Robinson Hot Air Engine.

[Dean W]

Ran quite well in the second vid, David.  Nice and smooth.  The first vid kind of made me smile.  Not laughing at you,
but at the stirling engine that gave off an exhaust gas cloud! 

[Bogstandard]

David,

I don't know much about this type of Stirling engine, but could you rig up an external 'tin can' radiator to keep it well supplied with cooling water. It could be a semi sealed system, with only the tin can having an open top.

The circulation should be automatic, by convection.

I have shown the water level as being below the top plate, but if it didn't caused any internal engine leaks, it could be above.


John

[madjackghengis]

Hi David, in watching your two videos, I've concluded I will have to end up duplicating that engine sometime in the not too distant future.  As you, I like an engine that does something interesting and that one is among the more interesting I've seen and makes a fine "table engine", even a wife could find acceptable, maybe.  I hope to see it running with coolant soon, and the system closed up properly as it was originally intended to.  I expect you will get a bit more speed, and a bit more longer running that way, and it will be worth the extra work to set it all to right I expect.  Very well done. mad jack

[Stilldrillin]

Thanks for all your comments Chaps! 

Stripped it again, this afternoon.
The only problem with a forum, your failures are public, as well as occasional triumphs. 

John, that is the way I intend to cool it. When/ if I get it sorted......   

David D

[Bogstandard]

Forget the failures David. We can't have perfection all the time.

It is the doing that counts.

John

[Stilldrillin]

Bitten the bullet! 

Screwed a piece of screwed rod into my carefully tapped plug threads. Gripped in the vice, and beat L out of it with me lead tup.... 

The ring had a drill dimple/ false start at it's inner edge. Got a blade under and levered it out....  (again).





Now, we're at rock bottom..... The only way is up, perhaps!

David D

[madjackghengis]

Hi David, it looks like you've got to the bottom of all of it, and now there is no way but up.  I expect you will have a much better running engine now that you are fixing it from before the screwup of the previous owner, and not having to contend with his errors any more.  It's good to see the pipe removed, and the prospect of having a fully sealed system allowing full cooling, and full engine pressure.  Sometimes there's just no substitute for a heavy hammer well applied. Looking forward to the return of the parts properly, to their appropriate place, and the video of it running like a scalded dog.  mad jack

[Bluechip]

Well Done that man ....   

I had every confidence in you ...

Onward and Upward ...

Dave BC

[sbwhart]

Well Done Dave

You can't beat a good wellying wif a big ammer.

Now you'll get it sorted proper.

Stew

[Dean W]

There ya go, David.  "Don't force it... just get a bigger hammer!"
And, "If it ain't broke, you're not hitting it hard enough".

[NickG]

Well done David, now just don't try taking it to bits any further now 

You'll definitely sort it once and for all now, just like the builder should of. To be fair, I think he's done  a better job on it than I could though!

Nick

[Stilldrillin]

Well, the ascent has started. 

Some months ago, I bought meself a couple of pieces of cast iron, £1 each, at a flea market. I was thinking flywheels, at the time.

Looks just the ticket.....




Turned a spigot on both ends. Time to bore out......




Largest drill I've got, 16mm......




At knock off. After some time spent boring through at .020" a pass, the hole is now around 1"+.

David D

[shoey51]

doing a grand job there mate keep up the great work

[Stilldrillin]

Thanks Graham! 

Three sessions today..... Had to keep resting the motor, as I could smell hot paint, or summat! 

This project has made me realise the pifflin' power output of a 7x12.

Started off at 20thou passes. Finished, only just managing to pull 10thou, though things were a little hot...... 




Got the bore roughed, 2.25 (-1/32")




Hope the o/d is a little easier. Don't like overloading things!

[Bluechip]

Dave

Oooh Dear .... you might do well to strip that motor  

Is it anything like 600w as per a Chester Conquest (20?) Mill, 'cos someone I know had a stinky motor after being used a lot on one of those, and we just saved it I think.

Briefly, he said the motor pongs and it's a bit stiff to turn, but it does turn. Not the mill spindle, 'cos it turns freely in neutral.
Not good sez I.
You may have got it so hot that it's taken up the end clearance on the armature. Give it a good hour or so to cool, see if it's freed off.
No, did not.
Will it free with use ?
No. Take it off. See whats really happened.

Some little black bits fell out, what are they?
Dunno. but not normal. Leccy motors never need a de-coke...

OK. Strip it. Take the brushes out. Remove the tie bolts.

It appears that there is some soft white jollop to take up clearance in the winding slots. This had got hot, melted, and run between the magnets and armature. There to carbonise with friction.

So, told him to very carefully remove any white bits that looked out of place, clean out the motor , re-assemble and give it a go.

Success. Motor free ..

Just tried to phone him, but he's away in Denmark. But his wife says she thinks 'he fixed the motor, and it's still OK'

He ??? I spent about 2 hrs on the phone, and sent some 5 e-mails with sketches ... spoon feeding the twerp ... Grrrrrr


May not be any relevance to your motor Dave, but ... if it saves one ..

