Tips for truing bandsaw appreciated - Woodworking Talk

Streamwinner · 07-19-2009, 04:18 AM

I need to true (balance) the upper wheel of my bandsaw and would appreciate any advice. Seems like there's an addition method (clamping or taping weights) and a subtraction method (drilling into the wheel spokes). I've already checked the tire and it's on evenly.

firefighteremt153 · 07-19-2009, 07:23 AM

im interested in this topic as well

GeorgeC · 07-19-2009, 07:23 AM

How do you know that wheel is not balanced? Is it a new saw or used?

What method do you intend to use to balance?

I would use taped weights for a static balance to get everything at the correct point. I would not leave these weights on when the wheel is running. Probably drilling is best for the running wheel if you can drill in a Position(s) that will not weaken anything.

George

woodnthings · 07-19-2009, 07:36 AM

There is "trueing" and then there is "balancing", they are different. If the outside dia of your wheel is not concentric to it's axle or hub, it needs to be machined. If the saw vibrates when running at speed, it may be the wheels or the tires, or the wheel is out of "balance".
If you remove the blade and mark the wheel with a piece of tape when it's at rest at the 6 o'clock position and spin it by hand, if it always returns to that position then it propably needs weight removed from that area, or weight added to the 12 o'clock position. I'd be leary about drilling into my bandsaw wheels, even the cheapest one I own, myself. If this is a newer saw, the manufacturer will be able to correct this, but would require the wheel be removed and shipped. If not, a good machine shop could do the job when a phone inquiry was made describing the issue. That's my advice.

bill

Julian the woodnut · 07-19-2009, 11:35 AM

Its no big deal to balance the wheel yourself. When drilling into the web of the wheel, just make sure NOT to drill all the way through. That is what weakens the wheel.

woodnthings · 07-19-2009, 08:20 PM

Using the built in bearings on the wheel shaft you can't get an accurate balance, since it's static, not dynamic. If the wheel is so far off it keeps rolling into the same position time after time, yes, then it's off at least a "ton". The ball bearings have internal friction due to grease, preloads, and rolling friction, so they are not "accurate" for a DYI balance unless...above. I'd be very suprised if the upper wheel is that far off. BTW what inspired you to seek this advice?
Does the thing vibrate like a washing machine on spin cycle? What is the issue your are working to solve? Can you visually see the wheel is not concentric to it's hub when spun on the shaft? Before I'd go drilling holes, I'd need more info.

bill
To static balance the wheel it would have to be mounted securely on a trued shaft, then placed on parallel knife edges to determine if it rolls one way or the other. A machine shop can make this set-up accurately, not a DYI project.

Streamwinner · 07-20-2009, 01:27 AM

Thanks everyone. Sorry for conflating terms, but I'm pretty sure the issue is a wheel out of balance (we use the term "truing the wheel" in cycling to refer to removing the wobble in the rim by tightening the spokes). Anyways, the issue came about as I've become increasingly annoyed by a slight wobble in the blade which, at times, prevents me from getting a straight cut (I don't have a table saw so I rely on the bandsaw for crosscutting). Even when I'm tuning the saw, I notice that the blade will wander from side to side so that getting the guide blocks properly spaced is difficult (I have replaced them with cool blocks). I noticed the problem when I replaced the tires a few months ago and spent quite a while running my screwdriver around the wheel to get the rubber even. The machine does wobble when on, and mostly from the top of the machine and not so much to cause me any concern.

I won't have time to take it apart and properly assess the situation until later this week. I'm not so sure the bandsaw is worth the hassle, since it's just a 12" Craftsman from 1978 that I bought on Craigslist for $25 (replacement wheels are no longer manufactured). I'd really like to just buy a nice, high quality (and high powered) bandsaw, but unfortunately it's not in the budget.

I will report back with a better description of the problem. My next step will be to clamp a steel rule to the frame to make sure the wheel is true. Then I'll spin check for balance as advised.

woodnthings · 07-20-2009, 04:43 AM

The replacement tires are not concentric to the original wheels. BTW I had the same saw years ago, aluminum housing/frame spring tension blade tightening if I recall. You're going to need to sand or grind the rubber? tires to be concentric and true to the wheel. You'd need to make a jig to hold a drill motor with a drum sander next to the wheel and rotate the wheel by hand or ...this sounds a little dangerous.... turn the blade teeth facing rearward and let the machine spin the blade while you hold the drum sander in a fixed location from the edge of the wheel. I would do it, I don't know if you would/should/could? Short of that a rough grit sanding block held to the wheel would probably accomplish the same thing, removing the out of round condition in the tire.
I don't recommend your screwdriver approach, too dangerous if something goes Murphy

on you.

A flying screwdriver would leave a nasty hole in something!
BTW, I used to lace my own bicycle wheels, worked at a AYH hostel bike shop in Chicago. selling and maintaining rental bikes in the '60's. Rudge was a popular name, from England, maybe. Campangolo deraillers, and hubs. Cool stuff for back then.

Streamwinner · 07-20-2009, 11:31 AM

I have the drum sander attachments for my drill, what grit would you recommend for sanding the tire?

Interesting to hear about your bike repair work. Sounds like you've had a few lifetimes.

Thanks again.

woodnthings · 07-20-2009, 11:21 PM

I don't know your skill level at this, so instead I would suggest a block wrapped in 36 grit abrasive. The block must be wedged or secured below the wheel at a 6 o'clock position and then gradually lifted up agaist the wheel pivoting on the fulcrum on the rear of the saw to maintain control. The blade must be reversed, teeth to the rear, for safety.... keeping in mind this is a relatively dangerous process, and I would only do it if I were comfortable with the set-up. If not, have someone spin the blade by hand, while you hold the block controlling the pressure against the tire. It would best to both spin the wheel and use a drum sander at the same time but that requires a secure set-up for the drill and drum sander. You might not be up to doing this, I don't know. But Safety First, Safety Last!
A whole 'nother approach is to redo the tire application and get it more uniform the second tiome around. That would be the safest approach, for sure.

bill

Clouseau · 07-21-2009, 11:07 AM

This is a much safer operation when done on a disc or belt sander. Go to the OWWM.org and OWWM.com web sites and search. A simple plywood fixture on the sander will allow you to safely and accurately crown your tires provided they are rubber. You could also make a similar fixture for the drill press. A friend of mine mounts them in his lathe a uses a sander/grinder. All of these meathods are safer and provide excellent results.

TS3660 · 07-22-2009, 02:00 PM

If you have an old blade, maybe you can grind the teeth of of it so the process is safer.