Which bearing for bandsaw

[gaston harris]

Need to replace upper wheel bearings on a 20" bs. The bearings I bought from VXB.com were 620SRS which had more play than the old bearings - they were cheap so I didn't expect that much from them but thought I'd try. But now I'm trying to find the correct replacement -the original bearings had 620SDU on the seal. Anybody know what SDU means. The person I spoke with at VXB was clueless. I had read on the board somewhere that a C/3 nachi might be a good choice. SKF bearing? Thanks in advance for advice.
Gaston

[Myk Rian]

http://www.advancedbearings.com/

[bob hertle]

Gaston

Are you sure of that number? could it be 6205 instead of 620S? AFAIK, 620 is an incomplete number and needs one more digit. 6205RS would be about right on a 20 inch bandsaw. 25 mm bore with rubber seal(s).

The DU designation usually stands for "duplex universal" but is never to my knowledge used with a 6000 series (conrad) bearings. Only with 7000 and 9000 series angular contact bearings. It has to do with the preload grinding of the inner and outer races, and the ability to achieve design preload in any of 3 mounting arrangements. You don't mention the name of the saw. If it's a Delta/Crescent/Rockwell or Powermatic, head on over to owwm.org and you'll find all the info you need.

Bob

[Don Jarvie]

Find the manual for the saw and see if the type of bearings are listed.

Did you save the old bearings? If so then use the same number on the bearing. Also measure the diameter of the shaft with a caliper so you can make sure the replacement will fit.

[gaston harris]

You're correct - the number on the old bearing is 6205DU and the replacement bearing I purchased is 6205RS. It is a 25mm X 52 X 15 so I know I have the correct size but I'm not sure of the correct type in terms of the inner workings of the bearing. It's an Agazzani 20" bandsaw. I'm wondering now if there might some play between the snap ring and the outer bearing race. Thanks for the replies. So DU is duplex universal - the old bearings also were made in Poland and it is 6205DU. Should I maybe try one of the angular bearings? Thanks Gaston

[Brian Myers]

I`ll second Myk Rian`s choice of Accurate Bearing. I get get almost all my bearings from there. Ask for Lynn she is great to deal with and is used to woodworkers looking for bearings. Please make sure to have all your pertinant information ready when you call them (bearing number and/or measured sizes). Accurate doesn`t make their living off of us little guys but is still nice enough to take the time to help us out. :) I would say either Nachi (Japan) or even better NTN (japan) (a few more pesos than Nachi). VXB bearings are cheap for a reason (china), every bearing I `ve gotten from them was sloppy.;)

[bob hertle]

Gaston

If you read my post again you'll see that I said the DU suffix meaning duplex universal, is never used with 6000 series bearings. Therefore, I would conclude that the DU in your case is part of the seal/shield designation. Angular contact bearings are not appropriate for the mounting you describe. (snap ring retention) They are always arranged for preloading. There are situations in which 6000 series bearings are preloaded, but they usually involve inner and outer ring spacers which are differentially ground. I doubt that Ag. went to that trouble. You need the manual or a parts breakdown.

My gut feel is that a pair of reasonable quality 6205xx bearings, like Nachi or SKF or Fafnir will be all you need.

Bob

[gaston harris]

Thanks for the advice everyone - I'll try a better bearing from Japan and see if I get better results. As usual I should have done a little more research first. Thanks Bob you're exactly right - DU is the rubber seal /contact seal.
Gaston

[Pete Bradley]

Hold up a moment. ANY bearings, down to the worst junk you can find in the hardware store, are going to have close enough tolerances that you won't have noticeable play as long as they're the correct size for the machine and installed properly.

What play are you seeing, radial or axial? It sounds like you're seeing axial. there should have been a circular spring on one side, or a spanner nut or other arrangement to take up all the play in one bearing, or some kind of jam nut arrangement. You mention a clip, I'm betting this is an import with both bearings on the same side of a shoulder and a spring for preload. If the spring is one of the ones with three sets of feet, facing it the correct way presses on the outer race, the wrong way leaves a gap that will cause play.

Take another look, the cause is going to be something simple. If you've already ordered more, no big deal, check it out when you swap them in.

[gaston harris]

Hey Pete,
I think you're right. There is no spring in the assembly but the spacer between the two bearings seems too loose. When I took the wheel off the spindle the spacer was floating loose between the bearings - the lower wheel spacer doesn't do this - it is tight. There is a bearing, a spacer, the other bearing and the snap ring. Not sure if the snap ring is bent outward slightly so not enough pressure is on the outer race but that is where the play is. The snap ring has a very small amount of scoring on it so I'll try a new snap ring. I may have bent it when I took the snap ring out. My snap ring pliers are probably not big enough - can't seem to find a bigger pair locally. Thanks for you're help.
Gaston

[Pete Bradley]

I took a look at a griz exploded view and it may be that your machine uses a "solid preload" arrangement. The inner races get squeezed inward while the outers are pushed outward by a spacer, or vice versa. If you have this, the bearings will be fairly loose until the wheel is mounted, and the mounting bolt will provide the preload.

Sounds like you've got the situation in hand anyway.

Pete