq6YstHRHuIhlIzxxgrPPcDjWYDZZYxMGLx3fs_0oX_iCemESZhBeB4QIsJrMRogTXonCE4Q8k_ECH2O6GG23Dl?width=640&height=480&cropmode=none)

If I had an arbor press and a set of broaches then the keyways would be really easy but I haven't been able to justify the cost for something that wouldn't get much use. What I do have is the slotting head that came as part of the package with the Aciera mill and I used this for the first time for the flywheel and governor pulley keyways. For use in the slotter the cutting bits are carried in simple 12 mm diameter tool holders and I made up another to take 5 mm round HSS bits. A block of scrap Al was the first test piece:

(https://sat02pap002files.storage.live.com/y4myFHyppxdjk8nCwSrUBHlDcDy8BQYKOw0RsnvayX_Sn3SaFEdBymluuJ53oeAgzCeeDur4zXRSOaimYa5lXSXbYYRWPFE2gSP15Fw7kUBdMYkpvfbYTJpfPcpaexYoxx9NQrvT4OgqZChj4Si7XxMYcAnmIeXiinL11TUoQis-LqPq-TWcinW-8Pv6SUPF70n?width=640&height=480&cropmode=none)

and when that 1/8" key just pushed in and sat there it was a good feeling!

The previous jig now came back into use after boring it out to give the slotting tool somewhere to run into and adding two M6 screws for clamping:

(https://sat02pap002files.storage.live.com/y4mPtm8Vrniqcz_KWsCswLYYvncfL5uqQ7dYqsjaZSSZmcuNlOO1105KSC063jmqRUzXajkxSRSTwxdlyUkdVozKOY2ky79w9eGaPp2V5W8QV7Po7sYujZSu1JUTrI6LwJKeU4zZYVQnwJHFeS6PHYDuEwiEVAxF_e4gD9FOIysCQy-2IQnhps_Epxy2uLva5Tt?width=640&height=480&cropmode=none)

That good feeling came back when the keys fitted nicely in all three parts:

(https://sat02pap002files.storage.live.com/y4m4O1ys3H_r8kYY1AqJqre0HVqONMgEIUZJIwwqZgzl9UKGphgHRtIxZNcKGT5WrIlclcJbofNVdivjotlhHXP3sk1GCWohYDiXFn8H-Era8S__ZUZ3VR-SNO7rugg_6ZFY0as1DG9fyKqhk99Tgim_8a9Fhxr5gqx_jga0K0rWy-E_tpIBopq_fbFVxWguZ8I?width=640&height=480&cropmode=none)

Because I haven't split the eccentrics I drilled and tapped them for M4 grub screws (no pictures) to prevent any possible sideways sliding and the progress so far looks like:

(https://sat02pap002files.storage.live.com/y4mak3toCsGyY3J-1LmlPRt_L7jsXTSUAvjY4Oi0JKKFqEpiLE5WDZksV7KHI1pGdlmsgwDQfVKTMZOWvpMqAYiKaJD7-C7twvxzaGAY33WwtnO7Ac8QM93xSyfuWFMabUlOoU6sjkhPKhWYZpR2XXKFvpikwOShF23AOuNY08lU03dli7azajaIaZSLzmZSxW2?width=640&height=480&cropmode=none)

There's still a long way to go to catch Tug but hey, this is progress!

David

Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on October 19, 2020, 02:46:50 PM
And good progress it is too David  :ThumbsUp: keep it coming.

I don't envy anyone having anything but I wouldn't mind having that slotting head  :D - a very nice facility when you need it eh?  :)

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: gary.a.ayres on October 20, 2020, 09:48:10 PM
... and I wouldn't mind having the Aciera mill. Pure class...   8)

Lovely engine developing here.
Title: Re: A Tandem Compound Mill Engine
Post by: kvom on October 21, 2020, 12:52:15 AM
If I understand the cutoff/trip action, the normal motion of the steam lever causes the lower arms of the admission valve to oscillate but pushing open, and the dashpots pushes the upper arms to close on the reverse stroke.

For cutoff, the governor links cause the triangular bar to raise the lower admission arm so that at some point it slides over the top of the lever allowing the dashpot to close the valve.

That motion in the running engine will be fascinating to watch.  :o
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on October 21, 2020, 01:02:01 AM
Thank you, Gary and Tug!

Gary, I hope the French workshop roof is in place - how is it going?

The Aciera was a once-in-a-lifetime opportunity that I only spotted on ebay because I happened to look at the right time. I now look out for them for sale here in Oz but I haven't seen another as yet. Even W20 collets and tooling are very unusual Down Under.
F3s and other Aciera universal mills are easy to find in Europe (and a few in the US) but the asking prices, when visible, are outrageous. It would be very interesting to know what the real price would be if one was to start bargaining as I would have thought that the market was pretty small.

The basic mill is quite worn in places (e.g. the x-axis feed nut but not the screw) but most of the attachments haven't had a lot of use. In fact the slotter looked to be seized when I got it home but turned out to be gummed up with old grease and I don't think it had ever been used. Not often needed but extremely useful when teh need comes along!

David
Title: Re: A Tandem Compound Mill Engine
Post by: gary.a.ayres on October 21, 2020, 08:54:37 AM
That was a great score, David!

You are right about the prices. Several thousand is the norm I think.

I saw an F1 on a sales website in France a few years back, and e-mailed the owner to discuss. He didn't get back to me (probably had sold the machine already), which was just as well really as it would have entailed a drive from North-Western France down to the Swiss border and thousands of euros to procure a machine that would probably have got soaked in the rain a couple of weeks ago due to the missing roof section...

My neighbour has now sprayed the machines with WD-40 and wrapped them in the kind of black plastic used for silage, and my builder friend and his helper will be arriving there this coming weekend to get started on the new roof. So, we're getting there. Not looking forward to seeing the state that my workshop and machines are in when I finally get over there, but at least it's going in the right direction now. Kind of you to ask - thanks.

Following your build, here. Immaculate work!   :popcorn:
Title: Re: A Tandem Compound Mill Engine
Post by: gary.a.ayres on October 21, 2020, 11:20:11 PM
which was just as well really as it would have entailed a drive from North-Western France down to the Swiss border and thousands of euros to procure a machine that would probably have got soaked in the rain a couple of weeks ago due to the missing roof section...

And just to be clear - thousands of euros that I couldn't afford...!
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on October 23, 2020, 10:21:24 AM
Yes Gary, if I'd had to pay the European dealer's prices the Aciera would not have happened! Just very lucky and prepared to pay just that little bit more than the next bloke. To be fair on the dealers the machine is a very early one.

As to the rust, Evapo-rust is a great product, hope it's available over there.

David
Title: Re: A Tandem Compound Mill Engine
Post by: gary.a.ayres on October 23, 2020, 01:28:43 PM
Amazing that you could get it cheaper in Australia than is available in Europe!
Still, these things are the luck of the draw sometimes, and you won that one.   :)

I haven't tried Evapo-Rust but I believe it is available here. Will check it out.

