Should there have been an oil seal?

I am attempting to restore an old woodworking bandsaw. I have removed the top wheel bearings. Should there have been an oil seal of some type in the areas indicated? The open bearing sits above this point and has a brass cover plate with a stauffer grease cup. The areas indicated seemed to be filled with very congealed grease which came out in one piece. I'm not sure how old the machine is, it had what I think are standard 6205 bearings in it.

Theres usually a witness mark on the shaft left by a seal lip. Where does the bearing go?

If there was an effective seal fitted below the bearing eventually the bearing would become flooded with grease because the excess would have no exit route from the bearing being charged by the stauffer grease cup,
Agree it does appear to be an oil/grease seal groove that you indicate.

Emgee

If you keep shoving grease in, the old grease will need to come out somewhere. At best it only needs to be a grease seal, possibly felt?

Deleted. Forum, or ‘puter running at snail pace!

Edited By not done it yet on 01/03/2021 17:55:09

The 6205 bearings are available with built in oil seals (6205 2RS) so you need not worry about greasing if you get them.

The bearing sits just above so the grease would just come out the back. I guess the grease may have been thicker 60-70 years ago? No witness mark.

Edited By pgrbff on 01/03/2021 18:11:19

I wouldn't have enough experience to used sealed. I feel safer being able to grease them.

Can you suggest any references on felt seals? I'll have a look myself. I am a bit surprised that there was no seal but the dimensions of this area differ on the two sides of the wheel so any seal would have had to be compressible. Would need to find a source of felt too.

It is an uninformed dumb decision to not use sealed bearings if they are available. You can do more harm than good by over-greasing open bearings. You seem to be taking the hard road at every step in refurbing this old bandsaw.

Motorcycle wheel bearings are normally sealed, they last for years without any maintenance. Car wheel bearings have been sealed for many years, also.

Edited By old mart on 01/03/2021 19:43:17

pgrbbf,

I wholeheartedly agree with using sealed bearings, not only do they retain lubrication within, but they also stop the ingress of grit and sawdust, probably the best reason for their installation. When overhauling my vintage car I used sealed bearings whenever possible they also stop leakage of lubricant onto nearby parts brake shoes in my case, and wood surfaces in your case.

Regards, Nimble Neil.

You obviously didn't read what I said, namely that I didn't feel I had the experience to chose. In my humble opinion this was neither a dumb, nor uninformed remark.

It's a wonderful thought. Sealed bearings would make life much easier.

I'm not an engineer, I'm a woodworker, and I only have my common sense to rely on, no experience in this field at all. But I find it hard to imagine that it is such a simple swap from a system where you continuously renew the lubrication around the bearings, to one where you have a small amount of grease that will not be changed until the bearing fails will give exactly the same bearing life. I am happy to be proven wrong. I'm trying to learn.

Recommended tension for a bi-metal blade is 25,000 to 30,000 psi. A 3/4" blade will need something like 800Ib of force to create that tension. (I'm not great at physics, so please don't criticise, this is what I have always been told)

A wheel bearing on a car would be quite a nuisance to continuously grease. A bandsaw is a lot easier.

Use sealed bearings. The technology has moved on since your ancient bandsaw was made. You think your bandsaw will stress bearings more than a 300kg motorcycle cornering at 250kmh? Those are sealed and last for years.

And adding more grease to a bearing does not increase its load capacity or anything else. The reason they had grease buckets on bearings was because they did not have good seals so they just kept adding grease to make up for the lost grease. It was a messy world back then.

Get the best name brand bearings you can access, such as SKF, FAG or Timken. Cheap Chinese bearings will not last as long or run as smoothly.

And if you want you could probably find a modern seal to fit that recess, just measure the ID, OD and thickness. If you fit that along with sealed bearings it would help keep sawdust away from the bearing and its built in seals and those sealed bearings will last forever.

Edited By Hopper on 02/03/2021 11:53:39

I would go with sealed bearings. Non sealed bearings tend to get over lubricated which can cause heat build up. Ideal grease amount in an unsealed ball bearing is about 30% of space left in bearing, which sent much. Felt seal should be oil filled and lubricated, you can’t mix oil and grease in the same area. You could fit lip seals both sides if the design of housing allows, but fit with the lip facing in and oil occasionally, this will prevent dust getting into the bearing area rather than stop grease getting out in the normal way.

Sealed "For Life" bearings are a relatively recent innovation, back in the late 60s and early 70s, vehicles were still using grease packed bearings.

A 2RS bearing removes all worries about greasing, and / sealing the bearing.

If you are unsure of what you are doing, over greasing a bearing will, at least cause overheating.

If available, 2RS bearings would be my choice.

Talk to your local bearing supplier to see what is available.

Howard

they are available, and cheaper than open for some reason. 25x52x15 2RSH SKF are less than £3 each inc VAT. That can't be right.

Totally agree with all above. Sealed. My bandsaw (modern) has sealed bearings. It's a case of fit & forget.

Steve.