Help with Bandsaw stalling out

[Phillip Mitchell]

I just bought a used, mid 80s era, 20" Italian bandsaw made by Steton (not very well known in US, but quality industrial machines similar to SCMI)

I'm able to stop the blade way too easily during a light to moderate re-saw cut. 5 1/2" tall Doug Fir and Western Red Cedar (dry) is what I was sawing....shouldn't be giving me these issues with this species and size. Even with a very slow feed rate, the saw blade will still bog way down and stop completely. I stop feeding stock and it will catch back up to regular speed in about 5 seconds.

I am smelling a faint burning rubber smell. I didn't think to note if the actual motor was slowing down with the problem or just the blade. Will have to try again to confirm. From my memory, it seems like the motor is still running while the blade bogs and stops.

The drive belt looks old (original ?) I don't really know exactly how much tension should be on the belt, but my gut tells me that it's too loose. More deflection than the Laguna LT18 sitting in the next room, when I check it's tension by feel.

Brand new 1" blade. 2 hp, 220V motor. Before I bought the saw, I had a feeling I may find the motor a bit underpowered during heavy re-sawing, but this isn't even approaching heavy re-sawing... The previous owner told me he replaced the rubber tires somewhat recently.

So, what would be my first course of troubleshooting action?

Tighten the belt? How tight? Replace the belt? How do I properly size and find the correct replacement? There is practically no dealer support for this brand and age of saw. I actually have the original manuals for the saw but they are in French and Italian.

Thanks for any help and advice?

[Jon Fletcher]

I would check blade tension first. If blade tension is ok then check the belt. From what you describe the way the motor takes 5sec to catch up it my be wired wrong or a bad motor. If the belt is slipping and getting burnt you'll see material on the pully where the belt rides in the groove. As for tension I believe just the weight of the motor should be enough. I can't imagine 2HP not being enough but then again, I dont do much resawing.

[Rod Sheridan]

As Jon indicated check belt condition for glazing or burned sections. Honestly I would replace the belt if it's old. Take it to a power transmission dealer and they'll measure it for you, and provide the correct bely

Check that the pulley is tight on the motor shaft, clean both pulleys

Verify that the motor is the correct voltage, and that you have the correct voltage by measurement.

Regards, Rod.

[Nick Lazz]

If the tires are good and you have decent tension on the blade I would look at the motor. I had a situation with my Laguna saw years ago from the factory where claimed HP was an absolute joke. They called it 'Saw Duty'. After calculating the actual HP they were off by nearly 1 HP. I got them to replace the motor.
Granted, my saw is smaller than yours but I have a 2hp motor on my Laguna 14SE saw and I can't run 1" blades. Tension may have been a bigger problem for me but power was as well with the original motor...seems 20" should have no problem tensioning that blade.
P = V(volts) x I(current) x Eff (efficiency) x PF (power factor)

[Grant Aldridge]

just to cover all the bases on machine setup, you do have thrust bearings adjusted properly right? I could imagine rearward deflection causing this.
As has been said make sure you have blade tension set correctly, also you said it's a new 1" blade but is it a resaw blade? A finer toothed blade could also cause this.
Last, have a look at the motor and cord wiring, something could be out of whack there!

[John TenEyck]

Another possibility could be that the run capacitor on the motor needs to be replaced. That happened on my J/P.

John

[Jack Frederick]

How about dirty/burned tires on the wheels. If there is burning or accumulated debris the blade can slip on the tires.

[John C Cox]

My 14" saw has a 1 1/2 hp motor from the factory.

I doubt a 20" resaw comes equipped with a 2 hp.... I would expect at least 5 hp.

First thing.. Find the saw's name plate. It should list the specs for the motor... Probably in KW... Convert to HP and go from there.

Next thing though. Check to make sure the motor is wired correctly. It should have a wiring diagram inside the motor cover for the various voltage configurations. Make sure you are giving it what it's supposed to be wired for.... For example - it could be that it's only running on 1 leg of the 220... It will kinda run - but it will destroy the motor in the process.... Or it could be wired internally for 3 phase 208 and you are trying to run it on 2 phase 220...

[John K Jordan]

Besides the obvious electrical issues to check... How many teeth per inch on the blade? Too few and the gullets can't clear the sawdust fast enough and the blade may quit cutting or get jammed up, depending on the wood.

Is the blade tensioned enough? Too little tension can cause major problems. I use a 1/2" 3 TPI blade an check the tension with a gauge. The factory tension marks are not useful.

For a new belt you can measure or take the old belt with you. If the old belt has numbers printed on it they may be able to cross-reference. The local NAPA stocks standard belts to fit almost anything. A link belt can be adjusted for length by removing links.

[Phillip Mitchell]

OK, thanks for all the responses. Let me try and respond to some of these.

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.

I have the original manuals for this saw, which states that the motor is 1.5 KW (2 HP according to a conversion from Google.) The original motor was replaced with an 2 HP Century motor (American made) at some point in its life. Nowadays, a 20" saw wouldn't be sold with a 2 HP motor, but back in '86 I don't think that was too uncommon as motors tended to be smaller in general than they are with today's new bandsaws.

I tested the saw and made a handful of cuts before I bought the saw and didn't have any issues. There was a 1/2" blade installed when I tested it initially, and re-sawed a 6-7" tall piece of white pine with no issues. Granted, white pine is about the easiest wood to saw, but Doug Fir and WRC shouldn't be difficult. Maybe there's something to the 1" blade, not having enough TPI? The saw was plugged into regular 220V receptacle at the sellers shop.

