How to Fix Noisy Kopp Variator Cones

[Steenkamp]

Hi All

I recently aquired a Colchester Chipmaster, it had a very noisy variator. I got quoted a small fortune to have it refurbished, so i fitted a VFD and left it at that. Or so i thought.....
Curiosity got the better of me and I called in a friend to help me strip it so we can both see how it worked.
 So opening up the cover plates we found most things in order, except for the "drive cones" that had a severe groove with a rough surface on the running faces. .
Next up was the balls, which were actually in great shape, the photos look a lot worse than the actual surface
The Cover plates and outer bearing race was also in very good nick!
I think this Variator was ran for a bit with a low oil level Thats why everything except the drive cones is still in very good condition Well, it helped me get the machine at a good deal

Next we made a arbor to mount the drivecones on with a push on fit and used the tailstock with a hollow centre to keep the drivecone on the arbor.

[Steenkamp]

We ran a file over one of the unimportant surfaces and saw that the file slides without leaving a mark so we decided to try face it with a hard carbide tip, it thrashed the carbide immediately    Very hard stuff indeed!!

[Steenkamp]

I had a ceramic/porcelain tip that i scrounged from a supplier as a sample a while back and decided to give it a go. as you can see from the  video it cuts spectacularly with lots of fireworks!!

[Steenkamp]

After facing the drive cones they looked very good, almost mirror finish!
So we cleaned out and reassembled the whole lot.
 Now it is running very quiet , much quieter than the lathe powering it 

[awemawson]

A fine job indeed 

It would be interesting to find out what steel they are made from - high manganese I suspect 

[Steenkamp]

Thanks Awemawson. I fitted the variator tonight, man that thing is heavy and cumbersome! She is running fairly quiet, no rough whining and banging anymore! Its actually very nice to have all that torque in the slow speeds!