Help with Bandsaw stalling out

[Phillip Mitchell]

Single phase motor

[Derek Cohen]

My money is on one or both of the following:

1. The belt from the motor is not tight enough. This will cause loss of power.

2. The guides are adjusted too tightly, and friction is limiting power.

or both.

Incidentally, my 1" CT plade is 1.3 tpi, and is driven by 4 hp. Increasing the tpi and into hardwood will require more than 2 hp. Keep the tpi count low for 1" resaw blades.

Regards from Perth

Derek

[Larry Copas]

Early Delta 20" saws had 1 horsepower motors and could resaw 12"....slowly.

3 tpi bands resaw freely. 6 tpi bands resaw smoother but take more power, dependent on species, sometimes too much power. Bands that have no set due to factory screw ups will stall the motor and make a burning smell. Have you checked to make sure the band has set?

[David Utterback]

Lots of good ideas here. I had a similar problem with an older Laguna LT18 and thoroughly checked the electronics. There was an extra, unattached screw in the switch box. When reassembled, it performed much better.

You may want to open up your electronics and check the wiring connections and remove any accumulated saw dust. In addition, changing the belt and getting appropriate tension may be the solution.

[John K Jordan]

I don't have a tension gauge, but am familiar with how to tension a blade. There is between 1/8-1/4" deflection on the blade with sideways pressure and the guides set at around 6" off the table. The 1" blade currently installed is 2 TPI. I have a new 3/4" 3 TPI blade as well, so I will install that and give it a try to see if the 2 TPI blade is the problem.

... Keep it coming!

Phillip, I'm going to speculate that the tension is not enough on your blade, based on this: I use a Starrett bandsaw blade tension gauge to check my blades and "calibrate" the indicator for the blades I commonly use. I have a 1/2" blade on the 18" Rikon and I checked the blade deflection just now with the upper guide about 6" from the table. I don't have a calibrated finger to push the blade but with moderate pressure my 1/2" blade deflected only about 1/16". If you are seeing 1/4" deflection with a 1" blade I wonder if your blade is not tensioned enough.

Before I got the tension gauge I tensioned by several methods, including flutter, deflection, pitch, and gut feeling. With the gauge I was quite surprised at how much I had to increase the tension to get to the manufacturer's specs. I found, for example, that my smaller Delta 14" saw could not possibly tension a 3/4" blade correctly even though the saw was advertised as supporting it. I had a terrible time with blades deflecting (bowing) in thick wood. This put a lot of stress on the blade and I had to cut very slowly to cut at all. All these things were solved when I dropped to a 1/2" blade and tensioned and tensioned it with the gauge.

I know now the 1/2" blade I use on the larger Rikon needs the saw's tension indicating needle pointing to well over the 3/4"" mark in order to tension properly. Since that blade only deflects about 1/16" I wonder if a 1" blade that deflects from 1/8" to 1/4" needs significantly more tension.

Do you know about the digital caliper method to make a free precision blade tension gauge? I haven't used this method myself but others have.
http://www.sawmillcreek.org/showthre...33#post2640833
bandsaw_tensioning_TenEyck.jpg

It may not be the direct cause of your stalling problem but it might be worth a few minutes to check your existing tension. Just a thought.

JKJ

[Phillip Mitchell]

Ok, at the shop now doing some troubleshooting. Thanks for all the replies!

I opened up the lower door and watched as the blade stalled. The blade and wheels slow down to a stop and the motor pulley still spins at its regular speed. To me this indicates the belt as the issue.

I had the chance to go by a local auto parts store earlier today with the belt in hand to try and get a replacement, but they didn’t have anything skinny enough in that length. I’ll try another store tomorrow.

Upon inspecting around this area, I’m not seeing a way to adjust the tension of the belt/pulley. I’m inexperienced in this arena, so maybe I’m just missing it?

I’m attaching some photos for reference in hopes that someone can point me in the right direction.

The markings on the belt don’t make any sense to me in terms of a specific size or helping to point out a proper replacement, but maybe the guys at NAPA can help me a bit more than the other auto parts store who shall not
be named at this time, but was open on a Sunday.

John, I actually cranked up the tension upon re-installing the 1” blade this time and it’s about 1/16” deflection with moderate pressure.

Edit: I inspected the motor wiring, as well as the switch wiring and it all looks proper to me.

[John K Jordan]

Upon inspecting around this area, I’m not seeing a way to adjust the tension of the belt/pulley. I’m inexperienced in this arena, so maybe I’m just missing it?

