Powermatic 87 Motor replacement

[Padizzledonk]

I have a powermatic 87 bandsaw, birthday is 1967. Its the metal working version of the Powermatic 81. Its basically a more robustly built version of the 81.

It has a 3ph 3hp motor on it now and i was planning on just getting a phase converter because i also have a Powermatic 68 12" tablesaw thats also 3ph, but I came across a 5hp 220 motor that has the same rpm, and found a similar 5 hp motor that has more or less the same rpm and hp as the 3ph motor on the tablesaw (+/- a couple 100 rpm) that together are less than the cost of the phase converter, not by a lot, but enough that I'm now leaning toward just swapping them out.

The problem is that I cant make sense of all these different motor factors... is a compressor duty motor adequate for these 2 applications? Farm Duty? What the hell is a "service factor" ? Is higher or lower number better? Whats the range im looking for? Duty cycle? Continuous? Common sense says yes, I want a Continuous duty cycle i guess because it will always be under load when its running? What kind of torque numbers should I look for? Is 15ftlbs good enough for a bandsaw or should it be higher or lower? Also, there are all these different motor start options, hard, soft, single or multiple capacitor, digital this or that.....

ugh....so out of my element with this stuff and the last thing I want to do is toss 900 bucks in the garbage for 2 motors that fall short of what I need.

I should mention that the bandsaw will be pretty much exclusively used for resawing hardwoods with a 1.25" blade. I am not concerned with it not being able to handle the extra hp or torque, the thing is a tank, its literally 1800lbs...the guide bar alone is about 30lbs and its no joke just a 30" long 2"x1.5" block of solid steel.

Any help is appreciated, thanks for reading

 

[Oka]

Without getting geeky about motors, the main thing you need is a commercial duty rated motor and the housing matches your current motor (the bracket and size are near the same). One important note- there is a lot of marketing BS on motors, the most important things are going to be: voltage/amperage motor housing type(see below), housing bolt up/attachment configuration and duty cycle.

A general statement about anything with a motor/mechanical operation: to make sure the tool lasts and stays in good opoerational shape, do not over drive the tool, think of a car motor. If the motor's max rpm is 8000 you would not run it at that speed and probably would back off between 5500-6000rpm because, it would sound like you are overworking the motor. This is true with anything. 65-70% is usually where you want to run the demand on the machine if it will be for long periods.

Farm rated usually means it can be washed down or can be exposed to weather. Compressor duty deals specifically with a heavy duty motor that can handle continuous start up and stop cycles (think of the duty cycle needed for an elec elevator motor).

Usually 1725 rpm motors have more windings and handle start torque needs better than 3450 rpm motors, general statement.

Motor service factor (SF) is the percentage multiplier that a motor can handle for short periods of time when operating within its normal voltage and frequency tolerance. In other words, it is a reserve factor that give extra horsepower when it's occasionally needed. A SF is an operational margin.

Here are the basic types and definitions:

The three most common types of mounts you will find are:

Rigid base: Is bolted, welded or cast on main frame and allows motor to be rigidly mounted.

Resilient base: Has isolation or resilient rings between motor mounting hubs and base to absorb vibration and noise.

NEMA C face mount: Has a machined face which allows direct mounting, bolts pass through mounted part to threaded holes in the motor face.

Motor code definitions

• Open Drip Proof (ODP)
• Weather Protected (WP1 / WP2)
• Totally Enclosed Fan Cooled (TEFC)
• Totally Enclosed Non-Ventilated (TENV)
• Totally Enclosed Air Over (TEAO)
• Totally Enclosed Forced Ventilated (TEFV)
• XP (Explosion Proof)

Hope it helps.

 

[Padizzledonk]

It did help actually. Makes sense. Ill scoop up this motor, its industrial rated and has all the right stuff that ill need.

Thanks a lot!

 

[bob vaughan]

Here's the manual.
Powermatic Machine Co. - Publication Reprints - Model 87 20" Band Saw | VintageMachinery.org
I checked the floor weight. Right at 1000 lbs. less motor. There must be a pretty heavy motor in your machine.
As to the motor, the manual shows a motor with an off-the-shelf Browning pulley so the motor size is going to be some standard size at least from the 1960s. Measuring the pulley bore will give a good hint as to motor frame size. I checked the printed archives and couldn't find a good frame size number. It will be on your motor's label. I won't even hazard a guess but I do have suspicions. Motor standard sizes changed in the 1960s and that has bit many 1960 machine owners on the ankle.