Delta Unisaw '40s, not sure what to do here.

[TheeChao]

Hello all,

Super new to the forum here.  Been woodworking for a couple of years now.  In the late spring a friend of mine gifted me his late grandfather's Delta Unisaw as no one else in the family woodworked.  I was super honored to receive such a legacy tool. Shortly after receiving it I attempted to rewire the motor from 230v to 115 as I don't have any 220v outlets in the shop at the moment (will be renovating and adding a number of 220v outlets next year).  In doing so I attempted to turn on the machine but it would hum for a few seconds followed by the breaker flipping. I'm thinking it could be a number of things (i.e. 115v motor vs. 110v/10amp wall outlet, maybe inspect the motor, ensure belts don't need to be changed).  After that I finally took a break to prioritize house projects.  Now that much of the in home projects are done I wanted to start at least doing some research to getting this saw back up.  I'm out of my league here and was hoping I could reach out for some help or background. Any help would be greatly appreciated.  Thanks all.

 

Best,

-Mike

[wtnhighlander]

Mike, there are a few possibilities.

1. Incorrect wiring connections. There should be a diagram on the inside of the motor's connection box, but they can be confusing.

2. Bad start capacitor. Those can-shaped objects attached to the motor housing are needed to create a phase shift in the electical windings, to allow opposing magnetic fields inside the motor to turn it. They are subject to deterioration from age, and failure often results in the symptoms you describe.

3. Mechanical binding. Did you see the saw run before you changed the wiring? With it unplugged, can you spin the arbor by hand? 

Start with those things, and post what you find. If there is still a problem, perhaps someone here that owns a similar saw can provide more insight.

[Mark J]

Welcome to the forum.  Lots of good information here.  I'll just share something I learned here.  Assuming you're in North America the standard for nominal voltages is 120 and 240.  Actual delivered voltage may vary a little, but that is what the power companies are shooting for. 

As a practical matter there is no difference between the terms 110V and 120V or between 220V and 240V (although the latter are more correct).  Similarly you needn't worry that a "115V" motor was connected to "110V" power.  It's all the same.

[TheeChao]

On 8/30/2021 at 3:47 AM, wtnhighlander said:

Mike, there are a few possibilities.

1. Incorrect wiring connections. There should be a diagram on the inside of the motor's connection box, but they can be confusing.

2. Bad start capacitor. Those can-shaped objects attached to the motor housing are needed to create a phase shift in the electical windings, to allow opposing magnetic fields inside the motor to turn it. They are subject to deterioration from age, and failure often results in the symptoms you describe.

3. Mechanical binding. Did you see the saw run before you changed the wiring? With it unplugged, can you spin the arbor by hand? 

Start with those things, and post what you find. If there is still a problem, perhaps someone here that owns a similar saw can provide more insight.

1. Wire connections are good based on the diagram on the plate of the motor.

2. Will have to inspect it when I've got a moment.  

3. Didn't see the saw run but when I attempt to pull the belts they want to spring back.  Not sure if that indicates anything though.  Will have to do a more thorough inspection.

Thanks so much for the insights.

 

On 8/30/2021 at 6:32 AM, Mark J said:

Welcome to the forum.  Lots of good information here.  I'll just share something I learned here.  Assuming you're in North America the standard for nominal voltages is 120 and 240.  Actual delivered voltage may vary a little, but that is what the power companies are shooting for. 

As a practical matter there is no difference between the terms 110V and 120V or between 220V and 240V (although the latter are more correct).  Similarly you needn't worry that a "115V" motor was connected to "110V" power.  It's all the same.

Noted on this.  Thanks so much for educating.

[wtnhighlander]

I believe the Unisaw uses a matched triplet of drive belts, which may have considerable tension. If the machine has been at rest for some time, the belts may have developed some "memory" for the tight radius of the arbor pulley. It might take a little force to get started, but once you move off that spot, it should rotate freely. If not, there may be something in a bind, or bad bearings in the motor or arbor.

IIRC, those Unisaw motors have an unusual mounting bracket cast as part of the housing. Makes replacement motors hard to come by / expensive. But a motor repair shop might be able to replace the bearings and even rewind it, cheaper than a new motor, shpuld it come to that.