Now what, a cooked motor? (Jet 1236)

[John Derbabian]

It looks as though my turning days are over now. Shortly after receiving my wings for consecutive launches from the lathe, the motor in my Jet is cooked. Anyone ever ordered/replaced a motor in a Jet JWL 1236?

Damn - I was so sure launch #4 was just on the horizon too. I guess I'll have to hold the countdown... :p

[Bernie Weishapl]

If that thing has a capacitor on it you might check that first. I thought I fried a motor on my first lathe and it turned out just the cap was bad. Got it for $9.36 locally.

[John Derbabian]

It started acting up on me prior to my last launch. I'd switch it on, you could hear the motor, but it didn't turn. I gave the chuck a little spin and off it would go. Once, somehow, it actually started turning in reverse. Now when I switch it on, the motor makes noise and nothing happens at all. I try to spin it up by hand and it still does nothing. The motor got very hot a couple of time and tripped the breaker once. That's all I needed. I shut it off and went to my room and cryed for a few. A couple of tasty ale treats later, I feel better. But short of buying a new lathe, I'd like to either get the motor rebuilt (if possible) or buy a new one.

[John Cooper2]

Think Bernie has this one nailed.

sounds like the start capacitor is fried.

[Don Eddard]

Yeah, based on the symptoms, it sure sounds like the start capacitor. Shouldn't be too expensive to fix.

[Ken Fitzgerald]

Based on the symptoms.....I'd bet on the starting cap and generally you can get them locally.

I'd also try blowing your motor out with a little compressed air.


Generally motors have a starting capacitor and a centrifugal switch. When you turn the motor on the switch is closed and the capacitor is in the circuit to provide a phase shift and cause the motor to start in a specific direction.

[John Derbabian]

Thanx guys. I did take the cover and fan off the end and blow the dust out of it. Where would I find the capacitor? Is it housed under the 'bump' on top the motor?

[GLENN THOMAS]

I had a lathe do exactly the same thing yours is doing. In fact it was a clone of the Jet 1236. Turns out the centrifugal switch came loose and slid up the motor shaft. If thats the problem all you have to do is reposition it and tighten it down.

GT

[Sam Yerardi]

John,

The capacitor will be under the 'bump' on the side of the motor. In your motor there are two windings - a start winding and a run winding. The capacitor is used in conjunction with the start winding to get the motor turning. Once it reach a certain speed, the start winding drops out of the picture and the run winding continues running the motor. When you said it started when you moved the belt, that indicates: either the capacitor is bad, or the starter winding is open (bad), or there's a lot of dust inside and it is fouling up the centrifugal switch that connects/disconnects the start winding.

The easiest way to check the capacitor is to either try it in another motor, or try a new capacitor in your problem motor. If you have a DVM or ohmmeter, you can check the capacitor as follows:

Unplug the motor
Disconnect the capacitor (one lead is enough for this test).
Momentarily short the two terminals (use a screwdriver for this - this removes any residual charge that could be there - typically there isn't anyway but I always do this out of habit)
Switch your ohhmeter to its highest scale
Apply the leads of the ohhmeter to the two terminals on the capacitor
Hold the leads on there throughout this test.
The capacitor will begin charging, and you will see the numerical value on the meter slowly begin climbing up
Eventually, that charging process will slow down.
What you are first wanting to see is - is the capacitor shorted or open? If it is shorted, you will read 0 on your meter. If it is open, you won't ever see it charge.
Second, does it charge like a capacitor normally would? If it gets to a number quickly and just stays there, it's probably bad.

This test is a rough go/no go test and is not completely conclusive but more often than not, it reveals very quickly if the cap is bad. What it doesn't show is if the cap is failing under heavy AC current which the meter doesn't supply.

You can also use the DVM or ohhmeter to check the start winding & switch wiring.

[Rod Sheridan]

Hi John, it could be the starting capacitor or it could be the centrifugal start switch.

The starting switch closes to run the start winding until the motor reaches aproximately 70% speed, then opens.

It's not uncommon for the centrifugal switch mechanism to stick due to dirt.

The switch mecanism will be on the shaft inside the motor, the switch contacts will be on a plate in the rear end bell. Examine the switch contacts also for arcing damage etc.

Regards, Rod.

[robert hainstock]

I'm certain this motor is identicle to the HF 34704 3/4 horse. I expect HF prices are better.
If memory serves, the centrifigal switch is there to open the power to the start winding when the motor gets up to speed. A simple continuity check would eliminate it. Good luck! :eek:
Bob

[John Derbabian]

Thanx for all the info guys! I really appreciate it. I won't get a chance to check it out until tonight. I need to get this thing up and running PDQ. I have a launch schedule to maintain!!! :D

[GLENN THOMAS]

Sent you an e-mail. Let me know if you didnt get it.

GT

[Paul Engle]

Factory mtr is 196$ plus frt.... look around for a rebuilder as the housing is made for them only, called propritetary .....

[John Derbabian]

Well, I checked out the two ideas that were presented - the starting capacitor and the centrifuge switch. On the cap, the guy at the counter used a meter that was labeled 'Capacitor Checker' and it showed a reading near equal to the rating on the can. I'm wondering (based on what Sam said) if this was a good, all inclusive test. Meaning that it placed a load on the cap. Man I sure hate to buy a new motor when is was just a capacitor. I'm thinking about just going ahead and buying the capacitor and trying it. If it doesn't work, well then the motor will end up costing me $10 or so more dollars. :rolleyes:

[Raymond Overman]

I would assume you purchased this more than 5 years ago? I'm not positive about the 1236 but WMH has a 5 year warranty on consumer lathes I think.

[John Derbabian]

Interesting because the web site states a 5 year warranty on the 1236, but the manual states a 2 year limited. Hmmmmmm....

[Tony Wheeler]

give them a call there real good about standing behind the products phone calls are cheap

[Paul Engle]

John, any other motor will not fit their lathe as the housing is spec made for them so you have to buy from them, you can have a mtr rebuilder rebuild but my guess from my last was ..... it is about the same price for the new, another motor will work but you will have to build own mounting plate, reeves drive , etc to get it too work. Let me know I allready went thru that, made my own mounting plate to fit DC mtr and converting to 3/4 hp DC Variable speed ( electronic control ) and using a HiLo var speed pully for the drive end and the Jet factory for the driven end.The spindle speed options are 25 rpm to 3000 and umlimited variation in between, needles to say I are very happy with this as I can now use my wood lathe for a horizontal milling machine on brass, aluminun, soft steel, etc and oh yeah .... wood.

[John Derbabian]

Well I got the motor back from service. Turns out it was a wire from the centrifugal switch that was rubbing and ended up being cut. Although the lathe was out of warranty (Jet started the 5 year warranty in the summer of 2006), a call to them resulted in a "No problem" response and they approved the work. I can't say enough about a company that stands behind their product, and goes the extra mile to make sure their customer is happy. I guess my flight status has been restored and now I can return to the 'launch' pad!!! :D Please fasten your seatbelts and return your tray to the upright and locked position... :p

[Scott Hubl]

Very COOL:cool: John.

Glad to hear they took good care of you.
I have heard more Good than Bad about Jet's or Powermatics CS.