Brand new bandsaw thrust bearing won't spin

[Pat Scott]

I'm stumped and so is the tech support guy at Laguna.

I have an Agazzani bandsaw that is 4 years old. I was cutting up some green (wet) Maple logs and the saw was acting like the blade was dull, even though it was a fairly new blade. I replaced the blade, and as is my usual habit I double checked the adjustment for all of the guides. That's when I noticed the upper thrust bearing had a slot cut in the face of it from the back of the blade.

I called Jesse at Eagle Tools to order a replacement part, and that's when to my surprise I found out that Agazzani had been sold a couple years ago. Jesse didn't have any thrust bearings in stock, but hoped to get some soon. Well, soon isn't soon enough when your bandsaw is dead in the water and you still have logs to cut!

I tried to find another dealer in the US that sold thrust bearings to fit my saw but struck out. My only option was looking like I had to replace the complete upper and lower guide assembly. Carter (Eagle) sells a replacement set for $320. Hmm, I can replace my guides with Laguna's ceramic guides for $280. So I call Laguna and in the off chance I asked if he had any Euro style thrust bearings since Laguna bandsaws used to come with Euro's. Sure enough he had one, price is $99. Ouch, that's 1/3 of the cost for just one bearing versus replacing complete upper and lower assemblies. In the end I went cheap and bought the part.

Remove the old part, install the new part, back to business. The first cut I made was a 16" tall wet log. Sparks were flying from the thrust bearing. What? It's not turning at all! I stopped cutting, the blade backs away a bit from the bearing, and I can easily spin the bearing by hand. It's nice and loose and works like it's suppose to. But as soon as the blade touches it, it won't turn and sparks fly.

I got through the cut by manually turning the bearing (NOT a good practice!). I lowered the upper guide assembly to about 8" to make some more cuts. The bearing spun like crazy, just like it's suppose to.

The next day I played with and readjusted all of the guides again and tried it. Now the bearing is spinning no matter how high the upper guide assembly is. Crazy.

Today I went to cut another 16" green Maple log, and the bearing won't spin. I lowered the upper guide to 8" and it won't spin half the time.
I don't get it. The bearing freely spins by hand, but when the blade touches it nothing happens. How can that be? And more importantly, what do I do to fix it? I didn't have this problem with the original thrust bearing. Makes me think I should have spent the $280 and upgraded to Laguna's ceramic guides with no moving parts.

[Erik Loza]

Space Age Ceramics makes a replacement thrust bearing for $27...

http://spaceageceramics.com/products/euro-thrust-bearing-pin/

Also, just some observations. Do with them as you will:

1.) If the blade is sharp and of the correct tooth set for green wood (a skip-toothh blade, not flat kerf), then I have never had to push hard. I HAVE had to push hard when the blade is dull and that, of course, gets us into a whole different set of problems.

2.) With a wider blade (>3/4") and straightline ripping, I set the guides so that they never touch the blade during the cut. I let blade tension do the work for me.

3.) The #1 cause cause of complaints about cut quality and guide damage I hear is all directly related to either too dull a blade or inadequate blade tension. Or a combination of both.

Best of luck with it.

Erik

[Pat Scott]

Space Age Ceramics makes a replacement thrust bearing for $27...

You gotta be kidding me! Ahh!! But thanks for the link!

I was wondering if it could be the blade. I'm using a Lenox Diemaster 1/2", 4-tooth skip, .035" kerf blade which was recommended by another woodturner for cutting bowl blanks from green wood. I was thinking about ordering one of my old blades and see how it does. The blade tension with the Lenox bi-metal blade is the same as it was with my old carbon steel blade. I'm going by the tension guide built into the saw, and am setting it a hair more than 1/2" but not quite to the 5/8" setting.

[Erik Loza]

I could see a 1/2" Diemaster clogging with wet sawdust and also, on a saw your size, there will be the issue of getting enough tension into a 1/2" blade to get it to cut straight without running into the thrust bearing, which seems like it is happening. For ripping green wood on your saw, I would us a 3/4" or 1.0" skip tooth blade. The surface finish will be gnarly but you're ripping logs, so that shouldn't matter. Something which clears material quickly. The Timberwolf AS blades have always done well for me. Hope this helps.

Erik

[John K Jordan]

Did you try "stoning" the back of the blade with a small stone? (could the back be too polished?) I often round the corners a bit while I'm at it.

