Table Saw Trouble!?!

[Bill Grumbine]

Good afternoon all

Today I was happily ripping and crosscutting on my tablesaw when it began to cough up blood, and it is near death. (Now for those of you reading this thinking I hurt myself, I write figuratively). The saw is a 1954 Delta Unisaw, with the triple vee belt drive. The belts are in good shape and are as snug as they should be. The motor began to stall as I was feeding the wood through the blade. I let up on the pressure, and it came right back up to speed. This happened a few more times, and then it did not come back up to speed, but just sort of moaned along at reduced speed and would no longer cut.

The problem is not in the blade, which is nice and sharp. The motor is the original, and is 49 years old. What should I look for, and what is it likely going to involve? The motor and frame are a different size than what is currently on these saws. Am I looking at repair, replacement, do I need an adapter of some sort, and is this going to be a major pain in the rump roast?

Thanks for any ideas and suggestions.

Bill

[Jim Becker]

Bill, I agree that the motor is at issue and suggest you remove it and take it to a motor repair shop. They can probably quickly determine what the problem is and either fix it or help you find a replacement with the proper frame type. You may just need a new component or a rewind.

[Carl Eyman]

Call your nearest motor rewind shop give them the motor specs on the phone and see what they will charge to rewind. You well may be able to get a new motor cheaper, but this saves you the hassle of mounting adapters, etc.

Before telling them to go you can be checking other motor sources. Are you familiar with Grainger? They have an online catalog which may indicate wether theyhave motors of a frame size to fit. Their paper catalog lists frame sizes giving the dimensions of mounting holes, shaft diameter, centerline distance of the shaft above the base etc. It is down at my shop, but if it will do you any good, give me the frame specs and I'll look it up tomorrow. Carl

[Randy Gleckler]

Bill,

I would guess it was the motor two (though I am in now way an expert). However, while I was recently looking for a motor for my new unisaw (new to me), I found a rebuilt one for about 1/2 the cost of purchasing a new one. Although over on Old Woodworking Machines.com they have some specs where you can get less expensive motors and built the adapter for the motor. I would suggest just having the old motor rebuilt. Good luck..


Randy

[Dan Stuewe]

Sounds to me like unbeknownst to you, you walked through a transporter and ended up in my garage and are using my tablesaw!

[Jim DeLaney]

Bill,
The problem is most likely within the motor, but it may not be dead yet! Even though it's a 'sealed' motor, it may still have gotten enough dirt into it over the 49 years to clog up the start switch. Since it's no longer coming up to speed, it may well be dirt/corrosion in the contacts on the start windings Removing the end cap and blowing it out with compressed air may help. Cleaning the contacts with emery cloth may also help.

Assuming all the wiring connections are good, it could also be the start/run capacitor - the 'can' on the side of the motor.

Don't give up on it - have it rebuilt if necessary. It'll be a lot cheaper than a new motor.

Unisaws use a proprietary motor type, with the (unique) mount welded to the motor frame. A new Baldor for a Unisaw (only aftermarket available in 3 hp, if I recall) is about $350.00. A new Delta motor will be a lot more.

Make sure you check all the power connections - from the plug, through the switch, to the connections on the motor itself. A loose or corroded one could be causing your problem.

Good luck with it!

[Mark Mandell]

Bill,

Got a 1.5hp "Bullet" motor?

Helped a friend "restore" his Dad's 1938 Uni. Installed a new Baldor @ $350+/- and had to do a bit of sheet metal to give clearance to the beast. Fired his up and learned that there IS a difference in 3 hp motors; that Baldor is half again the size of the asian in my JET. Torque (read applied cutting power) on the new one is phenominal.

If you can SIGNIFICANTLY beat the price with a motor repair / rewind, do so. Otherwise, I'd be happy to help you refit your saw. The motor bolts right in with no adapters needed. Only thing will be swing clearance.

I'll show you at the picnic.

Mark

[Bob Lasley]

Bill,

Jim hit alot of good points. While you're checking connections, check the circuit feeding the saw as well. Bad breaker, broken wire, bad receptacle can all cause problems. Sometimes you can measure adequate voltage with these problems under no load, but lose it when the load is applied.

Good luck,
Bob

[Bob Oswin]

Good afternoon all

Today I was happily ripping and crosscutting on my tablesaw when it began to cough up blood,

Thanks for any ideas and suggestions.

