First Steam Engine Build

[stevendavis]

Just joined Model Engine Makers last week as I found it perusing for information on building model steam engines. I've been looking at building a steam engine for a while now and found myself with a couple of Coles C 611 castings. I'll be getting started on one of them soon and will probably have lots of questions. I've only had my lathe for a couple of years now and still consider myself a newb! My first project was the PM Research mini lathe and I still have a little to do on it, but it taught me a lot. Here's a pic of the almost finished mini lathe and the casting kit for the Coles C 611.

[Thor]

 The lathe looks nice, good luck with the steam engine.

Thor

[pirmin]

Nice lathe, those Lathe models are no joke ! For a Beginner this is definetl< quite a achievement.

i made the PM Nr1 Mill and love mine.

good luck with the coles engine ! jkeep us updated

[stevendavis]

Thanks for the kind remarks!

[stevendavis]

I'll be getting started on the cylinder tomorrow, and possibly the piston. What kind of clearance should I be shooting for on the piston to cylinder fit?? I'll be using Teflon for the ring. Thanks

[Jasonb]

I don't measure mine, just go by the feel but if you want to put a number on it 0.001" on that size bore and with the materials listed on the drawing.

Dry fit without rings/packing

<a href="https://www.youtube.com/watch?v=Vp2Vrq1Ziw4" target="_blank">http://www.youtube.com/watch?v=Vp2Vrq1Ziw4</a>

[stevendavis]

Thanks Jason!

[stevendavis]

Spent the lastr few days working on the cylinder. It's going to take some time to post part 1 of the video series. Hope to get it done by the weekend. So far I've only messed up once. I moved the wrong axis while I was machining in the ports. Now they are .0625 off from center, but I think I can make it work. I'll try and get a few pics posted from the vids.

[stevendavis]

Here's a few pics of the progress so far. More detail will be in the vids. I used Mark P's process for setting the cylinder in the 4 jaw and facing one surface. Then I made another mandrel in the 3 jaw and super glued the cylinder on for the second facing operation. To face off the steam chest surface I used parallels and 1,2,3 blocks to set it as close to level as possible, then I machined that surface to spec.

Next I machined the port slots into the cylinder and as you can see, they are .0625 off of center, towards the crank side. I was really lucky to notice I made the wrong shift on the very first plunge, otherwise the cylinder would be scrap right now. I still have to machine the inside of the steam chest but it's really close the dimensions on the drawing already, though the slide valve is on the large side, so I think I can open it up a little and be ok. I'm probably going to remove a little extra material on the crank side as well, to compensate for my mess up. I also put a little bit of a hone on the cylinder once I bored it.

[stevendavis]

Here are the parts assembled, I started to blend the cylinder with the chest a little but I'm thinking about milling them to all match up, but that will also take away the cast look and I'm not sure I want to do that. Any thoughts on this?? Thanks

[stevendavis]

Looking to maybe put a flyball governor on this. Do they have size requirements? Thanks

[stevendavis]

Also,
Should there be two through holes in each intake port, or is one ok? Plans are not clear on this. Thanks

[Admiral_dk]

First - scale Guvenors are almost impossible to get to work well .... or should I say - the smaller the size the bigger the problem. Should also mention that I have never done any - but there has been rather many debates about this subject here over the years ....

So either search for some of the old posts here - or wait until one with more experience answers.

I'm not say it will not work - but they do need to be of a certain size to work well. Under that size many make a dummy version with as many details as they can fit / desire - but they do not regulate the Steam admission to the Engine.

Next one - ideally you have one big one (rarely round) - but I can count the number of ones I've seen build here (and elsewere) the last more then 15 years, done that way, on one hand.
The majority has 2-3 holes in parallel. That said - it has some to do with how easy/hard to do, how much work the Engine should be able to pull (most nothing), speed and efficiency > 2-3 holes.

Per       

[Jasonb]

For that size engine two 1/8" holes 5/32" to 3/16" apart (ctrs) would do.

Governors on this sort of size engine tend to be more eye candy than functional as they don't scale too well. Really only needed if you are going to have changing loads on the machine such as working a saw table

[stevendavis]

Thanks for the replies!! I'll plan on two 1/8" holes for each port, and maybe I"ll forgo the governor.