Author Topic: Arnold's take on the MEM Corliss  (Read 134622 times)

Offline steamer

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Re: Arnold's take on the MEM Corliss
« Reply #90 on: March 03, 2013, 06:20:58 PM »
Maybe.....If it were me....I'd support it....Perhaps you have more faith in 7" lathes than I...and maybe rightly so...

I have visions of a parting tool digging in big time.......

Dave
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Offline Jasonb

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Re: Arnold's take on the MEM Corliss
« Reply #91 on: March 03, 2013, 06:36:03 PM »
Dave, I was not suggesting trying to part it of but purely to turn the inside, outside and face while its easy to get at with no jaws in the way then saw/grind off the bit thats needed and then finish in the lathe.

Agree parting would be hairy even if you could get the parting tool in the right place which I doubt.

J

Offline steamer

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Re: Arnold's take on the MEM Corliss
« Reply #92 on: March 03, 2013, 06:39:44 PM »
Fair enough Jason....

Dave
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Damned ijjit!

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #93 on: March 03, 2013, 08:23:12 PM »
Thanks Tel.  Yes, the angle-grinder is an option...  Do you know if cast iron will harden around cuts like this? - I tend to stay away from steel that had been cut using an abrasive wheel; lost too many HSS cutting edges that way  :-\ .  I had a look, and it will be possible to use my bandsaw to saw it off too.  It's MUCH bigger than the saw is rated for, but with a clamp and some rotation during the job, it can be done... 

Cheers Stew; it will still be a while till I get to that big bit though.  I want to finish all the mountings and the base first, but the base is a bit chicken or egg - I need to know the flywheel size to finish that.

Thank you Vince; yes, I'm going to fabricate the flywheel.  That will be a whole job on it's own  ;)

Jo, the thought has crossed my mind to get a bigger lathe as well...  Fortunately I don't need to justify it to anyone, but the problem is financing the darn thing.  It took me three years to save up to buy my mill.  I had a kitty started for some other tooling and shop-related projects, but life throws one all kinds of knocks and that kitty had to go to another cause.

Jason, thanks.  I'm not rushing anywhere with that bit; it needs a good think-about.  It's _just_ too close for comfort to the lathe bed though; I think I have about 0.5mm clearance; if that much.  The last thing I want to happen is something going wrong and I end up with a ding in the lathe bed...

Thanks Steve.  From your side of the world, it might look cheap at the moment; our currency has been in a nose-dive the last year or so.  Fortunately this was old stock, so it was most likely bought in when the exchange rates were better.  Buying local, things can work out OK, but from overseas, I always have to check the exchange rates.  Sometimes I get lucky; last year when TheDROStore had their DROs on special, I happened to have the funds.  So I waited a bit and checked the exchange rates each day; fortunately at that point things were getting stronger, and when I thought it was a good time I ordered and paid.  Got it for N$ 7500 - and the very next day the exchange rate started a big slide.  If I'd hesitated there, just three days later I'd have had to pay N$ 9000 for it.  To put that difference in perspective, the Namibian monthly state pension at that point was just N$500...  Normally my overseas purchases are in US$, but on occasion, I've elected to pay in Pounds or Euros to take advantage of better exchange rates.  Funny stuff, these exchange rates  :headscratch:

Dave, thanks for the suggestions bud.  I don't have MT2 collets or a suitable collet chuck to use along with the 4-jaw, but that's not a biggy to turn up.  Don't know how often I'll use a bit of kit like that though... Hmmm, my small lathe has an MT1 spindle taper and it needs a collet chuck...  And I've got an MT2 to MT1 reducer sleeve... 
Then again, I could just shove a center in the spindle - I know that fits inside the 4-jaw.  Then use a between-centers bar to support the cat's head.   I have a nice and accurate 16mm between-centers boring bar that can do that job, so I'd only have to make the cat's head to fit to the bar. 
Unfortunately I don't have a buddy with a bigger lathe  :'( - in fact, as home shops go, I might possibly have one of the best kitted ones in the country.  I could take it to one of the local machine shops, but they'd never let me loose on their machines, so I'd have to pay commercial rates for machining I really want to do myself.  I guess I'm just a sucker for punishment  :lolb: .

Marv, good point about the carriage bolts - thank you!

