24" Minimax bandsaw bogging down....

[dirk martin]

I'm running a new carbon steel blade on my MM24 Minimax. 2TPI Hook, and 1".
Resawing 6" cherry, bogs the 5hp motor, if I feed it too fast.
If I keep bogging the motor for 4 or 5 boards, the internal breaker on the saw's switch trips, and I need to let it sit for 15 or so minutes, before it'll turn back on.
The saw's about 7 years old.
Does that seem right?

My sister resaws wider boards than that, on her 24" Grizzly saw, and she says it never even thinks of bogging down.
She's resawing with a 1/2" blade, at 3TPI.

[Jamie Buxton]

No, that's not right. With a five hp motor and a sharp blade, 6" cherry should not slow down the saw.

Are you seeing burning on the cherry? If you're seeing a lot of burning, that suggests the blade is dull.

Can you put a voltmeter on the 230 volts? It should not drop more than a few volts when the saw is running.

Does the plug feel real hot? If it gets hot, it isn't making good contact to the outlet.

Can you spin the wheels by hand? (Pull the plug before you reach inside the saw.) Maybe the blade guides are set too tight.

[Matthew Hills]

Is your blade facing the right direction? (seems like a silly question, but when I was buying a used planer from one guy, I asked how his laguna bandsaw performed as the blade looked a little funny facing up; and I've done this with a circular saw before)

Matt

[J.R. Rutter]

I have an old 20" saw with a 1-1/2 HP motor, which is pretty marginal by today's standards. I struggled to resaw using 3/4" + blades regardless of tooth count and style. I found that a thinner blade worked much better for resawing. While the beam strength is lower, if the saw and guides are tuned up, a more flexible blade works just as well. These days, I just keep a 1/2" carbide tipped blade on for everything except tight radius cutting.

[Rick Fisher]

Dirk.

I have a 24" SCM Bandsaw with a Baldor 5hp motor and it won't bog down at all. Period. Its spooky. I run a 1.3 tpi Carbide blade and had run a Lennox Tri Master 3 tpi.

I have resawn 2x10 Sapelli, 2x12 Wenge, and 2x10 Zebrano.. Loads of 2x10 Maple. Never even makes a funny sound.. I am convinced that the blade would fail first..

I have always felt I should have put a 3hp motor on my saw when I restored it as 5hp is so crazy over powered..

[Stephen Cherry]

Maybe check the amps and volts at the motor.

It seems like that would be the first place to start troubleshooting.

Is the belt slipping?

[Jim Andrew]

What happens if you just open the door and rotate the bandwheels by hand? Is there a lot of resistance?

[Ken Fitzgerald]

I have a MM-16 and I have sawn 13" apricot that was hard as rock with a 3/4" blade sent with the saw. In short, your saw should easily cut that.

I'd check the incoming power, the brushes on the motor and bearings on the two wheels. Something is causing the motor to draw too much current and trip the circuit breaker. It's not too unusual to have to wait for the breaker to cool down before it will reset properly.

[Erik Loza]

...check the amps and volts at the motor...

This ^^^

If motor internal protection is tripping, the motor is drawing too many amps under load. I would get out the voltmeter and see what you are actually getting at the switch. If the voltage is low, that would explain it.

Good luck,

Erik Loza
Minimax USA

[dirk martin]

No, that's not right. With a five hp motor and a sharp blade, 6" cherry should not slow down the saw.

Are you seeing burning on the cherry? If you're seeing a lot of burning, that suggests the blade is dull.

Can you put a voltmeter on the 230 volts? It should not drop more than a few volts when the saw is running.

Does the plug feel real hot? If it gets hot, it isn't making good contact to the outlet.

Can you spin the wheels by hand? (Pull the plug before you reach inside the saw.) Maybe the blade guides are set too tight.


First, a little more info.
I thought the blade was new, but just found out about 100 linear feet of 6" ash had been resawn with this blade.

There is no burning on the cherry at all.
The plug stays perfectly cool.
The wheels spin freely, the guides are not to tight.

[dirk martin]

Is your blade facing the right direction?

Matt

Yes it is.

[dirk martin]

Maybe check the amps and volts at the motor.

It seems like that would be the first place to start troubleshooting.

Is the belt slipping?

I have a VOM. How do I check the amps and volts at the motor?
The belt is not slipping.

[dirk martin]

This ^^^

.... I would get out the voltmeter and see what you are actually getting at the switch.....


Erik Loza
Minimax USA

Can someone be more specific as to how I do this?

