Bandsaw Upper/Lower Wheel Alignment Problem

[Dan Clark]

On crowned wheels that are nearly coplanar, when the blade is centered on the top wheel, it will be front of center on the bottom wheel. The wider the blade, the more front of center it will ride on the bottom wheel.

Can you put your bottom wheel back in the original location, and take a picture of the 1/4" and 1/2" blades on the bottom wheel when they're centered on the top wheel?

Phil,

I'm a bit confused. Are you saying that the condition I'm seeing is normal? This weekend, I'll post some detailed pics of the 1/4, 1/2 and 3/4 inch blades.

Thanks,

Dan.

[Dan Clark]

Ditto. I set the blade to center on the upper, and never worry where it is on the lower.

Myk,

Interesting point. If this is normal, I won't worry about it. OTOH, it's not clear if this is normal.

Thanks,

Dan.

[Dan Clark]

Blade alignment can change as the width changes because the tension is different. It takes 2X as much force to tension a 1/2" blade as a 1/4" one. That change in force can (indeed, does) cause the frame to bend. How much it bends depends upon how robust the saw is; with my 14" CI Delta it will deflect a lot if you try to add more force than about the standard 1/2" setting with a high tension Iturra spring. If you add more tension than that you can move the upper blade guides out of alignment with the lower. None of that causes the blade to go out of alignment with the wheels, however, unless the wheels don't lie in the same plane, or very close to it. If they aren't coplaner, and especially if they are off in both axes, the alignment gets worse the higher the spring tension. Whether that causes the blade to walk off the wheels depends upon how far out of alignment they are, but it sure won't track or cut true in any case.

Ever ride a bicycle with the wheels out of alignment?

John

John,

The 1412 is pretty robust. With the 3/4" blade on the saw, a straight edge held vertically against the side of the saw showed no deflection when the saw was tensioned. In any case, tension does not make any difference. With the 3/4" blade detensioned down to the 1/4" range, the 3/4" blade still shifted to the left.

Regards,

Dan.

[Dan Clark]

Last Sunday, I stopped by Rockler Seattle and tested my blades on the floor model. The blades acted the same way on both saws. This kind of implies that it's the blades. OTOH, I have difficulty believing that BOTH of the 1/2" and 3/4" blades are defective.

At this point, I wonder if it's the blades. To test this and since I wanted another 1/2" blade anyway, I bought a LENOX DIEMASTER 2 blade. We'll see if there is any difference from my Laguna 1/2" blade.

Regards,

Dan.

[Phil Thien]

Phil,

I'm a bit confused. Are you saying that the condition I'm seeing is normal? This weekend, I'll post some detailed pics of the 1/4, 1/2 and 3/4 inch blades.

Thanks,

Dan.

Hard to tell w/o seeing where the blade is landing on that bottom wheel. But yeah, the wider the blade, the closer to the front rim it will run on the lower wheel when centered on the top wheel.

[John TenEyck]

Dan, is the blade perpendicular to the table in both planes when it's fully tensioned? If it's not when checked along the back of the blade then the wheels aren't in proper alignment. If it's not when checked along the side of the blade, then the frame is deflecting so much that the upper wheel is being pulled to the right. The saw may be robust, but it WILL deflect and, at some point, it will become a problem. A 3/4" blade may be fine on the saw, I don't know, but there will be an upper limit.

John

[Edward Oleen]

Gentlemen: I hate to be a spoil-sport, but in this, and all difficult BS issues, I'd be guided by Louis Iturra. Get a copy of his catalog and read it. If you can, communicate with him.

[John Leake]

I would suggest taking a piece of aluminium 1x2x1/4" long enough to cover top and bottom wheels and then some. Then take some scrap aluminium or some very straight wood and make parallels to contact the wheel rims top and bottom, spacing out the vertical so it clears the saw structure, etc. Then place that "gauge" on the bandsaw being very careful to gently position it gently on the wheel rims. If the saw is properly aligned all four surfaces will make contact. If not properly aligned then your gauge will only contact 2 or three places. Do this will a blade installed and tensioned properly. If the saw needs alignment, then carefully examine the saw to determine what can be done to correct the alignment.

My Delta 14" saw I aligned that way after getting the height block installed. If the wheels are not parallel, and no mounting arrangement can correct it, then your saw either needs to be adjusted or modified to make them parallel. With my delta I would use very thin metal shim stock, for a welded up saw another approach will be required. For my delta, 1/2" is the maximum I attempt to run, in part due to the tension required, the other is the guide blocks are stretched to the limit for a larger blade.

