I looked into the horizontal worm shaft a little more and realized the whole thing was being held in with a set screw on the left side behind the housing containing the gear. The set screw sits in a divot in the side of a bushing on the shaft. The set screw retains the bushing which is constrained by a step on the shaft and the gear in front. It turns out my set screw was a little loose, but even once I tightened it I still had 0.008" of travel on the shaft. Near as I can tell this is just clearance for the bushing. I suppose I could just machine the bushing down enough to tightly fit a thrust bearing between it and whatever coupling I end up putting on the shaft. The end of my coupling could even have some sort of lock nut for taking up the slack. I am suprised to see a set screw being the only thing supporting the thrust of the Z-axis, but the manual says the clutch on the hand feed pinion shaft is designed to slip in case of the quill bottoms out against the stop.
Quint |