[HANK METZ]

Assuming it's been working well for you the last 7 years, I'd kinda suspect either the start capacitor has gone bad or the centrifugal switch circuit is malfunctioning- I assume single- phase supply use. With the start windings remaining in- circuit, it'll go into thermal cutout in about 5 minutes or so. unbelt it and let it free run and see if the motor case gets hot, if it's a winding problem she'll cook and trip- simple, easy, no meter needed first diagnostic step, if no problem then get more technical with the troubleshooting.

[Stephen Cherry]

Assuming it's been working well for you the last 7 years, I'd kinda suspect either the start capacitor has gone bad or the centrifugal switch circuit is malfunctioning- I assume single- phase supply use. With the start windings remaining in- circuit, it'll go into thermal cutout in about 5 minutes or so. unbelt it and let it free run and see if the motor case gets hot, if it's a winding problem she'll cook and trip- simple, easy, no meter needed first diagnostic step, if no problem then get more technical with the troubleshooting.

This sounds like a plausible explanation. And a great first step.

My troubleshooting strategy is to eliminate as much as possible, to measure voltage I would take off the motor connection cover, and measure it right at the motor. For amps you need a current clamp. I have one of these:

http://en-us.fluke.com/products/electrical-testers/fluke-t5-1000-electrical-tester-kit.html#fbid=-O5XMxcNF2k

But you can also use an accesory current clamp with a vom, you just clamp onto one of the legs, set up the current meter to match the ratio, and read the amps. Usually, one milliamp on the meter equals one amp through the clamp. Also, if you are not comfortable with electrical, it's no shame in asking for help.

[Erik Loza]

Can someone be more specific as to how I do this?


This sounds like a plausible explanation. And a great first step.

My troubleshooting strategy is to eliminate as much as possible, to measure voltage I would take off the motor connection cover, and measure it right at the motor. For amps you need a current clamp. I have one of these:

http://en-us.fluke.com/products/electrical-testers/fluke-t5-1000-electrical-tester-kit.html#fbid=-O5XMxcNF2k

But you can also use an accesory current clamp with a vom, you just clamp onto one of the legs, set up the current meter to match the ratio, and read the amps. Usually, one milliamp on the meter equals one amp through the clamp. Also, if you are not comfortable with electrical, it's no shame in asking for help.

Stephen's post, above, is excellent. I am with him on this: Yes, it could be a capacitor (whis is easy to replace, if so) but I would start with the simple stuff and work up from there. Checking the voltage at the switch and amp draw under load would be the first steps. I don't have any specific links to post but there must be videos on Youtube that show it.

One question, Dirk: Did your machine just start doing this or has it always struggled like this?

Erik Loza
Minimax USA

[Stephen Cherry]

Stephen's post, above, is excellent. I am with him on this:

Thanks Erik- I've been looking at this sort of thing for some time now.

Anyway, I would try Hank's plan first, and if it's not the cap, you need to dig a little.

One thing I forgot to mention, you want to measure the volts and amps under load, in the condition where the fault occurs. If the wiring is not up to it, the volts will drop and the amps will go up. If the saw is really working hard, the amps will go up, but the volts shouldn't drop much.

And Erik is right about the simple stuff first. I can't tell you how many times I have gone to an installation to help with some complex problem, only to find just a loose wire. When I was an engineer, the first thing I would do in troubleshooting is trace through all the wires, pulling on connections. Lots of times it just came down to tightening a screw terminal that was never properly tightened. That's probably not the case here, but almost always it's something not very complex.

[HANK METZ]

Thanks Erik- I've been looking at this sort of thing for some time now.

Anyway, I would try Hank's plan first, and if it's not the cap, you need to dig a little.

One thing I forgot to mention, you want to measure the volts and amps under load, in the condition where the fault occurs. If the wiring is not up to it, the volts will drop and the amps will go up. If the saw is really working hard, the amps will go up, but the volts shouldn't drop much.

And Erik is right about the simple stuff first. I can't tell you how many times I have gone to an installation to help with some complex problem, only to find just a loose wire. When I was an engineer, the first thing I would do in troubleshooting is trace through all the wires, pulling on connections. Lots of times it just came down to tightening a screw terminal that was never properly tightened. That's probably not the case here, but almost always it's something not very complex.
Thanks for the upvote Stephen, years ago I used to work for a company that sold medical and dental equipment nationally and internationally. Oftentimes when a problem came in to us in the service department we’d have to do a remote analysis to isolate and identify the problem, usually asking the Dr.’s assistant to perform simple, yet telling tasks that would help us analyze what was going wrong before we could get the problem fixed. You’re quite correct when you say it usually is a minor thing that is the cause, in fact we used to have a saying “when you hear the sound of hoof beats, don’t be looking for zebras”, in other words look to the likely stuff first.

