Author Topic: Muncaster's Joys Valve Engine  (Read 128858 times)

Offline smfr

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Muncaster's Joys Valve Engine
« on: September 16, 2013, 04:31:17 AM »
I've made a start on an engine I posted about over in Plans and Drawings: http://www.modelenginemaker.com/index.php/topic,2141.0.html, which is a two-cylinder horizontal engine with a Joys valve, by H. Muncaster. This was described in Model Engineer and Electrician in 1905. (starting on p 222).

Over the past 8 months or so I've been modeling this engine in Rhino 3D on Mac, to get a feel for the parts, and to prepare for manufacture. This is what the finished engine looks like:



The original plans have the engine at 22" long, which is a bit big for my little lathe/mill, so I'm building it at 2/3 scale, and checking the scaling with a scaled down CAD model. I was particularly worried about scaling the valve mechanism, so fixed my web-based valve simulation to simulate the 2/3 scale version: http://smfr.org/sim/joys-valve-linkage/ (requires a modern browser like Safari, Firefox, Chrome, or iPad/iPhone). The simulation also allows me to adjust the valve dimensions and see the effect of adjusting lap and lead on timing.

After scaling, the vital statistics are:
  • Stroke: 2"
  • Bore: 1-1/2" (or maybe 1-3/8")
  • Flywheel: 6" diameter
  • Overall length: 14-3/4"

I plan to build up the base from Al, use a solid block of cast iron for the cylinder block (ha, that will be fun!), probably build up the steam chest, most likely a built-up crank, bronze bearings etc.

But enough with the computer stuff! This will be my first barstock "historical" engine, so time to cut some metal!

Here's our starting point for the base; about $50 of Al from the remnants center, with the base sides already sketched out:



I was very glad to have the bandsaw to cut out the sides of the base, but I did have to make a table for it. Both sides of the base are taken from one lump of Al about 0.9" thick. I did a bit of chain drilling to give some maneuvering room:



and we end up with this:



Now I need to give myself a reference edge on those parts, so onto the mill with a rougher first, to take off enough to clean off the dings, and then a 1/2" endmill. The length of this engine is really pushing the limits of the tiny milling table on my Emco!



Once the bottom edge was good and flat, I could mark out the various levels, and the bearing points. At this point the bearing locations are my primary datum.

Now some milling to height. My top pieces will cover the sides, so I need to take their thickness into account.



At this point I needed to bore the fetching curved profiles on each side of the bearings; circles of 1" and 1.5" radii, which my little 1" boring head was not up to! However, when I bought my Emco it came with a box of freebies, various bits and bobs mostly suited to much larger machines. In this was this 3" Mesa Tools boring head:



with an R8 adaptor. My mill has an M2 spindle, so I had nothing to lose by converting that R8 adaptor to an M2! A spare M2 arbor was mounted between centers, and the cross-slide set at the appropriate angle with an indicator. Then I hacked away at the R8 adaptor. Then, getting close to final dimensions, this happend:



so I had to re-mount the left part in the 4-jaw, indicate it in, clean up the broken end and center drill, then re-mount to turn the rest of the taper, which was uneventful. A bit of Sharpie ink shows that it's a pretty good fit to the mill spindle bore. I know the MT-2 is pretty skinny for this boring head, and don't intend to push the boring head hard with this setup. But it gets me out of a pinch!



Back to the engine base. Here's the very big-looking boring head in situ:



Next problem!  :facepalm:  The boring head takes 3/4" tooling and all my boring bars are 1/2". Being too lazy to make a split sleeve, I raided my bottom drawer of unused endmills (including some meaty 3/4" mills that I got in a job lot). I picked out a worn-looking one, and ground down most of the flutes except for about 1/4" near the end, adding some relief so that the only part that should cut is the very tip of the flute. My first attempt resulted in quite a bit of chatter, but after some adjustment on the grinder it became fairly well behaved. Here I'm using some sharpie marking to check the contact points:



and it looks good. To get close to final cutting diameter I used some 1-2-3 blocks to get the required 2" and 3" diameters:



before backing out to start the cut, and going in about 0.075" per roughing pass. I'm quite pleased with the final result:



and we have something that's starting to look like an engine base:



There's a lot of profiling to do on the outside surfaces; I'm going to put in a 1.5deg casting angle on the exterior faces, and the interior of the bearing pedestals, and I'll cut away a lot of material under the left two sections. My current plan for fixing this together is to use a combination of concealed pins and JB-Weld, but I need to do a test join on some scrap to see how it holds together, and to figure out how much room to leave for the epoxy.

Simon
« Last Edit: September 25, 2013, 01:03:38 AM by smfr »

Offline sbwhart

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Re: Muncaster's Joys Valve Engine
« Reply #1 on: September 16, 2013, 07:03:20 AM »
Nice start Simon.

It looks like a very nice interesting engine that you have research in great detail.

I'll be quietly following along the build.

