Powermatic 81

[Wayne Jolly]

Could the black box be a blade welder??? It kinda looks like one I used in some classes a long time ago.

Wayne

[Dan Hahr]

There is an up-close photo of it but it is blurry. Most of the ones I see online don't have it. it looks like some kind of electrical box.

black box.jpg

Any ideas?
Thanks, Dan

[Dan Hahr]

Well...I picked it up today with the help of two friends. They had to do all the heavy lifting due to a bad arm injury.

Here's what I've got:

Powermatic 81 Gold paint scheme, looks like 1985 version. Baldor 2 hp single phase motor. Carter CP 500 guides. Junk blade. Start stop switch is missing the front cover.

The black box looks to be a magnetic starter. However, it has me totally confused. The information inside it reads that it is for 3 phase 480 volts. The power cord is for 125-250V but the one I posted above.

I have a 20A circuit that I use my Unisaw on and I would like to run it on that line, but is it even possible without changing the starter?

Any ideas?

mag starter.jpg
Thanks, Dan

[Ed Weiser]

Dan,

IMHO, I don't think that is the original motor on the saw. In general, small single phase motors do not require starters. Further, Powermatic usually branded their own motors on their saws. If you just plug it into a 20 amp 220v circuit I suspect you'll be fine and can just ignore or remove the suspect box. Is there an on/off switch that the power cord runs through? If not, you may have to put one on. A magnetic switch would be nice.

[Matt Day]

Trace the wires from the motor and see if it even uses the starter box. It's probabaly been bypassed and they just left it on.

Sweet find that it has a single phase motor! Get a new blade and cut some wood! Well, before that I'd do a thorough run through of the saw, checking alignments, bearings, wiring, belts, etc.

[Larry Copas]

These things are tough to figure out without seeing the whole machine. The box looks like it has a starter for a 3 phase 480 volt motor. If original, the heaters will be too small for 230 volt single phase. The starter will probably also have a 110 volt coil that is activated by a motor control (switch). The 110 volts may come from a transformer. In any case it is another concern when converting to single phase.

Given the picture of the 3 phase plug and the 2 hp single phase motor who knows how it is wired. With any used machine its always a good idea to verify the wiring is both safe and right. School machines seem to have the most wiring problems.

If you bypass the starter they do have value, especially if made in the USA.

[Doug Ladendorf]

Nice saw.

These things are tough to figure out without seeing the whole machine. The box looks like it has a starter for a 3 phase 480 volt motor. If original, the heaters will be too small for 230 volt single phase. The starter will probably also have a 110 volt coil that is activated by a motor control (switch). The 110 volts may come from a transformer. In any case it is another concern when converting to single phase.

Given the picture of the 3 phase plug and the 2 hp single phase motor who knows how it is wired. With any used machine its always a good idea to verify the wiring is both safe and right. School machines seem to have the most wiring problems.

If you bypass the starter they do have value, especially if made in the USA.

I wondered about the 110 (120v) option too. Single phase 240v only needs three wires, unless there is a need for 120v for a light or something which would add the neutral. (Or so I understand. I am not an electrician and did not stay at a Holiday Inn last night.) I don't see any other signs of that though.

Doug

[Dan Hahr]

The machine is wired through the starter. I can't say that it is done right. The motor pulleys were way out of alignment and the belt was twisted. The lower wheel axle is wearing through the door as it seems to be too far forward. It looks like the motor could be newer. I'm trying to post photos of the inside of the box and motor plate. Even Youtube doesn't have an answer for this one...

motor plate.jpgmag starter 2.jpg

Thanks, Dan

[Doug Ladendorf]

Dan, if you are stuck try posting to the Everything Electrical forum on OWWM.org.

Doug

[Dan Hahr]

Thanks, Doug. I haven't visited over there in a while, but I guess its about time. Thanks, Dan

[Rod Sheridan]

Hi, the machine has a size 0 nema starter which is large enough for the 2 HP single phase motor.

You will need to check what size the overload elements are, they need to be large enough for the 11 ampere motor current.

Please provide a larger, in focus photo of the control transformer.

It looks like it's a 480/240 volt primary, strapped for 240 volt at present however a more clear photo would help.

So far it looks like it may be all set for 240 volt single phase once you verify the above two points...............Regards, Rod.

[Dan Hahr]

Hi, Rod

From my research, it does appear that this should work with 240 single phase power, but I have no idea how to wire it. I talked to support at Baldor. A very helpful customer service rep told me that it is a 1986 motor, so it seems that it could be original. She said that it wouldn't necessarily need a starter, but I was thinking that getting those cast iron wheels moving quickly might require one.

There are 4 wires coming from the motor, and the same going to the cord. black, red, white, and green. My Unisaw is wired for 220 but I never looked at the wiring diagram; it was ready to go from the start.

transformer label.jpgtransformer top.jpgstarter label.jpg

Do these photos help? I think I may need to see how the motor is wired.

Thanks for everyone's help!
Dan

[Rod Sheridan]

Hi Dan, open the motor terminal box and see which two wires out of the red/black/white group are used ( one won't be used, the green ground wire will be used.

For sake of argument let's suppose that the red and black wires go to your motor.

You would then apply power to the red and black wires on the plug, and the saw should work. Please let us know how you make out...........Rod.

[Dan Hahr]

That makes sense, so I checked and the black wire is capped off at the motor. I pulled the plug off and switched it out with my table saw plug. Unfortunately my only 220 extension cord has two horizontal blades and the plug has one vertical and one horizontal. So until the am, I'm hoping this works.

As far as the black wire, is it safe to leave it taped off? I can always replace the cord.

Thanks for the help.

Dan

[Rod Sheridan]

Dan, it sounds like you then apply power to the white and red line cord, leave the black taped off at the motor.

Regards, Rod.