Thread: My bandsaw is full of gremlins.

The bearings in the wheels appear to have no sideways play.

Originally Posted by yeoman

The rear bearing has a groove in it. About the width of a blade. I don't remember it being that way when I bought it so that might have something to do with it.

I know Skew said different, and I have appreciated Skew's wisdom on a broad range of subjects on the forum over the years, the groove in itself may not be the problem. Carter aftermarket bandsaw guides have grooves in the middle of the thrust bearings as a design feature. http://www.carterproducts.com

If there are grooves there as you described them, I doubt that the blades would have made them. Without a groove to hold the back of the blade in the same place the blade would wander across the bearing enough to make a hollow depression, rather than a groove, if it has had enough use at all to make a visual impression on the surface of the bearing.

While the groove in itself may not be the problem, it would certainly exacerbate the problem of the bearings not turning.

Doug

Originally Posted by doug3030

I know Skew said different, and I have appreciated Skew's wisdom on a broad range of subjects on the forum over the years, the groove in itself may not be the problem. Carter aftermarket bandsaw guides have grooves in the middle of the thrust bearings as a design feature. http://www.carterproducts.com

If there are grooves there as you described them, I doubt that the blades would have made them. Without a groove to hold the back of the blade in the same place the blade would wander across the bearing enough to make a hollow depression, rather than a groove, if it has had enough use at all to make a visual impression on the surface of the bearing.

While the groove in itself may not be the problem, it would certainly exacerbate the problem of the bearings not turning.

Doug

A photo of one of the 'groovy' thrust bearings would help.

On my bandsaw, the lower thrust bearing is mounted so that the blade runs on the side of the thrust bearing, not the edge. ie The bearing is at 90 degrees to the blade. If it had a groove, the bearing couldn't possibly spin, since the rear of the blade would tend to lock it in place. Then, if the groove was deep enough, the join could catch in the groove, causing breakage. That may well have been the cause of the problem. Otherwise my guess from the beginning was that the side guides were adjusted too close, causing the blade to jam as the join passed between them.
There should be roughly the thickness of a sheet of paper between the blade and side guides, and about the thickness of a playing card between the rear of the blade and the thrust bearing, all measured where the blade is at it's closest.
In particular, the side guides need that gap, to allow for a slightly thicker area where the join passes between them.

yeoman, before trying to add weights for balance etc, check that the rubber tyres on the upper and lower wheels are in good nick and nice and clean. Any problems there could easily cause the side-to-side and front-to-rear vibrations that you describe.

Edit: I just checked over the guides on the Carter site here:
2400 by Carter Products
There's no groove in the centre of the thrust bearing. The side guide bearings appear to have a groove, or two bearings side-by-side, but nothing on the thrust bearing.

From my knowledge of this model of BS the bearings do not have grooves. They are off-the-shelf 608ZZ type, but I stand corrected if this is not the case.

As far as I can remember, the back bearings did not have grooves when I got it. Even more worrying, by the time I changed it, the bottom one had two grooves in it for some bizarre reason.

I'll try to take a couple of happy snaps when the lighting is a bit better.

I'll check the tires. They are fairly clean, but I suppose checking them for roundness is just a case of running a finger over them while turning the wheels?

Dave

Originally Posted by Hermit

On my bandsaw, the lower thrust bearing is mounted so that the blade runs on the side of the thrust bearing, not the edge. ie The bearing is at 90 degrees to the blade. If it had a groove, the bearing couldn't possibly spin, since the rear of the blade would tend to lock it in place.

In that case then the grooves are not like the Carter ones. The info I posted is irrelevant in this case.

Originally Posted by Hermit

Edit: I just checked over the guides on the Carter site here:
2400 by Carter Products
There's no groove in the centre of the thrust bearing. The side guide bearings appear to have a groove, or two bearings side-by-side, but nothing on the thrust bearing.

