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Milling machine - Sealed bearings (both side) vs one side open bearing

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Plastic
Joined
Aug 11, 2022
Hi all, with God's infinite grace I was finally able to get hold of Wells-Index milling machine.

I'm doing some TLC and I had to replace the pulley bearings. The design uses 2 one-side open bearing, with open sides facing each other separated by a spacer and greased up. I ordered a bearing from online store and they instead sent me a fully closed bearing.

Can I use the sealed bearings instead of one side open ones? What is the difference?
- With fully closed, I assume, no debris can get in, so shouldn't it be actually better?
- But with open side, there is grease which will help in lubrication, but it will also catch debris
- Manual suggests to grease only when we are changing the bearing. So technically one-side open is greased as often as the closed one.
- It is easy to obtain sealed bearings than one open side bearings.

I'm confused if sealed bearing is as good as one-side open or not. Should I use the bearings I got or should I return it and buy open-side ones.

Any suggestions?
 
Rubber seals or steel shields? Rubber seals are easy to remove, use a pick, get under lip and remove, steal shields can be slightly more difficult but they will come out. Is there a grease zerk to add grease while in use? If so remove a side, if not, slap those bearings in and get it working. I'm replacing some bearings this week, old ones were single side rubber seal, not greaseable once installed, will be replacing them with bearings with both sides sealed.
 
For pulleys with no grease nipple I think sealed bearings are a nice upgrade. I use them everywhere and cap the grease ports, unless they’re in an oil bath or something.
 
Rubber seals or steel shields? Rubber seals are easy to remove, use a pick, get under lip and remove, steal shields can be slightly more difficult but they will come out. Is there a grease zerk to add grease while in use? If so remove a side, if not, slap those bearings in and get it working. I'm replacing some bearings this week, old ones were single side rubber seal, not greaseable once installed, will be replacing them with bearings with both sides sealed.
Thank you for note. It is steel shields. There is no way to add grease in use, it completely sealed inside with no access and manual says to add grease only when replacing.
 
For pulleys with no grease nipple I think sealed bearings are a nice upgrade. I use them everywhere and cap the grease ports, unless they’re in an oil bath or something.
Thank you. Nice to hear the sealed bearings are upgrades!
 
There are three styles of bearings:
1. Open
2. Metal shielded
3. Rubber sealed or closed.

Metal shielded (2) have small holes which keeps particles out of the bearing races but still allow for atmospheric contamination.
But you can still add grease by palming. It's recommended to fully clean a bearing before adding new grease. If the design allows
for oil to enter the bearing through one side then you want a metal shield.

Bearings with rubber shields (3) do not allow atmospheric contamination and are not meant to be removed. But people do it
anyway and it's probably not going to hurt the seal if not done on a regular basis. For electric motors I use them.

If the assembly is a closed chamber then it doesn't matter what you use.
If the assembly is open on one side then a rubber seal should be on that side.
I do what jwearing does.
 
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downside of rubber sealing is that they ad heat and drag
Example We were testing a roller coaster with wooden track once The cars did not make it through So that was a big hassle to pull the car up to the next bump
frst we thought it jammed up in the track But once we removed the rubber shields on the inside of the bearings it went so fast only the second pair of brakes were able to stop it
Peter
 








 
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