Bandsaw belt tension/slippage

[Gord MacKenzie]

Hi folks,

I just purchased a used King Industrial 14" bandsaw. It was badly out of tune, so I checked and reset everything according to the manual and put on a new Tufftooth 3/4" resaw balde (3 TPI). I tested the saw with a piece of 8" maple 16 inches long. It will resaw this in about a minute. However, I noticed that the saw would just stop now and then for no apparent reason. Feed rate was steady, no anonalies in the wood, etc. I had already checked the tension on the drive belt and it was very loose so I tightened it as best I could. However, even after resawing for a minute, the drive pulleys are very warm to the touch and I think I smell the belt burning.

My question is, what method do you use to determine the correct belt tension? I've always heard that with moderate force applied to the side of the belt it shouldn't deflect more than 3/4".

http://www.kingcanada.com/Products.htm?CD=104&ID=19917

[Maurice Ungaro]

Hi Gord, welcome to the Creek!
You may want to replace the belt with a link belt. Those things won't slip for anything. They cost about $6 to $8 per foot, and are well worth it. Grizzly has a good price on them if my memory is correct.

[Josiah Bartlett]

Hi Gord, welcome to the Creek!
You may want to replace the belt with a link belt. Those things won't slip for anything. They cost about $6 to $8 per foot, and are well worth it. Grizzly has a good price on them if my memory is correct.

I'm going to disagree with that, I've found that they don't handle multiple HP as well as a nice AX profile belt, and when they do slip they wear out in a hurry. They require less tension to grip but the total amount of power a link belt can transmit is a lot less than a standard belt. There is much less surface area on the pulley in a link belt than a V belt. V belts grip from the sides.

I ran an 8 HP shredder on a link belt briefly. The link belt wore out in about 15 minutes. The good quality belts lasted several hours.

To the original poster, try replacing the belt. When Vbelts wear out they glaze and no longer grip well at all. Also, the belt that is on there may be the wrong profile. You need a power transmission belt, not an automotive belt Its probably 3L or A profile.

[glenn bradley]

I too have heard of folks frying linkbelts on high HP machines. My 3HP single belt machines work great with them as do my 1/2-horse machines and any in between. When I swapped out the belt on my 2HP bandsaw it got so quiet I thought something was wrong; it wasn't.

All that being said; I think a 3/4" blade on a 14" saw is a bit much unless you're running some decent power. If you have a 1/2" or so blade I would run a comparison with that. If you get no stall, you may want to run smaller blades. You could also stone the back edge of your 3/4" blade and try some sort of lube. I don't like to deal with the lube residue but some folks swear by it.

[Tom Veatch]

...My question is, what method do you use to determine the correct belt tension? I've always heard that with moderate force applied to the side of the belt it shouldn't deflect more than 3/4"...

In my opinion, 3/4" is too loose. I shoot for about 1/2" max. There's surely arguments both ways, but, again just my opinion, the motor should come pretty close to stalling before a belt in good condition slips.

As far as belt profile, check your op. manual/parts list. It may recommend/specify a belt size and profile. Also check and verify the pulleys are the right size and properly aligned.

[mickey cassiba]

The standard for tensioning a v-belt is 1/64" deflection per inch of free span(according to Dayton, anyway).
I use this rule of thumb on all of the machines I maintain, and regularly (every 40 hours of run time) check and re-tension as needed.
I have gotten great run time out of all of our belt drive machinery like this.
A little belt dressing helps with the long span belts as well.
Mickey

[Maurice Ungaro]

I ran an 8 HP shredder on a link belt briefly. The link belt wore out in about 15 minutes.

......That's kinda like a Great Dane humpin' a Dachsund - the result is not gonna be pretty. With all due respect, I think you used the link belt in a fashion it was probably not intended for. The OP has a 14" bandsaw. More than likely it has a 1 or 1.5 hp motor, he did not state. My personal experience has shown that a link belt on a 1.5 hp motor provided more direct power transfer, and kept the saw from bogging down more than with a normal belt.

I do agree with Glenn that a 3/4" blade on a 14" BS is more than likely going to cause performance problems too.

[Lee Schierer]

The standard for tensioning a v-belt is 1/64" deflection per inch of free span(according to Dayton, anyway).
I use this rule of thumb on all of the machines I maintain, and regularly (every 40 hours of run time) check and re-tension as needed.
I have gotten great run time out of all of our belt drive machinery like this.
A little belt dressing helps with the long span belts as well.
Mickey

That's what I've heard too. The motor should really stall before the belt slips. If the pullies are getting hot it is a sign the belt is slipping. The hot belt smell is a dead give away. It may also be a case where the belt is not the right type for the pullies. A 3/4" deflection would have the pullies about 48" apart.

I thought my bandsaw was underpowered until I got the belt tensioned properly. It will walk through 6" of cherry without stalling the saw or burning the wood.

[Gord MacKenzie]

Thanks for all the helpful replies folks. I did some more searching on the site and found the plans for a sled type jig that attaches to the motor and motor mount bracket in the base of the saw. It allowed me to both correctly tension the belt and align the pulleys. No more heat buildup or belt burning. I love this site!

BTW, my saw is a 1 HP and I can now resaw 10" thick maple with ease as long as I feed it slow and steady. Looks like about 1.5 ft/min feed rate works like a charm.

[Josiah Bartlett]

......That's kinda like a Great Dane humpin' a Dachsund - the result is not gonna be pretty. With all due respect, I think you used the link belt in a fashion it was probably not intended for. The OP has a 14" bandsaw. More than likely it has a 1 or 1.5 hp motor, he did not state. My personal experience has shown that a link belt on a 1.5 hp motor provided more direct power transfer, and kept the saw from bogging down more than with a normal belt.

I do agree with Glenn that a 3/4" blade on a 14" BS is more than likely going to cause performance problems too.

Of course it is, I had an extra link belt laying around and the hardware store was closed. My point was that link belts aren't always the best tool for the job.