 ;D I got in some more "Me" time this afternoon.
First I sawed a section off that 55mm EN8 bar I showed in the last post.  It was a bit large to chuck up with the 3-jaw chuck's inside jaws, so I switched to the outside jaws to chuck up the workpiece.  I faced of as much stock as possible using my normal left-hand cutting tool, but with the outer steps on the chuck jaws getting too close for comfort, I dug around my selection of cutting bits to look for an alternative, and couldn't find any.  So I broke out a new bit of 8mm HSS blank, and spent a couple or 10 minutes at the bench grinder and ground up an appropriate toolbit - to be mounted like a boring bar (sort-of parallel to the lathe bed - angled a couple of degrees to get the cutting tip in position). 
The original plans call for two locating pins/dowels between the cylinder head and cross-head flanges - I've ignored those and went for my own option; that is to turn a short close-fitting section on the cylinder head to match up with the bore in the cross-head to locate things.  During the design phase of the engine, I wanted to suggest this option, but I just didn't have the heart; poor Bob was getting inundated with suggestions and spent a lot of time re-drawing things.  In this photo, I've finished turning the spigot for the packing nut and the locating section:


After more turning, a bit of drilling, some boring (to get the hole to 8.75mm to tap - I don't have a drill for that) and tapping M10 x 1.25, this was the result:

I chose M10x1.25 as a "fine" thread; and because I have taps and a die for it.  It's used a lot on Japanese cars, and I happen to have these as I'm busy fitting a new engine to my old Toyota bakkie / pickup truck / ute.
The non-pleasing rings left around the bosses are there because I made slight under-cuts so that all the parts would fit together without edges fouling.  The "double" undercut around the bigger bit is pure un-excusable bad machining  :-[ - but nobody will ever see that  :LittleDevil: .  It'll do the job.

A quick trip to the mill and rotary table, and the mounting holes were drilled - just 5mm deep so as not to run into the chuck jaws:


Back to the lathe, and with the workpiece reversed in the chuck, I finished the back side to match up to the cylinder bore.  I know my 3-jaw chuck's outside jaws are pretty darn accurate - for the most part at less than 0.01mm run-out, so I was confident about just chucking up like this.  If I was in doubt, I'd have used the 4-jaw chucked up on the spigot end and clocked things up.:


The completed cylinder head:


After having a discussion with myself about those ill-fitting holes on the cross-head flange, I just drilled them out to 3.2mm from the original 3mm rather than filing each hole.  Nobody will ever know  >:D .
Now things fit together properly, and there's some stud-making on the horizon:


Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Online Jo

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Re: Arnold's take on the MEM Corliss
« Reply #94 on: March 03, 2013, 08:28:41 PM »
Wow that is coming on  :ThumbsUp:


Now things fit together properly, and there's some stud-making on the horizon:


My favourite past time, it seems to happen to almost everything I get my hands on to  :mischief:

Jo
Usus est optimum magister

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #95 on: March 03, 2013, 09:04:38 PM »
Sheezz... Took me a fair while to post up, and in the meantime a lot of posts happened.

Thanks Jo  :) - Yes, time to break out that stainless rod.  Fortunately I checked before finally posting this message; below is what I had typed up to your previous response - before seeing your last reply... - things could be badly misconstrued, but somehow I find it amusing  :LittleDevil: :
Quote
Thanks Jo, I like your way of thinking  :ThumbsUp: , and that's been on my mind as well.  I have to check some clearances, but with the face plate I can most likely swing a ring inside of the Myford's bed gap.  In fact, that was pretty much my own initial thoughts - even if I have to make the flywheel slightly narrower to fit in the gap

Dave & Jason, you're both right.  I wasn't even considering parting off this thing; just grooving the for the hold-down clamps on the smaller diameter table for my rotary table was plenty sphincter pulling enough.  I trust my old girl, but within reason.  On this job, she's going to be asked to do things at her absolute limits, and I don't want her to get hurt, nor myself. 

I do have the mill as well, and that also holds some options along with the rotary table.  I don't see the lathe's chucks as "just for the lathe" - they are just work-holding devices.  In fact, daunting as it may seem, I have quite a lot of options of getting this job done.  I just need to play machinist's chess and think through all the different machining operations to select the most suitable one.

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline vcutajar

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Re: Arnold's take on the MEM Corliss
« Reply #96 on: March 03, 2013, 09:22:45 PM »
Hi Arnold

Great, another update and I am still stuck here in Germany turning green with envy.

If you don't mind I have a couple of questions about your last update on the cylinder head.  Please be patient with my ignorance of steam engine workings.

What you called cylinder head, is it the same as what in the plans is referred to as rear cylinder cover?  Does this go between the cylinder block and the crosshead guide?

If so, am I missing something because on the plans I cannot see any mention of threads for the rear cylinder cover whilst you tapped yours 10 x 1.25?

Thanks Arnold in advance

Vince

Offline tel

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Re: Arnold's take on the MEM Corliss
« Reply #97 on: March 03, 2013, 10:16:36 PM »
Quote
Yes, the angle-grinder is an option...  Do you know if cast iron will harden around cuts like this? - I tend to stay away from steel that had been cut using an abrasive wheel; lost too many HSS cutting edges that way  :-\ .  I had a look, and it will be possible to use my bandsaw to saw it off too.  It's MUCH bigger than the saw is rated for, but with a clamp and some rotation during the job, it can be

It shouldn't do mate, the trick is to not be in a hurry  - mark the cut pretty accurately, then a shallow cut right around, taking your time, then follow a bit deeper, you might use up two or three disks, but that's still pretty cheap to gnaw a chunk of that. I've done similar things with the bandsaw, using it to cut stuff way over its capacity - but this bit might be too much of an ask. Where you have trouble with hardening of the cut areas usually springs from the use of those cut off or chop saws beloved of many, but I don't know if even the cast iron would harden if one was used with caution (not hanging an anvil on the pull down handle f'rinstance)

I agree with Jason in principal - machining as much as possible before cutting off could be a good thing BUT if you slide it back over the chuck body to reduce overhang how are you gonna get at the chuck keys?