 :ThumbsUp:
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on November 02, 2020, 05:33:06 AM
The connecting rod with its bearings should end up looking like:

(https://sat02pap002files.storage.live.com/y4mW_fThNsQlI7osxZGzNCSiYjtdWSB5T0Ay-igpXnHeb9LMJE1AAT-AgTbufXpFBegOEqiTCTfb5AUojAicexTnjVJ1KQP3QDxNqMtCERcKDFWk2ZZXXh1vbjsavDPZ3AhUbek_tQQrC4rIV2fh8TnKIs0Sbzrrbt3yLHsdhhSryBYVWtK3lMhZTfsjjH7bYt9?width=640&height=204&cropmode=none)

There was this piece of unknown but steel-like material just the right size for the connecting rod that had been sitting in the heap for a long time. It hadn't rusted but it was attracted by a magnet so maybe a ferritic stainless? Nevertheless it wasn't too hard to file and had been cut with a bandsaw so it was worth a try. Roughing out the outline with a 12 mm solid carbide endmill didn't go too badly:

(https://sat02pap002files.storage.live.com/y4mtDPvbOwXh3QKWTpGq3I8huR1Hg__eZ_52JdSRO0mXnZMBiAzYnE6SRqGikpvltRIh0jmhl6eNBHgBIhfif9NZmeO_a7ctNItFV9I_j7JRWloUrd-zeZpX5M4k3Q-TPO6daU_CyeWLm0J59KHuxFVvgUERpxYF_b8ox92MnnI7uHmuYbcOY8t8jt8lCUVrIh7?width=640&height=480&cropmode=none)

and produced a lot of pretty blue chips:

(https://sat02pap002files.storage.live.com/y4mGocpMJW-XtTDVdPAlTp5EFLSiiASAJtZT3Awjm-y16bRw4UHaeHUx_1EO0G9KSrRd9Rvyu7TmtkzVv03Frrqe7KtpC2W74y6swUOjr1dBCmm8fioWdjm547AaTMrxqmKaHSv2eUFBkvoFMi_nNCRT4lWDJW4YhdBYN_Pq6JMZ4RS2ftA-0PyE6thbOVJ95Cm?width=640&height=480&cropmode=none)

The machining sequence for the two ends needed a bit of thought and the first surfaces to be machined were the curved ends. Holes were drilled for a centre pin to align the part on the RT and the cutting of the radius went well:

(https://sat02pap002files.storage.live.com/y4mA_Rk1h1AWRPF1oGwSJrcMVYIGBa0uwL3N_NZaERTbkCFSvjselyQfmgc64Fv5LW60OqucrkTMiOaS6JM2LxvoUGeEpYqvdOfpm3f6PcnD3tXn_UQba_PjSXdxwMHjFOkAkjLDhWG9JZn-dexW64bgFXl0BUboGfjipeL-Ctko5Bh9p9QZhjLWydinTZ5ZzPg?width=640&height=480&cropmode=none)

although my miss-timed drilling of centres for machining the shaft can be seen and those had to be re-done which was one of those tasks where a universal mill comes to the rescue:

(https://sat02pap002files.storage.live.com/y4melobSk3U7XH_fHITLkvHFs-jRZjJRRlDkgJmEG-91kRsEBXlou8mdvEgbU8tlkdTNj_DH6AbkSaVm-GytdkTU5uJkfhN9CcTdJKWkZTWGNOB4e5I-cucmQk3MZkO6HMuhgx_tQl2QUskJTiIZC7IE8PI4iEv9k4HpRdhREY6xHaFJts86KayIZZihKXrxMfh?width=640&height=480&cropmode=none)

Mounted between those centres the shaft was first turned parallel, the internal ends roughed out and the outsides of both little and big ends turned to diameter:

(https://sat02pap002files.storage.live.com/y4mVlJSavvaln_23WhNjbNZryeiUcS6YY1J0lg-YWZi7bWMNqt5CcTB1jFlvvxs_YADVhP4Wm8J0Zf1VzY-yue5bS1fjrrQhuLjuPwX8ZpNjcgNF5U6jqNLJVWRVCSjSQRLPqciq4Wb7CJvvCQOh1llZgpTFrHuGY-KAWQRIqactBbUg8L1R_IADeq2kKTNDx0J?width=640&height=480&cropmode=none)
(https://sat02pap002files.storage.live.com/y4m_q5HLF7HZmlFiUmJyODpeS3nsdDFxHJNlemqpVo5Mu9FJ8KvqbL82SrNT0mPL5k_tlv7oiD9MT1tyGdIXqUO1mDqDaktcFpmzq1W37qxMFziIrJXyOyjwciFsoKGvSIKywUwt3mKB_AH3T1qASEuhgVDhT8MdlD_3WTEb4-AK-6jDw7Dr2LVU0u8dMPJM9vj?width=640&height=480&cropmode=none)

With the long slender shaft looking like it needed gentle treatment I, at first, took things slowly which gave the "unknownium" a chance to bite back. As soon as I slacked off the rate of metal removal the damn stuff work hardened and lumps formed where the tool didn't penetrate. (The second picture shows finish turning later on, I'd used a tough grade of carbide for the roughing). At first it looked like I'd have to start again with some FCMS but, with nothing to lose, I got brutal and a big cut went into the softer stuff underneath. There aren't any pictures of this part of the process, there was too much swearing going on. With the trauma over the part was re-mounted with a set over tail stock centre (sorry, no picture) and the taper turned, no messing about this time!

That's enough for today!

David

Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on November 02, 2020, 09:27:06 AM
Hello David,

Nice to see more progress  :ThumbsUp: but have to say looking at those burrs thrown up don't envy you the task of machining and finishing the two pockets. Certainly sounds (and, by the look of that spragly swarf)appears to have a stainless connection there somewhere  :) Lovely stuff  ::)

Just coming to the end of all the ferrous parts - lots of litle brass bits now.

Good luck with the remaining ops on the rod

Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on November 07, 2020, 11:14:19 AM
As Tug said, the next task is to dig out the pockets for the bearings and wedges in each end of the rod. Like Tug I was expecting problems and thought I'd try these two ways - it certainly looked like it was going to be a learning experience. The first one was started by chain drilling with a 3 mm stub drill and using the DRO to get the holes very close together. There was a lot of clamp juggling going on for this:

(https://sat02pap002files.storage.live.com/y4mGVo4uj_38oYZmKcmgUbCuBH5SHFwawzeF9HfnAUvu6-9vdREEeduINErbMxO6x-80C0xRdsjgM51jl0RU1TX4QZLNGMsi__fiCKaRGGKRT_GD9Qy361Bkxao-xXoJ4YVrvk-m2zplUtEHLYrbWRl0niTrtFpGCz6gtF8VnHlI88wj8iis3pZis_VucYouT-E?width=640&height=480&cropmode=none)

then the scrap was knocked out and the rough bits cleaned off with a 3 mm endmill:

(https://sat02pap002files.storage.live.com/y4m4OH1RAgrZhxWbvLur6BPqS8a-XwAYYTKefRg276GtjLo96O4nC84kI3AVFKpaMJw0pUVBws0CgYJ4CTf3Xgl2sJzjok1Jk29e-fd5zGNQugPCoaN_XR2JanIBcZUmWo9HFMhtW7FVtWkGrtGVUiIwHxHFT9ngAnGa2nK9yOB64kR9Kl4xokzU-XAy3-e7Zih?width=640&height=480&cropmode=none)

Either the drill had wandered or the part hadn't been clamped accurately because, with the top of the opening to drawing, the lower end still had slight scallops from the drill holes which are just visible in the picture above. On the second end I used a new centre-cutting endmill directly. This didn't do much better, no scallops this time but the finish wasn't that good:

(https://sat02pap002files.storage.live.com/y4mC2wCFS3eIblzRhbeErjsCSGvp7vQJuBC_bUcs0qTJOtFreWEMHrya9sCKb7KjeCYMR6VQ7a4zTXZLMutvCYeJTeCBsmKtE_eBPSfAnkboM3xPPv8dXoo9cUqr2liyYLE7ww-nE8hp99tLtxb8Vj7tY18uYw6e9gIvVhOLOIVChPcvv4sICpAp9x7pTxgODKg?width=640&height=480&cropmode=none)

However, what those pictures do show is the result of successive grades of wet-or-dry followed by Garyflex on this otherwise rather horrible material - it takes a lovely satin finish without excessive work.

