Bandsaw Blade Tracking Adjustments Etc.

JPG · Post by **JPG** » Sat Mar 16, 2013 1:37 am

Does the blade touch the upper blade guide bearing? It should not!

The wheels are thicker at the rim on the back side than the front(beveled).

The upper wheel cant appears inadequate in your pix. This would tend to exert greater pressure against the lower guide bearing.

The straight edge needs to touch both the top and bottom rim of the upper wheel(your 'upper pix' does not touch the bottom of the upper wheel, but rather is touching the hub).

If the straight edge is positioned correctly, I believe there would be 0 to negative clearance to the lower wheel.

The upper wheel needs to be canted. Remove the upper wheel, use a pipe as a pry by slipping it over the upper wheel shaft, and apply a twist to raise the outer end of the shaft.

If your upper wheel has a 'wobble'(bent), it may be possible to help correct the wobble by judicious use of the wheel to apply that twist(doing so with a straight wheel will warp the wheel). Only use the wheel until it is 'straightened', then continue twisting the shaft with a pipe. Only twist slightly and check cant between twists.

When a straight edge is held against the upper wheel(touching both the top and bottom at the rim), the straight edge should clear the top rim of the lower wheel by about a 1/4".

A 1/8" play(at the rim) in the lower wheel bearing is not excessive.

caleb · Post by **caleb** » Sat Mar 16, 2013 2:30 am

video 2 video 1

it looks like it is really far out.

Is the measurement supposed to be done with the blade tensioned up or not.

Because I get two very different results.

Without tension I am about 1/16th away from the wheel
with tension I am touching on the bottom wheel and the top wheel is not touching on the bottom.

ahhhhhh.

I don't know what happened to it.

JPG · Post by **JPG** » Sat Mar 16, 2013 3:20 am

Definitely the cant is not adequate!

When a straight edge is laid against the lower wheel, the straight edge should clear the top of the upper wheel.

I am getting suspicious of the upper wheel axle support arm. The pivot for that arm is also suspect. And finally the axle itself. The variance with/without tension indicates something is 'moving'.

It almost looks like someone has tried to make the wheels 'co-planer'.

algale · Post by **algale** » Sat Mar 16, 2013 8:57 am

JPG40504 wrote:Definitely the cant is not adequate!

When a straight edge is laid against the lower wheel, the straight edge should clear the top of the upper wheel.

I am getting suspicious of the upper wheel axle support arm. The pivot for that arm is also suspect. And finally the axle itself. The variance with/without tension indicates something is 'moving'.

It almost looks like someone has tried to make the wheels 'co-planer'.

I agree with everything JPG says in this message. I'd also add that in video2, the tension was inadequate for the blade (video1 showed correct tension for that blade, so I assume you know how to do it correctly).

Before I went ahead and started bending things (as was suggested in an earlier message), however, I'd take that upper wheel off, and take some pics/videos of the axle and axle support arm and ideally get some angle measurements off of it.

Then, if I were convinced that (a) something is wrong and (b) that there's no conceivable way that I had done something to it to make it wrong, I'd call customer service and get a return shipping authorization, pack it up well and ship it back to them to let Shopsmith have a look. They will fix it for free if it is a factory defect.

Bit of a pain in the neck but if you start bending things and make matters worse, Shopsmith may not fix it.

dusty · Post by **dusty** » Sat Mar 16, 2013 11:01 am

There has been some discussion in this thread about wheel wobble as a possible cause for the twisted blade. This YouTube video may shed some light on how to confirm wobble (whether bent wheel or bent shaft or bad bearings).

caleb · Post by **caleb** » Sat Mar 16, 2013 9:08 pm

Ok so here is another video to try to show the wobble. I didn't even think to check for wobble like what Dusty suggested until now.

http://youtu.be/3WNp65TaHPA

thanks

Caleb

caleb · Post by **caleb** » Sat Mar 16, 2013 9:14 pm

here are some pics with the wheel off, not sure what I am looking for thou.[ATTACH]20619[/ATTACH]

[ATTACH]20620[/ATTACH]

dusty · Post by **dusty** » Sat Mar 16, 2013 9:46 pm

caleb wrote:here are some pics with the wheel off, not sure what I am looking for thou.[ATTACH]20619[/ATTACH]

[ATTACH]20620[/ATTACH]

I don't believe you are looking at your problem in these two images. But then I don't believe that that forced movement of the upper wheel, as shown in the last video, is the cause of your twisted blade either.

I can move my upper wheel just as you do in the video but when powered the wheel does not wobble at all nor does the blade twist.

I know this offers nothing toward a solution but I have nothing to offer other than change blades.

JPG · Post by **JPG** » Sat Mar 16, 2013 9:54 pm

caleb wrote:here are some pics with the wheel off, not sure what I am looking for thou.[ATTACH]20619[/ATTACH]

[ATTACH]20620[/ATTACH]

Ok, the wheel moves excessively(wobble).

Question is, is it the bearing, or the shaft, or the arm, or the pivot that is allowing that much movement.

Real close observation will be required to determine the contribution of each.

I would start with the wheel off and apply similar forces to the wheel axle and see if the axle or the arm or the pivot moves. I would expect some play, but look for really obvious movement.

The wobble is an 'issue' separate from the lack of cant. I would address the lack of canting first as I believe it is the main cause of the twisting.

dusty · Post by **dusty** » Sun Mar 17, 2013 5:36 am

JPG40504 wrote:Ok, the wheel moves excessively(wobble).

Question is, is it the bearing, or the shaft, or the arm, or the pivot that is allowing that much movement.

Real close observation will be required to determine the contribution of each.

I would start with the wheel off and apply similar forces to the wheel axle and see if the axle or the arm or the pivot moves. I would expect some play, but look for really obvious movement.

The wobble is an 'issue' separate from the lack of cant. I would address the lack of canting first as I believe it is the main cause of the twisting.

Unless the wheel is moving back and forth (wobbling like an old wagon wheel), I don't follow your thinking here. Also, I don't see evidence of inadequate cant. The blade is tracking about where it should (especially if the backup bearings are not properly adjusted).