Obsolete Bearing Replacement

ClappedOutBport · Jun 14, 2020

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:

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. :cryin:

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.

Sound like a good idea, or no?

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.

Phil in Montana · Jun 14, 2020

Machine the gear for back to back tinkins, with a spacer in the center...Phil

Hbjj · Jun 14, 2020

I'm not a machine tool rebuilder but I used to be a repair machinist before covid...
I would bore each side of the gear for a .oo1 ish slip fit on your sealed bearing leaving the center .200 ish smaller than the od of the bearing
I would not remove the grease seals from the bearings
A washer to get the gear lined up and a spacer between the inner races and your good IMHO

Ive made this repair many times sometimes the bore has to be sleeved or welded up.
As far as cutting 50 rc I doubt the hub is hard usually it's just the teeth but you never know
Any real insert should cut 50 easy
Hss would if you go slow enough
Good luck

ClappedOutBport · Jun 14, 2020

Phil in Montana said:
Machine the gear for back to back tinkins, with a spacer in the center...Phil

Tapered rollers seem like an unnecessary expense since there is no thrust component. I looked them up anyway, and it seems like the od would be too large and the gear would get very thin if it worked at all near the outside.

Hbjj said:
I'm not a machine tool rebuilder but I used to be a repair machinist before covid...
I would bore each side of the gear for a .oo1 ish slip fit on your sealed bearing leaving the center .200 ish smaller than the od of the bearing
I would not remove the grease seals from the bearings
A washer to get the gear lined up and a spacer between the inner races and your good IMHO

Ive made this repair many times sometimes the bore has to be sleeved or welded up.
As far as cutting 50 rc I doubt the hub is hard usually it's just the teeth but you never know
Any real insert should cut 50 easy
Hss would if you go slow enough
Good luck

Definitely some good suggestions there. I didn't even think to go from both sides. Appreciate it.

john.k · Jun 14, 2020

I d go with needle roller bearings,if the load was high ,if low ,then a full width solid ,or sintered bronze bushing.......Solid bronze needing regular lubrication,as in grease,or a few drops of oil per day..........Needle rollers can be fitted just about anywhere ,but custom sleeves will be needed to avoid cutting hard steel components.......You might getaway with the drawn cup type,which are very economical.

Peter from Holland · Jun 15, 2020

I would machine the hole one diameter through and trough That is the easiest
You could hone it to size even then Or use emery cloth on a stick
2 Seegerrings in the ID of the bore and a spacer between the innerraces of 2 (RS type) bearings
No more than 2 bearings
Spacer here and there if need be

Peter

ClappedOutBport · Jun 18, 2020

john.k said:
I d go with needle roller bearings,if the load was high ,if low ,then a full width solid ,or sintered bronze bushing.......Solid bronze needing regular lubrication,as in grease,or a few drops of oil per day..........Needle rollers can be fitted just about anywhere ,but custom sleeves will be needed to avoid cutting hard steel components.......You might getaway with the drawn cup type,which are very economical.

I did look up needle bearings after your post but I didn't find anything I really was fond of. I'd need at least two of the ones I found to get the width right and then with the hardened inner sleeves you're looking at close to $80 or something.

Peter from Holland said:
I would machine the hole one diameter through and trough That is the easiest
You could hone it to size even then Or use emery cloth on a stick
2 Seegerrings in the ID of the bore and a spacer between the innerraces of 2 (RS type) bearings
No more than 2 bearings
Spacer here and there if need be

Peter

Machining all the way through would require that the gear be held in position only by an interference fit on the bearings, I'd like to be held a bit more solidly, like with Hbjj's suggestions about the shoulders. Does require twice the setup though.

Any more opinions before they go under the knife? Thanks to everyone btw.

Peter from Holland · Jun 18, 2020

ClappedOutBport;3569660 Machining all the way through would require that the gear be held in position only by an interference fit on the bearings said:
The seegerrings (or snaprings) will keep the bearings in place
It is effectivly a shoulder

Peter

Garwood · Jun 18, 2020

Keep it simple.

When that needle bearing was new it probably had more play than a new chinese ball bearing.

I suggest using just ONE sealed ball bearing. Look to see if they make a double row bearing in the same size you need. If it's cheap, buy that.

The stamped idlers on vehicle belt drives use single chinese 6203 bearings and go hundreds of thousands of miles at 5000+ RPM. A single bearing would last 1 billion years in that gear.

1635-2RS is a very common bearing with a 3/4" bore you can often find locally for $10.

ClappedOutBport · Jul 3, 2020

Well I got it done. Thanks all for the opinions. I went with Hbjj's method and bored the gears from both sides leaving a shoulder. Each gear got 3 spacers. So the stack up went like this: 0.135 spacer, bearing, 3/8" spacer, bearing, 0.135 spacer, washer, nut. So all the parts are identical for each gear so the next guy won't have to be so careful. I used R12 bearings so I only had to bore out 1/16". I bored the outer bore a few thousands deeper than absolutely necessary so that it would clamp up tight on the inner races. The 0.135" spacer instead of 1/8" gives about 10 thousands of clearance between the casting and the outboard washer. The gears were hardened, but not too bad. They cut well with carbide and left a good finish. Overall they came out really well and run just butter smooth, and they no longer rub like the original design did. I'm happy. Thanks again everyone.

ballen · Jul 8, 2020

ClappedOutBport said:
Well I got it done. Thanks all for the opinions.

The best way to say "thank you" is to post a couple of photos of the finished gears with the bearings in place.

ClappedOutBport · Jul 8, 2020

ballen said:
The best way to say "thank you" is to post a couple of photos of the finished gears with the bearings in place.

Ok, I will. I was going to post some in the main thread when I got back to it. I've still got to pull take it apart and pull the inner shields I'll get some pics when I do that.

ClappedOutBport · Oct 4, 2020

ballen said:
The best way to say "thank you" is to post a couple of photos of the finished gears with the bearings in place.

Well, I sort of forgot to get pictures when I reassembled it after stripping it to remove the shields. Sorry. But here is what I do have.

ClappedOutBport said:

I hope that is satisfactory, because I don't intend to tear into it again until I need to replace the bearings. -COB

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