Question on bandsaw wheels / tires

I know about needing a crown, but is a crown necessary on all three or
two wheels of a bandsaw or just the wheel used for tracking? Reason
I ask is that my belt sander I bought has only one crowned wheel out
of three, the belt snader I made uses only one crowned wheel, but the
premade polyurethane tires you buy for bandsaws are all pre-crowned.
IIRC only the tracking adjustment wheel on the DoAll at work was
crowned, but then again it was pretty hard to really tell if the
others may or may not have been crowned as the tires on it were very
old and worn and made up of mostly rubber inner tube material and
electrical tape, but it seemed to track fine.
So, do I need to crown one, two or all three wheels? If only one or
two which ones require it. I was going to crown all three, but that
can change if there really is no need for it.
Thanks for any input.
Roy
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Reply to
Roy
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My wheels on my metal cutting band saw has no crown... It has a ledge on the back of the wheels instead. the wheel tilts back just a hair to keep the blade tight to the ledge... My wood band saw has crowns on both wheels...
Reply to
Kevin Beitz
Is this one of the 4x6 horizontal/vertical bandsaws? Those can get away with that because they are designed for only a single width of blade -- 1/2". Anything much wider is likely to slip off (as well as to attack the cover), and anything narrower will have its teeth (at least the set) damaged by the contact with the metal wheels.
The crown is needed on saws which can handle a wider range of sawblade widths -- and with a rubber tire they don't damage the set of the teeth.
As do serious metal-cutting bandsaws.
Enjoy, DoN.
Reply to
DoN. Nichols
My powermatic (vertical) has a hard polyurethane tire on the bottom wheel, and is supposed to have a crowned upper tire. However the upper tire is worn concave. Still tracks OK, I just have to keep the upper wheel tilted back enough that the back edge of the blade rolls on the rear guide wheels. Considering I routinely push with 50+ lbs force on the blade edge, it's not like dragging on the blade rolls is a problem.
As for tracking "free", without benefit of the blade guides, one crowned wheel should be sufficient, it may just be a more finicky adjustment than two crowned.
Bob
Reply to
Toolbert
Yes, this is so. So what's the question?
Stan
Reply to
Stan Schaefer
Kevin,
If your metal cutting saw is like many I've seen it may be due to the guides on the horizontal metal cutting saw forcing the blade to twist at an angle. With the guides forcing the blade to twist, maybe a crown is not enough and the wheels need the lip on the back to keep the blade tracking properly.
I've been working on designing a horizontal woodcutting bandmill and I've found that there are all kinds of tires, crowned and uncrowned, and solid steel wheels (no rubber tires). So, it seems almost like a Ford vs Chevy issue. The large industrial saws seem to use crowned solid steel wheels, many of the smaller bandmills just use v-belt sheaves with a belt slipped over them for bandwheels.
I've seen a few internet discussions and papers on bandwheel crowns and I guess the physics of it can be pretty interesting.
Bob
Reply to
Bob Thomasson

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