A simple oscillating steam engine

I know this post is old... but I'm just making one of these for my first project, and it's teaching me loads, AND better to make mistakes and learn on this, rather than my S50 (yet to start)

What size spring did people use for this?

Edited By Lainchy on 13/08/2019 09:04:09

Edited By Lainchy on 13/08/2019 09:04:25

Looking good lainchy post some more info when you can

The spring strength is largely a matter of feel not to strong or there will be to much friction between the oscillating parts. Would be good if you could find somewhere to try a few to get the right feel

Have a look at dodwells posts when you can. From his first simple wobble he has made some really attractive models something for you to aspire to

Geoff

Thanks Geoff.

I've ordered a spring on the slow boat, 0.5mm x 6od x 15long. That's a real stab in the dark tbh, but if this is no good... Warwick model engineering show is in Oct. Base, flywheel and piston to go.

I did struggle with the 2mm long thread (M3 not 5BA) for the pivot axle, and ended up drilling it out more to 4.5mm depth and M4 thread. I might end up remaking the cylinder, but this is a learning curve for sure. That's the only bit I'm unhappy with at the moment. I really wanted to stick exactly to the plans... albeit metric rather than BA threads (because I have a stock of bolts from R/C helicopters)

Great fun though!

Ian

Edited By Lainchy on 13/08/2019 10:46:56

You can try raiding a few springs from old biros, I got a boxful of various size springs from Aldi for $5.00 - keep an eye out for them - I used one of those.

Bill

Cheers Bill. Will keep my eyes open. I tried rifling a few Biro's... but sadly, they're 3mm ID. A friend said about the unpressurised spray bottles so I need to check out some of those too.

...................... and if you want something that requires a similar level of skill, very interesting and completely different to your first one have a go at this one

**LINK**

Bill

Brilliant, thanks Bill

I also made this engine as my first ever attempt to use a lathe in anger. When I got it to run it took days to get the smile off my face. I had 5 attempts to get the piston right, "I'll just give it another skim,,,,,,,,,, another one for the bin" Learnt a great amount building the engine and now working on more difficult projects. As several people have said, great design and good step by step guide on Steve's website. John

I'm enjoying the build for sure, but also learning heaps. I got the piston OK, I think... there's compression and vacuum when it's dry, but a spot of oil should see it better. It's not a tight fit in the bore... but we'll see. Managed to edge a piece of Sapele yesterday with a router bit in the mill - and that had a coat of varnish yesterday.

I did struggle with the flywheel though. No probs hacking it down to the required outer dimension, but I wanted to put some relief in the faces... I am learning still very much. I'm booked on the Axminster small engineering course next week... I have my list of questions! I managed to do it eventually, but it wasn't a pretty process by any means. I'll see if I can get a picture tonight of what I've done, but I really struggled getting past the relief angle on the tooling. Ended up using a indexable boring bar, which really doesn't take finishing cuts well and was resonating - although I did try various speeds??

Getting there. Drilled the cylinder cap and threaded the cylinder this evening. Need to drill the bearing next. Base is made too, and 3 coats of varnish. Bit overkill really, but all good fun, and teaching me loads.

Well...short of a bit more polishing...a gasket...and a spring instead of a bit of silicon hose.... it's done First project complete.