Problem with MM16

[fred woltersdorf]

I have a MM16 that's about 12 yrs old, i don't use it regularly, maybe 3 times a month but I've never had a problem until I was cutting with it today, after I finished my cut I hit the foot brake and it would stop the blade as long as I had my foot on it, as soon as I took my foot off the blade would rev up to cutting speed. I can stop it with the main switch so I'm thinking it might be the micro switch on the foot brake. Any ideas? Thanks.

[Jim Matthews]

My MM20 doesn't have the interlock you're describing.

I make a habit of turning it off with the Magswitch, then using the brake.
The MM20 Micro switch (SQ3) is a Pizzato FR508

http://www.tme.eu/en/details/fr508/limit-switches/pizzato-elettrica/fr-508/

[Erik Loza]

Fred, it sounds like the footbrake microswitch may have moved out of range or possibly just failed. It happens. I'm trying to remember if they fail open or fail closed? I think open. Are you handy enough to work on it if I give a few troubleshooting tips?

Erik

[Fred Belknap]

Had a problem like that on a Grizzly bandsaw. I had forgot to open the bast gate on the dust collector and saw dust had built up around the micro switch.

[fred woltersdorf]

Thanks Erik, yes I think I can figure it out if you could guide me along.

[Larry Heflin]

I have the exact same problem on my MM 16. I fooled around with it a while back and figured out it was the difficult to reach micro switch behind the lower wheel. I just keep putting off having to deal with it since I think it will probably involve pulling the wheel. I'd love to hear any tips you might have Eric.

[Rich Riddle]

Despite what Erik and others are telling you about being a simple switch, unfortunately it's a death blow to your saw. Please forward your address and I will pick it up and pay you the scrap value. You don't want to be electrocuted changing that switch. That said, many times you can adjust your switch if it's moved a bit. Do you have access to a multimeter?

[Rod Sheridan]

I have a MM16 that's about 12 yrs old, i don't use it regularly, maybe 3 times a month but I've never had a problem until I was cutting with it today, after I finished my cut I hit the foot brake and it would stop the blade as long as I had my foot on it, as soon as I took my foot off the blade would rev up to cutting speed. I can stop it with the main switch so I'm thinking it might be the micro switch on the foot brake. Any ideas? Thanks.


Your start button is stuck in the on position or the aux contact that latches the starter in the on position is stuck.

My first efforts would be looking at the start button.........Regards, Rod.

[Edward Oleen]

Despite what Erik and others are telling you about being a simple switch, unfortunately it's a death blow to your saw. Please forward your address and I will pick it up and pay you the scrap value. You don't want to be electrocuted changing that switch. That said, many times you can adjust your switch if it's moved a bit. Do you have access to a multimeter?


EVERYBODY should have access to a multimeter - they are cheap cheap cheap at HF, and at one point they were giving them away when you bought something, like the little flash/work lights that I've got a dozen of stashed in various places.

[Erik Loza]

Thanks Erik, yes I think I can figure it out if you could guide me along.

Fred, I'm going to PM you my cell number.


I have the exact same problem on my MM 16. I fooled around with it a while back and figured out it was the difficult to reach micro switch behind the lower wheel. I just keep putting off having to deal with it since I think it will probably involve pulling the wheel. I'd love to hear any tips you might have Eric.

Yeah, it's a weird angle. If I have to adjust that steel tab that engages the footbrake microswitch, I shoot it with some PB Blaster first (they're always frozen...) and have had pretty good luck getting it with a ball-tipped allen head on my ratchet. It is "just" not quite a straight shot. A regular allen will strip it out.

The worst-case scenario is, as you mentioned, pulling the lower wheel but that's not a huge deal in my opinion. Time consuming? Yes. Technically challenging? No. I have done it at trade shows or on site with customers a bunch of times. PM me if you want some tips on it.


Despite what Erik and others are telling you about being a simple switch, unfortunately it's a death blow to your saw. Please forward your address and I will pick it up and pay you the scrap value.

HAHAHAHA.....


Your start button is stuck in the on position or the aux contact that latches the starter in the on position is stuck...

That's a possibility but I always look at the microswitch, first. Because it's the simplest thing to eliminate. Then, escalate from there. At least that's how I do it.

Erik

[Larry Heflin]

I apologize in advance for my lack of correct terminology, but I'll attempt to describe in lay, or childlike terms what's going on with my switch. I can actually see what the problem is on my saw. When you step on the pedal it raises the part of the pedal which holds the rounded plunger part of the switch that sits in the rubber boot. That moving part of the switch then pops up and shuts off the saw. With the saw turned off while working the pedal I can hear the switch clicking as the moving part moves up and down making or breaking electrical contact. I can also watch it as it's happening. The problem is that even though there is plenty of clearance between the part of the pedal that makes contact and the contact point of the switch, the switch part does not always pop up. I assume there is a spring of some sort that pushes the switch part up when the pedal is no longer depressing it. That spring must be very weak because the "plunger" part rises incompletely most of the time and doesn't make the audible click that happens when it is up enough to work the switch. By holding the pedal down I have room to work the switch with my finger and it seems to click on and off fine. But as soon as I let the pedal compress it again it resumes it's incomplete action. Sometimes if I hold the pedal down for 5 seconds or so, the switch will pop up. The switch is clean so I don't think it of a problem of it gunking up. I think it's a spring problem; a mechanical problem, not an electrical problem.

As far as doing something about it, I can get the switch cover off, but the switch itself is still firmly attached to the saw and I'm not sure what's holding it. I cannot reach the allen screws on the front of the switch to see if that will free the switch for further inspection. If I could get the switch off I could see if it's possible to replace the spring mechanism with something stronger. On my saw that would be the simplest fix. Other than that, it appears the wheel will have to come off to remove the switch and replace it with another switch that is subject to the same problem. I've been using the saw with a non-working pedal for over a year now, but I'd like to fix it sometime soon. I'm not afraid to pull the wheel, but I was unable to find clear instruction on how to do so when this problem first appeared.

Larry