Motor needed?

[Dudelive]

:icon_scraI have just got a table saw, craftsman [FONT=&quot]model # 113.298031[/FONT]. I was planning on fixing it up and when I got it and found out later that the guy before me had plugged it in and the motor smoked, although he said it ran except it hummed real loud and got hot just before it started to smoke .

So with that being found out after I had acquired the saw, now I am in need of a motor or rebuild or other suggestions. Was going to replace my 25 year old 10" shopcraft.

So suggestions as to anyone having a motor, or about the repair of this one.

Thanks
Dudelive

 

[merrill77]

I have a motor I acquired a few years back for a project that I never started. The plate says it is 110/220v 24/12a motor and is labeled as 2HP. The math on those numbers doesn't work out, though. I think it is from a central machinery saw (harbor freight). It is yours for what I paid for it - $30.

 

[Dudelive]

What is the frame size, rpm and shaft size?

You are right the numbers don't add up correctly.

 

[Gotcha6]

Actually those numbers are about right for a 2 HP motor. Good rule of thumb is 1 Kw per HP. 110 v @ 24 amps would get 2.6kw. Likewise for 220v x 12 amps. Using the motor on a 120 volt outlet should require a 30 amp breaker and 10 gauge minimum wire. You wouldn't see that much current draw until you had the saw at a full load such as ripping a thick piece of hardwood that was binding the blade. The kicker is that most household current in this country is 120 volts, and as such sometimes causes premature failure in 110v motors of the Harborius Freightus species. Earl Rasmussen uses these motors on some of his lathes but also incorporates a 120 to 110v transformer to protect them.

 

[ehpoole]

If the saw is equipped with an induction motor it is possible that the humming and smoke was from either a bad starting capacitor or from the centrifugal switch getting stuck 'on' which would cause the starter windings to remain energized long after the motor is up to speed (which the starter windings are not designed for).

Have you actually checked it the motor? Depending upon the motor -- and what was smoking -- there may or may not be permanent damage, so it is possible the existing motor may be repairable. If you opt to install a new motor, do not install a motor significantly more powerful than what the saw came with (doing so can damage the saw). I mention this because it can be very tempting to try and 'upgrade' the saw while you are replacing the motor.

 

[ehpoole]

As Dennis has stated, the expected running amperage for a typical 2HP induction motor is approximately 10-13A at 240V, and double that at 120V.

 

[Dudelive]

Dennis if I understand this correct then since I mostly use soft wood and have the shop wired already with 20amp outlets and breakers with 12 gauge wire then it would be borderline using it this way.

Hope there is another motor out there if this is correct.

 

[Dudelive]

If the saw is equipped with an induction motor it is possible that the humming and smoke was from either a bad starting capacitor or from the centrifugal switch getting stuck 'on' which would cause the starter windings to remain energized long after the motor is up to speed (which the starter windings are not designed for).

Have you actually checked it the motor? Depending upon the motor -- and what was smoking -- there may or may not be permanent damage, so it is possible the existing motor may be repairable. If you opt to install a new motor, do not install a motor significantly more powerful than what the saw came with (doing so can damage the saw). I mention this because it can be very tempting to try and 'upgrade' the saw while you are replacing the motor.

I don't have the schematic of the internal wiring of the motor. So I did disconnect the capacitor and give it a spin by hand and then plug it in while it was turning without load. It did keep running but there was a loud buzzing or humming and it never got to up to speed which tells me the run windings are shorted and I unplugged it very quick.

Thanks for the advice as not to upgrade to a larger motor although it is tempting.

 

[ehpoole]

Dennis if I understand this correct then since I mostly use soft wood and have the shop wired already with 20amp outlets and breakers with 12 gauge wire then it would be borderline using it this way.

Hope there is another motor out there if this is correct.

Please clarify whether you are referring to 120V 20A circuits or 240V 20A circuits.

You could safely run a 2HP motor off a 15-20A 240V circuit, but it would be unwise to do so at 120V as the motor's peak running load would be 24A -- well into the range that would overload your 120V circuits and potentially trip the breaker in mid project.

 

[Gotcha6]

Your biggest problem would be the same one I have presently. Using a 'Kenmore' table saw to which I installed an undersized emergency stop switch, the stop switch has a circuit breaker set @ 15 amps. If the motor gets in the slightest strain it trips the breaker on the switch. You will probably have issues with tripping the circuit breaker in the panel unless you rewire the saw and circuit for 220v operation.

