Duplex Vacuum, (Heinrici type stirling)

[ksouers]

The door looks very cool, Dean. I hope you're going to leave it unpainted.
The bare brass breaks up the black surface just enough to add some depth.

Very cool, indeed.

 

[Twmaster]

I have to agree with Kevin. That looks grand in nekkid brass.

Your work never fails to amaze and astound me.

 

[Deanofid]

Thanks guys! Bare nekkid brass it is, then.

Dean

 

[b.lindsey]

What can i saw.....bare nekkid is always good :big: Nice job on that door Dean!

Bill

 

[zeeprogrammer]

Looks gorgeous Dean.
I really like those feet too.

When you silver soldered the door, does it get cherry red as the solder melts? You know why I'm asking.

 

[4156df]

Dean,
That's a great looking door. Good things seem to happen whenever you get your jeweler's saw out.
Dennis

 

[Deanofid]

Bill, Zee, Dennis, thanks again, fellows!

Zee, yes, the brass was starting to get red hot, especially the thinner door handle piece. On smaller pieces, where the heat has nowhere to go, (I mean, no place for the heat to be wicked away), things will get red hot fairly fast.

Dean

 

[SAM in LA]

Dean,

You are really moving along on this build. The brass on black looks really nice. I'm looking forward to seeing your engine run.

SAM

 

[doc1955]

Wow I like that door Dean it looks super!
I still haven't taken the time to do a little practice run on silver soldering.
Looks great!

 

[Deanofid]

Sam and Doc, thanks again for your comments!
Sam, it runs! I made a short video of it going before I did any paint work. It's a few pages
back if you would like to see it.


Working on the little cooling fan today. I didn't do any drawings for this thing. I'd been thinking
about it for weeks. I know where it has to go, but still haven't decided how to mount it. It will be
mounted (somehow) under the back flywheel and run off an o-ring "belt".

Building the fan itself was a nice afternoon of simple shop work.

For the fan hub I used a piece of 3/8" brass. First, the pulley groove was cut using tool with a 60°
tip. The tool was ground from a piece of 1/8" HSS. When it had been plunged in to the depth I thought
I wanted, I just fed it toward the headstock until the groove was wide enough for the 1/16" thick o-ring.
Then a 1/8" hole was reamed down the center.

Then five slots were cut to hold the fan blades. To start on the slots, I used an index plate on the
headstock to make five little marks next to the edge of the pulley groove. After that each slot was
cut with a jewelers saw using the little marks as a spacing guide. The slots appear to be curved, but
that's an optical illusion. They're just cut straight onto the shaft.

This is the simple setup I used for cutting the slots. I put my small bench vise at an angle of about 40°,
and starting at one of the five marks made on the lathe, started cutting until I had a slot long enough for
the blades I had in mind. Once the first slot was done, I put a mark around the circumference of the piece
at the end of the first slot so I would know where to end the other four slots.

The blue line shown in the pic above was drawn in after I took the picture. I had cleaned off the original
line I made before I remembered to take a pic of the setup.

The 40° I chose for the angle of the slots just came out of the air. You have to get that kind of stuff
from somewhere! The reason I set the vise around was so I could make straight lines. Knowing I would
have the piece oriented the same in the vise each time I rotated it for a cut, I just kept the saw at 90°
to the edge of the bench to make my cuts, and all was well. Precision eyeballing.

The next thing needed was the blades. I cut a strip out of a piece of .010" brass, measured off five spaces
that would give me a fan of 1.5" diameter, and cut them off with scissors.

Cutting them makes the edges curl enough to make them unusable, so I smashed them all flat in the vise. Then
put all five pieces together in a sandwich and pinched them in a small machinists clamp and filed all the
edges square.

When I was happy they were all the right size, (and the same size), I used a pair of tweezers to put a small
bend in one end of each blade. In the pic, it looks like the end comes to a point, but that's actually
where the small bend is in the piece.

With that little bend, the piece is effectively wider than the slot, and when they are pushed into the slots
they stay put long enough that I can get them soldered up. At the arrow tips you can just see the bends,
if you look close.

These were done with regular solder. Using pliers, the solder was smashed flat enough that it would
help me keep it from getting everywhere, maybe.

With the blades soldered onto the hub, it now needs a ring of thin sheet around the OD of the blades.
The same .010 brass sheet was used for this step. After cutting it with the scissors I spent a little
time with the file getting the long edges parallel. When I was done with that bit, the piece was wrapped
around a 1" piece of round stock to get it to the correct diameter for the blades. The brass sheet is
kind of springy, so the piece had to be wrapped to a smaller diameter. When it was released from the
round stock, it opened up quite a ways.

A piece of aluminum round with a hole the same size as the hub is used as a fixture, first to make sure
the blades are all even, then to hold the outside ring in position with the front of the blades. Then,
more soldering.

I think that will work. It was pretty easy to get too much solder on the joints, since the flux ran all
over the place, and the heat was a little hard to control on such thin sheet.

When I figure out how long it needs to be, the back end of the hub piece will be cut off.

Wanting to see if it worked well enough to be worth while, I put it a piece of 3/4" round stock in the lathe,
put the fan on a 1/8" shaft, and using an o-ring, powered it with the round stock in the lathe.
It blows a satisfying bit of air, which is what I was wanting. Doesn't even wobble too much!

Thanks again for checking in!

Dean

 

[Twmaster]

Some day I want to be like Dean.... M&Ms and all!!

