Problems after changing bandsaw blade

big · Post by **big** » Wed Nov 17, 2010 4:48 pm

After using 1/2 blades (almost exclusively) for over a year with not problems, I decided to try the 5/8, since I mostly do re-dimensioning work. (OK, I hear everyone saying "why did you change what was working?"). At the same time, I changed the roller bearings because they were screaming.

Now, I can't get the blade to track properly. Yes, I've read the threads on set-up... I did that last year when I bought the machine and put the 1/2 blade and Cool Blocks on. It's almost like the angle of the table is off now, even thought I didn't remove the table to change the bearings. I cannot get a cut parallel with the fence.

If this makes any difference, I've noticed that I can't get the front edge of the Cool Blocks near the teeth without having the back of the blade contact the "bracket". Since I did this right before, and didn't change anything but the blade and bearings, I can't figure out what's wrong. I suppose I could mount the table crooked, but that seems like a sorry workaround.

Thoughts?

dusty · Post by **dusty** » Wed Nov 17, 2010 4:57 pm

I need to make certain that I understand your problem. Are you saying that you are trying to rip boards on the bandsaw and the blade wanders?

Without a fence - can you rip a board along a straight line drawn on that board? If yes, do you find that the board has been moved either left or right in order for you to have followed the line?

If yes - you are experiencing a normal band saw characteristic known as drift.

big · Post by **big** » Wed Nov 17, 2010 5:31 pm

yes, I can cut a straight line without the fence, and yes, it does move the board. If this is drift, I'm surprised I didn't experience it with the 1/2 blade.

If this helps, the teeth barely hang over the rubber of the upper wheel, and are just short of the edge of the rubber on the lower wheel. I don't recall this before.

The blade is barely in contact with all three roller guides. The Cool Blocks exert equal pressure on each side of the blade (just barely touching).

dusty · Post by **dusty** » Wed Nov 17, 2010 5:38 pm

Drift is a characteristic that can change with every saw blade you mount.

I'll check blade location on the wheel the next time I am in the shop. I run with a narrow blade most of the time but I'll change blades to see where it tracks. I believe that I am going to find that it tracks toward rear-of-center on the tires.

big · Post by **big** » Wed Nov 17, 2010 5:42 pm

Thanks. I searched for "drift" and found a lot of info, obviously. I just find it odd that I've used 3-4 blades already, and they tracked exactly the same. This fifth one is different. Odd.

SDSSmith · Post by **SDSSmith** » Wed Nov 17, 2010 5:52 pm

big wrote:After using 1/2 blades (almost exclusively) for over a year with not problems, I decided to try the 5/8, since I mostly do re-dimensioning work. (OK, I hear everyone saying "why did you change what was working?"). At the same time, I changed the roller bearings because they were screaming.

Now, I can't get the blade to track properly. Yes, I've read the threads on set-up... I did that last year when I bought the machine and put the 1/2 blade and Cool Blocks on. It's almost like the angle of the table is off now, even thought I didn't remove the table to change the bearings. I cannot get a cut parallel with the fence.

If this makes any difference, I've noticed that I can't get the front edge of the Cool Blocks near the teeth without having the back of the blade contact the "bracket". Since I did this right before, and didn't change anything but the blade and bearings, I can't figure out what's wrong. I suppose I could mount the table crooked, but that seems like a sorry workaround.

Thoughts?

big wrote:yes, I can cut a straight line without the fence, and yes, it does move the board. If this is drift, I'm surprised I didn't experience it with the 1/2 blade.

If this helps, the teeth barely hang over the rubber of the upper wheel, and are just short of the edge of the rubber on the lower wheel. I don't recall this before.

The blade is barely in contact with all three roller guides. The Cool Blocks exert equal pressure on each side of the blade (just barely touching).

I would not expect a 5/8" blade to overhang the edge of the rubber tire. A couple of questions.....did you get the replacement bandsaw rollers from Shopsmith? Assuming you did, is the bracket that holds the autotracking rollers installed properly (part 57 in the following diagramhttp://www.shopsmith.com/ownersite/partscat/bandsawexpview2.htm). These are the rollers that position the blade on the tires. Generally, the back of the blade, no matter the width, tracks on the same place of the tire because of the auto track rollers.

big · Post by **big** » Wed Nov 17, 2010 8:24 pm

I'm almost certain that the auto-tracking rollers were installed properly, but I see what you are saying about the blade positioning being determined by them.

