Bandsaw throwing narrow blades off wheels

pennview · Post by **pennview** » Tue Dec 20, 2011 11:10 am

Too much tension on a blade likely will cause the blade to walk off the wheels or peel off the rubber tires.

dusty · Post by **dusty** » Tue Dec 20, 2011 11:33 am

pennview wrote:Another possibility -- is the blade 72" or is it shorter? If the blade is shorter (like 73 5/8"), you shouldn't tension it according to the Shopsmith tension gauge, but rather it should have less tension than what shows on the gauge. Too much tension on a blade likely will cause the blade to walk off the wheels or peel off the rubber tires.

Are you sure of this??

JPG · Post by **JPG** » Tue Dec 20, 2011 11:55 am

dusty wrote:Are you sure of this??

Looks bas akwards to me also!:eek:

pennview · Post by **pennview** » Tue Dec 20, 2011 1:29 pm

((The information in this post is incorrect; see post #19 for corrected information))

The shorter length should read 71 5/8" (and not 73 5/8"). Sorry about any confusion on this. Don't know where that 73 5/8" measurement came from.

To reiterate what was supposed to be in my earlier post, some blades people use are actually manufactured for saws other than the Shopsmith 11", which use blades that are 72" in length. So, if the blade being used is shorter than 72", one should use less tension than that shown on the Shopsmith tension gauge. If they're longer than 72", they require more tension than that shown on the tension gauge.

If you apply too much tension to the blade, you likely will cause the blade to come off of the wheels. You also could peel the rubber tire off the wheel with too much tension.

bobgroh · Post by **bobgroh** » Tue Dec 20, 2011 1:37 pm

On the question of checking the hub orientation - I sort of did with a quick visual look. I don't see much difference in the length of hub but I will check later today. Thanks for your interest!

bobgroh · Post by **bobgroh** » Tue Dec 20, 2011 2:04 pm

pennview wrote:The shorter length should read 71 5/8" (and not 73 5/8"). Sorry about any confusion on this. Don't know where that 73 5/8" measurement came from.

To reiterate what was supposed to be in my earlier post, some blades people use are actually manufactured for saws other than the Shopsmith 11", which use blades that are 72" in length. So, if the blade being used is shorter than 72", one should use less tension than that shown on the Shopsmith tension gauge. If they're longer than 72", they require more tension than that shown on the tension gauge.

If you apply too much tension to the blade, you likely will cause the blade to come off of the wheels. You also could peel the rubber tire off the wheel with too much tension.

At the risk of exposing too much ignorance, I don't think the length of the blade affects the tension indication - the tension 'meter' responds pretty much only to the tension in the blade. The 'meter' does not respond to the arm position - it responds to the amount of torque on the arm that supports the upper wheel and that (through the radius of the wheel) is proportional to the tension on the blade. Rather neat, actually.

But maybe I am all wet. It happens!

beeg · Post by **beeg** » Tue Dec 20, 2011 2:19 pm

pennview wrote:The shorter length should read 71 5/8"...

I believe that the blade specs are 72" + or - 1/2". So that 71 5/8" blade, the tension gauge should be followed.

JPG · Post by **JPG** » Tue Dec 20, 2011 3:10 pm

bobgroh wrote:At the risk of exposing too much ignorance, I don't think the length of the blade affects the tension indication - the tension 'meter' responds pretty much only to the tension in the blade. The 'meter' does not respond to the arm position - it responds to the amount of torque on the arm that supports the upper wheel and that (through the radius of the wheel) is proportional to the tension on the blade. Rather neat, actually.

But maybe I am all wet. It happens!

The problem with different length blades is the adjustment range of the mechanism(the upper wheel will not pass through the top and vice versa. . .). Tis true the indicator responds to tension so it should be 'accurate'. Another brand difference may be what tension a particular blade works best with. I consider the marks to be a 'starting suggestion' anyway.

The 'longer' hub side protrudes about 1/4 " further than the short side.

pennview · Post by **pennview** » Tue Dec 20, 2011 4:34 pm

Well it turn out I'm the one that is all wet. I went to the shop and tested the tensioner, and the gauge only reflects actual tension, so what I was saying regarding less tension for a blade shorter than 72" or more tension on a longer one is incorrect.

The truth be told though, I've been doing just this with regard to longer or shorter blades, but now I know that I no longer need to follow this regimen.

Nevertheless, if you put too much tension on a blade it can cause the blade to come off of the wheels and may peel off the rubber tire. Years ago, I had this problem trying to tension a small Rockwell band saw. Too much tension resulted in stretched tires that needed to be replaced before the saw would operate properly.

JPG · Post by **JPG** » Tue Dec 20, 2011 4:51 pm

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!;)