Junkers CLM

[Michael S.]

Roger, I'm very pleased that all the work was worth it.

Michael

[Roger B]

Thank you both 

Next up is mass production of the air valves for the scavenge pump, 12 in all. The turning of the main valves, the spring caps and the spring guides were all carried out using parting tools so as not to have to keep changing them. The M3 stainless studding was cut with a junior hacksaw and finished with a file in the lathe. I have made 13 of everything assuming that at some point a part will be taken by the swarf gnomes.

[cnr6400]

 

[Kim]

That's a real production run, Roger!   

Kim

[Michael S.]

It looks like a successful series production 👍.

Michael

[Roger B]

Thank you all 

The series production continues. I finished of the spring guides and the moved on to milling the air valve bodies. The first stage was cut in 0.5 mm steps with a 3mm end mill at 10 000 rpm. The sectors were then cut with a 2mm end mill in 3 75° steps. Luckily my small RT just turns freely, winding a handle would have been tedious. Next step lots of deburring and polishing the sealing faces 

I am now looking at the rest of the scavenge pump, checking the piston clearance and marking out for the holes for the air valves.

[cnr6400]

 

[Roger B]

The hole for the air valves were drilled out 8mm and then 12mm. The 14mm recess was cut with an end mill, centring each time with a 12mm bar. Their is a slight overlap between the valves which can be solved with a little filing.

Next I milled a recess in the top of the cylinder block to allow the air to flow from the valves to the inlet ports. There are still the connecting holes to drill.

[Roger B]

Unfortunately I didn't allow for the 3mm thick pullrod cover plates so the first recess was too narrow. Back in the mill again.

A little bit of filing got all the valves in place so I polished the sealing faces on some fine abrasive cloth and started assembling them. The studs were Loctited into the body with a high strength grade then the rest was assembled using a medium grade in case I have to dismantle them in the future.

The next stage is to make a new, better fitting scavenge piston.

[RReid]

Lots of detailed and finicky work embodied in those recent sequences. Nicely done and great progress!

[Kim]

Lots of detailed and finicky work embodied in those recent sequences. Nicely done and great progress!

Wow!  I'll say!   Amazing work, Roger! 

Kim

[cnr6400]

 

[Roger B]

Thank you 

On with the new scavenge piston. It was machined to a close fit on the long axis but this is difficult to check as it tends to tilt and jam. The corners were then rounded and with a bit of hand fettling it fits. It is easiest to check using an adaptor in the bench drill as it keeps it square. The new piston is 0.05 - 0.08mm larger than the first attempt so hopefully it will seal well enough. Thermal expansion may be a problem but it is at the 'cold (inlet)' end of the engine so hopefully ok.

Next up were the air passages from the scavenge pump to the inlet ports. I hope they are not too restricting, if so I will mill them out to a slot. Finally a couple of counterbores in the piston to recess the fixing nuts.

[Admiral_dk]

Nice progress - fingers crossed and hope that you end up with a working Engine     

Per                

[cnr6400]