Got started building the power head today. I looked through my box of assorted bearings to see if there were any big enough to support a shaft big enough for a ER-40 collet chuck. Found 2) new 385-A tapered roller bearings (2” ID )without cups. Quick look online and 2 cups will be here tomorrow. Also found a piece of 2” x 1” DOM tubing.
So today I carefully indexed a 7” length of that tube in the 4 jaw chuck and then bumped the outboard end into concentric before supporting it with a center support. I spent about a hour to get that within 1-2 thou, first roughly and then indicated the taper off my other ER-40 chuck. Set up the compound to cut the 8 degree inside taper.
I used a 3/4” boring bar to cut the taper with the compound spinner handle rotated with a super slow cordless drill motor (actually 2 old drill motors in tandem sort of cobbled together but working great). It makes a far more even cut than turning by hand.
When the right major diameter was reached I took one more 5 thou cut on the slowest feed speed of the
drill device. I was expecting it would need to be ground to get a nice finish but was surprised at how good it looked. It wouldn't get much better if any with grinding. So then I put Dykem in 3 places around the taper and used a collet on a shaft to check the fit and contact area. To my delight it was near perfect.
DONE with that!!!
Next job, make a collet nut.
Thanks for your interest.
Aaron