Since these rollers set the back of the blade (non-tooth) side the same for each blade size, it would seem to make sense that the tooth side of the wider blades would stick out a bit further.

Since I'm using the cast iron bandsaw table, I think I'm going to get a Kreg fence tomorrow...even though installation will require that I drill holes in the table.

Thanks guys.

charlese · Post by **charlese** » Wed Nov 17, 2010 10:11 pm

big wrote:After using 1/2 blades (almost exclusively) for over a year with not problems, I decided to try the 5/8, since I mostly do re-dimensioning work. (OK, I hear everyone saying "why did you change what was working?"). At the same time, I changed the roller bearings because they were screaming.

Now, I can't get the blade to track properly. Yes, I've read the threads on set-up... I did that last year when I bought the machine and put the 1/2 blade and Cool Blocks on. It's almost like the angle of the table is off now, even thought I didn't remove the table to change the bearings. I cannot get a cut parallel with the fence.

If this makes any difference, I've noticed that I can't get the front edge of the Cool Blocks near the teeth without having the back of the blade contact the "bracket". Since I did this right before, and didn't change anything but the blade and bearings, I can't figure out what's wrong. I suppose I could mount the table crooked, but that seems like a sorry workaround.

Thoughts?

Although I don't have the cast iron table on my bandsaw, Here is a simple jig you can make that will save you the expense of buying and installing a store bought jig.
[ATTACH]10911[/ATTACH]

[ATTACH]10912[/ATTACH]

[ATTACH]10913[/ATTACH]

The block is curved, as you can see. When clamping the jig to the fence, the center of the block (the outermost part) is aligned with the tip of the blades teeth. To use the jig scribe a line (pencil will work) down the edge of the board to be re-sawn. Then adjust the fence and follow the line. This allows the operator to adjust the position of the workpiece to offset with any drift.

I wouldn't worry about teeth of the 5/8" blade edging a bit in front of the upper tire. This is probably caused by the tilt of the upper wheel - which is a good thing!

As said above, the position of the blade is set by the guide bearings. As for your blade rubbing on the "bracket" - this should not happen as the bearing should keep the blade from this rubbing. EDIT!! Whoops! Yes, you can put the "cool blocks" close enough to the teeth of a 5/8" blade to cause the back of the blade to rub on the bracket. The blocks only need to be backed off a little to end the issue.

You have been lucky in the past with your 1/2" blades working with no drift. Drift is a normal thing because of teeth slightly offset more on one side of the blade than the other. (also grain changes can cause drift) That's why I like my little jig so much. I can hold a straight line re-sawing very easily.

foxtrapper · Post by **foxtrapper** » Thu Nov 18, 2010 6:49 am

big wrote:...I've noticed that I can't get the front edge of the Cool Blocks near the teeth without having the back of the blade contact the "bracket".

[and]

...the teeth barely hang over the rubber of the upper wheel, and are just short of the edge of the rubber on the lower wheel. I don't recall this before...

Not sure I'm fully following you, but I'll give it a shot.

If the blade is deflecting that badly when you cut I'd suspect the blade of being dull (new doesn't not equal sharp, especially with cheap blades), the tension being inadequate, or you of simply pushing too hard.

If the blade is deflecting like that without you even cutting, I'd suspect the blade of not being truly flat.

From the tire comments, it sounds like the wheels are not running properly to each other. Like one of them either isn't set fully down on its bearing race when you replaced them, or was pushed down too far (not sure if that is possible with a shopsmith wheel).

keakap · Post by **keakap** » Sun Nov 21, 2010 1:12 pm

big wrote:...
Since I'm using the cast iron bandsaw table, I think I'm going to get a Kreg fence tomorrow...even though installation will require that I drill holes in the table.

If it turns out the 5/8 blade is okay other than the drift thing, you can easily "tune" the blade to eliminate its drift.

Then, you will be amazed by what you can do with the Kreg fence system, especially with the fine tuning add-on. Wow.