Bandsaw throwing narrow blades off wheels

dusty · Post by **dusty** » Tue Dec 20, 2011 7:04 pm

[quote="JPG40504"]What puzzles me is that I would think narrower blades would be LESS likely to climb the cant and slip off the front of the upper wheel.

Could it be possible it is first slipping off the lower wheel? If so, is the blade tracking against the LOWER blade backup bearing on the lower blade guides? That bearing controls positioning of the blade as it approaches the lower wheel. Are the lower blade guides interfering with the blade preventing it from riding on the backup bearing?

Does the blade slip off the wheels with the blade guides fully retracted from the blade? If it does, I think we need pix!]

If the upper wheel is canted properly, will the blade even attempt to come off on the front. Doesn't the canting force the blade back against the bearings.

JPG · Post by **JPG** » Tue Dec 20, 2011 9:49 pm

dusty wrote:If the upper wheel is canted properly, will the blade even attempt to come off on the front. Doesn't the canting force the blade back against the bearings.

Yes, which is why I do not completely understand and am looking for a different explanation in the lower wheel area.

I think we may have incorrectly been assuming it is slipping off the top wheel.

reible · Post by **reible** » Tue Dec 20, 2011 9:50 pm

This thread sounds interesting, I have yet to mount the new 1/8" blade I recently purchased and am interested as to how this is resolved just in case that happens to me.

At this point I might suggest that you disconnect the bandsaw from power source ie headstock and then run some tests by hand power. This way you can open the cover and see just what is happening as the blade turns.

Of course it could be a lot of things and it might be that the blade will not come off under hand power.

I'm going to start with an odd sort of question, the bandsaw without the blade on and cover open, will either the top or bottom wheel move in or out when you pull on them? (Pulling like you want to take them off.) If so then we will go on with that idea. If not then we are back to what others have been suggesting.

If none of the wheels will move in or out then mount the blade as you normally would. Leaving the cover off start rotation of the blade in the normal direction very slowly watching which and what way the blade moves on the wheel and at the bearings. If the blade has a bend in it you will see that as it comes around. If you can not see anything happening after say a dozen rotations then get a dowel or similar method to spin the top wheel faster, of course still watching for any trend of the blade coming off. If nothing is happening then speed up your turning...

If nothing else happen then this was all in vane, I'm hoping that is not the case. Hope this helps us all understand what is happening better.

Ed

JPG · Post by **JPG** » Tue Dec 20, 2011 9:58 pm

reible wrote:This thread sounds interesting, I have yet to mount the new 1/8" blade I recently purchased and am interested to how this is resolved just in case that happens to me.

At this point I might suggest that you disconnect the bandsaw from power source ie headstock and then run some tests by hand power. This way you can open the cover and see just what is happening as the blade turns.

Of course it could be a lot of things and it might be that the blade will not come off under hand power.

I'm going to start with an odd sort of question, the bandsaw without the blade on and cover open, will either the top or bottom wheel move in or out when you pull on them? (Pulling like you want to take them off.) If so then we will go on with that idea. If not then we are back to what others have been suggesting.

If none of the wheels will move in or out then mount the blade as you normally would. Leaving the cover off start rotation of the blade in the normal direction very slowly watching which and what way the blade moves on the wheel and at the bearings. If the blade has a bend in it you will see that as it comes around. If you can not see anything happening after say a dozen rotations then get a dowel or similar method to spin the top wheel faster, of course still watching for any trend of the blade coming off. If nothing is happening then speed up your turning...

If nothing else happen then this was all in vane, I'm hoping that is not the case. Hope this helps us all understand what is happening better.

Ed

I suggest spinning the lower wheel with the dowel.

Also the cover/tightening may alter things. Hopefully not!

If it continues, we may need to run it with the table off so as to observe more gooder.]not[/B] against the lower backup bearing or something is pulling it away.

reible · Post by **reible** » Tue Dec 20, 2011 10:15 pm

The reason I'm asking about the wheels are the fact that the top wheel is held on with a clip and it could happen that the clip is off... clip on my used machine was shot.

the bottom bearing has a metal clip that hold the bearing in the housing. On my saw the clip was bent and the let the shaft/bearing move in and out. Found that before I attempted to use the saw because it was really bent, a smaller amount may have gone unnoticed.

Ed

JPG · Post by **JPG** » Tue Dec 20, 2011 11:41 pm

reible wrote:The reason I'm asking about the wheels are the fact that the top wheel is held on with a clip and it could happen that the clip is off... clip on my used machine was shot.

the bottom bearing has a metal clip that hold the bearing in the housing. On my saw the clip was bent and the let the shaft/bearing move in and out. Found that before I attempted to use the saw because it was really bent, a smaller amount may have gone unnoticed.

Ed

So the lower wheel location might also be a variable.

You are correct, this thread is getting quite interesting!!!!

reible · Post by **reible** » Wed Dec 21, 2011 12:31 am

For anyone who might be lost at this point a couple of pictures in reference to the last few posts. As of now we do not know if this has anything to do with the problem but it is something you might want to check on your bandsaw.

[ATTACH]15311[/ATTACH]

Mine was really bent as shown. Sorry no photo of the "fixed" part but if the lower wheel can be moved in and out this is a potential cause.

[ATTACH]15312[/ATTACH]

Ed

dusty · Post by **dusty** » Wed Dec 21, 2011 5:04 am

If the blade is slipping off the back of the wheel, I would expect to find the blade behind the wheel. Is that where it is found or is it loose out front of the wheel?

dusty · Post by **dusty** » Wed Dec 21, 2011 6:53 am

reible wrote:For anyone who might be lost at this point a couple of pictures in reference to the last few posts. As of now we do not know if this has anything to do with the problem but it is something you might want to check on your bandsaw.

[ATTACH]15311[/ATTACH]

Mine was really bent as shown. Sorry no photo of the "fixed" part but if the lower wheel can be moved in and out this is a potential cause.

[ATTACH]15312[/ATTACH]

Ed

The way that piece is bent and the degree to which it is bent makes me think that it was done intentionally. The bolt that holds it in place would tend to flatten the bend if screwed down tight.

[ATTACH]15313[/ATTACH]

[ATTACH]15314[/ATTACH]
There is a slight bend in that part but it should be gradual.

On yours it almost looks like someone tried to drive the lower axle out from the back side without removing the retainer.

JPG · Post by **JPG** » Wed Dec 21, 2011 11:55 am

dusty wrote:The way that piece is bent and the degree to which it is bent makes me think that it was done intentionally. The bolt that holds it in place would tend to flatten the bend if screwed down tight.

[ATTACH]15313[/ATTACH]

[ATTACH]15314[/ATTACH]
There is a slight bend in that part but it should be gradual.

On yours it almost looks like someone tried to drive the lower axle out from the back side without removing the retainer.

Perhaps the PO tightened it with the bearing jammed and instead of pulling the bearing into the bore, the bracket bent. That would be my 'guess'.