Could running the saw without dust collection (just for quick test cut) cause enough sawdust to fall down and settle on to the rubber tires of the lower wheel, get between the blade and tire and cause this sort of slipping?

I'm still getting used to these Euro style guides, but to the best of my knowledge, I'm setting up the guides properly. For setup, I'm running the thrust bearing up against the back of the blade, then backing off of it the thickness of a folded dollar bill and locking it down in that position.

I can't speak directly to the other replies, as I haven't had the chance to get back and test the saw out. Will update as I'm able.

Thanks again for all the advice. Keep it coming!

[Brian Henderson]

You need to figure out where the problem lies, is the blade slipping on the wheels, is the motor slipping or bogging? It could be as simple as blade tension or bad tires or as serious as an underpowered motor. You might want to run the saw with the door open just to see what's turning and what's not.

[Jeff Duncan]

1st thing I'd check is the blade, even if new could be defective! Belts aren't that tough, something in the neighborhood of 1/2" of deflection for something that size under moderate pressure should be fine. Is the 220v single or 3 phase?

2hp for a 20" is not really under powered, we just think it is in here in the States. My 20" saw is 2hp and is only about 20 years old.... as long as the blade is sharp I have no problems cutting up to 12".... the key being good sharp blade. HSS blades don't last all that long if your cutting hardwoods, the softwood you mention should likely last quite a bit longer, but still not uncommon for folks to keep pushing long past blade change time.... guilty if this myself from time to time:rolleyes:

good luck,
JeffD

[Grant Aldridge]

Since it worked at the sellers shop you really need to check voltage at the motor. The cord could be wired differently than your receptacle

[Lee Schierer]

I am smelling a faint burning rubber smell. I didn't think to note if the actual motor was slowing down with the problem or just the blade. Will have to try again to confirm. From my memory, it seems like the motor is still running while the blade bogs and stops.

Tighten the belt? How tight? Replace the belt? How do I properly size and find the correct replacement? There is practically no dealer support for this brand and age of saw. I actually have the original manuals for the saw but they are in French and Italian.

Thanks for any help and advice?

When I first started using my 14" band saw thought it was under powered as I could do the same thing. I had read a lot about 14" Delta saws being under powered. When I finally watched what the motor was doing when the saw stalled, I found the motor was still running at full speed and the problem was the belt tension. When I tensioned the belt, the saw was an entirely different machine. It walked through the same cuts that had bogged it down with out even breaking a sweat.

Tighten your belts and you should be good to go. If the existing belt is old it would be a good idea to start looking for a replacement before you really need one.

[Mike Henderson]

Is it a single phase motor or a three phase motor? If it's a three phase motor you would have something to convert from single phase to three phase - unless you have three phase power in your shop.

If it's a single phase 240V motor and that's what you have going into it, I'd next ask if the motor is slowing down or if it's still running normally while the blade is stopped.

If the motor is running, first thing I'd check is the belt driving the lower wheel (from the motor to the wheel). If that's slipping, replace the belt and clean the pulleys.

If the motor is stopping, I'd start checking whether the motor is wired for the voltage you're putting into it. If it's wired correctly, check the run cap (if you have one).

2HP should be enough for that saw.

Mike

[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/showthread.php?250388-Bandsaw-blade-tension&p=2640833#post2640833
380500

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.

[Jon Fletcher]

What's the width of the pully on the outside diameter?

[Phillip Mitchell]

Don’t know the outside diameter right now, but I will measure tomorrow and report back. I didn’t have to loosen the motor from the mount to remove the old belt or put the new one on, but I did have to carefully feed the belt onto the groove in the bottom wheel, while slowly rotating and carefully used a blunt flat head screwdriver as a pry bar to get the belt into the groove. Had I known about that tension adjuster bolt on the motor mount, I would have likely gone that approach instead.

[John K Jordan]

Don’t know the outside diameter right now, but I will measure tomorrow and report back. I didn’t have to loosen the motor from the mount to remove the old belt or put the new one on, but I did have to carefully feed the belt onto the groove in the bottom wheel, while slowly rotating and carefully used a blunt flat head screwdriver as a pry bar to get the belt into the groove....

Yikes, I've never imagined installing a belt by prying it over the rim of a pulley but my "gut" feeling is if it went on that way and you didn't have to adjust the tension afterwards, the belt is now far too loose. Belts are not supposed to be that stretchy. I suspect the pulleys were set too loose to start with, the belt was a size too small and weak and now damaged, or something flexed or bent in the support when you forced it on the pulley. If you haven't, you might check the tension of the belt now it's installed.

BTW, before you measure the diameter of the pulley: I see Joe asked "What's the width of the pulley on the outside diameter?" I suspect he wants the width (not the diameter) to make sure you are using the proper belt.

Using a belt that is not sized for the pulley can cause problems. In particular, a belt should sit high in the v-groove so the sides tightly contact the sides of the groove. If the belt is not the correct width it might be riding on the bottom of the groove instead of the sides!

(Sorry, I didn't read all the posts. This may have been mentioned already.)

Note there are metric-sized pulleys too. One way to make sure the belt is the right width is take a pulley off and take it with you to the belt store.

JKJ