After using my new-to-me FP2 mill a little, I discovered that there was excessive axial play in the vertical spindle. It also seemed the radial play might be out of spec.
I pulled the spindle apart, cleaned it, and then with the spindle oiled with light oil only, I measure about 0.0008" or 0.020mm radial play. The spec I've seen is for 0.010-0.015mm, which means the radial play is well out of that spec.
I believe the two needle bearing sizes for this spindle are K-50x57x18 and K-45x52x18?
Now, I'm going to replace those bearings. Ideally I'll just buy a pair of replacement bearings, polish the races, drop the new bearings in, run the spindle in and then live happily ever after.
I've been in contact with DeckelDoctor about replacement bearings, and I've shot emails at Franz Singer and FPS also. Maybe they'll be able to tell me the appropriate size to buy, but I'd also like to understand how to size the new bearings.
It seems fairly standard for roller cage bearings to be size bucketed such that the needles in a single bearing have no more than 2um diameter variation. The nominal sizes of the buckets are 1um apart, as described e.g. in this document - see page B5.
The good DeckelDoctor sent me some size charts and by those charts, I believe that the bearings in my spindle are INA brand. The cages are each stamped - on both sides - with a number representing the size class (aka diameter tolerance). See this image of the larger bearing:
In my spindle, the KS-50 cage is stamped "3", which I believe corresponds to the -2 to -4 (um) size class, meaning the needles are nominally 3.5mm - 3um.
The KS-45 cage is stamped "7", which by the same chart is the -6 to -8 size class, with needles nominally sized 3.5mm - 7um.
To get into the spec above, I need to take out at least 0.005mm of play, which means I need needles that are larger by at least 2.5um. I believe my choices in size classes might run on even numbers, so I'd have to go to nominally 4um larger rollers.
This would translate to 0.020mm - 0.008mm = 0.012mm play.
Does my math check out here?
I pulled the spindle apart, cleaned it, and then with the spindle oiled with light oil only, I measure about 0.0008" or 0.020mm radial play. The spec I've seen is for 0.010-0.015mm, which means the radial play is well out of that spec.
I believe the two needle bearing sizes for this spindle are K-50x57x18 and K-45x52x18?
Now, I'm going to replace those bearings. Ideally I'll just buy a pair of replacement bearings, polish the races, drop the new bearings in, run the spindle in and then live happily ever after.
I've been in contact with DeckelDoctor about replacement bearings, and I've shot emails at Franz Singer and FPS also. Maybe they'll be able to tell me the appropriate size to buy, but I'd also like to understand how to size the new bearings.
It seems fairly standard for roller cage bearings to be size bucketed such that the needles in a single bearing have no more than 2um diameter variation. The nominal sizes of the buckets are 1um apart, as described e.g. in this document - see page B5.
The good DeckelDoctor sent me some size charts and by those charts, I believe that the bearings in my spindle are INA brand. The cages are each stamped - on both sides - with a number representing the size class (aka diameter tolerance). See this image of the larger bearing:
In my spindle, the KS-50 cage is stamped "3", which I believe corresponds to the -2 to -4 (um) size class, meaning the needles are nominally 3.5mm - 3um.
The KS-45 cage is stamped "7", which by the same chart is the -6 to -8 size class, with needles nominally sized 3.5mm - 7um.
To get into the spec above, I need to take out at least 0.005mm of play, which means I need needles that are larger by at least 2.5um. I believe my choices in size classes might run on even numbers, so I'd have to go to nominally 4um larger rollers.
This would translate to 0.020mm - 0.008mm = 0.012mm play.
Does my math check out here?