[Kelby Van Patten]

Do you have an alternate blade? If so, put the other blade on and see if it still bogs down. If so, it's the saw. If not, its' the blade.

If you don't have an alternate blade, get one!

[Rod Sheridan]

Likely causes are

- dull blade

- open run capacitor causing the motor to run on the run winding only, not the run winding and the start winding via the run capacitor(assuming it's the typical caapacitor start/run Euro motor)

Regards, Rod

[Mike Heidrick]

That is a 7.5hp 3ph saw. How are you powering it - true 3phase, DIY RPC, balanced and measured RPC, Static phase converter, properly rated VFD, correctly derrated VFD?

[Jamie Buxton]

That is a 7.5hp 3ph saw. How are you powering it - true 3phase, DIY RPC, balanced and measured RPC, Static phase converter, properly rated VFD, correctly derrated VFD?

That saw can be equipped with either a 5hp single-phase motor or a 7.5 hp three-phase. The original post says it is 5 hp.

[Jeff Duncan]

I'm with the guys who say look for simple things first…..like how fast is "too fast"? Are you using a feeder or running stock by hand? If your using a feeder and have it set for too high a speed….well that could be the problem by itself. If your hand feeding then you have to go by feel and experience. Carbon steel blades don't last long IME when re-sawing, so it's also possible your bade is already dull. You mentioned the blade was new….ish, did it cut the same when you first put it on? Doesn't matter much what the hp is if the blade is already dull. Personally I'd throw another new blade on the machine before trying to diagnose the electrical system of the machine…..but that's just me;)

good luck,
JeffD

[Jim Matthews]

First, a little more info.
I thought the blade was new, but just found out about 100 linear feet of 6" ash had been resawn with this blade.

That's the first thing I was taught to check.
Do you have another blade handy? It's the essential part of the problem.

I "friction cut" my second cord of wood back in 19(mumble-three) - before I learned you can sharpen chainsaw blades.
The third cord cut considerably faster.

What's a blade for your saw cost?
What's your time worth?

[Rick Wize]

Did anyone ever find a solution? I have a Minimax S45N with the exact same problem. I have had it for several years, but probably have less than 4 hours usage on it. Overtime these years in using it seldom, I noticed it was taking longer and longer to get up to speed (it began taking 20 seconds and then got longer & longer), now it just will not get up to speed and when I turn it on, it just runs slowly and will not cut anything without bogging down. I've opened the electrical box off the top of the motor and removed what I believe to be the start capacitor, but I'm not sure how to get to the run capacitor. Anyone have any ideas? I have attempted to upload a picture of the motor.

[glenn bradley]

I'd like to know too. My vote was a power level/delivery problem.

[Patrick Curry]

My apologies if this get's posted twice...the first reply didn't seem to register.

Try a new resaw blade.

I purchased a 4hp Laguna 17' earlier in the year. I also purchased 3 blades from a separate but well-regarded manufacturer. The band for resawing only worked briefly (70-80 bf perhaps). The motor started bogging down, etc. Very similar to what has been described here on this post.

Laguna was contacted and after some time on the phone they suggested I purchase their Resaw King. Even though they were discounting the price (I suppose because I had recently purchased the BS), I wasn't too excited about purchasing yet another resaw band. The one I had was supposed to be of high quality, and it wasn't cheap. But, it would at least rule out one possibility.

Anyway, the Resaw King made all the difference in the world and it's still in use, cutting that same stash of lumber (100 year old reclaimed southern yellow pine 7" floor joists).

Based on my experience with the other bands I purchase out of the gate (from the other manufacturer), I'm starting to think my BS just doesn't care for their brand.

[dirk martin]

Hi. I started this thread.

I ended up installing a new blade, and now I'm running fine.
I still don't feel my saw should bog down, however.
If my Grizzly saw doesn't bog, neither should my Minimax.
However, a sharp blade can make most any saw look good.

[Mike Heidrick]

Rick, yours is not the same issue. Getting up to speed is not bogging down in a cut. Yours sounds like start cap. My MM20 is at full speed in 3 seconds or so (guess) not 10 or 20 - that is WAYYY to slow.

[Erik Loza]

Rick, yours is not the same issue. Getting up to speed is not bogging down in a cut. Yours sounds like start cap. My MM20 is at full speed in 3 seconds or so (guess) not 10 or 20 - that is WAYYY to slow.

This ^^^

It doesn't matter if you have a 5hp saw with 20" cast iron wheels. If you are trying to rip with a dull blade or the wrong blade for the job, then that's an operator issue, not a machine issue.

Rick Wize, my gut reaction is start capacitor or possibly frozen centrifugal switch. Have you tested the capacitor that you pulled from the motor?

Erik Loza
Minimax USA