Unisaw Power Problem

[Kevin Ramler]

I recently took over a shop with a 2002 Unisaw. The saw had been running great until a couple of weeks ago when it started having problems starting. Sometimes it starts great, sometimes it kind of grinds and shakes a bit then finally gets going, sometimes it won't start at all, it just hums.

After doing some research and talking to delta I decided it might be a capacitor, so I took the motor into my local shop. They said everything looks great and charged me 80 bucks. I bring the motor back to the shop, hook it up, same problem as before. Now I'm thinking it might be the switch. So I take the switch cover off and try to start it up, when I press go, there are some blue sparks inside the switch as it tries to start. After a couple attempts everything clicks and the motor starts running. I took a video but can't figure out how to upload it.

So assuming it is the switch here is my question, right now the saw is plugged into a floor outlet that reads 250V, 30A. The output from the switch is 230V. The motor is 230v, 12.4 amp, 3hp, single phase. Will a simple switch like this http://www.grizzly.com/products/Sing...110-230V/D4157 work? Could the fact that the outlet is 250 be a problem?

[john lawson]

Sounds like the contacts on the switch are arcing. You could try cleaning/sanding them with some 400 grit and see if that fixes the problem. If they are pitted just buy the Grizzly switch. Looks like it should work.

[David Kumm]

Wouldn't cost much more to upgrade to a mag starter which is what the saw probably should have. Dave

[Steve Baumgartner]

Wouldn't cost much more to upgrade to a mag starter which is what the saw probably should have. Dave

Didn't 2002 Unisaws come with a mag starter? Mine is about that age and has one. I wouldn't recommend a simple switch.

Anyway, I had a similar experience a while ago that may or may not be related to yours (depending on where the blue sparks are - that's your main clue as to where the problem lies). Mine turned out to be due to a bad connection in one of the wires from the mag relay to the overload module. The saw would sometimes start ok, other times it would sort of grind and shake for a while, and other times not start at all. The jolt as the motor tried to start was vibrating the wire and causing it to lose connection. It turned out to be a connector screw that was stripped and not holding tightly.

[Kevin Ramler]

IMG_2742.JPG

Thanks for the advice everyone, Steve my problem sounds very similar to yours. Here is a picture of the switch/starter, the blue arrow is pointing to the area where I am seeing sparks from inside the component. I will check for loose connections today and see if that helps.

[Steve Baumgartner]

IMG_2742.JPG

Thanks for the advice everyone, Steve my problem sounds very similar to yours. Here is a picture of the switch/starter, the blue arrow is pointing to the area where I am seeing sparks from inside the component. I will check for loose connections today and see if that helps.

That's definitely a mag starter, the same as mine. The component at the top is the main contact relay, and the one at the bottom is the overload protector. Your arrow marks where there is a contact in the main relay. A small spark there is not unusual when the motor is stopped, as the motor creates a significant "bucking" voltage when the current is interrupted. The loose connection I found was in one of the two red wires that run from the top of the relay to the bottom of the overload protector, along the right side. One of the screws under the white strip at the bottom was loose.

Steve

[Duane Meadows]

Here is a better switch for the application...

http://www.grizzly.com/products/Magn...nly-3-HP/G4673

[Harold Weaver]

Duane is right on this one. That Grizzly starter should work fine. What you have is a similar switch that Delta went to in their later years as did many others. It is an IEC type starter. Part of our new disposable throw away society. That is why the are $78.00 vs. $300-$400 for a real Allen Bradley or Furnas starter that used to come on Deltas and Powermatics for many many years. Those IEC starters are common in Europe and Asia. Delta was using a very solid Furnas LVC mag starter on the Unisaw for a quite a while in the 80s and 90s, box mounted on back with remote switch on the front, but those went to the way side when they got cheap. I bought one of the LVC units used and it is now residing on the back cabinet of my PM66.