Powermatic 81

[Dan Hahr]

I just bought a Powermatic 81 bandsaw in a school auction. I may be crazy but I was unable to see it due to an injury. However, it seems go be intact and in decent condition. I figure I can spend a bit more money and have a nice resale bandsaw. I have to wait till the 24th to pick it up, but my patience is dwindling. My main worry is what motor I wound up with. I hope it is single phase but I don't recognize the plug. It was described as 240v. Can any of you tell by the plug? I will also attach the link to the auction.

Ok. I'll try that in a moment.

https://www.proxibid.com/asp/LotDetail.asp?ahid=7589&aid=84889&lid=21143791&rfpb=0#Top


Thanks, Dan

[Dan Hahr]

Here's a pic of the plug.

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[Matt Day]

Pretty sure it's going to be three phase, being from a school. And that looks like it could be a three phase plug, though it could be single too I believe.

[Rod Sheridan]

Here's a pic of the plug.

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Looks like a 3 phase cord cap..........Rod.

[Dan Hahr]

That's what I'm afraid of. What are your thoughts on getting a phase converter vs VFD vs replacing the motor?

Thanks, Dan

[Ed Weiser]

How many HP motor? If it's three or less (five or less for some brands) a VFD could give you a variable speed bandsaw with single phase 220v input--not bad, especially if you happen to need to cut other materials like plastic or aluminum. On a bandsaw a VFD is a relatively easy install.

[Matt Day]

That's likely a 3hp motor, and a VFD will cost a bit over $200. I have a Powermatic 2013 which is basically a newer version of the 81, and put a VFD on it and have been very happy with it. It's an easy install and allows variable speed, motor braking, and programmable starting time.

[Dan Hahr]

297054Any clue as to what the black box is on the back of this machine?

[Dan Hahr]

Matt.

Did you use the factorymation FM50? It seems that there are several versions. Which did you get? I can hook it up to 120 or 240 if needed.
Thanks, Dan

[Dan Hahr]

I am not sure what the HP is. I took a big chance here, but I hope the frame itself is worth the gamble. I figured I could put a cheap 2 hp motor on it and have a decent saw.

Thanks, Dan

[Matt Day]

Not sure about the box, mine didn't have one.

I got the FM50-203-C.

[Matt Day]

Not sure about the box, mine didn't have one.

I got the FM50-203-C. Total with shipping was $206. Thats going to be cheaper than a new motor, assuming the current one is good.

You need a single phase 220V electrical circuit, you can't power it with 120V.

[CPeter James]

Chances are 99% that it is 3 phase. 3 phase with a VFD is the way to go. I have two on a lathe and radial drill and am converting another drill press and milling machine to 3 phase/VFD because the operating of the machines are so much smoother with the VFD and you get speed control as a plus. You can easily make a remote control so that the controls are right where you want them and even have a readout of blade speed in ft/sec if you want. The wiring of the VFD is simple and you eliminate all the relays and other stuff in the "starter" box on the machine. It is a clean installation.

[Dan Hahr]

That will be my plan if it's 3 phase. Hope this works out!
Dan

[Rod Sheridan]

That's what I'm afraid of. What are your thoughts on getting a phase converter vs VFD vs replacing the motor?

Thanks, Dan

Definetly a VFD.

I have the saw with a VFD................Rod.

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[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.

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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?

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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...

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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.

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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.

[Dan Hahr]

Well, I bought a plug and wired it up. Pushed the start button and lo and behold, it fired right up. I turned it off but it wouldn't start up again. I worked the switch several times and it seems to be working right now.

I'm still a ways from cutting anything but at least I know I'm on my way. I put on the only blade I have and tracked it properly. I noticed that the upper wheel was cast or drilled way off of concentric. It looks like it is hopping up and down as it spins. The tire has been crowned concentric to the axle, so the outer rubber runs smoothly but it is worrisome to look at. Does anyone have a cast iron wheel that is way off center like this?

Also can anyone suggest a good replacement switch that will fit the PM 81? Mine is missing the outer cover, so I just have two small white posts to push next to two hot terminals.

Also, I've been trying to get on the OWWM forum but haven't been activated by the administration yet. Does it usually take several days?

Thanks, Dan

[Doug Ladendorf]

Forum activation usually doesn't take too long. Arnfest (big event) was just last weekend so I'm sure the mods are catching up.

[Dan Hahr]

While waiting for bearings and a belt to arrive, I've been checking everything and making sure it is in alignment. The wheels seem to be in alignment and the blade I have tracks nicely in the center of the tires, despite the awkward off centered axle. I guess this is normal, since there is a 1" by 2" by 3/8" chunk of steel bolted to the wheel spoke for balance with PM gold paint all over it. I thought the bottom axle was a little too far out, but it seems that the bottom door is just a bit bent in, just so the center of the door rubs the axle end. Any ideas on how to fix this would be much appreciated, as I have no idea how to tweak sheet metal!

I put the Carter 500 guides back on and noticed the slot in the housing below the thrust bearing (bottom guide) was all chewed up. I then realized that the lower guide is about 1/4 inch too far to the right. There is no adjustment in the guide or trunnion base. So I tried to move the trunnion base over to the left, but there is very little side to side play in the bolt holes. I squared up the base and that cancelled out the slight space I gained. I guess I could move the wheel axle over to the right, but then the blade would hit the blade guard on the left.

Anyone have any experience with this issue before? I guess my next move will be to try and elongate the four bolt holes in the top of the cabinet. Does anyone see any other option? It going to be a lot of filing....

Thanks, Dan