Often belt tension is adjusted by shifting the motor itself on the mount. That might be the reason for the oversized hole for the motor shaft.

Some have an adjuster bolt on the motor plate and some you just have to loosen the bolts and slide the motor a bit.

Remember if anything else is in the saw is adding friction the belt may already be tight enough. If the contact surfaces of the belt are slick from wear or burnishing the pulley may slip. If so you might roughen it a bit with sandpaper or maybe try some of the liquid belt dressing some people use on their cars. I've never used that on any belt.

JKJ

[Phillip Mitchell]

Here’s a couple pics of the motor / mount.

Looks like that tall bolt on the front left in first pic is coming through a slotted hole in the mount inself. I imagine this would allow some movement for the mount to slide, but it’s not too much room to move from where it’s bolted currently or there will be clearance issues in other places of the mount.

[lee cox]

I wonder if it could be a bearing on the big wheel getting tight as it gets hot?

[John K Jordan]

Here’s a couple pics of the motor / mount.Looks like that tall bolt on the front left in first pic is coming through a slotted hole in the mount inself. I imagine this would allow some movement for the mount to slide, but it’s not too much room to move from where it’s bolted currently or there will be clearance issues in other places of the mount.

Since the motor was replaced in the past you may need to make some modifications to adjust the belt tension, perhaps extending slots or cutting/replacing bolts. Or if the belt is in fact too loose it may simply be the belt is a smidgen too long or too narrow, which would do the same thing (by allowing the belt to drop too far in the pulley groove). Maybe it's the wrong belt for those pulleys. I don't have any idea of the specs for pulleys and belts from that place and time.

Belts can stretch and get too long, especially if the tension was too high at one point. Or maybe the belt tension is OK. You certainly don't want to get it too tight.

There are lots of resources to help check and get the right tension. This one looks reasonable or google how to check the tension on a v belt. Be careful about following advice from random youtube videos. Note what this says about the value of testing without a drive belt tension gauge. Perhaps you could borrow or rent one.

https://www.bestorq.com/library/techinfo/whytension.pdf

It's hard to know what to do without looking at it. I don't get to Boone too often but maybe someone else reading lives closer, perhaps someone with mechanical experience and a bandsaw blade tension gauge too.

[David L Morse]

Here’s a couple pics of the motor / mount.

Looks like that tall bolt on the front left in first pic is coming through a slotted hole in the mount inself. I imagine this would allow some movement for the mount to slide, but it’s not too much room to move from where it’s bolted currently or there will be clearance issues in other places of the mount.

I think that tall bolt is the tension adjuster. The mounting plate probably pivots on the back side. The nut on the underside applies upward force to the front end of the plate, raising the motor and tightening the belt.

You can easily verify if belt tension is the problem by levering the mounting plate up with a crowbar and putting a temporary shim under the bolt head.

If that fixes it you might want to replace the bolt.

[Lee Schierer]

Here’s a couple pics of the motor / mount.

Looks like that tall bolt on the front left in first pic is coming through a slotted hole in the mount inself. I imagine this would allow some movement for the mount to slide, but it’s not too much room to move from where it’s bolted currently or there will be clearance issues in other places of the mount.

I can't tell from the photos for sure, but it looks like the long rusty bolt in the first photo is your belt tension adjustment. If the other end of that mount plate is hinged, all you need to do is loosen the top nut on that rusty bolt and then jack the plate up with the nut that is underneath the plate.

[Rod Sheridan]

The markings on the belt don’t make any sense to me in terms of a specific size or helping to point out a proper replacement, but maybe the guys at NAPA can help me a bit



.

Hi Phillip, your belt size is a 3V475. It's a 3/8" wide belt, 47.5" long.

Any industrial supplier will be able to source that............Regards, Rod.

[Phillip Mitchell]

I replaced the belt with a new one and all seems well so far. The wheels/blade came up to speed initially much quicker than with the old belt and I got no slipping or bogging even when I re-sawed some Doug Fir 12” tall at a fairly quick feed rate.

Thanks for all the replies, hopefully it was just a old, worn, stretched out belt. The new belt tension is definitely tighter, but it wasn’t difficult to get on the pulleys.

[Jon Fletcher]

If you didn't have to loosen the motor to get the belt off and on then it's way to loose. I'm wondering if a 1/2" belt wouldn't be better. Also from your second pick it looks like the motor bracket is in a groove which tells me it slides. Hard to tell without looking at it.