The little blocks of steel and bronze for the wedges and bearings weren't exciting enough for much photography but the sine vice came into its own for cutting reproducible 16* faces for the wedges:

(https://sat02pap002files.storage.live.com/y4mhkn89EPSfEm4uUC5LUuZmkGYstY3lqqRoME_7zcjFEhGdeEDFYQKfla1v4okmRAX2_y2_XAlOiWJiCwxuZU0y8q73GTBaTXasMJp-uEuDsvSWpkhh8teA6GSoklc51FkYNXjmMDTQS1XyaMvRy4M4EUB6isNGch9mTqpJ0otNZGbVVeDpx5SNnQWT91LvE1o?width=640&height=480&cropmode=none)

Close to the last operation was to drill and tap for the wedge tightening screws with the bearing bits wedged in their final places:

(https://sat02pap002files.storage.live.com/y4mG0j7tNrAHpzC694_NIwzcX16VXZf80ogG6UMB5r_NyXzfEn-IN_SniAAtkg6dOLw6u885uXSD_MmaQ_HLFFkf7fcHRvKAmbzPGrPnwvFRrvjIUy4LA7QQxu_SJEnn2I82Ln4IqSAdxLwzeeUpjkEUtJZi8qnT7Vm1McTueZsp32jdt7pdJEMD7IVb1j9C7Sm?width=640&height=480&cropmode=none)

Sorry about the colour shift, lighting is dim and mostly halogen globes in the far recesses of the cave.

Now there are just the bearing holes to drill and ream and a couple of special screws to make for next time.

David
Title: Re: A Tandem Compound Mill Engine
Post by: kvom on November 07, 2020, 11:24:02 AM
Surface finish on an inside pocket doesn't seem too dire.

Stressproof is an excellent material for parts like that, assuming you can find it where you are.
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on November 07, 2020, 03:37:59 PM
All that effort with wet and dry paid off David  :ThumbsUp: - those radii came up a treat and good to see those pockets didn't cause too much stress (on you ;)) either

Very nice bit of kit you have there in that vice, that's one milling accessory I could do with at times - usually cobble a toolmakers vice in the six inch ::) Works but not repeatable with any degree of accuracy - whats the make of yours?

Not long for mine now - just final brass bits and the pipework to lag left to do.

Regards - Tug
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 04, 2021, 05:08:16 AM
Thanks kvom, unfortunately 1144 stressproof is unobtainable - at least the couple of mentions I can find in stock lists are for odd sizes. All sorts of supplies are much easier to find in the northern hemisphere.

Tug, sorry not to answer the sine vice question earlier but there aren't any markings on it, generic Chinese product I think. Despite that it works very well and makes accurate, and reproducible, angles a doddle. Now your engine is finished I really have to crack on  :)

The connecting rod looked like it was nearly finished two months ago but house maintenance and a nasty bout of gastro took a month or more out of that. The final little bits of work on the rod seemed to drag on and on but we're there now. One of the adjusting wedges moved in the vice and had some shallow gouges so I remade that; this time on the end of a larger bit of steel:

(https://sat02pap002files.storage.live.com/y4mhkn89EPSfEm4uUC5LUuZmkGYstY3lqqRoME_7zcjFEhGdeEDFYQKfla1v4okmRAX2_y2_XAlOiWJiCwxuZU0y8q73GTBaTXasMJp-uEuDsvSWpkhh8teA6GSoklc51FkYNXjmMDTQS1XyaMvRy4M4EUB6isNGch9mTqpJ0otNZGbVVeDpx5SNnQWT91LvE1o?width=640&height=480&cropmode=none)

You can just see the dud first attempt on the other end of the stock, 90* - 84* = 6* NOT 16*  :-[

After that was in place I polished the rod ends and tidied up bits of scuffing it had acquired on the bench, then made the adjusting screws to end with the whole looking like:

(https://sat02pap002files.storage.live.com/y4mPg47BOvQFedyuXhWk1GSkpRf4lwZfFgPPqXJE_i9zXJf6BkcyYHm8zZYDbiHYo_foNhM1283r-R-VUZ_3lKd43FTtcsmxO8pVHaBcLkWpm_3laz_TLLRN9kKtszHPNIDNIKjjRhcSekwfBC49L_fiZpGnStC7F3r8aAIpf8AYQzZSH68m0SgXV1rQDGSVCNq?width=640&height=480&cropmode=none)

The other bits waiting for finishing were the eccentrics. I gave these a fake split line with a sideways mounted tool in the lathe, polished them and glued in some fake studs and nuts. The fits on the crankshaft were almost good enough to prevent sideways movement but I added M4 SH grub screws to make sure.:

(https://sat02pap002files.storage.live.com/y4mak3toCsGyY3J-1LmlPRt_L7jsXTSUAvjY4Oi0JKKFqEpiLE5WDZksV7KHI1pGdlmsgwDQfVKTMZOWvpMqAYiKaJD7-C7twvxzaGAY33WwtnO7Ac8QM93xSyfuWFMabUlOoU6sjkhPKhWYZpR2XXKFvpikwOShF23AOuNY08lU03dli7azajaIaZSLzmZSxW2?width=640&height=480&cropmode=none)

I'm not entirely convinced by the appearance on the bench but when installed not much shows unless you really go looking for the detail. All the bits now fit together:

(https://sat02pap002files.storage.live.com/y4m5YNgmh2z7fJvSLUnPx92HX6jPb1GteSLj1AQ3lPkWmlEDzxjCfgLxe6wYKAs_U8_l6sY0PwcQrWIRtORVU1_JgRKqeKcxOjQ_IHKxvjWCEkMIclFta1YfXnlAz5pnzvbsr7m9MJAzc9fx9XSQ5MduXU41jNRRZdLS_ttf56zifbVRw5mDKZgz0HFUev1KBwT?width=640&height=480&cropmode=none)

The crank is still un-glued as I want to check the alignment with the slide before committing that final fixing. Now I have to take the base plates apart to drill holes for the slide and valve rockers, at least those bits are simple shapes after the con-rod.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Ramon Wilson on January 04, 2021, 09:31:34 AM
Ah, looking at that it's a real case of 'deja vu'  :D

Good to see you back home with some time to spend on it David - your con rod looks great and those eccentrics look fine to me  :ThumbsUp: (BTW Incase you missed it - I marked my shaft as per Peters annotation on the drawing and set the eccentric (CL marked) to them. Have not had to move either eccentric)

Thanks for the info on the vise - a forthcoming birthday treat to myself I think ;)

All the best for the New Year David, may it prove an ever improving one on the last and that you get as much time on your engine as you can :ThumbsUp:

Regards - Tug


Title: Re: A Tandem Compound Mill Engine
Post by: MJM460 on January 04, 2021, 10:42:33 AM
Hi David, sorry to hear that you have been unwell.  Glad you got over it ok

Good to see you back on the job and making progress again.  It’s looking very good.

