Jet jointer motor

[Daniel Shryock]

Hey guys, motor question for ya:
being given an old jet jointer (forgot to write down model, 6inch 1hp maybe 10 to 15 years old) but the motor doesn't really want to turn. Any recnditioning of it that I could try? Or will a motor out of a crafsman table saw wrk as a replacement (1.5 hp direct drive)?

Typing frm mobile device so please forgive me for being brief ;)

[glenn bradley]

First guess. Starter capacitor. The motor or the manual should spec the type required. You can generally prove this (before heading to the store) by giving the (switched off, belt removed) motor a spin and then applying power. If it runs, then the starter cap is a good bet. The starter cap does just what it sounds like; it give a push to the motor to get it in motion. Some motors also have "run" caps but let's no go there yet.

[Tom Veatch]

Glenn's probably right. Could you be a little more specific about "motor doesn't really want to turn." How does it act? What does it do - or not do, as the case may be.

[Daniel Shryock]

Sounds like a good guess. Turning it on gives a jolt but seems "stuck". Won't be able to look until sunday. Simple enough to replace I hope? And out of curiosity, would the craftsman motor swap be an option? Just have to out a pulley on maybe?

Thanks a lot for the help by the way!

[Daniel Shryock]

That's why I apologized for being brief :) but it seems to wan to turn, maybe turns once or twice and rocks a little bit. Hopefully that makes sense. Oh and wheni say "it" I'm referring to the cutterhead

[glenn bradley]

Still sounding like a cap so far. Take the belt off so the cutter is out of the equation. If you grab the pulley and give it a spin will it make a revolution or two and coast to a stop? If not we may have other issues. If so, give it a spin and while it is still moving (like within the first turn if possible) apply power. If it takes of and runs; cap. If it slows to a jogging stop; you exhausted my voluminous motor knowledge.

[Tom Veatch]

The craftsman motor could be an option. The deciding factor, in my book, would be if the frame size and rpm are the same between the two motors. If they are, it should probably be a simple bolt-on swap. If not, it could be much more complicated. Frame sizes and RPM should be shown on the motor's dataplate. I'm assuming the motor, coming off a table saw, would be appropriate for a jointer application.

Typically, in my experience, at least, if the start cap is bad, the motor just sits and hums but if CAREFULLY given an starting spin manually it'll pick up and continue running -maybe with a cord wrapped around the pulley like a pull start gas motor, if it can be done safely. It should go without saying, but remove the belts so the cutter head isn't powered before monkeying around with it.

Note, the motor is probably drawing Locked Rotor Current which is several times greater than the Full Load Amperage rating of the motor, so if you leave it turned on without it coming up to rated speed for longer than a few seconds, you'll likely trip the circuit breaker and/or risk further damage to the motor.

[Neil Davie]

The starting cap is the obvious first place to look, the second is the contacts inside the motor housing that hook the cap up. I recently bought a Grizzly drill press with 1 1/2 hp motor that didn't start reliably out of the box. They sent another that worked worse. The third worked fine. Afterword, I opened the other two motors and fixed them easily by bending the starting contacts to make and break correctly. I used an ohmmeter to check things out prior to closing things up.
Good luck!

[Daniel Shryock]

Thanks for all the input guys! I'll have to wait until a week from sunday to test this (thats when I'll be picking it up). I'll let you know for sure how it goes.

Assuming it is the starter capacitor, what does the replacement involve? Some soldering or is it bolt on kinda stuff?

[Daniel Shryock]

found this great resource - answered my last question :)

http://liutaiomottola.com/Tools/Motor.htm#mozTocId331889

anxious to start diagnosing...

[Tom Veatch]

Assuming it is the starter capacitor, what does the replacement involve? Some soldering or is it bolt on kinda stuff?

May have to cut and strip some wires, but I've used wirenuts to connect in the replacement and some have had screw terminal connections. Probably be obvious how to make the connection when you get the cover open.

Typically, the capacitor is inside that "bump" on the motor. A couple of screws hold the cover on. There may be two "bumps" or two capacitors under one cover. If so, there's a run capacitor as well as a start capacitor. Most of the time, when I've had a start cap go bad, it started leaking electrolyte. That would make it obvious which one is bad if there are two.

Two things to watch out for with replacing the cap, especially if you go with a local procurement. First the physical size must be compatible if it's going to fit in that recess and under the cover. Second, the electrical size, the MFD and voltage rating, needs to match the values on the original capacitor.

It's not a difficult task to replace the capacitor, and since it's all AC, there's no capacitor polarity you have to be careful of.

[Chip Lindley]

Daniel, concernng that Craftsman TS flex-drive motor, if it has a shaft diameter compatable with your jet motor pulley, you can certainly use it as long as the base allows you line it up with the cutterhead pulley. I assume both motors are 115v. 3450 rpm. Same motor rotation is the other factor.

But, sounds like a new start cap. will fix your problem. Keep us posted!

[Daniel Shryock]

I got a chance to run over there today. turned it on again, and after a second of humming, it started right up. turned off and on a few times and seemed to be working fine. So with my basic knowledge of such things, I'd say the starter cap sounds like culprit but is still somewhat functional and should be replaced?

fyi it is a green jet jj6cs "longbed", 3/4hp. anyone know much about these guys?

[Tom Veatch]

You can, of course, do what you're most comfortable with, but if it were in my shop, and didn't start immediately when switched on, and assuming everything else looked good, I'd replace the capacitor.

During that time it's humming and not running, there's a mess of amps running through the windings. Maybe not long enough to trip the breaker, but maybe long enough to cause incremental, cumulative damage. Start caps are cheap, on the order of $10.00 or so last time I replaced one, and are easy to replace.