countershaft bearing fit

[Omarttentmaker]

I've encountered this before. When fitting over sized roller bearings in both ends of the countershaft cluster, if the last bearing didn't fit, I was told to leave it out. I was never comfortable with this. Happened today, as with all the bearings in place and the shaft inserted in the cluster, the cluster spins and the shaft spins, but the bearings in the cluster do not. I'm thinking of taking one bearing smaller than the other 21 (say .001" smaller) and using it in place of the last over sized bearing. This would fill the gap in between the bearings but still allow for the bearings to rotate in the cluster. What does everybody think?

[mark59]

i have left a bearing out on the main drive gear 43 instead of 44 rollers when i got to about 0.0004 " oversize or larger, at that oversize adding one std bearing never fit, might work at 0.0008 to a thou os, really not sure with the countergear since you only have 22 bearings to start with per side, the old manuals mention leaving a bearing out but i always thought it was the drive gear only, see what the manual says. since countershafts are relatively inexpensive and usually wear the most why not replace it, is your shaft up to spec ?

[Omarttentmaker]

Manual doesn't mention leaving a roller out in the countershaft assembly instructions. the shaft mics .7554, so I'd say that was within spec. I did what I said I was gonna do. I pulled one roller that was .1254" and replaced it with a standard size roller, and voila! Bearings now turn when the shaft or the cluster are rotated. I mocked up the assembly and put one end of the shaft in a collet in the lathe, supported the other end with a live center in the tailstock. Ran it at 800 RPM for 5-10 minutes while holding the cluster. Everything seems copacetic.

[Paps]

Rollers run on a 360 degree circle over the entire circumference . One missing rollers takes less than a minute of a degree away. Better looser than tight.