Dave BC

[Bogstandard]

For goodness sake Stilldave, if it starts smoking, grab the vacuum and suck up all the smoke and save it in a jar. If you lose that, you will never get the motor running again.

Bogs

[NickG]

For goodness sake Stilldave, if it starts smoking, grab the vacuum and suck up all the smoke and save it in a jar. If you lose that, you will never get the motor running again.

Bogs

 

I'm surprised you managed to drill 16mm to be honest!  Good work David, what's going to be different between this and the old one and how are you going to make the flange?

Nick

[Stilldrillin]

Dave, John.
Thanks for the concern, and smiles Lads! 

I don't think there will be a problem..... Probably! 

Frankly, it smelt of hot paint after some 15 mins of ploughing. So, each time, I went and did something else for an hour or so.

At knock off, I shovelled out the black dust, and oiled round. Realised the headstock wasn't even aired, so I nipped the taper bearings a little, then ran it free for a few mins.

All ok, I reckon! 


Nick.
Essentially, I intend to face off the 6BA screw holes, including the part thread. Reduce the wall thickness by half, back to the neck, behind the small dia cover flange.

The counter bored new piece will slip over, held with some high temp sleeve lock, now on it's way from America.

I will then bore and turn to correct dimensions, with a larger dia cover plate flange, fitting into a thicker (3mm) steel cover plate. (Cos that area leaked as well).


Well..... That's the plan...... Probably! 

David D

[NickG]

Ahh, I see now... good plan, I think   

Nick

[sbwhart]

Looks like you've bin whipping them horses Dave

 

You can't beat making your kit work for a living.

Fix looks good.

Stew

[shoey51]

Looks like you've bin whipping them horses Dave

 

You can't beat making your kit work for a living.

Fix looks good.

Stew

im still confused but thats me generaly 

[Stilldrillin]

You're confused Graham??  

By 'ek lad...... Yer aught to try it from up close & personal!  


No machining time today, but got a few minutes to sort through the box of parts... The bloody displacer is wobbling on it's shaft!!  

The silver soldering has let go! It's only been in the box with the other parts....... Sigh........

Still, I've got all winter to sort it. And, I guess that will open up a new discussion on how to make the best displacer.  

David D

[Bogstandard]

Dave,

I know exactly how you are feeling.

I used to restore or fix badly made or worn out engines, and things made by other people never seem to come up to your own expectations of how it should be done.

I think in your case, by the amount of fiddling and tweaking you have had to do, it would have been easier to make one from scratch.


John

[madjackghengis]

Hi Dave, I'm not confused, just seeing what I'm used to seeing in my own shop, in someone else's   Being on medical retirement from the Marines, I tend to be the recipient of other's junk and garage clean out, as that tends to be in my price range.  I think you're idea will work fine, I know you'll get a much better performance when the parts are all up to your own standards, and until then, you won't be happy.  Given you're going to have to do something with the displacer, I'd recommend you use a stainless steel can for it, if you can find one that is a fairly close fit, with little excess space.  I've got two cans I cut out of used fuel filters for fuel injected cars with the medium pressure pump in the tank, requiring sturdy filters in between.  Right now, I haven't found the suitable sized container/body to run them in, but if you go to a repair shop, it's quite possible you can find a filter can that matches your diplacer cylinder bore minus the necessary clearance, in their trash can.  Both my cans came out of cars I had to replace the filter in.  I'm looking for a tempered glass chamber close to the size, so the displacer can be watched, but that's a different story.  The less heat the can conducts north, the more efficient the displacer acts in its part of the whole heat cycle, and a brass one conducts too much heat if you can find a replacement.
   All that cast iron work looks good, and I like the fact you're doing a bang up job of cleaning up a mess left by someone else, and think it will make a great improvement in your engine, and won't be a niggling thing left in the back of your mind all the time.  As you can probably tell, I wish very much that had happened to be left on my own doorstep, but I won't be greedy.  It's enough to see you doing the good job.  Now I'm really looking forward to seeing it finished and running. I've copied pictures so I can try to fabricate something that cobles together to look close enough to get the cast iron charm and antique look that engine has.  If you needed to, you could even take a sheet of stainless steel ten or fifteen thousandths thick, roll it in a tube and silver solder it, and solder a top and bottom to it, to get a right sized can if you can't find one.  What's the actual i.d. of the dispacer bore, if you don't mind my asking?  I might be able to find something of the right size and either send you one, or send you looking in the right place to find one.  I'd be right proud to help a cousin across the pond, particularly one who has done such careful work on a cock up.   It'd be the least I could do, frankly. mad jack

[Stilldrillin]

Dave,
I know exactly how you are feeling.

I used to restore or fix badly made or worn out engines, and things made by other people never seem to come up to your own expectations of how it should be done.

I think in your case, by the amount of fiddling and tweaking you have had to do, it would have been easier to make one from scratch.
John

Yer right John!
But, where would be the fun in that? I've always enjoyed "sorting things out", if I could......  

I am having fun..... Aren't I?  

Am I?  

David D