Rizzo.......

[Stilldrillin]

Time to start on another Orphan........ 




You've seen the pics of this one before. It's called “Justine's” by James G Rizzo. Published in Engineering in Miniature 2004.



Said never to have run. 

Looks ok..... Been picked up too many times, by the transfer pipe. I can actually feel it blowing from the displacer joint, when the flywheel is turned. 

Nil clearance at the ends of displacer 3/4" stroke. (Bump, bump, bump..... ). 

Stripped.......




Everything seemed ok. Don't like the glued in, displacer and cylinder plugs.....

It needed a better support for the pipe to displacer cylinder joint. So, I opened the socket to 6mm x 10mm deep, intending to fit a recessed, extended sleeve, to support the lower end of the pipe. Which was also araldited in place, only....... 

The displacer piston slid freely in the bore........ Didn't feel quite right........ 

The shaft slid out into my hand!!! It had let go from the displacer!!!!! 

Nowt else to do, but heat it up to loosen the glue, and release the bearing end cap...... 




Not a lot of location area. Might have worked better if the braze hadn't been faced off...... 




No penetration! It had only been held on by the brazing flux....... 




Oh dear...... Is this the start of another “Robinson rebuild” saga?   

Sheesh!  

[sbwhart]

Oh dear...... Is this the start of another “Robinson rebuild” saga?   

Sheesh!   

Well you sorted the Robinson out Dave I'm shure you'll sort this little Italian job and have it ticking over like a Ferrari


 

Looking forward to your adventures.

Stew

[lordedmond]

Looks like beauty was only skin deep in this case

the builder has ,looking at the pics made a nice job but let himself/herself down with the hidden bits



Stuart

[NickG]

Nice looking engine, was it a non runner to start with then?

[stirling lad]

the builder appears to have tried for a nice finish but seems to have cut corners on the bits that are'nt seen...show us how it should be done David..


   ...Mike..

[Stilldrillin]

Thanks for your comments Chaps! 

Nick, I know little about it's history. Bought from Ebay by a pal, who couldn't fix it. Swapped it me for a Mamod twin.......

It arrived accompanied by scans of Engineering in Miniature build pages.

The alloy power piston looks to be, as originally machined/ polished.

To me, (so far), the problem is reliance on "Araldite" to glue parts together...... As instructed! 

I'll chamfer the end of displacer shaft, to run in some silver solder..... But the other end is an alloy disc held in by some more glue! 

Guess that will have to come out first.......

David D

[sorveltaja]

David, are you sure, that you have the original plans?

Anyways, to my(lacking) knowledge, too much glue is involved, when working on such a high-temperature engine. As a shortcut, glue works for a minute, until it starts to shrink, then it starts to stink.

Bogs might have more correct answer, what comes to high-temp glues, and their use on engines, like yours.

[Stilldrillin]

Tapio.
I have the original series from the magazine.

The suggestion is to produce a shrink fit, with a "bonding epoxy adhesive", in grooves around the male component. 

I have much more faith in high temperature sleeve retainer.......




All affected joints will be parted and rebuilt, properly! 

David D

[Rob.Wilson]

Hi David

I am sure you will have this engine licked into shape in no time 


Rob

[Stilldrillin]

Thanks Rob! We'll see.......


Finally managed a little shop time this afternoon.  

Dunno why the flywheel was a mm or so, eccentric. But it's ok now! Topped it, mounted on it's shaft. Friction drive off the chuck jaws.

Two grub screws down the same hole, had me fooled for a while though.......




Chamfered the displacer hole and shaft end, remembering Boggy/ Stew's ring of silver solder, tip.

Only the second time I've silver soldered anything.......




The cold end plug held ok. Must be shrink fitted.

The cleaned up components..... Made the pipe supporting socket. Faced 1/32", or so from the inner face of the cylinder plug.....




Loosely assembled......




That's enough excitement for one day.  

David D

[arnoldb]

Looks great David 

  Watch the silver soldering; it can become addictive once you get the hang of it 

 , Arnold

[stirling lad]

Very neat n tidy work David, and great photos too!

 looking forward to the next installment..

   ...Mike...

[lordedmond]

I take it the magic smoke has remained inside the motor  with all this new work

[Stilldrillin]

I take it the magic smoke has remained inside the motor  with all this new work

Had that hot smell again Stuart, several times. 

So, I ignored it and carried on....... 

David D

[sbwhart]

Fee Fi Fo Thumb I smell another runner.
 


Stew

[Stilldrillin]

Fee Fi Fo Thumb I smell another runner.

Stew

Nah! Not just yet, Stew.......

Guess that's round one to Rizzo!  

Assembled, properly......




New support sleeve for the transfer pipe. Remade the cylinder head/ hexagon seal. Made a nice screw plug, with a ho ring. Sealed both ends of the pipe, into the fittings.  

Attempted to run it for, 10 mins or so..... It was trying. But, not very hard.  

Tomorrow, it goes into a bucket of water. To see if there are any leaks........

David D

[lordedmond]

I hope it can swim

[NickG]

the water bucket is a great test!

[stirling lad]

I hope it can swim

I would'nt worry about that, all ugly ducklings can swim but just like this one,,they're terrible runners! 


  ...Mike...  

[Stilldrillin]

I hope it can swim

I would'nt worry about that, all ugly ducklings can swim but just like this one,,they're terrible runners! 

  ...Mike...  

Nice one Mike!      

And so blummin true! 

No leaks. Only a little fuffle from the displacer bearing.......

Wondered if it needed more inertia, cos' the flywheel's a bit lightweight.

So, I fitted a 5" casting I just happened to have handy....... 




No difference at all........ 


Hmmmmm......... 

David D

[stirling lad]

yes but it's starting to look like a very nice paper weight,,   




   ...Mike...

[sorveltaja]

Dave, too bad you couldn't get it to run .

I assume, that you have checked, that dimensions of parts are correct? How about their materials?

[NickG]

Dave, what is the knurled bit on top of the power cylinder for?

Looks like you'll have to go back to basics, what are the clearances radially and on the ends of travel of the displacer, also, what diameter is the displacer and power piston? You want the displacer swept volume to be significantly higher than the power piston (look at the ones on you're robinson - the difference in diameters is huge). On this type of engine (gamma I think) the only way is to have a larger diameter since the strokes are the same running off the same crank.

Then it's just a matter of friction if the leaks are sorted.

Hope this helps.

you'll get there, these things are usually temperamental!

Nick

[Dean W]

It sure is a nice looking engine, David.  It will look even better when it's running!
I'm puzzled at the call for glue in the prints, especially in a heat engine.  Just doesn't seem right.
I think tracking down any friction, no matter how slight, is in order.  Also, be very critical of leaks,
however small they may be.
Nice looking flywheel there... ; )

Dean

[Stilldrillin]

Thanks for your comments Chaps! 

Nick, the knurled thumbscrew with O ring, replaces a 6mm bolt and fibre washer. Not completely sure why they  have a T junction. But it makes oiling the piston easy.....

As I reassembled, I checked it was to drawing spec.
Apart from 7/32" dia shafts, an alloy piston, and plain crank bearing, I couldn't see much wrong.......   

This one, on Ebay at the moment, seems to run ok!

The stroke is 3/4" (19mm).

Piston 26mm dia.

Displacer (only?) 32mm dia.

I wonder if the oversize displacer shaft, is altering the cold end swept volume, significantly? 


Anyroad!
I'm looking at reducing shaft diameters, needle/ ball bearings, new piston in a different material. Probably!

David D