MJM460

Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 25, 2021, 01:20:16 AM
It's good to be back again but there is always something to distract me from the workshop so progress is still slow.
The bits for the slide started out as the usual (for me) bits of scrap bronze and steel from the hoard along with the governor body casting:

(https://sat02pap002files.storage.live.com/y4mlx6HXqqZ9XPHH5PnB9pARgNXDFQ-FcFyP8eDhyg5puportqB8uBc4hRffR3uTFTL1PU0HfMVcUbEwWAQnDANp7o597cYtWlc0TCkFEaQ3X_h3gXfY1_Q2MDQyMo4B9mW44gp1AiGg0YX2qEQ80slfwGPB75pA3XGjXJ935GtqtyYRidi1pzApo0FdSI3VNrI?width=640&height=480&cropmode=none)

After using the bandsaw and squaring up on the mill the three parts of the slide start to look like the final product:

(https://sat02pap002files.storage.live.com/y4mlQwkQlTJjH75f9XDuIM4LyizobszhyIB_jnG7Vs1FS7LSKHqg9fwfvRzMs90HwRKUxAajqQdD063SZeOaGTfuMuiocdOjaPtRn8653h236i3MmF3CcbwZXz5eVHqiV5dXQoNPVcDemahg_o4kPkK3SOQcrOx_0HZPlKo6PdydqccYbKGauuTwZqVrKvzTycg?width=640&height=480&cropmode=none)

The main body was simple milling, as close to drawing size as possible, no pictures for that. The bronze slipper I increased in thickness from the drawing so that any contact with the keeper bars would be steel-to-bronze, not steel on steel. Accurate size is also needed as the four screw holes need to be accurately located in both parts, CS head screws don't give you any room for error. The marking out was as a sanity check as the DRO did the hard work:

(https://sat02pap002files.storage.live.com/y4myW2E-sh7iheOwtoLnizAxomhhGPo6Cx_wH9nR3HAHeCTlSsVs5-XRaYvwpDoHyyvqHrCBi3rlgHh__oV8QTPYB-FfvnHpFjisCn_tzgUGL6jf73jiqZc3BoTBeGBTA6T50dvmLyJpSuOJt20WaacT6e30yhZYbvnlVjT7OBr5ODh6l9PeWk4Jo96NTLbYjaW?width=640&height=480&cropmode=none)

The crosshead itself I made twice (measure once, cut twice wasn't it?) and has a lot of details to get right. The pin hole is reamed 1/4" one side, 5/16" the other so that side had to be done with a D-bit (I don't have any Imperial machine reamers):

(https://sat02pap002files.storage.live.com/y4miKRBw9y6jFx1KJgWdowl-iuwi-X8YH0czSEbajRHdEX2VMKIJr6QU1G5xUmSstfX8epy4K7z37MXO61-O7LWfSrWLVHA398L9oSMDcKxNQIi3qptcJjxgj4YcSpNjGzzn1mb15u6EwptwlTH-lH9X9Kk1bHwQPGimtClz1JYSbBUDFMOij7_2lt9hDNbjYWX?width=640&height=480&cropmode=none)

then the slot for the connecting rod little end milled out in one plane:

(https://sat02pap002files.storage.live.com/y4m3hKynQdCSs8ZbyWJejf6hAZDo1xm8CJwpPq2-K8AF2_pxzvTZ930Jj9p71cND8l86-BCKZvIcHSWdtORxs2GbNW13TVeuRKO1CxkoFrzRsp8AqrOELayF1nmVMvRon-N-A7eyR7DemzRYcF31Sigep1k1Ppyaofxl7Thw56jOuz_BuMUMmadQqM8p-xa7cWZ?width=640&height=480&cropmode=none)

and then the other to square off the end. This is all quite tight around the little end, can't leave the slot with rounded corners:

(https://sat02pap002files.storage.live.com/y4mKpzy4dTQ2ihJi3GzslBlsgxRJPAKnoPxNiNnPr32VDMi2ArThi5SH5s22KqaRZhk9oKbpuuy3ZqF00QfaOi5zgVZi7tF1Na54nAmLV8GIKfH0k2YnDp4QKq3GCCAnI5isMCUBoJfysyBsPLP90pf9EdQZRaJJbPFWXDi6m7nq9z1w25j2ePJ6yPiNY9DPxwV?width=640&height=480&cropmode=none)

The slide body has a slight taper on the ends, I left that until last and used the sine vice with black marker to indicate when the cut had gone far enough:

(https://sat02pap002files.storage.live.com/y4ms5src1fzXNsmgdvmE2L05knq6JyHfWLV26xP0dPhCGBkWF4bPjF_6Bw1K4mH3Fy6_SM1AlF0In87VOJg2yNGwOJygbcX4qtF8TAzMn5QwJOlxNTtYJnMQOMatQFUuymlk_1pSePbQD59vDxNkXBgJHzJW59aHGyJKNQXtjZRfY3OKs05uDkrpdJL8qbfwdY_?width=640&height=480&cropmode=none)

Having the four CS screws and both bits line up gave a good feeling:

(https://sat02pap002files.storage.live.com/y4m6Ec4kEMIgO8GIFdhsrWUwMoSvElWWOkZjG7OGuVX8h2VQBRLvyuh4W-jVTaDYTIlb_wcGGo38HDplbisdC8qE__1IrVOR-iKh3vlIqhs-UJXiVkHQnP7LZ4L_1AAxoM6PYVR86HSJyDtnkdvXAjutB4WHklzY_klKt9oJODwCRDVcJSs6klmhCNqCfuPGxGh?width=640&height=480&cropmode=none)

and having the four 8BA studs fit spot-on improved the feeling again:

(https://sat02pap002files.storage.live.com/y4m1gXsJS84L3VDmdzfwdSGdq9vVnXy4OuVasO03FVQwWKGLe_HmWYzEXggOzPM2KtzA99zlzvH27-J2AJ6JbBLfo1B_cDhENzqRqU7iLGI3bRw1ISxMZy6KNfCg9l0eX9AUSEAi2RcZmzJWI-4jsAbItoANtEPh56-XwrHOBsWlsMT2bNouAWW6k7oG1dt6Dke?width=640&height=480&cropmode=none)

The corners of the slipper were rounded off to make sure it could travel the length of its slot.

Interruptions and errors aside, this all seemed to take longer than it should have but the result is satisfying!

David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 14, 2022, 04:24:30 AM
Crikey just looked at the date on the last post, nearly a year since I last reported any progress! Hope some of you are still watching.

When I got the engine assembled with the slide I found a very disturbing wobble that pulled the crankshaft from side to side. This was "one of those times" in a project when I must have needed a break and I simply set everything aside and moved on to other things; there are plenty of those around here.

When I motivated myself to go back and diagnose the problem it didn't take very long. I first suspected that the con-rod bearings were out of line with each other but work with a surface plate and V-blocks proved that one wrong, alignment in both planes was very good (and very pleasing!). Spinning the crankshaft between centres quickly showed the crank was wobbling, how in Hell's name did I manage to drill and ream the hole for the crankshaft so far out of square? Anyway, re-drilling the hole and making a concentric steel bush fixed the problem - and removed any excuse for not making progress.

With the con-rod sliding, and the crankshaft turning, nice and smoothly the eccentrics needed the rods and brackets to extend their reach towards the still imaginary valves. This lot needs to end up looking like:

(https://sat02pap002files.storage.live.com/y4m5rYe_G91YC-AX0K4-QdgXQWl3jnO_7qH5H6vJrAJnW2V0M7afGxUXv-yDjpGmdYitBA2nmyDKU7N8XHkcuruw3ayiLz9Licr3bGmP9VYTkoxFnxYdjwD-cwAzgVOv0JVKUrXoNgMx6wfPB8-w2t4YNO2T3Z762f4zuiSJLSBPGf_VZ9HlTgeMvIK43-maeEw?width=640&height=480&cropmode=none)

The eccentric strap palms were carved from the solid on the end of a piece of bar:

(https://sat02pap002files.storage.live.com/y4mN31pOsKcjTCra7-b35J5i0VPGwvxpDX9NzuhSjm3XCZw94BQa8q4kFEgoW46wvLN79ZAq8UVO1mca_q8LMEK9HNkP2c9MI43Elosuxcdu3iX6Nrj0rfvWhaY_7eaDD7ri6LA8G4CM3pzVcvxUSzq7gZ_cj470dYMOmUUVVfqiHFVeRpNonKyW4EwWLMrnu-b?width=640&height=480&cropmode=none)

parted off and cleaned up to thickness:

(https://sat02pap002files.storage.live.com/y4mOjJPI7I0xczZe-kGeIAJDsSG0bvE5U39AvrXYRgB3T-H3MV16hqaYMmMgE2lYagCd0BAEqeW5dvPjiUaUtiXC69kClH3d8GILsWAgw8mqDPG4qwYD5nUdpXv1q_zvauwJuAVu3cCEEKrhzNzYt9JeZAc-FHru2I9Ch2UvKv08oHa5bRohp67LGsljkLFMqkN?width=640&height=480&cropmode=none)

with the sides squared off and the stud holes drilled these improved the look of the eccentric straps:

