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Bandsaw belt jumps

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Forum topic by flwoodie posted 05-22-2013 08:11 AM 1147 views 1 time favorited 31 replies Add to Favorites Watch
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flwoodie

26 posts in 584 days


05-22-2013 08:11 AM

Topic tags/keywords: bandsaw band saw belt pulley craftsman belt jump belt walk

I recently bought an older Craftsman 12” bandsaw, and it worked great until I was cutting some hard maple and the belt jumped. I loosened the tension of the blade and reinstalled the belt. With no tension of the blade, the belt stays put. As soon as I put tension back on the blade, the belt walks off. The belt seems to be in good shape. The lower wheel pulley doesn’t have any play. The motor shaft doesn’t seem to have any play either. All the bolts seem to be tight on the motor. And the cradle that holds the wheel pulley and the motor moves as a single unit, so I wouldn’t imagine there were any alignment issues.
Any ideas?


31 replies so far

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JoeinGa

3699 posts in 760 days


#1 posted 05-22-2013 12:55 PM

”so I wouldn’t imagine there were any alignment issues.”

Did you check the alignment with a straight-edge JUST TO BE CERTAIN there isn’t any issues with that?

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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flwoodie

26 posts in 584 days


#2 posted 05-22-2013 01:53 PM

Well, last night I got down and checked the alignment of the 2 pulleys, they seem to be way off. So i loosened the set screw on the shaft and moved the pulley closer to alignment. I put the belt back on, turned the saw on and it worked. Problem was, as soon as the saw bogged a little, the belt jumped again. So, I put the belt back on, but as soon as i turned the wheel, it started to jump off just as it had done originally. So, I readjusted the pulley again, bringing it further into alignment, and same scenario. Worked fine, put a board on, bogged down, jumped.
My concerns are:
a) the pulleys still do not seem to be really aligned.
b) i can see the set screw marks on the shaft of the motor from the past, and they are closer to the motor, rather than farther away. (farther away being closer to pulley alignment)
c) i don’t know how much more shaft I have left to work with being that this setup is underneath and difficult to get to and adjust.

I’ll post pictures to help show in a little.

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JoeinGa

3699 posts in 760 days


#3 posted 05-22-2013 06:04 PM

OK. Brainstorming here.

What size motor (hp) has that thing got?
When it starts bog down, the blade is (in essence) stopping but the motor wants to keep turning (and driving that belt along with it).
The belt might be “grabbing” the blade pulley and as the blade pulley slows down the moving belt jumps off of the pulley from the torque of the motor.
Does the saw have any small flat brackets designed very close to the pulley that are supposed to trap the belt and keep the belt on the pulley?
If so, these brackets my be adjusted too far away from the pulley to keep the belt in.
If it doesn’t have these brackets, look for signs that they may have been removed, or broken off.

Without looking at it, I’m trying to picture anything else that might be checked.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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JoeinGa

3699 posts in 760 days


#4 posted 05-22-2013 06:04 PM

Oh, by the way… WELCOME to Lumberjocks! :-)

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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SCOTSMAN

5594 posts in 2338 days


#5 posted 05-22-2013 06:45 PM

Blade is maybe a tad too big me thinks so anyway check it with another blade smaller by an inch or thereabouts. Alistair

-- excuse my typing as I have a form of parkinsons disease

View woodenwarrior's profile

woodenwarrior

131 posts in 948 days


#6 posted 05-22-2013 06:52 PM

This sounds very similar to a problem I had with my 14” bandsaw when I modified it to take a 2HP motor as opposed the stock 3/4 HP it came with. What type of drive pulleys are turning your wheels, v-groove or serpentine style? For the v-groove style you could take a look at link style belts (I’m not a fan but I’ve heard others rave about them) for the serpentine style make sure the belt is tight on the pulley and not slipping when force is applied through cutting wood. Another thing to help with slipping belts, if that is the problem is to run some sand paper around the pulley to slightly roughen up the surface a bit to give the belt a bit of “grab”.

-- Do or do not...there is no try - Master Yoda

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flwoodie

26 posts in 584 days


#7 posted 05-22-2013 06:52 PM

Thanks =]

It is a Craftsman model 113.248210. It says 1 HP max.
I don’t see any evidence of missing brackets.
You can can in the photos the alignment, and also the distance I have moved the pulley outward by the clean metal on the shaft.
Here are some photos…

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woodenwarrior

131 posts in 948 days


#8 posted 05-22-2013 06:56 PM

Do you have the ability to pull that main pulley out some? By your photos it looks like your drive pulley is just hanging on.

-- Do or do not...there is no try - Master Yoda

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flwoodie

26 posts in 584 days


#9 posted 05-22-2013 07:00 PM

The belt seems pretty tight, it takes a bit of effort to roll the belt back on after slipping. I have used 2 different blades, nothing crazy. And used a 4 tpi and a 6 tpi, both being 1/2”

View Surfside's profile

Surfside

3372 posts in 926 days


#10 posted 05-22-2013 07:04 PM

Some one had that problem before, you have to check the idler and motor pulley alignment.

-- "someone has to be wounded for others to be saved, someone has to sacrifice for others to feel happiness, someone has to die so others could live"

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woodenwarrior

131 posts in 948 days


#11 posted 05-22-2013 07:07 PM

Other than the pulleys being misalligned, do you notice any back and forth play in the wheel when it’s turning? I wonder if the wheel bearings are worn and allowing the wheel to tilt slightly throwing that belt off.

-- Do or do not...there is no try - Master Yoda

View Straightbowed's profile

Straightbowed

717 posts in 1051 days


#12 posted 05-22-2013 07:12 PM

your belt pulleys are nowhere near close to coplaner, this will not work period, the pulley on the bottom drive of the bandsaw is way out of line that needs to be inline with your motor pulley, do not move the motor pulley no more set the pulley on the bandsaw out far as possible then maybe you can move your motor pulley back, then maybe it will align

-- Stevo, work in tha city woodshop in the country

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Dallas

3212 posts in 1240 days


#13 posted 05-22-2013 07:13 PM

Move the driven pulley out and the motor pulley closer to the motor.

I have the same saw, had the same problem plus my driven pulley was egged out.

Make sure the keyways are good and tight and the key is correct, not cut down.

Good luck.

-- Improvise.... Adapt...... Overcome!

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Straightbowed

717 posts in 1051 days


#14 posted 05-22-2013 07:14 PM

your pulley on the bottom wheel can go out a mile move it out and it should align with the motor pulley easy

-- Stevo, work in tha city woodshop in the country

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flwoodie

26 posts in 584 days


#15 posted 05-22-2013 07:17 PM

No, I’ve tugged on the wheel, pulley, motor shaft, everything seems to be snug.

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