Little history - many years ago (over 40) I watched a guy trim about 2' off a CI pipe about that size in the street with just a hand hacksaw and a couple of small cold chisels. Again he made a shallowish cut right around with the saw and wedged it apart with the chisels - crude? prehaps, but only needed to fit in the joining collar of a water main, so .....
The older I get, the better I was.
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Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #98 on: March 03, 2013, 11:33:51 PM »
Hi Vince  :)

Please do ask away; I'm as much an amateur as you are, and I'm sure our more experienced members will pitch in as necessary.

Yes, I called it cylinder head, but on steam engines it's most likely more appropriately termed cylinder cover, in this case the rear cylinder cover based on its position in the drawings..  At the risk of riling up Bob Maryak, this bit is also called the inboard cylinder head/cover.  And Yes, it goes between the cylinder block and the cross-head guide - in my last photo, you can see it sitting between those.
On the plans, there is no reference for the threads for the packing nut and threads - this was left to "builder's choice".  I chose M10x1.25 because that seemed appropriate with the finer thread, but normal M10 will work, or even M12.  And for non-metric sizes, 3/4" or even 1/2" would work.  Finer threads are better suited here, as that would make adjusting the packing nut easier, hence my choice of M10x1.25 rather than the normal M10x1.5.
I hope this helps; if not, please do ask away - it's good to get questions  :ThumbsUp:

Kind regards, Arnold

PS - What are you getting to eat in Germany Vince ? - I can highly recommend Haxenbrat und Kartoffelknudel mit sauerkraut.  - I skipped a lot of umlauts here...
 
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline tel

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Re: Arnold's take on the MEM Corliss
« Reply #99 on: March 03, 2013, 11:56:26 PM »
I used 3/8" x 32 ME in mine. Strictly speaking, at least in how I have always understood the terminology, that is called the 'rear cylinder cover'.
The older I get, the better I was.
Lacerta es reptiles quisnam mos non exsisto accuso nusquam

Offline Maryak

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Re: Arnold's take on the MEM Corliss
« Reply #100 on: March 04, 2013, 05:34:07 AM »
At the risk of riling up Bob Maryak, this bit is also called the inboard cylinder head/cover.  And Yes, it goes between the cylinder block and the cross-head guide - in my last photo, you can see it sitting between those.


Takes terminology to a knew level  :facepalm: and takes more than terminology to rile me up. Only two things I hate being called and that's calling me late for pay muster or calling me too late, the liberty boat's at the gangway  :old:

Best Regards
Bob
« Last Edit: March 04, 2013, 06:07:01 AM by Maryak »
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Offline vcutajar

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Re: Arnold's take on the MEM Corliss
« Reply #101 on: March 04, 2013, 06:28:46 AM »
Thanks

So that's where the gland nut goes.   :Doh:

Good thing you mentioned tapping the cylinder head because I would have missed it. :-[

Vince

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #102 on: March 04, 2013, 05:40:53 PM »
Pleasure Vince, no worries  :)

I felt like a bit of machining after work today, so I stole an hour and a half out of my study time  :-X

The front cylinder cover is not a difficult bit to make, so I hacked a bit of stock off some 40mm EN8 round bar and started turning it up.  Here the boss that fits in the cylinder is done:


Before reversing the workpiece in the chuck to finish the other face and outside, I first moved the lot to the RT on the mill and drilled the mounting holes, as there would not be a lot to chuck up on, and drilling the mounting holes later could cause issues with the drill running into the chuck jaws:


Then I flipped the workpiece in the chuck, and turned the OD to size as close to the chuck jaws as I dared without actually cutting into the jaws.  To add some "visual appeal" rather than just have a flat cover, I free-hand turned an approximate dome on it:


I finished the dome with a file and then emery to get it looking a bit better:


To get rid of most of the burrs visible on the rim in the last photo, I just flipped it in the chuck again, and skimmed off the burrs.  There was still a tiny bit left; the last bits I removed with a file after removing the workpiece from the chuck.  The completed cylinder cover:


And sitting on the cylinder block:


Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline vcutajar

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Re: Arnold's take on the MEM Corliss
« Reply #103 on: March 04, 2013, 06:01:10 PM »
Good idea the dome cover.  When I get to that part I might do something similar if you do not mind me copying your idea.

Hopefully tomorrow will be back home and I can continue playing with the flywheel.

Vince

Offline Alan Haisley

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Re: Arnold's take on the MEM Corliss
« Reply #104 on: March 04, 2013, 08:32:04 PM »
Love it.
Alan
Near Raleigh, NC, USA