Is it necessary to grease a pillow block bearing?

[Drew Riley]

I'm specifacally talking about these:

or something like it.


I mean, those are sealed bearings pressed into the cast iron housings are they not? What exactly are the grease zircs for? Am I missing something?

 

[Brad Lilly]

The pillow block bearings I have bought have a small groove around the bearing and a small hole to allow the grease to flow into the bearing. Some don’t have this feature, but if it has a grease fitting I would grease it. Hopefully you can see what I’m talking about in this picture

Regular use of grease increases bearing life and reduces frustration from fixing stuff

 

[EdCaffreyMS]

I agree with Brad......they wouldn't make the effort, or spend the extra money/manufacturing time if it didn't need it. I've got bearing like that on many machines in the shop, and about once every couple of months, depending on use, they get a shot of good quality grease. The KMG gets the snot used outta it, and it get's a shot of grease in the bearings at least every two weeks.

 

[scott.livesey]

hi,
i would make sure they are full of grease, Mobile XHP is available most anywhere, is inexpensive, and lasts a long time. I would use a hand grease pump, $10 or less. pump until you see grease coming out 360degrees. if it is accessible, i would pump the grease while the machine is running. always wipe off any grease that comes out. i would start out once a month, if the grease coming out is clean, go to every two months.
the old sailor

 

[Drew Riley]

The pillow block bearings I have bought have a small groove around the bearing and a small hole to allow the grease to flow into the bearing. Some don’t have this feature, but if it has a grease fitting I would grease it. Hopefully you can see what I’m talking about in this picture

Regular use of grease increases bearing life and reduces frustration from fixing stuff

I see how it's useful for that bearing, but it doesn't appear to be a sealed bearing either (or at least the same type as the one I pictured. Maybe they both are). I guess one way to settle it is to cut the housing off of an old set of sealed bearing pillow blocks.
I normally do grease them, but I was just curious if it was really doing anything for sealed bearings.

 

[Brad Lilly]

You should not need to cut anything, the bearing should roll out. Take a piece of shafting and insert it in the bearing (it dose not need to be the proper size) and twist the bearing to line up with the slots on the housing and it should slide out (It is hard to explain). If you live in Nova Scotia the whole thing will be a solid mass of rust and you will need to use a large hammer, pry bar and cutting torch.

 

[Drew Riley]

I agree with Brad......they wouldn't make the effort, or spend the extra money/manufacturing time if it didn't need it. I've got bearing like that on many machines in the shop, and about once every couple of months, depending on use, they get a shot of good quality grease. The KMG gets the snot used outta it, and it get's a shot of grease in the bearings at least every two weeks.

I just always thought that maybe there was an "unsealed" pillow block, and that the manufacturer just used a universal housing in order to cut cost. Kind of a one size fits all deal.

 

[Drew Riley]

You should not need to cut anything, the bearing should roll out. Take a piece of shafting and insert it in the bearing (it dose not need to be the proper size) and twist the bearing to line up with the slots on the housing and it should slide out (It is hard to explain). If you live in Nova Scotia the whole thing will be a solid mass of rust and you will need to use a large hammer, pry bar and cutting torch.

haha. One way or the other I will get it out.

 

[Drew Riley]

On the other hand, it may just push right out. I'm actually ordering a new set of pillow blocks for my NWGS because of an excessive amount of play in the self aligning bearings.

 

[Brad Lilly]

haha. One way or the other I will get it out

I have never seen a tool yet that I can't break.

Most of the time you can replace the bearing and keep the housing. I have seen the bearing seize and spin in the housing, then you are buying a whole new unit unless you spot it quick.

 

[BossDog]

Let me start by saying I am entitled to be wrong on this.
The top picture is a sealed bearing and will not benefit from greasing the zirc fitting. The grease will simply squirt out of the housing and make a mess. You do not want the sealed bearing to spin in the housing and that can happen with too much grease. Remove these by using a rod inserted into the bearing and rotating the bearing in the housing 90 degrees to line up with the cut out notches you can see in the rim of the housing, the tap out from the back. The housing has a zirc fitting so you can replace the sealed bearing with an open bearing like the second picture.

the 2nd bearing will benefit from occasional, sparing grease. Too much grease has the rollers lock up and hydroplane on the grease and wear one side of the roller(s) flat causing premature failure. After a bearing failure exactly like this on my KMG, I called Rob and he explained that to me. I took the bearing apart and that is exactly what happened. I rarely grease them any more and have far fewer failures.