(https://sat02pap002files.storage.live.com/y4mXvFASkOqRtMvPfpEV1PLmKIa5qx-ilFq8gZ6q4NZ3gxJw73boTw3Z7iaKqJmHEkFRmWQsvkQGFSbkpwaIs1ThgIzG8ekXiHFb_inqIFuBEwNWw1WZ87R6wJvJZI4U2K6eo9heusBxfNkIymGpHkIR1c1xTI4kVp3cn9I-CN5UDCkPW-WklB78_He8OyN651o?width=640&height=480&cropmode=none)

I'd bought in an offset tailstock centre a while ago with the tapered eccentric rods in mind and the rods came out of FC stainless rod with shallow cuts - mercifully it really was free cutting and there wasn't any work hardening:

(https://sat02pap002files.storage.live.com/y4mGCGuOW4i334gKCg-pZ7jOTivQBRmoDqzsU3yEOK04v8tspbndKk7QczVX6a2ZU5kla0M2_he19r-4bUvGBuUlPywNJEZHBKFVyUDxtokWF4u_4LtnacpLuyforr2ag9BP1hixGUYkhfb5klBXuasX98JnOQb2DQ8r-z3E2JlaIt42YGe6GFMuwk_PdiM62RO?width=640&height=480&cropmode=none)

This all went together to look like:

(https://sat02pap002files.storage.live.com/y4mB9QvWvk2pkYbH1vxcw3LC6yqRQjdwdR-Q4Fji0G_WDvmlrWhPFeOGy1iASrNdKkj1Rll4LY_k7RHMhWiqAOM1_gwMhueTQQAGywnSJNObOkipnYSNTRsLNQZEHJ9hhY-c_ygC4QTfHYV9PeZ7P0e29khh8CdbJzM0Pz3tWe5002z02A4ZTvB9cB_y1uq4yZq?width=640&height=480&cropmode=none)

David
Title: Re: A Tandem Compound Mill Engine
Post by: crueby on January 14, 2022, 04:46:18 AM
Great to see you back at this engine!
Title: Re: A Tandem Compound Mill Engine
Post by: Kim on January 14, 2022, 05:08:10 AM
Nice work on the eccentric rods, they look great!  They certainly are long and spindly - tapering those must have been a worrisome operation!

Kim
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 14, 2022, 05:53:39 AM
Chris and Kim,
Good to have you back!

My first thought when I looked at the drawings of the rods was that it would be difficult bordering on impossible to avoid the tapers going fish-bellied. I was also doubtful about the "free cutting" claim on the SS I'd bought. Turned out I was wrong on both. The tool was a very sharp Crobalt bit in a Diamond toolholder and I had the RPM high with the self-act driving and the rods turned out well.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Jo on January 14, 2022, 07:49:28 AM
Crikey just looked at the date on the last post, nearly a year since I last reported any progress! Hope some of you are still watching.

Nice to see some more progress on this David, I won't admit to how many years it has been since I worked on my one :-X  and I still have not worked out what to do with such a large model if I ever finished it   :noidea:

Jo
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 16, 2022, 12:36:17 AM
Jo, When I first looked at the drawings I circled the cross-compound version as my choice. If Bob P had been willing to ship the castings I could well have gone with that one but Bob (and later on airline weight limits) saved me from myself there. Even the tandem compound is covering 3/4 of my fitting bench AND it is getting heavy, really heavy. If I'd started the big one I think I'd be changing my mind about now and making the two sides as individual engines. For some reason right-hand engines seem to be more popular (could be wrong on that, just an impression I've come to) so a left-hand might make a change. Just a thought...

The drive to the valves is split into two with a set of rockers mounted on two "fulcrum brackets" to use the term from the drawings. These came as a pair out of one block of steel:

(https://sat02pap002files.storage.live.com/y4m8TFTGi5sr9N1Qq1ubCB2jFZJN5roN9cYJh7NPay5UQwqsFj8cX5-Fpcfsze-MVkhJUpLZjtHrc0GAWyVqp0sVvs8NwLIHtRWo5ItZ8YQnpWLCSfSGcbs-YlOlbSycihuO1SvIyYViQ6WOh6-Y3ng2gYtfhm4YAHht98Al8spKDR5SCxTe90oqF52PtABnhVy?width=640&height=480&cropmode=none)

holes drilled in two planes:

(https://sat02pap002files.storage.live.com/y4mJwkfCXmwBvuFcaJMSjXG8-VZ6L_RkiFX05k5bC83oqF9eIgexxZ8cnvj09TufBTMdXQVoOHx4KTJbsTDbewcVY0mcaDDXYE_BBAcJT20uyrq3bojv0AFEZCooYdcCLtdUu-I2bYXUIPJg5h-9mvcP-p7G3N1tntAMh3Fq7iEGfEvusWMuHqD8tSivcot_fBS?width=640&height=480&cropmode=none)

sides milled to the correct angle:

(https://sat02pap002files.storage.live.com/y4mmpixjMXjRJ5d7qTwaNjGxqhoSAwnKy-CuJF1gk_I8KE0G2xGL1XBEHM3hRRISl1VTZeFpIoSMp1FyeQnH20NGzs201DkAXgkE9VEVVEf15ou-0k_gX_LRVBViGFnLAZk3VVrkGx95USd4pJNCMXym02cm5bzh7BJoNxAUMupft562nEeSbdDpb45GUlf59o7?width=640&height=480&cropmode=none)

which gets the parts to here:

(https://sat02pap002files.storage.live.com/y4mdJlzuKDE64KkM_7W-AMgyFb4Po4Ojgvar6wVL_4Dkw7RjjTjM7MN11QQB13bVjSSRtcN_qsva8F7uvC3CyNhU_qKOsmVnwYiYM8EMJkmARTAI_Zx9yvPKk3knc8ptzg89MGEKEJdChVjDMuPNU7T06DMlata7FLqrJ0kz-g8YkGDJj2a9gofMkfowSBS-qtL?width=640&height=480&cropmode=none)

which when cut in two and filed with the help of buttons look like:

(https://sat02pap002files.storage.live.com/y4miZwx2LZhz9kPxCqV4jb6GyJKtL0YwCm0trRxwdlDJ9ceYe7K7xaiQZBvSYMC_QjWPiH4_di6hYeDAFQrsXlV9sW2bwe5SDEaGkXOePbFI7sEyg3u1jo9sHi_BTf_lglYkpZRW3QxrVQvuUq1kLDsMKoeRSLbFcCFWgn6F0eO3OZfCfkolUQFCR99h-RQkGpj?width=640&height=480&cropmode=none)

The rocker pivots and shafts were simple turning jobs and then the fit to the base was tried:

(https://sat02pap002files.storage.live.com/y4mGcg2MkQ9f9Wd6SoVpZ7YxhTH_96Q3qWKbDZMu39roVr_V-0glFQAThwzO4BHzdl4x6y-F_P8m_ECei1-Z5P0Zgmp28caqzwvEv_eDklLWS7NckaHKvfxgU-YP7X6AI9qDEhipKXfjrpJOoLYXG-HWXz-JDzJuAlNplX9VTpqIIcGxMdlfvtAux00nmV2cIb2?width=640&height=480&cropmode=none)

Only small parts but very satisfying to make.

David
Title: Re: A Tandem Compound Mill Engine
Post by: derekwarner on January 16, 2022, 10:49:23 AM
David......an image from a few days back has some intrigued

May I ask, what are the hexagon double-ended inserts in the edit bigends? eccentrics?.....too simple for a screw-in grease lubrication?

