Stirling Engine ... of sorts ..

[Bluechip]

Hi Troops

Few pics. of a Stirling Engine on the go.

Designed ...  .. on the fly from the contents of the scrap bin.

Elegance was not a primary objective ...

And a couple of pics of a tube bender I belatedly decided to make after devising methods sundry and diverse of destroying perfectly useable copper tube .. 

Did have an experimental poke at heating the hot end, pulled the displacer back, and the power piston popped to BDC .. 

So, something's happening ... maybe ..

We will see ...

BC

[Brass_Machine]

Well I think it looks fantastic. 

If you ever decided to do up drawings (if you haven't already). I would give it a go as my next build!

Eric

[Stilldrillin]

That looks determined and purposeful Dave!  Well done.........

Looking forward to the runner vid.

David D (The pretend one).

[Rob.Wilson]

Looking Great Dave 

Looks like you have had the hot cap warm 


Rob

[Bluechip]

Alas, Eric, can't do drawings ...  only c-o-c .. in the event the thing runs, I'll strip it, do some pics and give the major dimensions. I don't think other things really matter too much, depends what is available that's about right.

Yes, Mr. SD   I would like to see a vid. too .... probably more than you actually ...   

Didn't give it all that much heat, just looks like it. Nice colours anyway, might varnish it ...

I was quite surprised how the power piston moved. The copper pipe is only perched in the banjo's, not soldered. No o-ring on the displacer shaft. The power cylinder head had no gasket and just 3 of the 6 capscrews in not tightened up.

Might just be a runner ... eventually.

Doesn't matter anyway, I hear there's a geezer at Chesterfield takes duds in ...   

Orphans, I think.

Put it in a basket wrapped in a shawl. Leave it by the front door, ring the bell then swiftly leg it ... 

BC 

 

[Stilldrillin]

Doesn't matter anyway, I hear there's a geezer at Chesterfield takes duds in ...    

Orphans, I think.

Put it in a basket wrapped in a shawl. Leave it by the front door, ring the bell then swiftly leg it ...  

BC  

That often happens Dave!    

One recently arrived unannounced, from Australia!  

David D

 

[Bluechip]

Another Hot Air engine ??? Non-runner ?? Huxtable 2 ??

Good Lord ...

How many does that make ??


BC

[DaveH]

David,

Looking good,
Looks elegant to me 

 
DaveH

[madjackghengis]

David you may well want to see it running more than I, but there's lots of 'I's' out here, is it possible for us, combined to want more than you do?  Personally, elegance is present when form follows function, and things are clean and square, round is round, and they show actual use.  By my perspective, I believe that will be quite a fine engine and you won't need to leave it as an orphan, but I wish people would leave their orphans on my step   That is a very nice job, and really looking forward to seeing it run.   Cheers, mad jack

[saw]

Nice work 

[Bluechip]

Thanks for the replies folks ... bit more progress ...

[1] That transfer tube thing ... which requires two banjos fixing at right angles ... and in the correct place ..

One idea was to soft solder them on in situ ... but all I have is the electronics 60/40 stuff ... serious doubts about that. Another alternative is tinmans solder  ( comsol ??? ) which has a higher melting point but it's not cheap and I have no other use for it AFAIK.

Then I found out about JB Weld Steel Reinforced Epoxy. This appears to be OK up to 315^oC.

Having got some I tried it out. Bit of 1/4" brass round, tickled with steel wool to clean it, poked a a 1/4" hole in the end a bit of 5/8" x 3/8" steel flat and epoxied the two together. Just pushed in and rotated a bit. Left it for two days ..
Scrounged Norm's Infra Red thermometer, [ nice, must get one, new toys always welcome ] applied propane torch, thermometer said about 430^oC , well, it did come apart with a good heave via a 10" adjustable, but I would guess about 40 ft/lbs.
Remarkable product, not cheap, but then neither is solder ...
I doubt if that tube will get anywhere near 300 odd C in free air.
So, the tube is now epoxied together.
Good enough for me, chief. We're in business...

Made two gaskets from .25mm PTFE sheet, as per Bogs' write up elsewhere in MM..
Cut out with an OLFA Compass Cutter and the screw holes done with Maun hole punch pliers.
I do have some small wad punches, but they made a hideous mess, so got a new tool ... [ toy ]

[2] The displacer guide bush leaked like a sieve .. should know by now steel bar is undersize, and reamers cut oversize ...
So that has been remade, this time the 5/16" shaft hole has been bored out to suit the actual 0.309" which passes for 5/16" rod ..
A lot better, couldn't have been much worse actually ...

Tried the warm it up and see bit, when the displacer is pushed in and out there is quite some push and suck on the power piston rod ...

Maybe the Gods are smiling on their humble servant ???