Your mileage may vary. There is a lot of variables here: type of grease, volume, frequency, run time, phase of the moon, etc.

 

[Drew Riley]

Let me start by saying I am entitled to be wrong on this.
The top picture is a sealed bearing and will not benefit from greasing the zirc fitting. The grease will simply squirt out of the housing and make a mess. You do not want the sealed bearing to spin in the housing and that can happen with too much grease. Remove these by using a rod inserted into the bearing and rotating the bearing in the housing 90 degrees to line up with the cut out notches you can see in the rim of the housing, the tap out from the back. The housing has a zirc fitting so you can replace the sealed bearing with an open bearing like the second picture.

the 2nd bearing will benefit from occasional, sparing grease. Too much grease has the rollers lock up and hydroplane on the grease and wear one side of the roller(s) flat causing premature failure. After a bearing failure exactly like this on my KMG, I called Rob and he explained that to me. I took the bearing apart and that is exactly what happened. I rarely grease them any more and have far fewer failures.

Your mileage may vary. There is a lot of variables here: type of grease, volume, frequency, run time, phase of the moon, etc.

That's about in line with what I suspected, but was unsure.

Thanks everybody.

 

[12345678910]

I agree with Brad......they wouldn't make the effort, or spend the extra money/manufacturing time if it didn't need it. I've got bearing like that on many machines in the shop, and about once every couple of months, depending on use, they get a shot of good quality grease. The KMG gets the snot used outta it, and it get's a shot of grease in the bearings at least every two weeks.

If you ask Rob, I'm sure he will verify it for you but there is a post either here, BF, where Rob mentions that the original bearings are sealed and greasing doesn't get into the bearing. He doesn't bother to remove the Zerk, or replace it with a plug.


http://www.bladeforums.com/forums/showthread.php/527487-Greasing-a-KMG!?p=5259536#post5259536

and

http://www.bladeforums.com/forums/showthread.php/527487-Greasing-a-KMG!

If you've replaced them with non sealed bearings then go ahead and grease away.

They just make all those bearings the same since some will need it, but stocking two different ones - those with and without is more expensive.



(and I'm so happy to see it being referred to as a Zerk instead of the other dozen names I've heard.)

 

[timgunn]

Pillow blocks are often used where precision machining is not practicable. The rolling-element-bearing part of the the assembly often has a spherical outer surface to allow it to align perfectly with the shaft on assembly. Even where the high-speed rolling-element part is sealed, grease is still needed on this spherical bearing surface.

I think the method for changing the bearing in the top picture is to withdraw the shaft, rotate the bearing into the horizontal plane and withdraw it through the clearance slots visible in the photo. Reassembly is the reverse of this procedure.

Without greasing, there's a good chance the bearing will not rotate to allow this.

 

[rhinoknives]

I agree with Brad......they wouldn't make the effort, or spend the extra money/manufacturing time if it didn't need it. I've got bearing like that on many machines in the shop, and about once every couple of months, depending on use, they get a shot of good quality grease. The KMG gets the snot used outta it, and it get's a shot of grease in the bearings at least every two weeks.

I purchased a KMG a few years back while my Hardcore products grinder was down with motor problems. I noticed that the small wheels bearings in the idler wheel were hot enough to burn me once while changing a belt and that they were marked China mfg.

So I replaced them all with USA made sealed bearings and have been fine every since. I was not happy since I thought I had purchased a domestic made machine with domestic parts.

Laurence

www.rhinoknives.com

 

[Drew Riley]

Just a little update: I was able to rotate and remove the old set of bearings form their housings on my NWGS, and they apeared to be similar to the first set of bearings pictured that had the grove cut all the way around them for grease. The new set I put in were the same. So rotating the bearings and checking is definitely the way to go.

I put just a couple pumps of grease into each bearing as opposed to pumping until it starts to come out of the sides. Hopefully these don't develop play as quickly as the last set.