Derek
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 16, 2022, 11:11:33 AM
Derek,
They are meant to be dummy oil pots. The original drawings show a 3/16"x40 ME tapped hole with an oil passage through to the eccentric but I can't see anything drawn that would keep the dirt out. I'm pretty sure the originals would have been be lubricated with oil rather than grease. I guess they'd look more convincing with a knurled top rather than the hex but I don't have a microscopic knurling tool. I'll think about some of these little details a bit later on. I'll also have another look at what Tug did with his.

David
Title: Re: A Tandem Compound Mill Engine
Post by: steam guy willy on January 16, 2022, 02:11:20 PM
Hi David , When I need to reproduce small knurlings I push a small /medium or large crosscut file against the round part and push down really hard with the headstock free to turn. The file needs to be quite sharp though >>>>

Willy
Title: Re: A Tandem Compound Mill Engine
Post by: Jasonb on January 16, 2022, 04:19:05 PM
The wheel that usually runs against the flint on a lighter makes a reasonable fine straight knurl on softer metals.
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on January 18, 2022, 10:42:23 AM
Willy and Jason,
Thanks for the tips re very fine knurling. I haven't owned a cigarette lighter for a very long time, I'll buy one when I get out again and have a look.

It's also a while since I had any really sharp files either and they aren't easy to find around here these days, I'll have to look on line.

David
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 23, 2022, 06:28:23 AM
The various valve and eccentric rods are supported part way along by rocker arms that are pivoted to the brackets described in the last session. The rocker for the slide valve is a single piece, for the HP cylinder the steam and eccentric valve drives each have their own rocker. The original drawings don't have any suggestion as to how these are to be made, probably they were intended to be silver soldered steel fabrications. It was seeing Tug Wilson's model that started me off on this one and I seem to have picked up his liking for JB Weld as well, so the rockers started off as rod and flat strip:

(https://sat02pap002files.storage.live.com/y4m2eAYBAnpWwjrWuQtsaXbeDqbRuK_b-XSe-nJzEVkfstIC0INkW7wEe1W8Z-6Fu1ikBFSzxdP1vsaiS2TRDuf5tUUGXQZ3OE71LN9tQQ9auwEkF8EMy92KPJFdmp32ATHEBZvGOxFT2aNSvkdVGpV3He4xVQkTbivhscu_um1XasFev6wSC_86fBD3sCKoZyb?width=640&height=480&cropmode=none)

and these were prepared by drilling and milling:

(https://sat02pap002files.storage.live.com/y4mBWHOmq1MGCoaK7HxjaCPKdC7wuppuKKaRYtyPS4_9ulMKzVv2qlTK2KzjIkveLdAp3r-lCK_dMBVqUPg1D6L2wkqCuYJWYVerA2toF9AF4jvI3UpHAMru0hSa74hhVjuQZ5Se3ppo3FqHlGy5kzOV9JmG0aEnX-35Vysh4R7a_WO-uD3J_pxxX1Fce45pUNX?width=640&height=480&cropmode=none)

(https://sat02pap002files.storage.live.com/y4mzzd9S55H--C30ScIZ0aAnjz_Vn1sXqCkrytvvu_oOvsJUAT7Bw6-tCNF8Pp3KR-FCi41-BazG4EnvKYeTHJekGhZrayR082ghSJkdHNiKwBG5FBqChNDZd0iX42hKoEqwCwRRsxFyDZ3sfGFF2Vt7_iQmg1EClfXzOW1VOZ7Nj8k1ADGflubkj4V-cD5F3Pv?width=640&height=480&cropmode=none)

then the arms and pivots drilled for pins:

(https://sat02pap002files.storage.live.com/y4mogZ57QRYE38m_SF_zTBj274OhcqE_af7kxQulFlwq3oOgl0e2f-JMx7FdKK639AQLmHmuVuMoqg_a6h0cbKlLXqJrbnpU2f0qVWL4uEg88RJ6LadwFpOzeCfRjXiyeMTZcNpJGgZMPtASiSLKN_84hpllXey2ijblksdUd65bulv6I-7cpeNSfoMpz8cC8We?width=640&height=480&cropmode=none)

I carefully avoided handling the camera when JBW was around so the last picture is of the finished slide valve rocker:

(https://sat02pap002files.storage.live.com/y4mWLw1Y8fVybtq8jAT7jL6Lev90yqhz15JzYe5KfLM7vQlpvkSdbZYlQpn4EdnJrC4kCaYMoZwAHETofEHx5VjluK1pZXP2_C2P-hJ2dLyNh9CmCL365U8HmAZEwdyF85wzxs_7TVUEF3SEDvdPmbxpdZwo4JpYY0LTjINRZ8DX6hBZw-EzVyJDDuprQiqVKNM?width=640&height=480&cropmode=none)

Most of the fillets of JBW turned out well, one or two will need a little bit of cleaning up later. The pivot pin is shown because I made those first to help with lining it all up before the epoxy set and that worked out well.

Next it's back to machining the last five iron castings for the HP cylinder - more on that later.

David


Title: Re: A Tandem Compound Mill Engine
Post by: propforward on February 24, 2022, 01:28:52 PM
Excellent work here! Great progress.
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 24, 2022, 09:38:16 PM
Thank you Stuart - all and any encouragement helps!
Title: Re: A Tandem Compound Mill Engine
Post by: Admiral_dk on February 25, 2022, 11:14:25 AM
Great looking progress David  :ThumbsUp:

What's next ?

Per
Title: Re: A Tandem Compound Mill Engine
Post by: wagnmkr on February 25, 2022, 11:53:22 AM
Nice work so far. Watching with interest.
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on February 27, 2022, 10:29:49 PM
Thanks wagnmkr!

Per - the next steps are to convert these:

(https://sat02pap002files.storage.live.com/y4mPzUUEecJjkwP5hvVYwVEjtINT8PuBoIC8FFBTPKIkCMFcoVFjPmq7cJ8l1dhkQ6kjYO_cISih3cGLxwPp3Cy2HCLtKS_mtzdhbF8wra-j0ZWWTDVtTmlRGRACgh1qi-9a88BJX7QHZ9-KV5DRh7FQabkFotLNwPt0AHYQQ4TwhhvELWlZX9ycY3dKOOVYgZP?width=640&height=480&cropmode=none)

into this:

(https://sat02pap002files.storage.live.com/y4mojONM0Z8lIyhgDZ7N8DaxhUhzlb2r5X547_SeZOuMFC8a1Mh-k7bPISOvmMcs7DvZlqB1sHrrbXFJ-X4lElp--6ueGtBG9dNYUW3MELOOSU09xA6j1oJUG8p2rLtkyRLRXtZcW5aDQOQyWYQAX9inLp1WN_8hAxbsg3o7PJK3gsHtLjJv2URmFfcyCGkCtvc?width=570&height=480&cropmode=none)

which will need a few other bits and pieces along the way.

David
Title: Re: A Tandem Compound Mill Engine
Post by: Admiral_dk on February 28, 2022, 11:41:59 AM
Ah - I forsee quite a bit of measuring in your future - make sure you get your datums right  ;)

I could see myself using a lot of time to contemplate the best way to solve this - especially the cylinder with all it's holes ....

Still following  :cheers:   :popcorn:

Per
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on April 05, 2022, 01:20:51 PM
Yes Per, there's a lot of measuring going on just now:

(https://sat02pap002files.storage.live.com/y4mGxsWMD2iIH4TU6hPJVLqZd_TbxYIw1emO0aEAwwUoJt2eVtZC3rKYC0F602n4qltaLc6bJHQ-U7IHxOINVgAVom8wOTD9WF5Jphta31h_ya2ogkv-Ugys7r5LwVbwdUZoopz2oNjNCoSpud7OUYvPLYQc_Nj0_xpwbEkzNYqxrh7V-wuafKDJvMgcixprNzQ?width=1382&height=978&cropmode=none)

Any holes marked as on a PCD I'm drilling using the "circle of holes" function on the DRO, all others are marked out and located with the DRO.