 

[4156df]

Dean,
That's a very nice fan and a neat technique. About your 40 degree angle...when I made the exhaust fan for my tractor I spent way more time than it was worth stewing over what the "proper" angle should be. I ended up with about 40 degrees for no good reason. Interesting that we both came up with the same angle. I bet we could start a holy war on some boards regarding what that angle really should be.
Dennis

 

[doc1955]

Dean nice I was thinking the same along the line of flattening out the solder I was planning on giving that a try when I work on my fan. I have a ways to go to get there. Have you ever tried flattening silver solder and doing that? If so did id work out.
The angle of the blades in the fan I'm working on is 32 degrees. It has been to warm and humid for me to do any shop work I need to get air.

Precision eyeballing :big: :big: I like that comment!
I also like your smiley face plate.

 

[b.lindsey]

Another great photo essay Dean, and a nice result on the fan and given its small size and the thinness of the blades, impressive work as well. Speaking of small, I saw an ad on TV last night for some new M&M's with pretzels inside them. I can see the prodution line now...all these people with magnifuing visors on and using tweezers to twist all those teeny tiney pretzels. Gonna have to buy some of those and dissect one to see how it's done. Anyway...great post as always!!

Bill

 

[zeeprogrammer]

Very nice Dean.
Nice tip on bending the blades so they stay seated.
Was it pretty fiddly?
Looking forward to seeing it all run.

 

[SAM in LA]

Dean,

Your fan came out well. ;D

When soldering such thin materials, how did you control the heat so the parts would not just burn up? scratch.gif

I found your video on page 13. I had seen it before and just forgot about it. My forgeter works great, its my rememberer that gives me problems. ;D

SAM

 

[Deanofid]

Mike, Dennis, Doc, Bill, Zee, Sam, thanks to each of you once again! I always appreciate
everyone's comments.

About your 40 degree angle... I ended up with about 40 degrees for no good reason. Interesting that we both came up with the same angle.
Dennis

Yes, it's kind of strange, Dennis. If you remember, some months back we both made a steam lubricator on the same day in completely unrelated posts. We must be cosmically linked.
Boy, I sure got the better part of that deal!

I bet we could start a holy war on some boards regarding what that angle really should be.

And if that didn't work, we could almost surely get one going on gears... !

Have you ever tried flattening silver solder and doing that? If so did id work out.

Doc, yes, I've flattened hard solder wire. It's about like flattening baling wire. I use a ball pein on a mild steel plate and beat the pucky out of the wire. It will get fairly flat but takes some work.
I've also used my arbor press, but it takes some serious grunt on the handle. Hammer is probably better.
Regular solder should do fine for your fan blades, though. Using that, you wouldn't be able to pull them apart with all your strength. Surly wouldn't get that much force on them just spinning at the rather lazy rate that a stirling fan rotates them.

Nice tip on bending the blades so they stay seated.
Was it pretty fiddly?

Zee, the fan blades stayed in the slots just fine while I soldered them. Fiddly part was getting the outer ring round and making a butt joint on that with the solder.

When soldering such thin materials, how did you control the heat so the parts would not just burn up?

Sam, I used a regular propane torch and turned the flame down low as it would go without going out. Then just didn't get it too close to the piece and all was fine. These were soldered with normal solder, not brazing wire, so didn't have to get terribly hot.


Thanks all!

Dean

 

[doc1955]

Thanks Dean!
I'll see how my test pieces go when I get there.
I may change the plan to soft solder instead we'll see how it goes.

 

[Deanofid]

Today's post shows building the bracket for the fan. I thought of three or four ways to do it, but they
all ended up seeming 'clunky' the more I thought about them. Settled on something fairly straight forward,
and hope it fits in with the general theme of the engine.

Laid out what looked right on a piece of 1/16" brass sheet.

Then more saw work. Bet people are getting tired of seeing this sawing stuff. Well, there won't be
much more of it! (Yes, it's finally, nearly, almost done!)

When the piece was sawed out and filed a bit, I put it into the vise with the long skinny part sticking
up and laid a piece of wood against it. Tapping the wood from the side bent the piece over nicely.

I turned up a small bush that will hold a stud for the fan to rotate on. Using regular soft solder, I
snipped off a piece about 1/16" long and dropped it into the hole in the bush. A drop of flux in the hole
and a quick shot with the propane torch an it's stuck.

The regular solder I usually use for things that do not need high silver content brazing wire is called
96/4 solder. On the package it will probably say "Silver bearing solder", which is exactly what it is.
It's soft, 96% tin, 4% silver, and for a soft solder is plenty strong. It needs a liquid flux like Harris
Stay Clean if you want to get the most from the solder. With that flux it will flow very
well, and easily solder copper alloys and most kinds of steel, and copper/brass to steel. PM Research
sell it as a soldering kit for their models, hobby stores carry it under the Harris name, and I think
Home Depot has it for internet orders. The solder and flux come in the same package.

After soldering, the bush was used to guide a drill bit through the brass sheet, the end of the piece past the
bush is cut off, and the corners rounded over with a file.

That's the piece finished up.

Mounted to the engine with a mock-up shaft for the fan.

Fan goes on like so. The shaft will be cut to length and I'll either thread it for a nut
or cut a groove in it for a circlip.

At this point, I just need to make a pulley for the crankshaft to run the fan. I'm not at all sure
I like the brass fan against the aluminum of the engine. I may paint it to match the flywheels. For
certain, if I leave it brass, it will need to be finished off better.

It's almost done. I had been pretty enthused about pin striping the base after seeing Dennis' beautiful
Kouhoupt steam tractor, but after playing with it for a while trying to get practiced up for it, I'm
now reluctant. The opportunity for a royal screw-up is pretty evident after trying it a number of times.
It may just have to be the way it is!

One more shop session should see this engine done. Won't be long now.
Thanks again for checking in!

Dean

 

[mklotz]

Dean,

With those nice flat surfaces, would it be possible to cut your pinstriping design into a sheet of self-adhesive paper, apply it to the base and then hit it with an air brush or a rattle can?