2 sawstops crash in 3 days

[Kevin Groenke]

I lurk occasionally and only seem to post SS related items, my apologies.

There does seem to still be a fairly balanced audience here, and being early adopters I figure that our experiences may be of some assistance to others.

So:

Hey folks,

Last Wednesday we had a 5hp single phase SawStop go down. The saw went instantaneously from running fine to struggling to spool-up and tripping the breaker(gggrrrrnnn pop). I suspected the start capacitor and a call to SS service affirmed the diagnosis and the start and run capacitors were on their way overnight.

Friday morning as I was installing the capacitors on saw #1, saw #2 went down with the EXACT same symptoms. I thought, "well at least this one will be working in minutes". Finish the repair, flip the switch....... gggrrrrrnnnnn pop! Uh oh, I don't have a functioning tablesaw and there's like 30 students who need to make 1000's of little mdf blocks, and half a dozen site models.

So, we get the design/build site saw out of the closet, and I spend much of the afternoon with Tony/Chad at SS, trying to figure out what's up. Ultimately we bypass all the electronics by running a cord directly from the motor to the plug. Same thing, gggrrrrrnnnnn pop! - BAD MOTOR. SS is sending two motors under warranty (5yrs).

I'm out til Tuesday, but pull a motor as soon as I get a chance (don't know why I didn't stay late on Friday to do this?). All I find is a crack on the centrifugal switch, but it seems to open and close fine. I put the motor back in the saw (really easy remove/install btw, like 5 minutes to pull this motor). Hit the juice.... SAW STARTS!!! Off, back on.... gggrrrrrnnnnn. WTF??? So, I open the back of the motor and sure enough, the centrifugal switch is open instead of closed. Fortunately this motor is designed with the centrifugal switch outside of the main case so it can be changed without opening the motor (I don't think I've ever seen this before, it's cool). Once I made this determination by completely removing the first motor, I was able to diagnose, remove and re-install the centrifugal switch without taking the motor out of the saw, nice. So, I pulled the switches, tig welded the point of failure and re-installed. Eureka, the saws start, stop and start again... BACK IN ACTION!

Back to SS, I call Tony and let him know what I found. He's interested, but doesn't seem to have a problem sending whole motors when the switch is the only bad part. I'm told there are no field serviceable parts in the motor. Oh well, I guess we've got two back-up motors for our tablesaws.

Apparently SS upgraded the motors fairly early in production, but here is a potential failure you may want to watch out for.

Cheers,
KG

Kevin Groenke Director, DesignFabLab
University of Minnesota

[Mark Rios]

Very nice heads up, Kevin. Thanks for taking the time to help out those who may encounter this problem.

[Anthony Anderson]

Thanks from me too Kevin. The guys at SawStop are great to work with. Excellent service.

[James Phillips]

Mine had the same problem and they replaced the motor no questions asked. They do have a new motor and it is physically larger, but will still fit no problems. I have had no problems since

[Kevin Groenke]

That's interesting I didn't get the impression from the techs at SS that this has been a common problem. I'm surprised that they haven't done any autopsies to determine the cause of this failure.

The replacement motors just arrived. I checked the centrifugal switch and it doesn't appear to be any different in these "upgraded" motors than that in the failed motors.

Since our 2 saws (of the first 100 off the line) failed nearly simultaneously, I suspect that there will be more instances of this failure as more saws get more hours on them.

If sawstop doesn't decide that this part is user serviceable they may be replacing alot of motors in the future.

Oh well, not my problem.

-kg

[Mike Heidrick]

Kevin, when did you buy yours and do you know when the "upgraded" motors were put into production?

[Carl Crout]

What brand are these motors?

[Kevin Groenke]

The saws were delivered 12-29-04. SS didn't indicate when the motors were upgraded. I compared the motors (externally) pretty closely and there is NO discernible difference between the new and the old. As the pic's indicate, the centrifugal switches at least appear to be identical.

If it's any consolation, I've replaced centrifugal switches in Baldor, Marathon and other motors by well respected manufacturers. I'm having a hard time explaining to myself why I was reluctant to pull the motor in the first place. I suppose because I knew that a call (or several) to SS would remedy the situation, this of course often isn't the case with other manufacturers equipment.

There is no indication of a manufacturer on the motors other than SawStop, LLC and MADE IN TAIWAN. But below the SS sticker on the original motors I found another sticker that says KE TING LTD.

[Don Bullock]

Kevin, thanks for the heads-up on this one. In my home shop it will take me a long time to put as many hours on a saw as you have on yours, but it's still important to know about.

[Ted Baca]

From what I read here is it only the %HP motors that are doing this? I have the 3HP, but is it possible that a electrical surge took place?

[Mike Heidrick]

I have only read of these two motors owned by this one member (with the saws being used by 30 or so students correct?) doing this - no other instances. Quite a few of us 5hp owners with no issues.

[Kevin Groenke]

More like 300 students. Our saws frequently cycle on/off 100's of time a day (they also sit largely idle during the summer). Yeah, we probably have many more hours on these saws than many other owners, but it's only been 3 years, a motor should last immeasurably longer. Our 14" bandsaws cycle 2X more frequently and they're going on 10+ and 6 years on those motors without any failure.

I'll be surprised if we don't start hearing reports of motor failures due to broken centrifugal switches in the 5hp 1ph SawStop in the future (maybe the 3 hp too, the switch is probably identical).

Fortunately SawStop will know what's going on and, if past experience is any indicator, will address any problems quickly and professionally. Perhaps they will even preemptively send replacement stationary switches in order to minimize users' downtime in the event that their motors do fail.

Regards,
Kevin Groenke

[Mike Heidrick]

Thanks Kevin for the heads up. I will save the post. Who did you work with at SS?