However, before any holes could be drilled the castings needed any hard skin removing and cleaning up to size. As with others of this set of castings there wasn't much machining allowance (close to zero on some dimensions) so the first process was a lot of casting fondling to try to avoid mistakes - there looks to be little hope of any replacements.

The seven-tooth cutter came in to it's own on the cylinder block sides and ends:

(https://sat02pap002files.storage.live.com/y4mB0faDzNGLQXellzJU3u6QS2s8zxzhgKYVakh8xPNP6NinCYo7xGbVpx1AYIqAOVhiOoiOnorvSJBIQnWA9_-FOEVQ1-6QdoeG3ClpLaSHDRZA-d-vkF7cIL1U6ig1Rktw9ZrrYyXGvFmPB_ubw6pepBVdoo-87001gf8lmaY6qbI4FrvWN0FiDgtDSV3vx0-?width=640&height=480&cropmode=none)

(https://sat02pap002files.storage.live.com/y4m-TcQ6maeyD4qfxRRWpfrXgh5jPaax_lkGEgSUY7NWcrj135hhrvuS2mui-K8b9s96ggUIePJGZPLQ2Vs97bQ_nTh2MtkWv5PzOzbFpAEk2KvajZiCvK2-Jo-tLZryVCW2BgFl7uaNqJ-A9IS80z-_4Zb9RhJFI0mom9G4_657jmJbqOG7jP_zvPBcUSF6l9I?width=640&height=480&cropmode=none)

and the end faces where the covers have to seal given a good finish as well:

(https://sat02pap002files.storage.live.com/y4m7-Hj5PApBMk3C_C1ZHQFlNie9jU5qzq8kK8kyPXr5n3xRdwBaLbil7QVunV2vXpKzKm7lhIuE6k-MkOoefiPR65Mp-S1tHYE34jFI2M2ftRguW834zfHf3AGbGvJU7-K_tQbQQuIUdTYP1KtwmIT3-Woyjl4Bx8qfhJcdj5xa2mP4ecyXg85Xr5S5WLuNQ9J?width=640&height=480&cropmode=none)

Before machining the cored hole for the bore I measured the as-made centre height of the slide which turned out to be 0.009" low:

(https://sat02pap002files.storage.live.com/y4mmc6VhowA5Cm8B5ci6nqy1YIzVrYE6jsOOlw2dnRgicXz0T36IB3iduhynEo6piGteOQ6ahI1z20ZNZvj-btjfrufAQOcfjIl3s9QC1fxFv5AeAbpZkfc1wYE4vTRJwRORb53syoi7VFnuxRkWYm4OgL7feWxoZf0tmBlF9m6DP3Yi8o4K63nhU9aiOnBa77p?width=640&height=480&cropmode=none)

The other careful measurement was of the lathe centre height above the boring table. In the picture it may be just possible to see the shims under the bottom (datum) face of the block. The angle plate nest was particularly necessary so that the block could be turned end-for-end, my longest tipped boring bar was just too short:

(https://sat02pap002files.storage.live.com/y4m2Tqm-tUh_T68_sTqDEtcPI3GfKXvMz1s8FnQk28uAetrxIVCICmMB6fnN5J1PZ-wIUBBP6qaxm5gXJ1csmgaPqeP7BU5Yz-Y7bELtaPe-4A9YaDxhfFcrwgFXGhw-Md4naWxuNzIOQZlUecEZKuOz6RYYO4cbRCbDi6ZeKZMIPHNPBpeAUorRLDAGOxsjSsM?width=640&height=480&cropmode=none)

The bore was finished with a between-centres bar which took all my attention to get right so no pictures of that.

Before I get to drill any stud holes there is a lot of detail to add to (actually, subtract from) the block, I'll post that next time.

David

Edited to replace pictures lost due to finger trouble :embarassed:
Title: Re: A Tandem Compound Mill Engine
Post by: MJM460 on April 05, 2022, 01:35:09 PM
Hi David, great to see more progress on this one.  It’s a fascinating project.

MJM460

Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on May 06, 2022, 08:31:09 AM
Thanks MJM, good to have you along!

I had a major bit of finger trouble when cleaning up my directories on OneDrive and deleted the one that held all the pictures for this build. The originals were still on the local HDD so "all" I had to do to get them back was re-format them to 640x480 and upload to OneDrive. The bit that really took the time was working out which picture went with which bit of text and replacing them in what I hope is the right place. All done now so I'll get back to writing up the build.

With the HP cylinder block nicely squared, and the bore in the correct place, I could start in to drill and (mostly) tap the 142 holes that perforate it. The logical place to start seemed to be for the cylinder securing studs. Getting these in the right place needed an alignment piece to align the cylinder on the piston rod centre line. This piece was just a stub of Al turned to a close fit in the bore and bored at the other end to fit over the boss on the slide. With that and using a shop-made transfer punch the cylinder was fixed down front and back:

(https://sat02pap002files.storage.live.com/y4maMeaXEWEWoIqBQCR9lEWLqzk9y1_0tZEt_HtMpngAv7pSqkOUY4Y4l0t-aZUZem8dTR1J6e5DAwQ10HqnFmQITAG7z0fCjw4-9FsqDXa2Glw-sKle4pmyzd-3XRYTW871WIu8w73Iii2g9ehgy6LMiKvJiMGVe_8V1qT1LK-iiwMLkM0BG3ACF6eTFbewMnV?width=640&height=480&cropmode=none)

and checked with the HP piston and its rod:

(https://sat02pap002files.storage.live.com/y4mIN2a-z1grPDQzjPDZHwGDEE68Ig7bGhbSMd9IVZedMlKGrcx6pzcZefUr1_WwvB86aOI1UIj0_5zIPcGySMC0EWqbGpvKzQqTgQXovnLg2VVdxqhFVMDAf7S734vFhB7QfH_rt2Tlhr6u3eC8RTfrBq2AD1crmmkI1j2WIAn-ChYIInOu9n7_jdyaYWkDQOM?width=640&height=480&cropmode=none)

With some confidence that the cylinder would go where it was meant to I milled out the steam and exhaust chambers top and bottom of the block:

(https://sat02pap002files.storage.live.com/y4msbJnzSnQkSzWwBTj8Oylht020i5hozgZVrZwYsYjN5EjfjuAKOvBLJdWxLBPV_nREZSXKVxradYBcEhq8f7PwHlf8Y5RGztbzJZMYpz-8rnod53TBoKhPIcTW7s3zyBr4G74xZFlhshF62oY5Kkt2r11zo7P7t-mpodFfx0WL94-SqAcHIPCZmLdeftyTt0I?width=640&height=480&cropmode=none)

and drilled and reamed the holes for the valves:

(https://sat02pap002files.storage.live.com/y4m8LUake9lVJQvq4lWv9hXCrSNci_gimOLZaLGp-EjTrCsp4SvIjbIPiPLryNiREUYI5xjNiWuDJEzTm7_ggN3tcaMQEkLpTSQ8R7_VrEWmsg7levoXoNqJfYbzO5mXwgxFp4aNhP-8PS53STK8ZHcp63VZzjlB9aYJ7mo7Ywgb0V3Xc7oQwWv0Av5lq1JYYhK?width=640&height=480&cropmode=none)

The steam passages were cut with a shop-made cutter, first in the bottoms of the chambers:

(https://sat02pap002files.storage.live.com/y4mG_HsReMMxT8n4xUMEmJOzwwt7IXsf63Su2-58-kcD_IW4n2GRFi-mdZ0QFGL-wlB5IzRiACDwZ5JlpWwYEfQpIMy37uHIXfi2qHBHhFdlRqvpgji0wsLnuxvelYmbntRbl9bSTvXcKxVojHQK5z6ZkbFtwoRahUYrOSeDQxWnA6T7xltFEvJrRIudBggplWo?width=640&height=480&cropmode=none)

then from the bores to connect to the valves:

(https://sat02pap002files.storage.live.com/y4mu6sAuYkX-o0oSRyoBEr4JhKbXbD25LPzIbL3C8FOVIxLsBo7SHleGHVUOId_hS4gmuWZmtCyQJL-tS1Ks2_21a5r5qNxsNt5GsuSvF3T_DvTpJ-ZdMFX_8E08ut2dEvN05H8ssO7AQnDkZkMWuI1JjMomqnnKgh7i-TeUPU48vQ04nWmFxmKCWNpyNG_YuoN?width=640&height=480&cropmode=none)

Two of the pictures above have hints of the Brunswick Green paint I'm going to use for the final finish - hope you like it!

