Troubleshooting a New Slider

After getting a variety of advice on finding the source of trouble, a woodworker finds out his new sliding table saw had a bad motor from the factory. September 3, 2014

Question (WOODWEB Member) :
I thought I would try and get an opinion from you folks regarding my new saw. I purchased the new SCM Nova SI 400 saw that was on promotion this last summer. I'm in southern Alberta, Canada. My power set up is an American Rotory 20 hp rotary phase converter (CSA approved). The saw gave trouble right from the start and would not run after assembly in our shop. The brake on the saw motor was malfunctioning and had the blade locked up at all times. This saw has a brake that is engaged when the saw if off and then when you hit the on switch it releases the blade; there is also a separate switch to disengage the brake that allows to change blades and so on when the saw is off.

So a few weeks wore on, I had the power checked and that was fine but I did notice the saw controls were covered with iron filings from the factory - they had installed the electronics before milling the holes for the beam mounts?! The dealer sent out an inexperienced guy and obviously didn't know what to do, etc. then they finally picked it up and took it back to their shop and determined the main contactor burnt out and that the motor rectifier was bad. They had it running in their shop and brought it back - now the saw runs as long as the brake is disengaged (loosened off) - it's sort of like a composite disk that uses an electromagnetic force to apply pressure to stop the blade.

Anyways, the saw works now but the brake does not. The dealer doesn't want to replace the motor thinking it must be my phase converter causing the voltage is a little high and that's causing all the issues. My electrician doesn't agree. The saw is a 230v Italian machine that's had the CSA done and stickers applied.

Here are my voltage tests: did not test to ground since that is not a reliable test of actual voltage: #3 is the manufactured leg from the phase converter:

Saw off:
247v between 1&2
243v 1&3
255v 2&3
Saw running:
241v 1&2
234v 1&3
232v 2&3

My electrician said that bit of extra voltage should not be a problem unless the saw is somehow ultra-sensitive. The brake itself only runs on #1 and #2 legs of power so it's not a 3 phase component of the saw. I'd like a fully functional saw but I don't know who to believe. Pretty frustrating to say the least!

Forum Responses
(Cabinetmaking Forum)
From the original questioner:
A little more info on the saw:

10.5' slider
9 hp main blade
1 hp scoring
Manual blade raise
Manual tilt
Itís not a saw with a bunch of gizmo's other than the brake.

From contributor C:
What about the ground? I would venture to say the rotary phase converter is tied from its supply, but is it continuing the ground? Has the electrician verified it is grounded properly as well as the saw? I will tell you I had to buy a 208v Champion compressor for my shop because in Kaesar, Champion, Ingersol Rand and other's opinions 208v is not enough for a 230v compressor. I did what they said. We do have the si350n slider and haven't had one bit of problems with it. Have you called SCMI?

From contributor H:
The power should be fine. There is a 1 amp fuse for the brake and it's good if the brake gets power and doesn't disengage. The brake is bad and the motor needs to be replaced. I bought the SI 400 as well. No issues, but I don't have a phase converter. It does seem to jolt to a start though. Call SCMI if for no other reason to make record of an issue for later possible disputes for warranty.

From the original questioner:
No problem with the ground. Actually both 1 amp fuses are blown in the saw that run the brake - they pop immediately when the saw starts. I've gone through about a dozen fuses troubleshooting and at about $10 each SCM can find the problem themselves. I'm basically relying on the SCM dealer in Calgary to sort out this problem but I will call SCM directly soon if the dealer won't replace the motor. He said they've sold 25 of these saws in Western Canada and mine is the only one having this problem and he suspects it's my phase converter. I would also agree that the startup on the saw is not that smooth - we felt the startup is a little abrupt and could be better.

From contributor H:
If the fuse keeps blowing than the brake is bad. I have a couple customers running them off a phase gen without an issue but they do start hard. Tell the dealer to stop being lazy. Call SCMI and tell them about the brake issue so that you can get your motor.

From contributor J:
I have a SCM Nova 300 and it runs on 208 volts, never a problem! I know a guy that runs a phase converter and it took out the motor on his SCM wide belt because of a large variance in voltage.

From contributor B:
I have a SCM 350N that also runs on a American Rotary 20 hp RPC. The same RPC is also connected to 220 to 600 volt transformer and runs my 5 hp DC at the same time. Iíve never had a problem in the last eight years. I would go directly to SCM. Techs are like a lot of other trades, good ones are hard to find.

From contributor F:
Like Contributor B said, I would give SCM a call. I also agree that good techs are hard to come by. I also live in Western Canada and am unaware of any good ones.

From contributor A:

Call your electrician and make sure the grounds are tight at the box, entrance side at the meter base and customer side at all lugs. In my past life I installed KU Satellite systems. Inevitably we run into some problems and we would sink a ground rod at the rotary phase converter, per the design engineers. It would solve a lot of issues of interference in the racked electronics sides of things. Recently, my edgebander would revert back to Italian once a week and lose all settings in the plc, loose neutral at the service entrance. Equipment was showing it was grounded, but still had a float, enough to lose memory. Just to let you know my edgebander has an isolation transformer in it.

From the original questioner:
The dealer is somewhat responsive if I push a bit but I'm in agreement that this dealer like many others is not great. I will call SCMI this week at least to report my issues for warranty reasons. The dealer has the new motor so I think he'll get it done for me. If he had just changed out the motor right away rather than try to repair and troubleshoot this all would have been a distant memory I'm sure. Thanks Contributor A - I will check if grounds are tightened down sufficiently.

From the original questioner:
Just wanted to finish this thread. The dealer finally just replaced the motor and everything is running perfectly. It was a faulty motor the whole time and my phase converter seeming had nothing to do with my issues with the brake. It was a long haul getting this resolved let me tell you, lots of my time, downtime and electrician visits. Thanks to everyone who made suggestions!