Stew
A little bit of clearance never got in the way

Offline Jo

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Re: Muncaster's Joys Valve Engine
« Reply #2 on: September 16, 2013, 08:55:11 AM »
Nice to see you have started your next engine so soon after finishing the last  :ThumbsDown: It looks much more interesting than a Stuart Victoria  8)

I don't know if it will fit your boring head but I noted that you can buy the adaptors separately from the heads from some of the suppliers.

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Muncaster's Joys Valve Engine
« Reply #3 on: September 16, 2013, 11:33:43 AM »
Looking good so far Simon. I think I would add some socket head screws to hold things together rather than rely on JB weld, you can counter bore the heads and fill the holes.

J

Offline b.lindsey

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Re: Muncaster's Joys Valve Engine
« Reply #4 on: September 16, 2013, 11:51:16 AM »
Great start on what should be a very interesting engine Simon. I will be following along as well. I tend to agree with Jason on the JB Weld, though the addition of pins as proposed would certainly strengthen those joints.

Bill

Offline Brian Rupnow

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Re: Muncaster's Joys Valve Engine
« Reply #5 on: September 16, 2013, 01:18:25 PM »
Very interesting build. I will stay tuned.---Brian

Offline tvoght

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Re: Muncaster's Joys Valve Engine
« Reply #6 on: September 16, 2013, 01:34:31 PM »
Hi Simon,
I'm really interested in this build, especially the valve gear.

As to fastening the frame together, on my Upshur Farm Engine I took the approach Jason has suggested - socket head cap screws with plugged counter-bores.

Starting at post #6 here:
http://www.modelenginemaker.com/index.php/topic,341.0.html

--Tim

Offline vcutajar

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Re: Muncaster's Joys Valve Engine
« Reply #7 on: September 16, 2013, 02:00:46 PM »
A good start Simon.  I will be surely following along.

Vince

Offline Dave Otto

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Re: Muncaster's Joys Valve Engine
« Reply #8 on: September 16, 2013, 02:32:21 PM »
Nice CAD work Simon,

Also good to see another new project in the works; I'm looking forward to following along with your build.

Dave

Offline Tennessee Whiskey

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Re: Muncaster's Joys Valve Engine
« Reply #9 on: September 16, 2013, 02:41:23 PM »
Looking great Simon, if the Stuart was a warm up project I can only imagine what this one will be, now that you're on a roll :cheers:

Whiskey

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #10 on: September 16, 2013, 04:50:02 PM »
Nice to see you have started your next engine so soon after finishing the last  :ThumbsDown: It looks much more interesting than a Stuart Victoria  8)

Thumbs down because I didn't make a nice wooden base to put it on the dining room table?  ;D

I'll get a round tuit. Eventually. Actually another engine on my to-do list will involve a bit of woodwork, so I'll be keeping my eyes open for some good bits of hardwood.

I don't know if it will fit your boring head but I noted that you can buy the adaptors separately from the heads from some of the suppliers.

I've kept an eye out for these, but MT2 adaptors for large boring heads (and facemills) are very hard to come by, I think because they aren't considered beefy enough.

I'll think about using socket-head screws to hold things together. I'm just a bit worried that I'd get the depth wrong and reveal a head in the profiling process.

Simon

Offline Jo

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Re: Muncaster's Joys Valve Engine
« Reply #11 on: September 16, 2013, 04:57:08 PM »
 :embarassed: Sorry not intentional I meant to use:  :ThumbsUp:

Jo
Enjoyment is more important than achievement.

Offline Jasonb

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Re: Muncaster's Joys Valve Engine
« Reply #12 on: September 16, 2013, 06:16:14 PM »
Don't worry unduly about teh screw heads they machine OK, as you can see from the ones in this flywheel rim.


Offline GailinNM

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Re: Muncaster's Joys Valve Engine
« Reply #13 on: September 16, 2013, 09:23:37 PM »
Great going Simon.  Joy's valve gear has enough "monkey motion" to make it fun to watch yet not too much to be confusing to the observer. 
Gail in NM
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Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #14 on: September 25, 2013, 01:00:07 AM »
Not too much progress over the past couple of weeks. I tried making a finger engine as a gift for my nephew, but the geometry didn't work out so it will sit around begging for some parts to be remade.

I did, however, do a test joint with JB Weld to preflight the joining of my base parts together. I turned a couple of pins, with some grippy sections, and filed a flat to avoid hydro lock when putting things together:



Matching holes drilled on a couple of offcuts, and I cleaned everything with denatured alcohol:



and assembled the joint with a clamp:



After a week of curing, I put the short end in the vice and yanked the long end up and down. I felt a couple of pops as the epoxy detached from the flat mating surfaces (perhaps I should have roughed them up more), but it held around the pins and the joint didn't become loose, so I think this technique is plenty strong enough for my purposes.

[Edit] maybe I should have roughed up the insides of the holes with a burr too?

Simon