Hi guys,
A month or so ago, I finally popped the spindle caps of my recently acquired 1921 11" SB27A, after finding my headstock was 0.050" lower than my tailstock (which should not have been the case, and after all other potential causes were dispelled). The worn bearings were nasty (see photos), and had been improperly shimmed, and at least the large bearing was subsequently starved of oil from the shim blocking oil flow, etc. I was able to get the spindle fairly well adjusted, but it needs new bearings, which is my current project. I have the 932/SAE660 bronze for the bearings, but grabbed some aluminum round for a trial and test-fit. I have OD of the large test bearing complete (on the working lathe), and am working on the ID of the large test bearing. This is where I could use some recommendations...
I was targeting ~0.001 > spindle diameter for the plain bearings, then planning to split, similar to as described here. When taking spindle dimensions, for boring the bearing ID, I've run into a snag. The spindle is tapered on both contact patches, from wear (pictured below). 0.012" taper on the large contact patch, and 0.008" taper on the small contact patch.
I could use some recommendations on how to proceed. The options apparent to me are below, with one of the first 3 being preferred:
1) Bore bearings to 0.001" > spindle smallest diameter, and hope the bearings wear in to the spindle taper.
2) Try turning the spindle contact patches back to round; easiest method coming to mind being to run the spindle with one bearing cap off at a time, while trying to stone the contact patches back to round.
3) Taper new bearings to match the current spindle wear.
And with a much larger hurdle to clear (cost and time, both of which are limited):
4) Buy a replacement spindle.
5) Make a replacement spindle.
Any recommendations would be appreciated. This is my first time making split||plain||bronze bearings, so if I've missed something big, please let me know.
Thank you,
SB27A
Original lower bearing halves:
Large lower bearing half:
Small lower bearing half:
Current spindle wear:
A month or so ago, I finally popped the spindle caps of my recently acquired 1921 11" SB27A, after finding my headstock was 0.050" lower than my tailstock (which should not have been the case, and after all other potential causes were dispelled). The worn bearings were nasty (see photos), and had been improperly shimmed, and at least the large bearing was subsequently starved of oil from the shim blocking oil flow, etc. I was able to get the spindle fairly well adjusted, but it needs new bearings, which is my current project. I have the 932/SAE660 bronze for the bearings, but grabbed some aluminum round for a trial and test-fit. I have OD of the large test bearing complete (on the working lathe), and am working on the ID of the large test bearing. This is where I could use some recommendations...
I was targeting ~0.001 > spindle diameter for the plain bearings, then planning to split, similar to as described here. When taking spindle dimensions, for boring the bearing ID, I've run into a snag. The spindle is tapered on both contact patches, from wear (pictured below). 0.012" taper on the large contact patch, and 0.008" taper on the small contact patch.
I could use some recommendations on how to proceed. The options apparent to me are below, with one of the first 3 being preferred:
1) Bore bearings to 0.001" > spindle smallest diameter, and hope the bearings wear in to the spindle taper.
2) Try turning the spindle contact patches back to round; easiest method coming to mind being to run the spindle with one bearing cap off at a time, while trying to stone the contact patches back to round.
3) Taper new bearings to match the current spindle wear.
And with a much larger hurdle to clear (cost and time, both of which are limited):
4) Buy a replacement spindle.
5) Make a replacement spindle.
Any recommendations would be appreciated. This is my first time making split||plain||bronze bearings, so if I've missed something big, please let me know.
Thank you,
SB27A
Original lower bearing halves:
Large lower bearing half:
Small lower bearing half:
Current spindle wear: