Should ball bearings be cleaned and re-lubricated periodically, or is it better to replace them?
My band saw has two ball bearings to guide the blade, and I use a variety of bearing-guided router bits.
Here’s what I have on hand:
- LPS F-104° degreaser (http://www.lpslabs.com/product_pg/degreasers_pg/F104.html)
- KEL pure silicon spray (http://www.kelloggsprofessionalproducts.com/)
- LPS 1 greaseless lubricant (http://www.lpslabs.com/product_pg/lubricants_pg/LPS1.html)
- LPS Force 842 dry molybdenum spray (http://www.lpslabs.com/product_pg/lubricants_pg/Force842.html)
- Panef white lithium grease
- WD-40
- 3-in-1 oil
Will any of these be useful?
Janet
Replies
Maybe
Almost all of the better quality ball bearings used in home shop equipment have rubber seals that prevent you from effectively cleaning and regreasing them, they are "Lubricated for Life" as they say in the advertising. There is no way to clean and regrease these bearings, although if they are noisy or sticking you can sometimes get them to free up and work better for a short while by giving them a squirt of penetrating oil which will seep in past the seals. You can recognize a sealed bearing by the rubber seal, which is usually black, around the tubular inner race of the bearing.
Some lesser quality bearings are shielded, they have metal covers on the sides of the bearings that aren't as effective as the rubber seals at keeping the grease in and the dirt out. A shielded bearing can be cleaned out by soaking it in a thin solvent, like paint thinner and then lubricating it with oil. Shielded bearings will have metal covers on the sides of the bearings but no rubber. Some router bearings and bandsaw blade guide bearings are shielded. The router bearings, if you can clean them out, should ideally be lubricated with a special lubricant made for the application since the bearings are subject to extreme speeds. I have seen the lube in a few WW'ing catalogs.
On the bandsaw you are better off just replacing the shielded bearings, if they have problems, with sealed bearings or with fixed ceramic discs which work better in my opinion.
Ceramic Discs?
John - The only ceramic side guides I have seen are the block type a thrust bearing disc. The side guides on my saw (14" Shop Fox) are smaller than the thrust bearing. Are the ceramic discs available in different diameters? If so, where can I get some?
pete
Pete,
The round ceramic thrust bearings on the Shop Fox saw appear to be the same as those on almost all 14" band saws so I think that the bearing that is commonly available, 3/8" thick, 1 5/32" OD, with a 3/8" hole will fit your saw. The bearing doesn't spin by the way, so it doesn't have to be a perfect match, it just needs to fit on the old mounting bolt. I looked and found the bearings on Hartville Tools' site, I am sure that it is available elsewhere.
Thank you/ Bearing lube
Thanks for reminding the Knot heads, I'm not being derogatory, about router bearings. Even the best router bit bearings are just dust shielded and some even have a extra "dust" shield deflector. As a Tech Rep. for a major woodworking catalog I get many calls about seized up or sluggish bearings and just about all of the problems lead to lack of maintenance. I've found that Bostic bearing lube works the best. I find that I can soak a bearing in lacquer thinner over night and then blow it out well with compressed air, and repeat the process if necessary, and then relube with the Bostic bearing lube by slowly flooding the shield and repeating the process. The lube is unique in that it goes on and in like a thin oil and then converts to a grease like substance and contains NO silicone.
Clean and lube often, very tough to over lube.
"What we need . . ."
Your comment about bearing lube reminded me of the GMC ad where the truck shows up with 55-gallon drums of Elbow Grease.
So I'm somewhat inexperienced with routers. Just to be sure - when we refer to router bearings, it is the router not the bit, right. I have had bits seize but not the router so far.
hey tink,
think we're talking bit bearings here...
mine get pretty gummed up and keeping them cleaned and lubed prolongs the bearing life.
eef
Small sealed bearings are really expendable items and are not designed to be lubricated. Shielded bearings can be lubricated as several replies have stated. The "quality" of a bearing is not determined by the seals or shields. Many high precision or super precision bearings are open frame bearings which require continuous re-lubrication in operation.
I would not use 3 in 1 oil on a high speed bearing. It is a vegetable base oil which breaks down at high temperature.
Lithium grease works well on low speed, high load bearings. It has too much drag at high speed. The rule of thumb I'm used to in millwork plants is grease up to 3600 rpm (line frequency motors).
I've seen Wd40 used on lots of bearings in portable tools. Maintainence guys will replace sealed bearing with shielded bearing on line tools so they can be maintained this way. It's not ideal, but it works since it does penetrate past the shields into the bearing race. Oil sold as "air tool lubricant" also works well.
Wear
It occurs to me that the cutting edge of a bit could decrease with wear or sharpening, changing the cutting diameter. If it is a bearing-guided bit, the amount of offset changes, too.
Do bearing-guided bits lose any significant amount of accuracy?--and does this happen before the bearing needs replacing?
Janet
It depends on the nature of the bit, I suppose. Sharpening a flush-trim bit with a bearing probably defeats the utility of the bit. But, doing so on, say, a rabbeting bit is probably less of a problem. Bearing life can be affected by various factors, including the type of wood being cut (if it's a sheilded bearing as opposed to sealed). But, that also affects the life of the cutting edge. No bit lasts forever - a fact that keeps bit manufacturers in business. ;-)
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