ClappedOutBport
Cast Iron
- Joined
- Mar 30, 2016
Hi all.
I'm working on a Sidney Lathe (thread here) and the change gear bearings are totally worn out to the point where the hardened sleeve has partially disintegrated. I've looked fairly far and wide and I cannot find anything close, and if I could it would be very expensive. If you know of a special something that would do feel free to look, but I don't think it exists anymore. I don't have the exact width, but the ID is 3/4", the OD is 1 9/16" and the width is roughly 1 1/2". The thrust is handled by nothing more than the gear sliding against the frame and outer washer.
So, what I'm thinking of doing is replacing it either with a set of ball bearings or with a bronze bushing.
If I did the bushing:
For the bearing replacement I was looking at using R12 ball bearings as they have the right ID and the OD is only large by 1/16". I kind of drew up a plan of how I would do it. Please excuse the fact that the drawing quality sort of falls apart. Left Side is current, right side is my plan.
My current plan of attack:
If I did the bearing:
Thanks in advance.
PS, I read the rules and I know it says not to talk about bearing replacements here. I figured since this is a non-standard replacement that requires some re-engineering and maybe permanent modification of obsolete parts, I'd best ask the machine rebuilding experts. If I'm wrong please move my thread and I won't do it again.
I'm working on a Sidney Lathe (thread here) and the change gear bearings are totally worn out to the point where the hardened sleeve has partially disintegrated. I've looked fairly far and wide and I cannot find anything close, and if I could it would be very expensive. If you know of a special something that would do feel free to look, but I don't think it exists anymore. I don't have the exact width, but the ID is 3/4", the OD is 1 9/16" and the width is roughly 1 1/2". The thrust is handled by nothing more than the gear sliding against the frame and outer washer.
So, what I'm thinking of doing is replacing it either with a set of ball bearings or with a bronze bushing.
If I did the bushing:
- What type of bronze? SAE 660?
- What should my wear surfaces be? A 1 9/16" bushing pressed into the gear running on a hardened steel bushing clamped onto the stud? A smaller bushing just running on the 3/4" stud?
For the bearing replacement I was looking at using R12 ball bearings as they have the right ID and the OD is only large by 1/16". I kind of drew up a plan of how I would do it. Please excuse the fact that the drawing quality sort of falls apart. Left Side is current, right side is my plan.
My current plan of attack:
- Bore the gear to about 1.624 leaving around 1/8" of the original diameter towards the back.
- Press in a 7/16" wide R12 2RS bearing with the inner shield removed
- Press in a 5/16" wide R12 open bearing
- Make a spacer with an internal groove and hole in it so that grease can always flow into the bearings
- Press in another 7/16" wide R12 2RS bearing with the inner shield removed
- Use a very thin washer against the inner race to keep the outer washer from rubbing on the gear and outer bearing race.
- When clamped with the nut all the inner races and spacers should be snugged up tight and will not be able to slide on the stud, and there will be just a whisker of space between the frame and the outer washer.
If I did the bearing:
- Should I space the two outer bearings out as much as possible like shown even though the shell gets pretty thin near the outside? Or should I place them inward, to where they are right under the line of radial force from the gear?
- Should I neglect the middle bearing if I space them outward?
- The book says gears are between 48-50 HRC. Will I be able to bore these with carbide or will I need CBN?
- Indicate off the teeth or the bore? Shouldn't matter I'd reckon.
Thanks in advance.
PS, I read the rules and I know it says not to talk about bearing replacements here. I figured since this is a non-standard replacement that requires some re-engineering and maybe permanent modification of obsolete parts, I'd best ask the machine rebuilding experts. If I'm wrong please move my thread and I won't do it again.