Pipe and Bolt Engine Mod-Up

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RussellT:
Ok.

Here's a bit more progress.

After an abortive effort at making the big end from the threaded part of the bolt a second one was made from the unthreaded bar. The con rod was shaped to fit the bush by hitting it with a hammer and then filing.

It was fluxed and a couple of tiny bits of silver solder placed on the nail head with the bush on top. I heated it with the blowlamp, the silver solder melted, a little nudge with a rod to get it central and it was done.

It was threaded with a die and the piston tapped to fit. The thickness of the nail will only give about 50% thread engagement but that'll be plenty.

The cylinder head (part of the bolt) was drilled for a steam passage and tapped for a plug.

A plug was made from another part of the bar.

The stalk will be cut off when it's finally fitted.

The cylinder head was drilled so that I could take a plunge cut with a half inch end mill.

Then a pocket was milled out for the cylinder. This was a little more complicated than I expected. The end mill (clearly marked 1/2") wasn't :bang: so I had to wiggle it around a little.

So the parts were fluxed,

and silver soldered.

and cleaned.

I think the reflection from the flash flatters in the last photo. It doesn't look that good in real life.

Needless to say various things went wrong along the way.

I was checking the length of the conrod and discovered that in my calculations for the steam ports I'd missed a factor of two somewhere. I had to shorten the conrod and redesign it a bit. :doh:

I had to have three attempts at silver soldering the cylinder head to the cylinder, first it wasn't square and then it leaked. However it's all done now and the piston still fits.

I've used a two inch bolt and that has provided the cylinder head and the cut off head of the bolt. I used 2" of bar for the cylinder, 3/8" for the piston and 1/4" for the big end and another 3/4" for the plug. Given the bits used just to hold bits for machining, parting off etc there is no bar left. I think the head of the bolt will be a hub for the flywheel.

As an aside I've been thinking about flywheels. There is of course no reason why they have to be round and for a slow speed single acting engine I'm thinking it might actually be an advantage to be out of balance so that gravity can help with the return stroke.

The steam ports are going to be the trickiest part of this. After my mistake with calculations the ports are very small and difficult to drill but I'm still thinking about that. :scratch:

More to follow.

modeldozer:
:clap: :clap:

Abraham

vtsteam:
Wow, cool Russell! :clap: :clap:

You're not the only one moving back a step -- I decided the cylinder wall was just too uneven so tried reaming it, which worked, but the result was the piston is really pretty sloppy in itnow. So I have to make another piston.

The cool thing about this project is you learn first hand what order to do things in, and why, and what goes into the design of an engine. And how to solve little construction problems. Even if in principle you think you already know. All the mistakes are better than second hand knowledge. I bet the next one either of us builds from scratch goes together a lot smoother. And imagine the luxury of being able to use regular stock materials!

Though, sometimes I think.....it's overcoming the problems that make it fun. I had a teacher a long time ago, now deceased, who said "The more rules, the merrier." Back then, in the late sixties, I thought that couldn't possibly be true! But now I think I understand what he meant by that better. It's not the rules, but solving challenges within bounds that is the merry part. :beer:

vtsteam:
I turned a piece of a very large nail -- a spike, really, but somewhat bent. After turning straight I drilled it .192 to fit my other nails, then bored it and brazed it and a bit of cast iron to the top of the cylinder by way of a valve guide.

RussellT:
Thanks Abraham and Steve.

You're right Steve - it's a bit like those jobs you do where you haven't got the right tools and have to work out how to do it with what you have got.

On to the flywheel. After thinking about unconventional (not round) designs for a flywheel I've gone all weird and decided to make it round. I took a large bit of tube (a scrap motor casing) and put it in the lathe.

I'm using the rear toolpost and the tube just fitted in without taking the top slide off although I had to take the toolholder off.

That's it done. I chamfered the edge while it was in the lathe.

Here's the kit of parts.

You can see the hub has been drilled with pilot holes for the spokes. They were positioned by scribing lines from corner to corner on each flat of the bolt head.

It was back to the lathe to set out the holes in the rim. This is my setup for dividing into 6. I used the lathe tool to scribe marks on the rim. The spirit level is used at front and back of the lathe.

Here's a trial assembly.

The next job is to fix it together. I think I'm going to silver solder it but loctite would probably be OK too.

I've also (I think) solved the problem of how to make the steam ports. :smart:

I've a feeling this engine might sound like a bag of nails when (if) it runs. :lol:

Russell

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