Author Topic: Muncaster's Joys Valve Engine  (Read 159491 times)

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #225 on: February 16, 2014, 05:35:58 PM »
Simon I was always tought when soldering part slike this to tin both faces first, that is apply a thin layer of solder, wiping off any excess while still hot. You then put the two together with a littel flux and heat to "sweat" the joint together. This tends to give a closer joint with less solder and as you can see the two surfaces you are sure they are fully coated with solder

You're right Jason, I didn't follow the normal "sweating" procedure, mostly because I forgot what it was  ;D  But this seemed to work well. I needed accurate matching of the parts because I was already very close to final size (got a bit carried away), and the thickness of the joint doesn't really matter (other than for strength) since it all gets cut away for the bearing gap.

Zee, yes, we're pretty badly affected by drought here in the San Francisco Bay Area. Not in imminent danger of running out of water like some smaller places, but we're at 38% of normal rainfall for the year. What I find odd is that there has been very little public education about what to do to save water  :shrug: Back in the UK everyone would have had flyers through the door by now, and would be getting ticked off by neighbors for watering their lawns too much. Here there's just the odd story on the news and I see lots of lawn irrigation still going on.

Simon

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #226 on: February 16, 2014, 05:40:03 PM »
You mentioned the spiral reamer might do better than a straight reamer because of the solder.
I've not come across a spiral reamer. Does it help move shavings out of the way?
Are there other cases where a spiral reamer would be preferred? Or rather...what are the advantages?

Hi Zee! Spiral reamers are useful when the hole intersects, and runs parallel with a joint; with a straight reamer the entire flute is going to encounter that joint at the same time, possily causing chatter or other problems. If I remember correctly, the normal spiral type is a "right-hand cut, left-hand spiral" which pushes the swarf out in front of the reamer.

Simon

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #227 on: February 17, 2014, 06:16:06 AM »
Fitting the conrod bearings took longer than expected, but I'm happy with the result.

I milled to create the flanges with a 1/4" end mill. The vise is still accurately set up, and I have a digital indicator set up to track cross-slide movement. After locating on the fixed jaw with an edge finder at the start, I used the indicator to get an accurate slot width which I could repeat for all edges of both bearings.



After getting the slots to depth and width, there followed lots of trial fits with the usual Sharpie marks, pinched fingers and grunting :D



The end-stop part provided a useful way to test for parallelism, so I could file until it slid all the way up to the base of the slot.



So, not too much to show for half a day in the shop, but I'm please with the fit; both are a snug sliding fit.



I left the little end flange overly long, because I have to figure out out how best to hide my boo-boo with the slot depth  :thinking:

I also have to start thinking about how best to open up the slot for the cotter wedge; filing with some guides is the current favourite.

Simon

Offline Don1966

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Re: Muncaster's Joys Valve Engine
« Reply #228 on: February 17, 2014, 04:28:04 PM »
Simon the extra time has payed off, you have some quality pieces there. Your whole project so far you have added that extra attention to detail and that has been a plus as far as I am concern. Great work buddy and I like.......... :praise2:

 :cheers:
Don

Online Kim

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Re: Muncaster's Joys Valve Engine
« Reply #229 on: February 17, 2014, 04:54:25 PM »
Hi Simon, I couldn't agree with Don more!  Great work, and wonderful attention to detail.  :ThumbsUp: I'm really enjoying following along with your build!
Kim

Offline fumopuc

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Re: Muncaster's Joys Valve Engine
« Reply #230 on: February 17, 2014, 07:50:09 PM »
Hi Simon,I am sure it will be a very extraordinary engine at the end. Waiting for the next steps.
Kind Regards
Achim

Offline kvom

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Re: Muncaster's Joys Valve Engine
« Reply #231 on: February 23, 2014, 09:09:37 PM »
Jasonb told me that you were building this engine after I posted my intention to build it from castings.  So I spent most of the morning reading the entire thread.  I was impressed that you are maintaining a lot of the draft angles and other decorative details from the castings.

I've ordered the plan set for the full size kit.  I saw the finished engine at Cabin Fever last year, and have been thinking about this as my next "big" project when my loco build is done.  Since I have a CNC mill, I suspect I'll have an easier time with some of the parts than you will.

