Welding a base to a motor

[rslaback]

I recently picked up a Delta Unisaw that ate the rear bearing of its motor. The saw uses a unique mounting base. In order to save money I bought a replacement with a standard NEMA 56 base knowing that I could fab up an adapter. As I look at it I'm half tempted to just cut the weld that hold the custom base on and then just weld that to the new motor. Obviously I'd have to stitch weld the bracket on slowly to avoid heat damage on the windings. What are the other reasons this is stupid and I should just make my adapter and move on?

 

[PCustoms]

If the new motor ever needs to be changed then it's a custom job.

Too much risk of causing issues.

Make the adapt and move on

 

[Garage Junkie]

Interested in the discussion, as i may need to do the same for a delta lathe.

My guess (based on my experience with industrial motors) is that you could weld it up fine without damaging windings provided you take some basic precautions.

My plan was to swap the delta motor for a 3 phase and use a piece of 1/4" plate to act as an adapter. I have not seen the new motor yet, so I don't know how easy this will be to do. I was planning to bolt the motor to the adapter plate and bolt the adapter plate to the gearbox. But if that doesn't work, my backup plan was to simply weld my plate to the new motor baseplate and then drill the mounting holes where they need to be.

 

[Damon L.]

They do make adapter plates:

43-802 Motor Adaptor Bracket For Right Tilt Unisaws

www.renovoparts.com

Personally, I would have the original RI motor rebuilt as it is most likely leagues better than any new motor you could put on there. Lots of Unisaws out there that pass the nickel test with their original motors.

 

[Damon L.]

If you really want to use a new motor, and I assume you have fab skills. Look here:

Alternate Motor Mounts for Your Unisaw - VintageMachinery.org Knowledge Base (Wiki)

wiki.vintagemachinery.org

 

[Tim in Indiana]

I've done exactly the same three times to replace a Unisaw motor. Worked fine each time. Cut off the old, cut off the new motor plate, weld on the original.

 

[Firebrick43]

Isn’t the original motor a 145 framed motor?

 

[rslaback]

Isn’t the original motor a 145 framed motor?

Yes. The original motor has a 1 piece 145 base on it that seems like it could easily be removed and welded onto a new 3hp TEFC.

 

[rslaback]

I've done exactly the same three times to replace a Unisaw motor. Worked fine each time. Cut off the old, cut off the new motor plate, weld on the original.

Any tips?

 

[rslaback]

They do make adapter plates:

43-802 Motor Adaptor Bracket For Right Tilt Unisaws

www.renovoparts.com

Personally, I would have the original RI motor rebuilt as it is most likely leagues better than any new motor you could put on there. Lots of Unisaws out there that pass the nickel test with their original motors.

The original rear bearing seized causing damage to the rear plate, the main shaft and heated the motor enough to melt the coating off the windings. It's not worth a rebuild.

 

[Firebrick43]

Yes. The original motor has a 1 piece 145 base on it that seems like it could easily be removed and welded onto a new 3hp TEFC.

Didn’t realize there were 3hp 56 frame motors. Most I have seen stop at 1.5 hp and a few 3ph at 2hp. Wonder if you got one of the “compressor” motors that Hp claims are make believe? What is the FLA on the motor nameplate?

Most steel case motors are not that hard to disassemble partially but not many allow the stator/field windings to come out easily as it has to resist and transfer the torque of the motor to the base. I would not weld on a motor frame unless the stator was out or was going to be rewound.

 

[The Cobbler]

Following along, I've wondered this myself. wonder if you could blow some air thru the motor to help keep it cool?

 

[Firebrick43]

Following along, I've wondered this myself. wonder if you could blow some air thru the motor to help keep it cool?

The slots where the winding route thru the core are not going to allow air to flow through them. And that the rub. If the wires closest to the outside of the frame get to the melting temp of the varnish, game over. And that is the opposite side where the air would be blowing through the center

The more common f class varnish is good to 155 Cand H Class varnish 180 C

 

[PCustoms]

If I absolutely had to do this I'd look at tearing the motor down to avoid any inadvertent issues.

But I can't think of a reason to not use an adapter in this case.

 

[joe49]

Mig or smaw? Very short welds like 3/8'' and immediately cooled with compressed air till you could lick it each time and skip around. Remember cooled till you can lick it each time before you move on.

