Keep Losing Blade off Band Saw

D

Dazed&Confused

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Dec 25, 2014
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Hello all,

I recently purchased a Dayton 3Z365A Horizontal Bandsaw which seemed well used but in pretty good shape.

It is a much older but similar to this:
http://www.grainger.com/product/DAYTON-Horizontal-Band-Saw-2LKT4?functionCode=P2IDP2PCP

This saw has all metal wheel with a ridge on the backside of the wheel, no tires. When I purchased it the blade would continue to move outward off the drive wheel, but I thought with some adjustment I could get it tracking straight. To be clear the blade continues to move off the wheel and eventually off without cutting and with/without the guides in place. The two wheels were certainly not coplanar, so I adjusted until they were. The blade still came off. I tried just about the whole range of blade tensions and it would come off at all of them. I also tried multiple blades, I'm unsure if any are new/used but everyone of them...same result. All the blades were the same size (1/2") which I believe to be an acceptable size for this unit. I then pulled off the drive wheel to see if it was tapered. I mounted it in a 3 jaw chuck with and found most of the way around it was .001" or less of a taper, but in one section of the wheel around .004" tapered. Would this be enough to cause the blade to work it's way off? Also the drive axle has some play, around 0.02" in and out, and .01" from side to side, could this be my problem? I've played with this thing for a while now and I don't know what else to adjust, and before i go and turn the drive wheel in the lathe and/or pull out the axle (which i'm unsure how to at this point). I figure I would check with you experts, as i'm very new to all this.

Thanks!
Kyle
 
It sounds like you have bad bearings. That would let the blade walk off.
That apers to be the standerd 4x6 saw. do a serch on 4x5 band saw. There is a lot of info out there.
 
Yes I would say bearings also. I have the HF 4X6 and the top bearing was gone. Same thing was happening. thomas s
 
Take a close look at the alignment of the blade as it comes into the guides. Site down the line to see if they are straight. Does the blade track straight when in the cutting position? Could be the guides are guiding the blade off and they need adjustment. I had a problem with the blade coming off mine and the cause was the guides to align the blade to cut the metal were not adjusted well and the blade guided off.
 
I would remove the guides and run the blade slowly by hand if possible. Usually
the wheels are crowned a little bit towards the ridge so the blade climbs up against the ridge. If they are not crowned a little the blade will walk off . With the
wheels coplanar, and crowned, the blade will walk right to the ridge and stay there...
At least that has been my experience.
 
Sometimes you just need to make the blade tighter a lot of the ones I've used need it very tight but then no problems.
 
I agree with the other to make sure the bearings are good first, the saw will never run right with a loose bearing.

The whole saw will flex when the blade is under tension.
It is not enough for the wheels to simply be co-planer, they must be co-planer under tension.
Shim one of the wheel out so they are in the same plane with no tension. Then adjust the blade tilt on the adjustable wheel so that they are co-planer under tension.
When properly adjusted, the blade should ride the crest of the crown under tension - it should not walk to the front or back of the wheel. You will need to remove the blade guides to verify this.
If the saw frame has been slightly tweaked, you may have to re-shim one of the wheel after checking it under tension.

Worst case the frame is twisted and it will never run properly. You might be able to get the wheels all planer using tapered shims to get the axles parallel. If tapered shims fail, the machine is junk and you have nothing to lose by breaking out a big cheater bar and twisting it back into shape. I worked with a guy who did this once and it worked fine for him, I was pretty amazed lol. He put 12" rods where the axles go, sighted along them, and just kept twisting until they lined up.

-Josh
 
Thanks for all the help guys! I don't think it is the guides as the blade comes off the wheel even without the guides in place. Also I've tried just about every blade tension from fairly loose to as tight as I can, still coming off.

So I think that leaves me with either a bad bearing on the drive wheel allowing it to slop around in and out, and also from side to side. Or the drive wheel is tapered. Just to be clear the drive wheel has a very minor taper away from the ridge. Are you all saying this should be tapered toward the ridge? That could be the issue then? I will likely pull the gearbox apart and check the condition of the bearing. Likely replace even if it seems fine to me. Then try again and if that fails turn the drive wheel in the lathe to remove the slight taper.

Thanks!
Kyle
 
I assume you have adjusted the ''tilt'' of the idler wheel. There are adjusting screws on it.
 
Yeah Jim, I have adjusted the tilt of the idler. The wheels when I purchased were badly out of plane. However by adjusting the tilt I was able to get them coplanar, but the blade is still coming off. Thanks though!

Kyle​
 
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