Junkers CLM

[Roger B]

On with the pull rods. The second one was turned to 8mm for most of the length and then reduced to 6mm at the end. I then modified a grooving tool I had previously made to give an (approximate) 0.5mm radius. This was then used to cut a stress relief groove for the end of the thread and to radius the transition between the 6 mm and 8mm sections. The end was then threaded M6 x 0.5mm.

Next I need to machine the little ends to fit a 15mm diameter ball race. I have a 15mm plug gauge so I will try to get the fit correct. There is always Loctite as a back up 

[Roger B]

To mark out for radiusing the little end I needed a centring plug. This was quickly made on the Proxxon lathe from an offcut of 6mm silver steel (drill rod).

Finally I needed to look at how to cut the three slices for the big ends. They could be sawn on the band saw and then milled true but it looks like I can just about use a slitting saw in the lathe which will be easier in the long run.

[Admiral_dk]

I get why you need to make the Long-Rods in two pieces - but how do you ensure thay are the same lenght afterwards 

Having threads in the pieces themselves introduce another problem in my mind (I really hope I'm wrong here) - where you now have both length and angles interlocked (360 more potential problems) ....

Best wishes

Per     

[Roger B]

Hello Per, I have a solution planned. The thread is 0.5mm pitch so half a turn is 0.25mm. I will able to skim this much off the pad on the end of whichever rod is longer. I could also just shim it as the big ends are designed in three pieces so I can adjust the compression ratio. The little end and the pad we be aligned parallel on the surface plate and then be left there for the Loctite to cure. (The drawing is in picture 296)

The next step was to centre the rotary table and set up to radius the little ends. I knew that the clearances would be tight. The pair came out quite nicely  I will leave the 'ears' on for the moment to help with clamping to bore for the little end ball races.

[Kim]

The rods are coming along nicely, Roger! 

Kim

[Roger B]

Thank you Kim, it's a slow process 

The rods were supported using a couple of 6mm HSS tool blanks as parallels and then were centred under the mill chuck. The bore was opened out to 10mm and then 13mm. Taking small steps the bore was opened out until the go end of the plug gauge (14.98mm) just entered. The bearing wouldn't go in under finger pressure so I am hopefully in the right area for an interference fit. Next I cut the 'ears' off with a hacksaw and finished profiling the end with a 3mm radius tool.

[Roger B]

The second rod was finished in the same way and I started cleaning then up. There are some machining marks on the shaft where the two turning operations met that I will have to polish out although there is not much bending stress at that end of the rod mostly tension when the engine is running.

[Admiral_dk]

Glad that you have planed for it all and the result looks good 

Per