 

[rslaback]

Mig or smaw? Very short welds like 3/8'' and immediately cooled with compressed air till you could lick it each time and skip around. Remember cooled till you can lick it each time before you move on.

MIG was the plan. I was thinking basically tacks on top of tacks. That's the only way I can stack dimes anyway.

 

[rslaback]

Didn’t realize there were 3hp 56 frame motors. Most I have seen stop at 1.5 hp and a few 3ph at 2hp. Wonder if you got one of the “compressor” motors that Hp claims are make believe? What is the FLA on the motor nameplate?

Most steel case motors are not that hard to disassemble partially but not many allow the stator/field windings to come out easily as it has to resist and transfer the torque of the motor to the base. I would not weld on a motor frame unless the stator was out or was going to be rewound.

14 to 15 amps

 

[Firebrick43]

NEC single phase table 430.248 have 12 amps for 2hp and 17 for 3hp so it’s not too far off.

 

[rslaback]

If I absolutely had to do this I'd look at tearing the motor down to avoid any inadvertent issues.

But I can't think of a reason to not use an adapter in this case.

I believe the adapter makes the motor hang down just a bit further in the cabinet which can mean the need for longer belts and possibly having to modify the cabinet.

 

[PCustoms]

I believe the adapter makes the motor hang down just a bit further in the cabinet which can mean the need for longer belts and possibly having to modify the cabinet.

V link belts

Got a pic of the two motors?

 

[rslaback]

V link belts

Got a pic of the two motors?

Sure.

 

[whateg01]

If your adapter is made with the new motor's mounting flanges out to the side, it looks the offset is pretty close to the same. Just a matter of everything clearing the cabinet etc.

 

[no704]

The clear answer here is that you must buy a laser welder to prevent overheating that motor when welding it!

 

[Andy1234]

I've done it multiple times via MIG welding.
Clean the old paint off, have a good (clean) ground that's as close as possible to the weld, and then do a series of tack welds. Take your time, and space them out; the key is to keep the motor housing from getting hot enough to melt the insulation/varnish off the wires inside the motor.

 

[rslaback]

Upon further inspection, this just got much easier to accomplish.

 

[rslaback]

Don't even have to fill in the old plug weld holes.

 

[The Cobbler]

is your plan to drill the bracket & bolt it in place?

 

[rslaback]

is your plan to drill the bracket & bolt it in place?

It was. But the thinness of the housing is making me nervous for a motor that hangs from the bracket.

 

[rslaback]

It was. But the thinness of the housing is making me nervous for a motor that hangs from the bracket.

I'd say it's pretty safe to weld it on without overheating the windings.

 

[Firebrick43]

I'd say it's pretty safe to weld it on without overheating the windings.

I would say so. Makes me really question the Motor name plate ratings however.

 

[rslaback]

I would say so. Makes me really question the Motor name plate ratings however.

Not too much different than the OEM motor windings.

 

[Firebrick43]

Not too much different than the OEM motor windings.

The pic makes the od of the stator look much smaller on the new motor?

 

[whateg01]

From the pics, I disagree. Looks like there's more space between the windings and the case than the windings are thick on the new motor. Old looks to be twice as massive.

On the upside, the motor will burn up before the bearings go out!

 

[rslaback]

Didn't even need to weld it.

 

[The Cobbler]

might be a lot of torque for just a hose clamp?

 

[rslaback]

might be a lot of torque for just a hose clamp?

The hose clamps are just so I can install it and find what I think will be the best clocking position to avoid having to cut the cabinet. If it was permanent I'd use duct tape too.

 

[rslaback]

From the pics, I disagree. Looks like there's more space between the windings and the case than the windings are thick on the new motor. Old looks to be twice as massive.

On the upside, the motor will burn up before the bearings go out!

The new motor has the winding returns much more toward the center while the old one has them further out. But the actual windings are about the same size and roughly the same diameter. The through hole for the stators on both motors look to be the same diameter.

 

[Damon L.]

That factory bracket is way different than the ones on my (67) Unisaw. Mine are just plates welded to the case.

I would have no problem doing what you are doing, personally. Plug weld that bracket onto the new motor.

 

[rslaback]

Got it clocked to where I like it. Looks like all that's left is the sparky bits.

 

[no704]

Burn it in!