Bill
Don't do anything till you have blown it out with compressed air and changed the capacitator. Its in that big can on top of the motor.
The bearings may be shot. Try oiling them. If this helps replace the bearings.

After this take it off and get an expert opinion.

Good luck!

Bob

[Carl Eyman]

Did you stick your nose down close and sniff? If you smelt burnt insulation, you almost certainly have burnt windings. Of course, a burnt out capacitor smells about the same, but if you are directing your nose to the inner part of the motor, you are probably smelling windings. From your description of the failure that is what I suspect. LOL

[Glenn Clabo]

Bill,
Can you change the brushes? I think them old motors are different but it sounds like it may just be the brushes are worn.
Worth a try...it's much cheaper.

[Jim Becker]

Can you change the brushes? I think them old motors are different but it sounds like it may just be the brushes are worn.

Induction motors don't sport brushes. Only the noisy Universal motors typical on smaller tools have them.

[Glenn Clabo]

Not brushes exactly like we think. As I remember the lesson I got from an old electrical guy...and I ain't no expert...strictly a mechanical guy...but I believe the old time motors on Unisaws have a squirrel-cage rotor which consists of thick conducting bars embedded in parallel slots which are short-circuited at both ends by means of short-circuiting rings. A wound rotor has three-phase, double-layer, distributed winding. It is wound for as many poles as the stator. The three phases are wyed internally and the other ends are connected to slip-rings mounted on shaft with brushes resting on them. The brushes are connected to an external resistance that does not rotate with the rotor and can be varied to change characteristics. In fact an Induction motor can be compared with a transformer because of the fact that just like a transformer it is a singly energized device which involves changing flux linkages with respect to a primary(stator) winding and secondary(rotor) winding.
Once again...don't trust me on it...talk to a real motor guy.

[Phil Phelps]

I grew up on the '49 model Unisaw here at the shop. All the years of great service, it was always uderpowered. When the motor died in '76, I replaced it. But, I think the frame only alowed me to raise the HP by half. It is still uderpowered. If, indeed you replace the motor, see if you can't bump it up to at least 3 HP if it wasn't already. Your motor look like the one illustrated? We'll be anxious for the results. Good luck.

[Bill Grumbine]

Thanks everyone for the ideas, plans of action, etc. One thing is for sure, whatever is going to happen probably won't until after this particular weekend, or maybe during the weekend. ;-) I've got a big piece of furniture to spray, and I was fortunate in that I was able to cut out all the tap handle blanks I need for a regular turning job, so I'm set for the next week. And, next week is filled with turning students, so the saw will be sitting idle anyway. If it was going to break, this was a good time.

For those of you coming to the picnic, we can discuss options while examining the beast. I would like to keep the original motor if possible. The cabinet has a cast iron motor cover, so messing with that won't be fun if it comes to it...

For the rest of you, stay tuned for the exciting conclusion...

Bill

[Paul Geer]

Glenn's right about this one except they are brushes, we have the same saw in one of our shops, one day the motor got hot enough to start smoking, I removed the covers on the end to see what happened and saw 4 sets of brushes. The motor man we deal with called the motor a general purpose type.

[Ken Garlock]

the electric motor warehouse. It is well recommended by Bill Pentz as a source for cyclone blower motors. They have a series of Leeson motors for cabinet and contractors saws.

Electric Motor Warehouse (http://www.electricmotorwarehouse.com/woodwork_motors.htm)

I have never used them, and only know them through the comments of others.

[bretgreen]

What you need is to get new brushes for your motor. A good motor rebuild shop should have exactly what you need. While you have the motor case cracked open you should ask about having the berrings replaced. It sounds to me like you have an original RI motor. Hopefully that is all it is.


Good afternoon all

Today I was happily ripping and crosscutting on my tablesaw when it began to cough up blood, and it is near death. (Now for those of you reading this thinking I hurt myself, I write figuratively). The saw is a 1954 Delta Unisaw, with the triple vee belt drive. The belts are in good shape and are as snug as they should be. The motor began to stall as I was feeding the wood through the blade. I let up on the pressure, and it came right back up to speed. This happened a few more times, and then it did not come back up to speed, but just sort of moaned along at reduced speed and would no longer cut.

The problem is not in the blade, which is nice and sharp. The motor is the original, and is 49 years old. What should I look for, and what is it likely going to involve? The motor and frame are a different size than what is currently on these saws. Am I looking at repair, replacement, do I need an adapter of some sort, and is this going to be a major pain in the rump roast?

Thanks for any ideas and suggestions.

Bill