David
Title: Re: A Tandem Compound Mill Engine
Post by: RReid on May 06, 2022, 04:16:40 PM
I hate it when my fingers twitch at the wrong time! Glad you got it sorted out.
I like both your shop made cutter and it's application. Good ideas to file away! :ThumbsUp:
Title: Re: A Tandem Compound Mill Engine
Post by: Kim on May 06, 2022, 04:36:04 PM
That's a very neat cutter for your steam passages!  Like Ron said, I'll have to file that one away.
I also like the green color you painted the base.  I think it will make a great looking engine!

Sorry about the loss of your pictures, though I'm glad you were able to recover them.  That's always a pain!

Kim
Title: Re: A Tandem Compound Mill Engine
Post by: Roger B on May 06, 2022, 08:11:11 PM
That's some good, if slightly worrying, machining. Glad all went well  :ThumbsUp:  :ThumbsUp:  :wine1:

Good save on the pictures  :)
Title: Re: A Tandem Compound Mill Engine
Post by: deltatango on May 19, 2022, 12:38:58 PM
Thanks everyone!
The little shop-made cutter was 7/8" OD and 0.1" thick, turned from solid silver steel rod, teeth backed off by hand and hardened. I didn't try to reduce the temper any which was just as well because after use it was clear that the inner bits of the 0.1 thickness weren't as hard as the outside. The cutter did the job but needs some TLC before being used again.

The last bit of outside shaping for the cylinder block was to put a 1/2" radius on the top corners. For the first time ever I used the radius function on the DRO with a 12 mm round-nosed cutter to do the work:

(https://sat02pap002files.storage.live.com/y4mVJFGHVDKLmBQZH3zXMSOVlH7yKQIVmt8lcZb7uc91Oox0rpJ2IMKdtaM02wBSLyfrbK5_i6mwD25UpZTO3cnnjMlfMtr1pnxsMcJAuYrRmIuUsJgida8DFydmUVMdzRGuP70yi2dnkfZk4GDTWk2hNYVH_zRDnPmvZiGXQfNygIxg1uI1MME4bHucpNaQvGW?width=640&height=480&cropmode=none)

The process is tedious but gets there in the end:

(https://sat02pap002files.storage.live.com/y4mM1oBxMJa9MPckiNprn9N3Ei877HBDLQo5R3IndzF9xsshjhmRLLylVdDcNmYcZ1-mFWrPuE2_VMZkmNjFoQJFjvoBDrxTRRU9Jjoswi2nb1OVGXqFUSjdCwzMGc9Sp-bOOXEU_1KFPu7CXUHd7_xoXIDGqn7oV36PhhxJptZ2_hk17oyziFLgmpUhgd0uqpY?width=640&height=480&cropmode=none)

The finish is good enough to clean up easily with a file:

(https://sat02pap002files.storage.live.com/y4m32FZtKi6lpRNYIhOTFIYQbxMExzeaEH4uwaEA5gBfX6n4KMtBBleJ8nD7un8UauPBl2H6e8bPeeOEdPRB93ZFJ-wzqmUqbWXZPDNERIaxrEVFDvGWz_P1n4q11R7XJDBpJgL7MAO87mT70eiPstYWu3HeaGG1STJje_6xhHsXwopUAxjir7Uvf9xXvI4yvKT?width=640&height=480&cropmode=none)

The cylinder covers were two rather rough CI castings which I started in the 4-jaw to turn the outside edge and the chucking spigot:

(https://sat02pap002files.storage.live.com/y4mNlqQxDpNJLBNJL9Nb9gFVsNxAg0zBH8FVTKVJdZhY-nuUNIfULnck0FQJFgnHsd9Qr6Jk30gat1g3Gw3kgv4Im_yxWM2X_kMmOEt4DErDZmIx5wg8QE-zUvs0PJIoBIZFTJ3sCpGXwwadHjGBoSmXFPTVb4RXxdlTLn4XNSt-CtXcoxFIx-eNobEYVtVY1-a?width=640&height=480&cropmode=none)

turned round and held in an ER32 collet to machine to fit the cylinder bore (and, for the rear cover, make a recess for the piston securing nut to slide into at the back end of the stroke):

(https://sat02pap002files.storage.live.com/y4mxosYyU5u3zHdHkCjI8igh984IPEWrDNFf8o3IvwbMA491rFWWmN_-PO1ArJV8Ajodiz_TNnPs2p9uBfRt_3Pj3jx9y0ruwjh-f89rx5qsJX2Uy_Cng8tBDfgpkgiWCqfLGE8lm5FBOjTXzhP_0wBC17EPSBlA1CNbGy47WCgy5STjxAWA5DnYTeN2-vUwCtR?width=640&height=480&cropmode=none)

I kept the chucking spigot on as long as possible and used it to hold the parts to mill the clearances to connect to the steam and exhaust passages in the block:

(https://sat02pap002files.storage.live.com/y4mPbw2G0SQvVAbZ7w2n9CsWS3H1CKeinDwTS3M7wG6XvH1PqdUuUaAbbG4ylduNZwgGPfMely_iza8lnDLksBHiZYFOeIAmoWAwiZDpOyYUW9nlrWTPehqMrwPtQfo9FU60H7ZvC0KYlKuJs8tbYlYQDlLc_beuJia8Z9CImd9dWrPJduFe-tI5xiLJnsPQQ9n?width=640&height=480&cropmode=none)

With the same setup the DRO came into use again to drill the ring of 12 clearance holes for 6BA studs and three 8BA tapped holes for forcing screws to help with dismantling:

(https://sat02pap002files.storage.live.com/y4m6bwgXYdlWlIkmsIcCb6GdvMdaXEaAmqoG7ZSDJ44ooH5DPrw3UTfTwX5BYHcrDZY4uKqyu9dsweHL3ea5iei0KVY0XjadQ1_gP9WhXALCdAC5amzVzngxZ9Cx8JkJ98tzyf0N4uFuKjHgvPdu_Caup5X_qkbbMLA8PhhXMHuwHtW0FtzCQTE1wrMvOC5JxBe?width=640&height=480&cropmode=none)

At first I thought that these three holes were just to stay true to the original but when all the studs are in place it turns out that they're necessary, very necessary! The last act was to remove the spigots, clean up the flanges to thickness and bore out for the O-ring gland:

(https://sat02pap002files.storage.live.com/y4mg3rPLwhtZfmzdSBMdbgNTDp33aMcovbvCUogfHldBZNPXnHOCyfEG_cjQeEiNlogC31xYE-IMrVCo53VQuYVC2kONA-pb6JAoubL4l9xPGt7tPmLOPZxqtjzzrPX-Ar2qaOqzokGD5yR929lYbsKc8oLXqboIu7bftt3jPeWduC8JcSi6JUrQRPscoHQ2IfZ?width=640&height=480&cropmode=none)

Then there were eight 5BA, 48 6BA and 24 8BA studs to make but I'm not going to share the boredom of that with the forum, there'll be a progress picture next time.

David