[Chris Parks]

I would suggest taking a piece of aluminium 1x2x1/4" long enough to cover top and bottom wheels and then some. Then take some scrap aluminium or some very straight wood and make parallels to contact the wheel rims top and bottom, spacing out the vertical so it clears the saw structure, etc. Then place that "gauge" on the bandsaw being very careful to gently position it gently on the wheel rims. If the saw is properly aligned all four surfaces will make contact. If not properly aligned then your gauge will only contact 2 or three places. Do this will a blade installed and tensioned properly. If the saw needs alignment, then carefully examine the saw to determine what can be done to correct the alignment.

My Delta 14" saw I aligned that way after getting the height block installed. If the wheels are not parallel, and no mounting arrangement can correct it, then your saw either needs to be adjusted or modified to make them parallel. With my delta I would use very thin metal shim stock, for a welded up saw another approach will be required. For my delta, 1/2" is the maximum I attempt to run, in part due to the tension required, the other is the guide blocks are stretched to the limit for a larger blade.

As soon as the saw frame is subject to tension all that aligning is lost especially if the blade is the maximum the saw can use. Perhaps it would be better to tension the saw, check the alignment, release the tension and note the difference. After that any change needed to bring the tensioned saw into alignment can be made if needed. What you propose is like wheel aligning a car with no weight on the front wheels.

[Phil Thien]

Before the OP makes any gauges or makes any more adjustments, I'd sure like to see where those blades on running on the bottom wheel when centered on the top.

[John TenEyck]

As soon as the saw frame is subject to tension all that aligning is lost especially if the blade is the maximum the saw can use. Perhaps it would be better to tension the saw, check the alignment, release the tension and note the difference. After that any change needed to bring the tensioned saw into alignment can be made if needed. What you propose is like wheel aligning a car with no weight on the front wheels.

Not in my experience. If the wheels are aligned with no tension, they are aligned when tension is applied, at least with my saw. The only thing that changes is the upper wheel gets pulled to the right under tension as the frame deflects. That does not effect how the blade sits on the wheels, assuming the wheels were coplaner to start with, but it does effect how the blade runs in the upper and lower guides. If the wheels were not coplaner to start with then you may very well be right. That would tell me to go back and align the wheels properly to begin with.

To the OP, you've heard several ways to check wheel alignment - all involve getting a straight edge on the four wheel rim surfaces. A piece of plywood cut out where it needs to be to fit over wheel covers or frame is the simplest. You can have an answer in 30 minutes.

John

[glenn bradley]

Last Sunday, I stopped by Rockler Seattle and tested my blades on the floor model. The blades acted the same way on both saws. This kind of implies that it's the blades. OTOH, I have difficulty believing that BOTH of the 1/2" and 3/4" blades are defective.

Hard to believe or not, this sounds pretty conclusive. If the blades misbehave on another saw, it's not your saw.

[John TenEyck]

Hard to believe or not, this sounds pretty conclusive. If the blades misbehave on another saw, it's not your saw.

If that were true wouldn't they not lay flat on a bench, etc? Seems like such a simple check.

John

[Phil Thien]

Hard to believe or not, this sounds pretty conclusive. If the blades misbehave on another saw, it's not your saw.

While I agree with where you're going with this I'll go one step further: I'm not sure there is a problem with the saw, or the blades.

My experience is that people center a blade on the top wheel and expect it to be centered on the bottom, as well. But, it doesn't work like that.

I've participated in at least ten threads here and elsewhere about just this issue.

[Dan Clark]

Overall, this issue is resolved. At first, I adjusted lower wheel so that the 3/4" blade was centered on both wheels. That worked fine, but then the 1/2" and smaller blades were misaligned in the opposite direction. Worse, the 1/8" blade would not stay on the wheels at all.

Then I adjusted the lower wheel so that the 1/2" blade was centered on both wheels. This resulted on the 3/4" blade being misaligned but not too bad. And the 1/4 and 1/8" blade was misaligned somewhat in the opposite direction, but again, it wasn't too bad. And the 1/8" blade stayed on the wheels. Overall, it's a good balance.

There was one other issue with the upper wheel - the bearing was making noise. Laguna sent me a brand new wheel and now it's extremely quiet.

With the issues resolved, the 14-12 is an excellent saw, IMO. It's smooth, quiet, powerful, and has lots of good features - including the ability to resaw 13" out of the box.

Regards,

Dan.