 

[ehpoole]

I don't have the schematic of the internal wiring of the motor. So I did disconnect the capacitor and give it a spin by hand and then plug it in while it was turning without load. It did keep running but there was a loud buzzing or humming and it never got to up to speed which tells me the run windings are shorted and I unplugged it very quick.

Thanks for the advice as not to upgrade to a larger motor although it is tempting.

From your description it sounds as if the previous owner may have plugged a motor wired for 120V into a 240V receptacle (via a suicide plug).

 

[Dudelive]

From your description it sounds as if the previous owner may have plugged a motor wired for 120V into a 240V receptacle (via a suicide plug).

Darn I never gave that a thought but you may be right as my boss has a compressor that can be run on either 110 or 220 volts and all you do is flip a switch. He currently uses it as 110 and has the switch locked to prevent disaster.

On the motor plate of the saw motor there are no references to 220 volts, so that mat be what happened.

Maybe someone will pop in with a working motor for sell reasonable.

 

[Dudelive]

merrill77

• Re: Motor needed?
  I have a motor I acquired a few years back for a project that I never started. The plate says it is 110/220v 24/12a motor and is labeled as 2HP. The math on those numbers doesn't work out, though. I think it is from a central machinery saw (harbor freight). It is yours for what I paid for it - $30.
  ​

Thanks very much for the offer. Hoping someone has one that will not require rewiring of the shop.

Thanks
Dudelive

 

[merrill77]

Actually those numbers are about right for a 2 HP motor. Good rule of thumb is 1 Kw per HP. 110 v @ 24 amps would get 2.6kw.

I was using actual 746w = 1 hp. 12a x 220v = 2640. 2640 / 746 = 3.5hp. The plate rating is for power consumed. If the 2hp is implied to be the power delivered to the work, then the power loss from resistance, friction etc, is nearly 50%. Even HF motors aren't that bad - hence why I said the numbers don't add up. But, anywhere engineering and marketing meet, that is to be expected. Someday I'll get used to that :>

 

[ehpoole]

I was using actual 746w = 1 hp. 12a x 220v = 2640. 2640 / 746 = 3.5hp. The plate rating is for power consumed. If the 2hp is implied to be the power delivered to the work, then the power loss from resistance, friction etc, is nearly 50%. Even HF motors aren't that bad - hence why I said the numbers don't add up. But, anywhere engineering and marketing meet, that is to be expected. Someday I'll get used to that :>

More typical efficiencies run around 70-85%.

However, the bulk of your confusion stems from the mistaken presumption that watts and amps are interchangeable.

Watts = Volts X Amps X Power Factor
1.98HP = (220V x 12A x 70%pf [x80% Eff]) / (746W/HP)

Math doe not seem so awfully bad now, does it?

Have a great day.

 

[merrill77]

What is the frame size, rpm and shaft size?

3450 rpm
shaft is keyed and a tad under 5/8"

what's "frame size"?

 

[Dudelive]

After all the excellent advice that has been given here and even as much as I would be willing to try it, I just don't think it would be wise. There are too many wise people pointing out the problems of trying and things that can go wrong.

Thanks for the offer.

So I will just have to wait and find a closer match. Heck 3/4hp would not be a bad idea I don't think.

In answer to your question as to what is frame size....that is where and how it mounts to the equiptment. Mine is G56Z and as I understand the "56" is what is looked at I think.

 

[ehpoole]

In answer to your question as to what is frame size....that is where and how it mounts to the equiptment. Mine is G56Z and as I understand the "56" is what is looked at I think.

Most of the jobsite/cabinet saws usually aim for motors drawing around 12-15A at 120V, or about 1 to 1-1/2HP.

The 'Z' in G56Z generally means that there is something special about the shaft, either over or under diameter OR (more probably in this case) longer or shorter (most likely longer) than the standard 56 frame.

 

[Mike Camp]

Grizzly sells 1 and 1.5HP enclosed motors for around $200. They should fit any contractor style saw including yours. The 1HP should run fine on a 15A 120V circuit and the 1.5HP on a 20 120V circuit. At least according to Grizzly.

G2533 Motor 1 HP Single-Phase 3450 RPM TEFC 110V/220V
G2535 Motor 1-1/2 HP Single-Phase 3450 RPM TEFC 110V/220V

 

[Dudelive]

Have been looking at them and hoping to find a used one first. Although with a used one you have to say enough is enough and just bite the bullet. Something to think about.....thanks for the reminder.