Table Saw motor upgrade

[blueman]

I have a 20 year old 10" Craftsman table saw with a 13A/1.5HP (3HP "Peak") motor.

I am finding that the saw seems to bog down when ripping even 3/4" plywood (let alone hardwood) despite the fact that the saw is now near perfectly aligned (via a dial-indicator) and I have upgraded to machined steel pulleys and a link belt.

Part of the problem may be due to the fact that the upgraded pulleys are 2.25" and 2.5" vs. the original 2.5" and 2.5".

But that aside, how hard and expensive would it be to upgrade the motor?

- Any suggestions of where and how I could find a good motor (and be sure that it is a quality replacement)?

- Could I get a (meaninfully) more powerful 110V motor (it is on a 20A circuit) or would I be better off getting a 220v motor?

Thanks!

[blueman]

If it is any help here are the specs of the original motor Model:820030 Mfg Model: T55HK-499 13A/1.5HP 3450 RPM

[Limp Arbor]

Anything else change like the location and/or the outlet/extension cord?

If I'm using this calculator correctly you could be loosing about 10% at the blade with the pulley change.

[Leon]

Is the blade clean and sharp?

As mentioned by some one else, make sure you are not using an extension cord and or use one that is of proper gauge and length. I had the same problem on a 1983ish model 1 hp Craftsman. I simply aligned the saw and put a sharp good to premium quality blade on the saw.

I would suggest going to a premium quality saw blade, the Forrest WWII "regular kerf" 40 tooth would not be a bad choice. Regular kerf because I learned a premium quality regular kerf blade will cut faster than a lesser quality thin kerf blade. The regular kerf will yield better results than the thin kerf also.

If you still need help go to the bigger motor. The blade will be a great investment regardless if you still have to upgrade the motor or not.

[Lew Hodgett]

If the motor can be reconnected to operate on 240V, do it.

If not, replace motor with largest 56 frame, 240V motor that will fit and use existing motor for another application.

Trying to operate a T/S at 120V is a down hill adventure.

It's a loser all the way.

Lew

[Jim Weisgram]

Most certainly. Are they arranged so that your blade is spinning faster (hence less torque available) or slower (more torque)?

What kind of blade are you using? That could make all the difference. Do you rip with a rip blade, combination blade, or what? Thin kerf? Carbide, I assume? Is it sharp?

With your contractor type saw, you could perhaps upgrade to a 2 HP motor, and probably not a 3 HP. Is that extra 1/2 HP meaningful? Marginally, I'd guess.

A 2 HP 110V motor would likely trip your 20 amp circuit breaker now and then, by the way. You'd be better off using 220V, or a 30 amp circuit (which means 10 gauge wire).

Grizzly sells motors and I suppose they are the same as in their table saws. I've never heard anybody complain about their motor quality. I have several Grizzly tools and they serve me well.

Here's their catalog page with motors listed.

'd be looking at $240 plus shipping, I think.

I wouldn't do it, without first making sure about the blade(s) I am using.

[bridgerfafc]

look for the obvious: belts rubbing, motor wired for wrong voltage, dull blade, dirty blade, belt tension too tight/loose, motor running hot.... hmmmmm, what else?

[Artemus]

Assuming your saw did not bog down before your changes ... Then the upgraded pulleys are the logical culprit. If the 2.5" pulley is on the motor then you are now spinning the blade faster than it originally did and the available torque is less. Try putting the 2.25" pulley on the motor. The blade will spin a bit slower but the torque will be higher. This will make it less likely to bog down but your feed rate will be a bit slower than original. Art

"blueman" wrote ...

[Kevin]

For what it's worth, I have a very small Delta table saw (TS-350) with a 1 hp motor. It cuts 3/4 hardwood ply, 1.5" oak, etc. with absolutely no problem. It's well aligned and I use a sharp blade. It seems your problem should be solvable without going to a larger motor.

Kevin

[Tom Veatch]

No. You would be marginally successfully running a 2HP motor on a

120v/20A circuit. You could do it, but expect frequent nuisance trips when exercising the saw at its maximum power.

without a doubt!

But before you do anything, you should determine conclusively what is causing the low power of your saw. A number of things to consider have already been suggested. If you're running through an extension cord, that's the first place I'd look for the problem. Running 12 to 14 amps through a small gauge extension cord will definitely choke down the power available from the saw and likely cause a few breaker trips as well.

3/4 stock should not present a problem to a clean, sharp, well-aligned thin kerf blade on a 1.5 HP saw.

Tom Veatch Wichita, KS USA

[J. Clarke]

Agreed. Running my 1.5 hp saw on a 25 foot 14 gage cord and a 15 amp circuit it bogs during rips. Running it on a 12 gage cord and a 20 amp circuit it doesn't. Eventually it's going to have its own 220v outlet.