Dennis at Heritage Model Engines told me a bit of the history.  Seems 5 modelers in Detroit some years ago used the Muncaster drawings to make patterns and had the castings poured.  However, they didn't get the valve drawn properly and only one of them got a working engine.  It's not clear if the error was in Muncaster's drawing or in their interpretation.  Dennis modeled it in 3D CAD to get a working valve train, and apparently had access to the patterns.  So he's been selling the castings and drawings for 10 years or so.

Enough about my plans for this.  I will mention that with respect to the conrod bearings, I recently saw an example where a loco builder used a solid bronze bearing for his main rods, and then covered them with a thin brass sheet with an engraved line to simulate a split bearing.  Doing this saves the problem of a working wedge.  I'll have to wait until I get the drawing set to decide if that's a good way to go.

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #232 on: February 24, 2014, 12:38:36 AM »
Jasonb told me that you were building this engine after I posted my intention to build it from castings.  So I spent most of the morning reading the entire thread.  I was impressed that you are maintaining a lot of the draft angles and other decorative details from the castings.

I've ordered the plan set for the full size kit.  I saw the finished engine at Cabin Fever last year, and have been thinking about this as my next "big" project when my loco build is done.  Since I have a CNC mill, I suspect I'll have an easier time with some of the parts than you will.

Dennis at Heritage Model Engines told me a bit of the history.  Seems 5 modelers in Detroit some years ago used the Muncaster drawings to make patterns and had the castings poured.  However, they didn't get the valve drawn properly and only one of them got a working engine.  It's not clear if the error was in Muncaster's drawing or in their interpretation.  Dennis modeled it in 3D CAD to get a working valve train, and apparently had access to the patterns.  So he's been selling the castings and drawings for 10 years or so.

Enough about my plans for this.  I will mention that with respect to the conrod bearings, I recently saw an example where a loco builder used a solid bronze bearing for his main rods, and then covered them with a thin brass sheet with an engraved line to simulate a split bearing.  Doing this saves the problem of a working wedge.  I'll have to wait until I get the drawing set to decide if that's a good way to go.

That's an interesting bit of history, Kvom! I'm pretty sure my valve train will work, having done a 3D model for the main engine parts, then a valve simulation to check the valve workings after scaling (http://smfr.org/sim/joys-valve-linkage/). I've no idea if the valve timing is "good", however!

I'm fairly confident that I can do the rest of the parts from bar stock and fabrication, other than the valve guide which will be a real head-scratcher! I still think it's doable by whittling, though.

I've done the wedges; you'll see an update later today  ;D

Simon

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #233 on: February 24, 2014, 07:19:49 AM »
Where were we? Ah yes, all the bearings had been fitted to their square holes, but still needed their tapers and respective wedges.

And to fit the wedges on the conrods, I had to make some square holes. I opened up the existing 3/16" hole with a 1/8" end mill followed by a 3/32" end mill, to reduce the amount of filing required:



watching a couple of digital indicators to keep the holes to size. Then I decided to use the traditional approach, filing! To help keep things square, I milled up a couple of filing guides from some gauge plate (O-1 hardening):



then heated to cherry red, and quenched in water (for some reason I have better luck hardening in water than oil; maybe I just need a bigger oil pot). What I didn't expect was the distortion; the slots pinched in by about 0.005", which required some tedious stoning to make these fit to the conrods. I should have left a bridge piece at the top.

So now I could fit these to the conrods, using a machinists clamp to hold them in place while getting things set up in the vise:



I had to stock up on some files:



You'd think that Nicholson would have a catolog that tells you the dimensions of each file, right? So you can get a file that fits into a 3/16" x 5/16" hole? Not so! :hammerbash: The catalogue that I managed to find (with some trouble: Nicholoson don't appear to have a web site) only gives length, not width or thickness. So I took my business to Grobet who have a better cataglogue, and found some of their nice pillar files on eBay.