I held a number of Carter blade guides in my hand at last year's Working With Wood Show and many, but not all do actually have a groove in the thrust bearing. I have never seen the grooved bearings on the website either but they exist in real life.

You can see grooves in the bearings on the blade stabilisers Band Saw Stabilizer® by Carter Products

You are correct that there are some guides where there are double side bearings, made for the wider blades.

Doug

Those are some amazing bearings. Nothing at all similar to how mine ended up. The grooves in mine were only a couple of mm deep, and not centered across the width of the bearing.

I've tried to be fairly diligent with keeping the bearings spaced correctly. I could be wrong, but I do not think the bearings were too close to the blade. Either side or rear.

Originally Posted by yeoman

I'll check the tires. They are fairly clean, but I suppose checking them for roundness is just a case of running a finger over them while turning the wheels?
Dave

Yeah, I was sort of thinking of pieces torn from the edges, heavier wear in some areas and so on.

Something I'm still not clear on. In the pic below, are your thrust bearings oriented as in A or B? My bottom one's like the one in A, unlike the one on Carter's stabiliser, hence my comment earlier about the groove locking the bearing and/or causing blade breakage.

Thrust Bearing Orientation.JPG

Originally Posted by doug3030

In that case then the grooves are not like the Carter ones. The info I posted is irrelevant in this case.



I held a number of Carter blade guides in my hand at last year's Working With Wood Show and many, but not all do actually have a groove in the thrust bearing. I have never seen the grooved bearings on the website either but they exist in real life.

You can see grooves in the bearings on the blade stabilisers Band Saw Stabilizer® by Carter Products

You are correct that there are some guides where there are double side bearings, made for the wider blades.

Doug

Doug, as far as I'm aware, only the Carter stabiliser has a groove, their std thrust bearings and most common thrust bearings don't have a groove. Maybe they should, though, if oriented in line with the blade as in B in my post above.

Hermit, the thrust bearings in my saw are the same as example B.

I haven't noticed any degradation of the tires as such, but I will check for flat spots or excessively worn areas.

Originally Posted by yeoman

Hermit, the thrust bearings in my saw are the same as example B.

Ah, then my comments about the groove locking the blade and/or breaking the blade are irrelevant in your case. Still a sign of pretty heavy wear, though. That bearing surface is fairly hard.

I was picturing type A and a groove in the side of the bearing.

Originally Posted by Hermit

Doug, as far as I'm aware, only the Carter stabiliser has a groove, their std thrust bearings and most common thrust bearings don't have a groove. Maybe they should, though, if oriented in line with the blade as in B in my post above.

Hermit, I have held carter blade guides in my hand that have grooves in the thrust bearings. They exist. Always as shown in example "b" in your excellent diagram. It would make no sense in bearings oriented as per example "a", of course.

In fact I cannot see any advantage in orientating the bearing as in example A except for ease of manufacture. "A" would create much more friction and some minimal sideways forces. Orientation "b" would still provide as much support and less friction, and if the back of the blade is running in a groove it has to increase stability.

DOug

Originally Posted by doug3030

Hermit, I have held carter blade guides in my hand that have grooves in the thrust bearings. They exist. Always as shown in example "b" in your excellent diagram. It would make no sense in bearings oriented as per example "a", of course.

In fact I cannot see any advantage in orientating the bearing as in example A except for ease of manufacture. "A" would create much more friction and some minimal sideways forces. Orientation "b" would still provide as much support and less friction, and if the back of the blade is running in a groove it has to increase stability.

DOug

No, I can't see any advantage either. Still, many bandsaws have them that way. A space-saver, I figured.

There's many examples of both types here: https://www.google.com.au/search?q=b...2&ved=0CDoQsAQ

A lot show the grooves on the side of the bearing that I mentally pictured, too.

Yoeman! I still think the grooves may have developed through the lack of tension on the blade and/or pushing the material through the saw too aggressively without letting the blade do its work.
Other than that I cannot suggest anything else.