BC




 



 

[doubleboost]

That is a very nice looking job
I do like to see nice bends in pipe work
John

[Bluechip]

That is a very nice looking job
I do like to see nice bends in pipe work
John

Hi John

So do I, ... now I've done it. 

Not so keen on looking at all the wrecked tube in the crap bin ..

That bender works quite well, was going to make one years ago with alloy formers etc. then decided to see if PVC would work, being a cheapskate. It does, for copper tube anyway ..

Quite chuffed ..

BC

[madjackghengis]

Hi BC, while I'm a big fan of epoxy, it never is finished setting until it has turned to dust, in reality, and heat is what determines the time of its demise.  As a former electronics tech, I've long used top quality eutectic solder, 63% tin, 37% lead, rosin core, and while it is not recomended for structural use, I've found that it only matters when one gets into large scale use, and the fact eutectic solder melts at 361 degrees F, and is liquid until it solidifies suddenly, at the temperature it freezes at, it is the easiest to use when wicking is important, and is good for almost any use but a steam boiler, where temperatures in an area could go above that degree, and where silver solder is the minimum reasonable.  In most model building, it is as strong as any other, as long as one doesn't push the envelope with it.  I also use it to tin copper and other metals when I'm going to use a low temperature silver solder, as it is a better wetting solder, and will be displaced by the silver solder when it is applied.  I use zinc chloride for flux, which washes clean with water and is an "active" flux.  A "eutectic" alloy is one where the metals are a perfect match with all the different molecules being completely mixed.  This makes for a solder which goes from liquid to solid rather instantly, and vice versa, where a solder such as fifty fifty will melt slowly, going through a stage of mushy solid into slushy semi-liquid, and then liquid, and do the reverse on cooling.  It is good for a "wiped joint" such as using it to connect lead piping, but it can easily leave crevices in the crystaline structure that seep if one works it too much, or moves the parts before it is solid enough.  I look forward to seeing this engine completed, and watching it run.  It's a looker, and appears to have lots of personality already.   Cheers, mad jack

[Bluechip]

Hi Jack

In retrospect you're probably right about 60/40. It's not actually holding the parts together, just there to block the holes .. 

Still, it's epoxied in now, and we shall see. If the epoxy lets go, no big job to re-do it.

Not done much today, miserable backbone giving me some grief again. Just milled the crank supports to the correct height. Only roughed out in the pics.

BC

[NickG]

Nice work Dave, I love stirlings, it looks great. 

Nick

[Bluechip]

Well, it runs ...



BC

EDIT

The wretched engine is far quicker than Photobucket ... what's buffering anyway ???

[doubleboost]

Runs greeat
Looks a good size as well (i do like a big engine)
Well done
John

[Bluechip]

Hi John

Yep, I'd noticed your fetish for big engines ... that Marine Engine of yours ... 

What does it weigh anyway ??

Had a bit of grief with the PTFE power piston. That locked up. Had to skim some .002" off it.
I think I read somewhere that many polymers expand a lot...
It's been running at a fast tickover for some 30 mins. Did not tighten up after that, so I presume it's about right now.
Although it feels a bit loose.

Needs a fair bit of heat to get away, but then it just goes on a sniff of flame.

Anyway, I need to look at the Displacer crankpin bearing. It's that making all the clattering. 5mm bore ballrace on an undersize pin. Knew all about it, but wanted to get the contraption going.
If you look closely, there are several screws missing... might even stick some in. 

Big improvement after the other night, went like the clappers for about 90 secs...
Until the hot cap solder let go .. 

Have fun

BC

[Stilldrillin]

     Yeee.... HAAaaarrrrr!! 

Blummin well done Dave! 

That runs nicely... 

(As far as I could tell, with P bucket's buffering). 

David D

[Bluechip]

(As far as I could tell, with P bucket's buffering). 

David D

Isn't it just a right PITA ..

Youtube desn't seem to do it so much.

So why P/Bucket ??

BC

[Stilldrillin]

(As far as I could tell, with P bucket's buffering). 

David D

Isn't it just a right PITA ..

Youtube desn't seem to do it so much.

So why P/Bucket ??

BC

No idea! 

Mostly, I don't bother to watch P bucket vids.......

Only suffered this one 'cos it was yours...... 

David D

[lazylathe]

Awesome stuff Blue!!!!

I like the fact that it runs for a long time after the heat is removed!!

Great work!!!

Andrew

[DaveH]

BC,

Nice one

 
DaveH

[Dean W]

'
Runs very well, BC.  I like it!  Since it will go for a half hour at a stretch, it sounds like you got
all the important stuff just right, too.  It's interesting that it runs with a polymer power piston.
I've tried that twice in engines over the years.  Neither would go until I changed them to a more
heat tolerant material.

Youtube desn't seem to do it so much.
So why P/Bucket ??
BC

Pbucket just seems to be lousy for videos.  I usually don't watch vids there either because of
that buffering nonsense.   But, wanted to see yours run.

Dean