Bandsaw blade tracking?

[Ben Fleis]

How centered do I need to be, and what's more important: the blade centering on the tire, or that the wheels are coplanar? As it stands, I can adjust the tilt of the top wheel and lose coplanar to get better centering.

Here's what I've got right now, w/ the wheels almost perfectly coplanar. Is this good enough, or should I be ordering shim washers, or doing something else?

-b

[Pete Bradley]

If you can get the band to run centered on both wheels, it really doesn't matter if the wheels are coplanar.

It might just be the photo, but it looks like your lower wheel is tilted under. This machine may have an adjuster for that. If in doubt though, see sentence #1.

Pete

[Frederick Rowe]

Ben- I'm with Pete. If your BS blade is tracking consistently and can be centered on the wheel tires, then don't go any further. By your photos, the blade is a bit past the crown of the tire. Make the adjustment on your upper wheel and if it holds steady once centered, stop. My experience has been that upper to lower wheel co-planer is an adjustment made when blade tracking isn't held or is inconsistent. That when referenced from the side of the wheel accessible from opening the doors, may not reflect the true co-planer referenced from the center of the tire. One wheel may be cast a small amount thicker than the other. Rely on the tracking of the blade under proper tension rather than a static measure of wheel to wheel co-planer from a straight edge laying across one side of the wheel.

[Dave Hale]

By looking at your pics, you either need to remove a shim from the top or add shims to the bottom. If you don't, when you use a larger blade (1/2" or larger), it won't be supported by the tire properly and the teeth might even be off of the bottom wheel. You want the blade tracking in the center of both tires, at least that's my understanding and that's how my Rikon is tracking.

(begin edit) After looking at your pics again, I think you're saying if you tilt the top wheel back, you'll get the blade tracking in the center. If that's true, ignore what I said except for the fact that a larger blade will need to be tracking to the back of the tires more. I also think it's better for a smaller blade to be tracking more towards the center of the tire considering the curvature of the tire (higher in the center), but others with way more experience than me might have other ideas. (end edit)

[Ben Fleis]

I should use the tilt adjustment on the top to center, and shim the bottom to center it. As far as I have ever seen, there is no way to adjust anything on the bottom wheel. I will give this a try tomorrow morning, and see what I get.

Thanks, gents.

-b

[Alan Schwabacher]

I would not worry about making the wheels parallel except to make it easier to track a large blade in the center. The force on the saw frame from tensioning the blades will affect wheel parallelism, so do any checks and corrections with your largest blade properly tensioned. Then just adjust the tracking control as you install each blade, without messing with reshimming the wheels. Small blades do fine riding on the crown of the tire, even if the wheels are not perfectly parallel.

I am talking about ordinary shop bandsaws in the 14" range.

[Pete Bradley]

I should use the tilt adjustment on the top to center, and shim the bottom to center it.

Shimming the bottom wheel may not do a lot to center it. The primary thing that drives the position of the band on the wheel is the crown. The band is always seeking the highest point on the tire. When you adjust the tracking knob, you're adjusting the angle of the wheel and therefore where the highest point is.

If it were me, I'd adjust the tracking so the band is centered at the top and be satisfied with that as long as the saw works well, as I expect it will. You'll need to check the table and guide bar adjustments of course.

This is a new machine, right? The most important thing is getting experience with it. That will give you a much better feel for what's really important.

Pete

Pre-emptive notice to potential posters: I know there are flat wheel band saws out there, this isn't one so please don't confuse the issue.

[Mark Singer]

Tracking is adjusted by shifting the blade on the tires. More forward and it steers "right" more inward and it steers "left" . For some reason this is not commonly known.. Try moving the blade by tilting the wheel. On the bigger saws with large blades, like my 1" TRIMASTER the tracking is not much of an issue since the blade is more rigid and is supported with more surface contact. My little 14" bandsaw tracks perfectly and has virtually no vibration with the Olson MVP which BTW is a terrific blade!

[Ben Fleis]

So I *did* shim the bottom and use the tilt on the top, and it rides the crown on both. Curiously, I used a plywood shim plus a real washer on the bottom. (The wood is not subject to any force -- it rotates w/ the axle.) And I resawed some 6" cedar planks last night, which went quite well after table top and fence alignments.

This is a new machine, right? The most important thing is getting experience with it. That will give you a much better feel for what's really important.

Actually, it's not. I just bought the riser kit for it, and after installing the kit, the tire came loose (literally started rubbing the sheet metal carcass) and the blade popped off. Previously, I had adjusted entirely by the tilt knob, but I never knew what was more important between coplanar and tilt. Since it was a new blade and new tires, I figured it was time to ask.

Shimming the bottom wheel may not do a lot to center it. The primary thing that drives the position of the band on the wheel is the crown. The band is always seeking the highest point on the tire. When you adjust the tracking knob, you're adjusting the angle of the wheel and therefore where the highest point is.

This is the part that confuses me. Why does the blade seek the crown? My intuition says that under tension, it should seek to wander off the blade, so I've never understood how it stays in the first place.

Thanks!

-b

[Pete Bradley]

My intuition says that under tension, it should seek to wander off the blade, so I've never understood how it stays in the first place.

Seems counterintuitive, doesn't it? You'd think you'd want a low spot in the middle, but it isn't so. My 6X48 belt sander uses the same principle, it's got a slight crown with a tracking adjustment that tilts the roller.

Pete