Well the little follow rest project to turn some long but thin 4140
shafts worked out really well. Both the 17mm and the 20mm shafts came
out within 0.005mm or 0.0002" over the full 24" length. I was very
pleased. I made the follow rest from 3/4" plate which bolts to tapped
holes in the top of a standard Aloris wedge type tool holder. It
extends from the tool holder, over the top and back of the workpiece,
supporting two sealed ball bearings on slides milled into the plate.
The outer races of the bearings run directly against the workpiece,
just aft of the cutting insert. This was the second iteration of the
follower, in the first iteration the slides simply rubbed against the
shaft. Unfortunatly, this setup would only work okay for a few
minutes, as the coolant did not prevent the rubbing ends of the slides
from wearing. Once any wear set in chatter would start.