Little brass wobbler - progress so far.

Hi,

I recently made this simple little engine that I intend to mount on top of a small candle powered boiler.

I wondered if anyone can offer a bit of advice - at the moment it runs great on live steam and once started will run till the kettle boils dry (about 70 - 80 mins).

The slight problem with it though is it can take 10 minutes to start - it just won't run till it's thoroughly hot for some reason - ordinarily that might not be a problem but with a very small candle boiler it may only hold enough water for perhaps 20 mins of use and I'm concerned it will never fully get hot enough to operate well

Any one got any idea how to improve things ?

The video isn't the best quality I took it on impulse but you get the idea.

**LINK**

Peter.

Edited By JasonB on 12/11/2015 20:32:28

As promised ... I'm watching

MichaelG.

Ah but Michael can you fix the bloody thing

I've put the you-tube video straight into your post if thats OK

Two possibilities

1. there is a tight spot somewhere in teh engine that loosens off when the metal has been heated by teh steam and expands. If it runs on air from cold then this is not likely to be the problem

2. which is I think more likely is that with a cold engine and such a small steam supply is that as the steam gets to the cold engine it just condenses on the cold metal and turns to water. Try warming the engine first with a hair drier or hot air paint stripper (on low) then light up your boiler.

See ...Peter ...My role is just to bump your questions occasionally, until some engine mæstro arrives.

MichaelG.

Thanks Jason, it spins freely so I'm more inclined to thinkyour second suggestion sounds more likely.

Initially the piston didn't have a ring but I've now cut a very small groove that I've packed with a bit of rolled up PTFE tape - once its had a drop of oil it has a pretty good seal and runs faster that it did without the ring. I'd hoped that may get it running sooner but made little difference.

I've seen similar engines run of a candle but I guess I'm not going to know till it's finished.

Hi peter really enjoy your build treads ,how the potty mill engine coming along have you done any more to it?

Hi Mal, I've got the cylinder, piston / rod and the crosshead slides done, at the moment I've put it on hold a while as to be honest I'm struggling a bit, I'm not engineering trained and sometimes get confused interpreting the drawings.

I'd like to restart it and even continue the thread but I'm tad worried I'm making a mess of it.

Peter warts and all build threads are welcome, at best posting the problem may reward you with suggestions of how to recover the situation, at worse it may stop you putting any more work into a part that needs to be scrapped. Either way it will serve as a good reference for others of what to avoid or be careful of.

The current engine I'm writing up elsewhere has a problem with the cylinder/piston fit which will require one part remachining the other completely remaking but its in the posts so anyone makeing that engine or a similar one will not do what I did . We are not all perfect

J

I love those little oscillators Peter, but although candlepower is quite romantic, what about an upgrade to a miniature spirit lamp made to resemble an old fashioned oil lamp.....or perhaps a "candle" with a miniature butane gas flame? I am thinking also about the black smut that candle flame deposits on surfaces with which it comes into contact. Just a couple of thoughts. Keep up the good work.

Mick

Thanks Jason,

I've been doing a lot of thinking, I still think the site is in decline by becoming to diverse and build work now seems to less a part of the site.

However it now clear that little will get done to change the situation so rather than walk away I'm going to resume the 'Potty mill' thread in the hope others will follow suit.

Mick,

I hadn't thought of a spirit burner, thanks for the suggestion. I had intended making the boiler and base including the pedestal for the tea light, in view of what you say it might be better to get it working on the boiler first before I start constructing the heat source.

I don't think they have it now, but there used to be "The gnat power" completion at one of the Model Engineering Exhibitions, this was mainly ruled by the hot air enthusiasts, but no one seemed to be able to get enough power from a Tea Light candle to run a steam engine.

The burner I use on my smallest hot air engine uses my usual wick of a bundle of iron florists wire (.028" I think), in a 1/8" wick tube, this has a slightly bigger flame than a candle.

Here's my wee wobbler.3 mm bore x 6 mm stroke

Ian S C

Edited By Ian S C on 13/11/2015 10:42:23