A 12 gage extension cord isn't horribly expensive and even if it doesn't help the saw problem it's a useful thing to have, so if it's on an extension cord that would be the first thing to try IMO.

Every Craftsman saw I've seen except the very cheapest ones can be rewired for 220 just by moving a few jumpers and changing the plug. Before buying a new motor I'd suggest trying to obtain a copy of the manual--you might have to do it in two steps--get the saw manual, find out what motors it took, then order the motor manuals. Check the motor and see if it has its own model number and if so you can get both the saw and motor manuals at the same time, if they're in stock. If the saw manual says "don't rewire for 220 even if the motor can be rewired" it's likely because their power switch only opens one leg of the circuit, which with 220 means that there's juice in the saw even with it turned off--if you ever need to poke around inside it and forget to unplug it you can get a shock--you can take your chances or you can order a 110/220v power switch from Grizzly for 15 bucks or so plus the cost of a handy box.

[blueman]

OK - a couple of follow-up questions:

1. The manual says "It is wired for operation on 120 volts, 60 Hz alternating curent. IT MUST NOT BE CONVERTED TO OPERATE ON 23) VOLTS.

Is this warning just do to the fact that the switch would be dangerous (unless it too were converted) as you mention above or could there be something fundamental about the motor here? Note: it was one of the higher end saws (about $500) when purchased about 17 years ago.

1. I could not find any reference to the motor by googling on the net. Again the specs on the motor are: Model:820030 Mfg Model: T55HK-499 13A/1.5HP 3450 RPM

Also, when I called Sears they couldn't help me out. Any thoughts on how I could verify that the motor is rewirable and then what I need to do to rewire it?

1. How big is the power "boost" when taking a given motor and rewiring for 220v? Will the difference be significantly better than just using 12 gauge vs 14 gauge cords?

i.e., will the difference be big enough to make the rewiring worthwhile?

Thanks, Jeff

[blueman]

I am running on a 20A/12 gauge circuit but I am using a "heavy duty" outlet strip with a 9 ft 14gauge cord (note nothing else is used on the circuit when I run the table saw). Also, I noticed that the table saw itself has about 6ft of 14 gauge wiring after the switch and maybe another 3-4 feet between the motor and the power switch.

Would I likely notice a *significant* difference by replacing the cord on the saw with 12 gauge and using a 12 gauge extension cord or outlet strip? All-in-all I would be replacing about 15-20 ft of wiring

Thanks

[Tom Veatch]

There is no power boost to the motor from the rewiring. Actually, the coils inside the motor see exactly the same voltage in either case. The coils in a dual-voltage motor are connected in parallel for the low voltage case and in series for the high voltage configuration. The voltage drop across each set of coils is the same in either case.

The only "improvement" from rewiring a dual voltage motor for high voltage comes from a reduction in the amperage flowing through the wiring that feeds the motor. The amount of transmission loss (voltage drop and power loss) is a direct relationship with the amperage. Double the amperage and you double the voltage drop in the wiring from the transformer to the wall socket. Since the power dissipated in the transmission lines is a function of amperage squared, doubling the amperage increases the lost power by a factor of 4. Likewise halving the amperage reduces the power loss to 1/4. However, this is only significant if the power loss at low voltage is significant. In the majority of installations, it is not.

In a few cases, transmission losses can be significant enough that going to a high voltage configuration will show a noticeable improvement in the motor performance. This can be seen most frequently when the motor is at the end of a high resistance wiring path; either very long wire runs or light gauge extension cords. It is most likely to be apparent in the motor startup. Since the amperage draw is much higher during startup cutting the loss in half can significantly affect the power available to the motor during the startup.

With that said, a direct answer to your question about whether it's worth it or not, is a big "maybe, but not likely". If you run the motor off of a long, light gauge extension cord, then you'll probably see a significant improvement. If your wiring is near code limits for voltage drop, then you may see noticeable improvement. In all other cases, it will be difficult to detect any difference in the motor operation.

Tom Veatch Wichita, KS USA

[Nova]

I'd ditch the outlet strip first. It might have a 14 gauge cord running to it but the internal wiring could well be smaller.

[Tom Veatch]

AWG 14 copper wire has a resistance of .002575 ohms/foot. AWG 12 is .001619 ohms per foot.

(Ref.

20 feet of 14 ga wiring with 20 feet of 12 ga wiring (actually 40 feet of conductor) would reduce the wiring resistance by .03824 ohms. Assuming a 15 amp current, you would gain about 0.57 volts at the motor. Significant? Probably not. However, during the startup surge you could be drawing on the order of 90 amps for a short period of time. Under those conditions, you'd gain about 3.4 volts at the motor. That could make a noticeable difference in startup performance.

Tom Veatch Wichita, KS USA