'TINY' another tiny engine but vertical and water cooled

[gbritnell]

Hi again Kvom,
Here are some pictures of the machining of my flathead crankshaft.
1. Flats milled on stock for locating in fixture.
2. Main journals roughed on mill.
3-4-5. Fixture block being setup and indicated in the 4 jaw chuck on the lathe. End mill shank was used for setting offset.
6. Crank locked into fixture block. Front shaft supported by tailstock clamping block in live center. Preparing to cut #1 throw.
7. Tailstock support block against live center.
8. #1 journal finish turned.
The 2 blocks, headstock and tailstock, are the same size. Once the crank  is clamped into the headstock block with the set screw against the flat the tailstock block is slid onto the front shaft and rotated until I can lay a parallel bar against the sides of the two fixture blocks to line them up. I put small machine clamps on to hold the parallel in place while I tighten the set screw. This insures that the crank axis in parallel with the lathe axis (not twisted).
If the crank is somewhat fragile in nature, tiny journals etc, you can just rough mill each throw one at a time and then return the crank to the fixture blocks.
I have tried making built up cranks for multi-cylinder engines in the past but no matter how I try I always get a twist or misalignment to them.
gbritnell

[gbritnell]

This is the Hall transistor holder being milled on the end of a piece of round stock. The part was drilled and  reamed on the lathe and then necked out to the proper thickness. It was then put in the mill vise to have the shape milled.
The next picture is the magnet disc and Hall holder mounted on the engine.
The last picture is with a 1.00 micrometer to give an idea of the size.
gbritnell

[b.lindsey]

Thanks for that last picture with the mic George. The engine is smaller  that I expected even though I know you are the master of "tiny." Great pictures as always too!!

Bill

[gbritnell]

It's down to making some of the small add-on parts, muffler, carb and spark plug. When I started this build thread I mentioned that I wanted to minimize the use of brass on the engine mainly to make it resemble a full sized engine. So the next part, the muffler is made from 12L steel. I also thought that making a replica muffler would be more attractive so I drew something up. The two halves are held together with 1x.25mm stainless screws with .05 spacers in between. I turned the outside shape and then made a collet from a piece of aluminum so that I could dish the inside a little. Not that it needed it but I just felt like it needed it.
.

[gbritnell]

The next part is the carburetor. For those of you that have built one of these you know how tiny it is. The venturi is a combination of a reduced area in the fuel tube and a .02 cross drilled hole. The needle valve was made from a .03 sewing needle. It was supposed to be .025 but I didn't have any needles that size. I don't have any pictures of the construction as I have to use a magnifier to create them as it is.
There are 3 parts, the body, the fuel tube and the needle valve. I'm going to have to come up with a fuel tank that will locate right under the carb so it won't have to pull the fuel too high.

[gbritnell]

A couple of pictures of the almost complete engine. Tomorrow I'll make the spark plug and mount the Hall transistor into it's bracket.
gbritnell

[b.lindsey]

Well this one is going to be over way to quickly George, but it sure is a beauty!!

Bill

[10KPete]

Come on, George! You're not getting away that easily. Where's the water pump? The plumbing? The radiator?   

Pete

[gbritnell]

Hi Pete,
When I made the last engine a true hit and miss it never heated up at all so I'm guessing this should be the same. I had in mind making one of the old style thermo-syphon systems where the hot water rises, goes to a triangular or conical screen, drips into the retainer basin and then is circulated back into the engine. With this running so cool I don't know if that would even occur although it would still look pretty neat. Another option would be to gear a pump from the cam gear and circulate the water. I can't use the crankshaft because there's no more room available for pulleys or gears.
gbritnell

[gbritnell]

When I built the last engines I only made one spark plug per engine so this time I thought I would make two while I was at it. The thread is 8-40 and the insulator is Corian. It has a .025 music wire center electrode and arcs to the body of the plug. (no ground strap) For those fellows who have built one of these engines you can see how I changed the plug angle to get farther away from the rocker arm.
gbritnell

[gbritnell]

I'm currently working on the gas tank and bracket. The bracket will be aluminum and screw to the side of the engine frame. The gas tank is brass, .625 dia. x .750 long. I still haven't quite figured out how I'm going to feed the carb yet. I made a drawing for the bracket and figured the easiest way to machine it would be to mount a piece of aluminum on the rotary table and that way I could do all the holes and angle in one setup. The first operation was to drill and bore for the tank.
gbritnell

[10KPete]

Well George, I just had to kid you about the cooling system. That whole thing probably doesn't hold more than a teaspoon of water anyway. Well, maybe a bit more.....

And with a gas tank that small it couldn't run long enough to get hot! 

Pete

[gbritnell]

Hi Pete,
I actually thought about it for aesthetics purposes.

[gbritnell]

I have the bracket finished. The first picture is the bracket after machining.
The second pic is with the excess material removed and the part filed and cleaned up.
Third pic is the tank slid into the bracket.
Fourth pic is the bracket being drilled for 0-80 screws.
Fifth pic is the bracket mounted with the tank.
The remaining pictures are self explanatory.

[10KPete]

Beautiful! That's so much nicer than most tank mounts. Very much in keeping with the 'theme'.

 

Pete