This is a puzzler. Hey, I understand there are two bearing configurations. Does the back of your blade bear against the outer circumference of the bearing or against the side of the bearing? (I've had both types) If against the side, is the bearing made for side forces? Did you try flipping it so the back is towards the front?

Does the bearing spin easily when rotating the upper wheel by hand with the bearing temporarily moved to be in constant contact with the back of the blade? Is the bearing surface perpendicular to the blade or are there forces at an angle? Also, is it a shielded bearing or a sealed bearing (with a rubber seal)? I understand some sealed bearings have more resistance to turning.

Curious.

A bearing supplier can usually provide any bearing if you have the exact dimensions or carry it to the supplier.

JKJ

[Pat Scott]

I did stone the back of the blade. My blade contacts the flat face of the bearing, not the round edge. There is no way to flip it, and the bearing is made for bandsaws. The original bearing had GS456 on the front, the new one has GL456 (which Laguna said is fine). I don't know what GS and GL stand for.

Here's a picture similar to my saw showing the type of thrust bearing that I have.
333855

I have thought about swapping the upper and lower thrust bearing since the lower is still the original. I did try and push the blade against the bearing and see if it would rotate, but I couldn't get it to work like that. I hadn't thought about the easy way that you suggested and simply adjust the bearing so it touches the blade! I'll give that a shot.

I thought if the upper guide doesn't track parallel to the blade that it wouldn't touch the bearing evenly and maybe that's part of the problem. But I didn't have any problems with the original bearing, so I'm leaving this as a last resort. The tracking is real close as is. With the upper guide raised all the way up, there is just a bit more gap between the blade then there is when the guide is lowered (saw 1/16" more).

[Rod Sheridan]

Pat, you need a much coarser blade for green wood.

I use a 1" blade with 1.2 TPI if I remember correctly.

Forget the guides, you don't need them for that work, adjust them so they have a bit of clearance from the blade so they don't touch..........Regards, Rod.

[John K Jordan]

I process a lot of green wood to make turning blanks. My green wood processing got easier when I switched from 3/4"+ blades to 1/2" x .024 3 tpi blades, about $12 each made locally from Lenox stock.

According to my Starrett bandsaw blade tension gauge it is almost impossible to get the manufacturer's suggested tension on the larger blades on vertical shop bandsaws without the feeling like I will over-stress or break something. No problem with my Woodmizer sawmill.

JKJ

[Alan Schwabacher]

...I noticed the upper thrust bearing had a slot cut in the face of it from the back of the blade.

...the bearing won't spin....I didn't have this problem with the original thrust bearing.

The fact that the original bearing got a slot cut into it indicates that you did in fact have a problem with it not turning. If the new one doesn't turn either, perhaps the blade doesn't contact it close enough to the edge.

[Bob Vaughan]

Check the travel of the upper guide arm (rod). It should travel up and down exactly parallel to the blade. An out-of-tune upper guide will shove the thrust bearing against the back of the blade when all the way up, but when lowered, it will travel away from the blade. Get a good square and set it on the table. Raise the upper guide and see if it varies from square. Another trick is to back off the thrust bearing to just barely touching the back of the blade when the upper guide is at its topmost position. Lower the guide to the bottom and see if it varies away from the back of the blade.

It sort of sounds like the upper guide arm isn't moving parallel to the back of the blade, thus when in the uppermost position, there's tremendous thrust against the thrust bearing.

[Pat Scott]

The fact that the original bearing got a slot cut into it indicates that you did in fact have a problem with it not turning. If the new one doesn't turn either, perhaps the blade doesn't contact it close enough to the edge.

OK, that's a good point! What I meant to say is I never had a problem with the upper bearing until now. I think the reason the blade cut a slot in the original bearing is because as I was cutting some logs I noticed the tracking was off with the blade farther away than normal. On the fly I adjusted the tracking and continued cutting. What I think might have happened is there was build up on the wheels that caused the tracking to get off in the first place. Then I adjusted it and inadvertently went too far or the build up came off. Now the blade is pushing way too hard against the thrust bearing and jammed it.

[Pat Scott]

It sort of sounds like the upper guide arm isn't moving parallel to the back of the blade, thus when in the uppermost position, there's tremendous thrust against the thrust bearing.

That's what I thought too. I didn't use a square, but just did a quick visual. I tensioned the blade and looked at the distance between the blade and thrust bearing at about 8" high. There was maybe 1/32" of gap. Then I raised the guide assembly to 18" and the gap increased to about 1/16". I would prefer they are the same, but I didn't think this small of variation could cause the problem?