Junkers CLM

[Admiral_dk]

You have made quite a number of parts since my last comment -> good to see the great progress 

How much is missing before you can see the pistons going up and down in a trial assembly ?

Per

[Vixen]

Hello Roger,

The top yoke looks rather nice. Always good to see the (almost) finished item

Mike

[cnr6400]

 

[Roger B]

Thank you 

Per, it just needs the pistons and gudgeon pins although I should put another side on the crankase to keep things square.

[Roger B]

The holes for the gear shafts were bored 4.5mm and then reamed 5 mm. Although I had marked out the positions the spacing was set using the milling machine. After a quick sanity check the inlet and outlet ports were drilled a little deeper that the gear cavities will be. To maintain the positions when boring the cavities I used a stub mandrel held in an MT collet. The body was then located on the stub mandrel and clamped to the face plate.

[Roger B]

The bulk of the material was removed with a 10mm end mill and the final boring was done using a 6mm three flute end as a boring bar. The two end cavities were finished first followed by the centre cavity.

I then moved over to the Proxxon lathe to cut a 6mm Oilite bush to length. This was supported on a length of 6mm silver steel held in the tailstock chuck.

[Roger B]

Next I needed to open out the centre shaft hole for the bearing bush. The stub mandrel was released and pushed back into the collet then the hole was opened out with a 9mm drill. The hole was bored out to around 9.5mm to ensure concentricity and then reamed 10mm. The body was then removed from the lathe and the bearing bush was pressed in place. The 5mm stub mandrel was replaced with a 6mm one and the body was refitted to the face plate to allow the bush to be faced to length. A quick trial assembly and the gears all turn smoothly 

[RReid]

final boring was done using a 6mm three flute end as a boring bar.

Another useful idea to file away for future use.
The pump is coming along great!

[Kim]

Very nice little pump, Roger!  It's coming along beautifully! 

Kim

[cnr6400]

 

[Roger B]

I got the springs for the air valves and put one together as a trial. It seems to work well on just breath pressure 

<a href="https://www.youtube.com/watch?v=ugS5tZOr1KE" target="_blank">http://www.youtube.com/watch?v=ugS5tZOr1KE</a>

I decided that as well as the pistons I should have a flywheel for the first rotating trial. I initially looked at a RCM 125mm casting and a 100mm mild steel blank but both seemed out of character so I choose a piece of 80mm mild steel. This also made life easier as it would fit in the 3 jaw chuck.

It was cleaned up and then I started a 12mm reference bore. I will make a taperlock for the final assembly.

[Roger B]

I then ran a boring bar through the hole to ensure everything was concentric and reamed it out to 12mm.

The recess is started with a boring tool cutting back and front by reversing the lathe ) a benefit of not having a screwed on chuck   

[Roger B]

The flywheel recess was then opened out with a diamond shaped tool before moving on the radius the corners using a 6mm radiused end mill as the cutting tool. I have done this before on brass and aluminium but it was not very successful on this piece of steel. I will try and clean it up using the cutter in the conventional way on the RT.

The taperlock bush is made from cast iron, avoiding similar metals in contact which may pick up/gall. It was drilled, bored and then reamed 12mm.

[Admiral_dk]

Good to see progress again Roger 

That flywheel is not far from the maximum you can do in your Lathe (unless you find a different way to hold the Stock ....

Per     

[Michael S.]

Hello Roger,

I think I just learned something again. A good idea to use the cutter to round out the corners in the flywheel.

Michael