Grinder bearing replacement - RZ vs. RS?

[Lou Jacobs]

My Delta grinder started making a bearing noise, coincidentally? immediately after I accidentally ground into and shorted out a lamp cord (!) that was hanging behind the grinder. Grinder continues to work fine, but now has a sort of scratchy, dry bearing sound. I just took it apart and the bearing is labeled 6203 RZ. I’m having a hard time finding that bearing, but do see 6203 RS available, including option made by Timken. I know that the letter designation refers to the material that the seal is made from. Any reason not to use RS? Thanks for advice!

 

[Brent@TurnRobust]

RZ seals are really more for dust, RS seals actually seal the bearing. They might run just a tiny bit hotter, but probably nothing you'd notice.

 

[Lou Jacobs]

RZ seals are really more for dust, RS seals actually seal the bearing. They might run just a tiny bit hotter, but probably nothing you'd notice.

Thanks so much Brent! Appreciate your quick response.

 

[Doug Rasmussen]

Lookup Motion Industries, they have stores all over the country and IME the best prices. Tell the sales person what rpm and usage and let them suggest the correct bearing.

Older machines didn't use sealed bearings in many cases because the kind of seals available back in the day caused too much friction heating of the bearings. Seals are much improved these days.

 

[Lou Jacobs]

Thanks Doug! I’ve already ordered replacements and have pressed off the old bearings, waiting for the new ones. The machine isn’t that old. I bought it new in 2016, so was surprised when the bearing went, but I think I may have somehow “cooked” the lubrication when an electric charge shot through it.

 

[Richard Coers]

Woodturners really seem to be a group that worries about bearings. With such little load on grinders, the bearings should last a couple lifetimes. Just pop the seal out and put a little bearing lube in there.

 

[Bill Blasic]

My Delta grinder started making a bearing noise, coincidentally? immediately after I accidentally ground into and shorted out a lamp cord (!) that was hanging behind the grinder. Grinder continues to work fine, but now has a sort of scratchy, dry bearing sound. I just took it apart and the bearing is labeled 6203 RZ. I’m having a hard time finding that bearing, but do see 6203 RS available, including option made by Timken. I know that the letter designation refers to the material that the seal is made from. Any reason not to use RS? Thanks for advice!
View attachment 66800

Here I thought that I was the only person in the world who turned on the grinder and POW the 80 grit CBN wheel cut thru the 220 line that I forgot to reroute to make sure that didn't happen. And yes the grinder does have a different sound but so far it's just the sound but I do keep an eye on it. I suspect that the electricity may have pitted the bearings a bit. Thanks as it might be the same grinder and I'll now know about bearing number.

 

[Lou Jacobs]

Just pop the seal out and put a little bearing lube in there.

I’ve been under the impression that sealed bearings couldn’t be repacked. I’ll give it a try and keep for backups if successful, as the new ones are expected today. (Just what I need, more “spare parts” to stash away somewhere!).

Here I thought that I was the only person in the world who turned on the grinder and POW the 80 grit CBN wheel cut thru the 220 line that I forgot to reroute to make sure that didn't happen. And yes the grinder does have a different sound but so far it's just the sound but I do keep an eye on it. I suspect that the electricity may have pitted the bearings a bit. Thanks as it might be the same grinder and I'll now know about bearing number.

Bill, thanks for confirming my experience! I wasn’t sure if I was imagining the correlation between grinding through the power cord (in my case a 110 volt light on the bandsaw) and new noise.

 

[Brian Gustin]

I’ve been under the impression that sealed bearings couldn’t be repacked. I’ll give it a try and keep for backups if successful, as the new ones are expected today. (Just what I need, more “spare parts” to stash away somewhere!).

Not much point to trying to repack them if the below is true....

Bill, thanks for confirming my experience! I wasn’t sure if I was imagining the correlation between grinding through the power cord (in my case a 110 volt light on the bandsaw) and new noise.

Yes, I'd imagine if you got a nice shot of 120V power @ 15-20 amps (or even 220v) running through a metal path to ground where part of that path involves what was likely an incomplete contact point,(namely the balls in the ball bearings in relation to the bearing races) there's gonna be some arcing (like an arc welder) that is going to leave spots on those highly polished bearing races, resulting in permanent damage, noise, accelerated wear leading to failure.

 

[Lou Jacobs]

Yes, I'd imagine if you got a nice shot of 120V power @ 15-20 amps (or even 220v) running through a metal path to ground where part of that path involves what was likely an incomplete contact point,(namely the balls in the ball bearings in relation to the bearing races) there's gonna be some arcing (like an arc welder) that is going to leave spots on those highly polished bearing races, resulting in permanent damage, noise, accelerated wear leading to failure.

Exactly Brian. Thanks for confirming my suspicion! I’ll be out in the shop in a couple of hours and remove the seal on the bearing to have a look. I suspect that’s what I’ll find.

 

[Lou Jacobs]

Just an update: I received the new bearings yesterday and got them installed and the grinder back together. It is humming like new and taking several minutes to spin to a stop after the power is turned off. I was able to open the one bad bearing and see pitting on one of the balls. In spite of repacking it with grease it still feels rough when I turn it, so it’s in the trash. The other removed bearing spins like new, so it’ll go on the shelf as a spare. Probably destined to draw dust for years before my executors wonder why I ever saved it.