I thought I had a neat solution for replacing the ER11 collet chuck adaptor. But there is a slight issue with this cunning stunt. As you can see, the main body has a through bore of about 8mm. That is somewhat larger than the 60 degree centre pip in the Autolock chuck which is responsible for the accurate radial location of the inboard end of the cutter / collet chuck. So the only way around this would be to create yet another adaptor that would sit in the end of that bore, with a centre hole for location.
This would be getting rather messy. Not only would I need to bore out that hole (to ensure it is concentric) but I'd also need to make up a mating part with a centre hole. All of those features would have their own tolerances which would stack up in the final assembly. I'm needing something better than 10um total runout at a guess, so this concept doesn't sound as if it would be worth all the buggerage.
At this point, I chanced upon a familiar looking component on the Arc Euro website. This is the exact same ER11 collet chuck adaptor that came with the speeder in the first place.
The only obvious difference is the rather large / clunky nut. Obvs the only sensible thing to do was to order a few of them. And yes, in the flesh they are clearly the same part:
- Set up stock in 4 jaw
- Centre drill, then support with tailstock
- Rough and finish the taper
- Thread 20tpi