Muncaster's Joys Valve Engine

[Don1966]

Simon you have been doing some very impressive work bud. Some way I keep missing some of you posts.
I believe Achim was talking about a stud holder like the ones G H Thomas mentions in his book " The Model Engineers Workshop Manual" if you have this book look on page 276 Fig. 25.3 Stud Holders. I think this would help you a lot.

Regards Don

[smfr]

Thanks for the reference, Don! (Runs to grab GHT book). Looks like I have a bit of reading and fixture making to do 

Simon

[Jo]

I will be interested to hear how you get on Simon: I made one and couldn't get on with it: maybe the thread was a little loose as it wouldn't hold the studs 100% true.

Jo

[smfr]

Looks like GHT's fixture only grabs the threaded part of the stud, but I suppose if you tried to grab both the threaded and non-threaded parts, you'd have to be very consistent in the diameters for it to hold securely. It sounds a bit fiddly to make, but I'll give it a shot. A 4BA holder isn't too small...

Simon

[smfr]

In between fiddling with studs I got the cylinders honed and lapped.

I picked up a brake cylinder hone for a dollar or so at an estate sale, so that was put to use honing the cylinders:



It was pretty slow doing until I upped the pressure on the stones, and ran the lathe a little faster. However, it was really hard to tell if the finish was improving (I don't think these are fine stones?).

I had previously made up a couple of plug gauges from cast iron, about a thou over my original plug gauge, and another thou up from that:



so I could use these to check the bores periodically. After honing, the 1.379" gauge slid through nicely, but the 1.380" was a no-go.

I would have liked to have made up a nice Ramon-style D-lap, but had no copper sheet, so modified an aluminium lap made for an earlier project by turning it down from 1.5" and cutting some slits:



It already had a taper in the bore, with a matching tapered plug for adjustment. With the lathe running slow and a glove on my right hand, I worked both bores on the lap:



periodically cleaning off with degreaser (boy, what a mess!) to try with the plug gauge. I went up through the grades of green Timesaver lapping compound mixed with some thin (spindle) oil:



and eventually got both bores a sliding fit for the 1.380" gauge. The finish isn't perfect by any means:



but the worst of the machining marks are gone, and I plan to use cast iron piston rings with a cast iron piston, so I think they'll bed in nicely.

Simon

[zeeprogrammer]

Following along Simon.

You mention estate sales quite often. Hm...I wonder if there's much of that in my immediate area.

[smfr]

Thanks for following along, Zee!

Yes, estate sales have been an great way to build up my machining tools collection. I keep an eye on Craigslist (searching for "machinist") and estate sales come up a few times a year (sadly!).

Simon

[Don1966]

Looks like GHT's fixture only grabs the threaded part of the stud, but I suppose if you tried to grab both the threaded and non-threaded parts, you'd have to be very consistent in the diameters for it to hold securely. It sounds a bit fiddly to make, but I'll give it a shot. A 4BA holder isn't too small...

Simon

Simon if you noticed that the stud holder is slit at three places and threaded.  With the nut and the taper the fixture will lock around the threads and the end screw is used to lock the stud in place. GHT also said to put flats before you slit it. It should, if done correctly put your stud dead center. Don't forget to harden the parts.

Regards Don

[smfr]

Looks like GHT's fixture only grabs the threaded part of the stud, but I suppose if you tried to grab both the threaded and non-threaded parts, you'd have to be very consistent in the diameters for it to hold securely. It sounds a bit fiddly to make, but I'll give it a shot. A 4BA holder isn't too small...

Simon

Simon if you noticed that the stud holder is slit at three places and threaded.  With the nut and the taper the fixture will lock around the threads and the end screw is used to lock the stud in place. GHT also said to put flats before you slit it. It should, if done correctly put your stud dead center. Don't forget to harden the parts.

Regards Don

Right, I read up about it yesterday. Shouldn't be too hard, but I'll probably be and use a die to thread for the nut on the front. Also I don't have any 60TPI taps, so the depth stop thread is going to be 40TPI. We'll see how that goes...

Simon

[kvom]

Speaking with Dennis and Lee at NAMES, I found a bit more of the model's history insofar as his castings/kits go.  Seems the Detroit guys actually saw Muncaster's engine in England before deciding to make the castings and build them.  When the first completed version failed to run properly, they did an analysis and it seems that the valve journal pedestal was too close to the cylinder.  When moved away, the engine was able to run successfully. 

Muncaster's drawing shows the distance between the journal center and the main bearing center as 5.375", while Dennis' plans show it as 4.879.  That's almost half and inch difference, or half that in your case.  You might want to give Dennis a call before building these parts.  He's a good guy, and I'm sure would be able to tell you the story here better than I.  Contact# is at http://historicmodelsandreproductions.com/

[Coopertje]

Great build simon. Very nice looking parts, setups and write up. Should be an insperation to build this engine too in future. For me at least it is!

Jeroen

[smfr]

Thanks Kvom and Jereon, and sorry I didn't reply sooner. Work has been eating up all my time recently 

I did have some time in the shop this weekend, and messed around with studs. I followed the advice of Achim and Don (and thanks, Don, for pointing me to GHT's book  ) and made a stud holder. Since that was a little adventure in itself, I posted about it over in the Tools and Fixtures section.

So I should be able to make more headway on studs now!

Simon

[smfr]

I had a bit more shop time this long weekend, and decided to make a start on the valve guide standards, fabricated from brass.

Some slices of brass bar are cleaned up by milling:



and various bits of 1/8" sheet are cut to size in the bandsaw, giving us the raw material:



These standards have an A-frame shape, so I milled about 5deg off each side of one part to make the A, and milled 1/8 slots in the other two sides, and some slots in the base. I then drilled and tapped for a few 2-56 screws to hold things together for soldering:



Here we're set up for silver-soldering, using Harris 45 (a highter temperature solder, since I have to do a second heat for the head). Some iron wire holds the base in place:



and ready to go:



The results are reasonable; I could have used a bit more solder and given more of a gap to flow but they are plenty strong enough.



Now I did something stupid  I wanted a nice fillet, so cleaned things up, applied soft-solder flux, heated them again and applied soft solder to the joints:



Why stupid? Well, I had another hard solder joint to do, and have read that soft solder contaminates silver solder joints and weakens them (and of course the heat will remelt the soft solder). However, with fingers crossed I soldiered on (no pun intended  )

I marked out for the center of the valve guide axis, and clamped on the milling table, locating using wobbler:



then drilled and bored up to 9/16", the diameter of the head:



Ideally the sides would be tangiential to the head, but this is close enough:



A bit of 5/8" brass bar was turned down for the heads (only showing this photo because I'm using HSS cutters more, and am quite please by this finish!)



and we're almost ready for more silver-soldering:



I drilled a hole through the side of each and put in a peg to keep the heads in place for soldering. Here they are after that:



The silver solder seems to have been taken up just fine, and not adversely affected by the presence of soft solder, though if this were a high-stress part I'd be more worried.

Next came a bunch of cleanup and fettling to make them look more like castings; I only had time to do one this evening, and it could still use a bit of work:



and this is what they look like in situ:



The base of the standard still needs trimming down to size, and I'll drill and ream the center hole in the same setup for accuracy.

Simon

[Jo]

They went together well 

Jo

[Kim]

That's some very fine fabrication there Simon! Well done I'd say.  I think you've got this solder thing down pretty well.
Kim