grease fittings on a grinder

[Brad Lilly]

Anyone try putting grease fittings on the rollers of their grinders? I'm thinking if I remove the inside shield on the bearing and drill a grease channel on the arbors of my grinder it might make the bearings last longer. I like grease and hate sealed bearings.

 

[EdCaffreyMS]

Are you talking about the contact and/or idler wheels? If so, my advice is Don't. The bearings that came in my Wilton machine (20+ years ago) were "open" type bearings....... and I went though them like water until I got smart enough to installed shielded bearings. Concerning the grease fittings, I think its a very fine line when dealing with grease and belt grinders..... all that fine steel dust is drawn to the grease like a magnet..... just sayin.

I also think that if you put "zerks" anywhere in the driveline, its going to be just enough change to cause increased vibration.

Now, if your talking about the main drive shaft bearings (like on the KMG), mine came with zerks installed, and sheilded bearings. I MIGHT put a "pump" of grease in each bearing a year......it just doesn't need much attention.

 

[BossDog]

Anyone try putting grease fittings on the rollers of their grinders? I'm thinking if I remove the inside shield on the bearing and drill a grease channel on the arbors of my grinder it might make the bearings last longer. I like grease and hate sealed bearings.

knife grinding is a pretty hostile environment for "open" bearings.

one of the downsides to non-sealed bearings is that with too much grease the entire bearing can spin inside of the bearing mount vs. just the inside of the bearing spinning with the shaft.

on a tangent....
I've seen lot's of guys grease the bearings on a grinder because there were zerks and zerks needs grease right? It's like a compulsion. I know this from personal experience. The problem is most bearings are sealed now days and that grease has no where to go except around the outside of the bearing which does it no good and can cause the entire bearing to spin in the bearing housing. Most sealed bearings should not slip in the bearing mount but give it enough grease through that stupid zerk and it will. Again, I know this from personal experience.

Zerks are to grease non-sealed bearings only. If you get a grinder that has zerks on it, that might only mean that bearing mount was cheaper with the zerk than with out.

I've used bearings that can be greased via the zerk. Messy, nasty things. If you over grease which is easy to do. The roller bearings tend to slide instead of roll which creates a flat spot on the rollers and leads to early failure. After a couple times of this, I switched to sealed bearings and don't have that issue any more.

 

[Drew Riley]

I more/less treat bearings as a consumable, although as long as you're not running them at 10,000 SFPM, and you're not side loading them or interfering with the seals, sealed bearings typically last a significant amount of time.

As for pillow blocks, most of them have channels going around the periphery of the outer race, with one or two small holes for grease to make its way into, though it does help to make sure everything is lined up correctly, and grease would probably be better injected with a syringe of some kind as it's a lot more precise than the zirc and grease channel.

 

[John Wilson]

I'm a huge believer that lubrication is the single biggest bang for the maintenance buck, and the most overlooked aspect of machine life. Having said that, the only good use for a non-sealed bearing anymore is typically an environment where foreign matter intrusion into the bearing can't be stopped. Grease is nothing but oil suspended in a base, referred to as "soap". Modern oils (grease) does not get "used up" in the bearing. Lubricants today are light years better than what was available just a decade ago. In the past, the oil would come out of suspension leaving only the soap in the bearing, and therefore the grease needed to be replenished. When you shoot grease in a bearing, the purpose is to push out the old soap that has lost its lubricity due to the oil being gone, or because the grease has become contaminated with foreign matter due to intrusion. On a grinder, an open bearing would allow more foreign debris intrusion than greasing the bearing would ever flush out. Just greasing a dirty zerk ruins more bearings than people realize because the grease gun pushes the debris into the bearing. Truth be told, the best thing a maintenance man can do is leave the glob of grease on the zerk alone when he pulls the gun off. Then you wipe the glob off just before you grease the bearing again.

A sealed bearing is better in almost every way, unless the bearings are being run underwater or in a caustic environment. If the oil doesn't leak out, the grease never goes bad during the life expectancy of the bearing. Modern bearings last a very, very long time if they are sized right for the application. Obviously the quality of the bearing matters, but if a bearing is wearing out prematurely that's a materials problem. (Chinese bearings) Chinese bearings are like Harbor Freight tools. You know what you're getting. It's a price point decision that is either right or wrong depending on your needle of cost vs value. A good, quality sealed bearing from FAG, NSK, and the like will run 24/7 for a couple of years in a factory environment. Chinese bearings are cheaper than any decent grease you would put into them.

 

[EdCaffreyMS]

It's a price point decision that is either right or wrong depending on your need of cost vs value.

Thats a great statement! It applies to SSOOOO many things we as knifemakers do. Just this morning I replied to another thread on stabilizing....... that statement would have been ideal to reference my feeling on "professional" versus home stabilizing.

 

[John Wilson]

That was me with the stabilizing question, haha! I really appreciated all the of the thoughtful responses I got on that. Thanks for taking time to help me out.

 

[scott.livesey]

sealed bearings are filled with grease designed to last a lifetime. the company i used to work for, GKN, spent millions on developing "lifetime" grease to be used on the bearings and other moving parts inside the axles and CV joints used on most front wheel drive vehicles. if you buy "sealed" bearings from a reputable manufacturer, you should never have to worry about grease.
as Boss pointed out, most people overgrease, then compound the problem by not removing any excess when done.
we did at times add grease fittings to pillow blocks and other bearing housings. the idea was not greasing the bearing, but protecting the bearing and other parts from the harsh corrosive atmosphere it had to function in.