I found that wine (actually beer  :DrinkPint: ) corks make good small file handles:



and after some tedious filing, marking up and holding up the light, we get far enough to insert what will become a wedge:



The wedges started life as some bits of 3/16" 1018 bar, with each end mill down, then turned and threaded:



by holding in the 4-jaw chuck, centering on a punch mark on the end:



These wedges have a 4° taper, so we need a wedge to get matching angles. With the help of some trig I use the "two parallels separated by a known distance" technique and use it to mill a bit of scrap Ally:



which is then stamped with the angle for posterity. Here are the bits, with some marks to make sure I cut the angles in the right directions:



The two wedges are easily done in one go, sitting on the 4° wedge:



Feeling please with myself, I then proceeded to mill one of the bearings undersized  :toilet_claw: and the other with only barely enough on the angled face. At assembly, the bearings should be snug with plenty of travel left in the wedge for later wear adjustment, but the wedge on my better bearing is at mid-travel already, and on the bad bearing it runs out of travel  :hammerbash: I'll rescue the bad one by silver-soldering on a bit of material and re-milling the angle, but I can't do that now because it'll melt the soft solder.

So now it was time to drill the hole in the conrod bearings. They were marked up in situ, measuring from the crosshead hole to get the right throw. The hole center is pretty close to the solder joint, which is good. After a bit of thought I decided to drill the bearings in situ, holding the conrods in the vise, hoping that this would lead to better alignment. With things set up I checked for alignment in two axes; the first:



looks OK, but the second not so good, probably because I'm clamping down on imprecise faces on the conrod big end:



A bit of shimming of the vise fixed that:



and now I could drill in stages:



leaving a bit to be taken off by boring to make sure the hole is straight:



before reaming at low speed:



Both done!



After some trimming of the flanges, I rounded the corners:



and we're left with this little lot:



I plan to mount the bearings on an expanding mandrel to skim off the surface and leave a bit of a raised ring in the middle to avoid the main bearing surfaces from contacting the crank throws, so I haven't yet cleaned up the surfaces.

While mucking around with bearings, I also finished off the crosshead bearings. They take a wedge too, so that required another angle, 14° this time, again cut with the help of some trig. It was used to mill down some bits of 1018 steel:



and to cut the angle in the crosshead bearings, so we can have another fun fitting session:



That wedge could have a little more leeway, but it's close:



Both done:



These bearings will also get a skim to take them to final width. I presume they should stick out a tiny bit from the sides of the crosshead, to keep the forks from marring the crosshead sides?

Once I've skimmed the bearing faces, they can be separated by melting the solder, any required remediation done, and then the mating faces milled a tiny bit to create a gap.

And when the bearings are complete, I can get back to the crankshaft and actually put some moving parts together  :cartwheel:

Simon
« Last Edit: February 24, 2014, 04:44:59 PM by smfr »

Offline ths

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Re: Muncaster's Joys Valve Engine
« Reply #234 on: February 24, 2014, 12:10:41 PM »
It's all very special Simon, looks great.

Hugh.

Offline Rivergypsy

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Re: Muncaster's Joys Valve Engine
« Reply #235 on: February 24, 2014, 12:40:27 PM »
Hi,

I've only just caught your build, but very nice work - well done!

Dave

Offline vcutajar

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Re: Muncaster's Joys Valve Engine
« Reply #236 on: February 24, 2014, 04:29:34 PM »
Can't wait to see it finished.  I really admire your patience and dedication you are putting in this project.

Vince

Offline Roger B

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Re: Muncaster's Joys Valve Engine
« Reply #237 on: February 24, 2014, 07:49:15 PM »
Really nice work Simon  :praise2: :praise2: I find it hard to judge the size, but if the files are 'normal' Swiss file size (2-6mm) those are some pretty small parts  :ThumbsUp:
Best regards

Roger

Offline fumopuc

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Re: Muncaster's Joys Valve Engine
« Reply #238 on: February 24, 2014, 09:02:17 PM »
Hi Simon, that all looks brilliant.
Kind Regards
Achim

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #239 on: February 24, 2014, 09:32:59 PM »
Thanks for the comments, all! It really helps with the motivation  :ThumbsUp: :ThumbsUp:

Really nice work Simon  :praise2: :praise2: I find it hard to judge the size, but if the files are 'normal' Swiss file size (2-6mm) those are some pretty small parts 

Roger, the squares on the mat at 1-inch squares, to give you an idea of scale.

Simon

 

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