Killed ANOTHER motor

J

joe_m

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It's turning into another cr@ppy day here in the desert. The dead machine this time is my Powermatic 8" Jointer, 1HP 115/230 motor wired for 230, probably made around the time JFK was President. I ran it for 5 minutes today and it was fine, came back to it 20 minutes later and it just hums very loudly.

I unplugged it, bypassed the switch and plugged it back in again - same thing.
I turned the belts by hand and they moved smoothly, but I took them off to try it without any load at all - still just a large hum.
Turned it on and tapped the capacitor a few times, still just a loud hum.

Each time I turned it on and just got a hum, I only kept it on for under five seconds but when I gave up fiddling with it and decided to take it off the mount it feels hot to the touch.
It's got a 3/4" shaft with a 2-groove pulley on it and that pulley moves very easily - the motor isn't binding.

What did I do? There are no motor repair shops in this town. The guys at the electrical supply store are just salesmen. I know nothing about electricity and I know more than they do so going for local help is out of the question - I'd have to drag it up to Tucson. I can order a new one at Surplus Center online for under $200 but they don't have anything that size/speed (or slightly bigger) with a 3/4" shaft and the biggest spare I have sitting in my shed is only 3/4 HP.

Please advise....
 
sssfox said:
Those salesmen should be able to sell you one of those.
Click to expand...
Thanks, but the last time I went in to see them I said "I"m wiring a VFD and I need - " And the guy at the counter says "What's a VFD?"
Before that I needed a switch for flipping power between two different 220V outlets. I explained to the guy what I needed and was told such a monster didn't exist. While he was cutting me some new cord so I could make a 220V extension cord, I wandered his two 10' long aisles and found my non-existent switch on display.
To be fair, they probably only exist to provide electrical supplies to people wiring houses - that's where I got the new panel, riser, cap, ground cable when I had the house upgraded to 200 amp. Of course while the electricians were dismantling my old panel I had to run back into town to get the correct size riser, cap, and ground because what they said was county code didn't quite mesh up with reality.

So I don't have a warm fuzzy feeling inside that they will be able to provide me with the correct capacitor on a 50 year old motor and I'm sitting here with another 150 bf of walnut to surface so I guess it's a trip to Tucson on Monday.
 
I found a 2hp motor online that might work. (surplus center part #10-2619) It's got the power and it's the right speed, right direction of rotation - and they've got the right sized 2-groove pulley for another $12 so I might be in luck. At first I was confused by the "compressor duty" description but now I understand that this is a fancy way of saying it's heavy-duty, not that it will only work for running an air compressor. So I'll probably just order it tomorrow and be done with it rather than trying to repair the vintage one. That way I'll have a new motor and the tool should last another 50 years. Plus it will have more power which is good because an 8" jointer really needs 1.5 or more HP and the original just had one.

Joe
 
Joe,
pull the start capacitor out and go shopping with that in your hand. At least you will be able to stick something under the salesmans' nose in answer to their blank stares.
Also here in Aus, auto electricians carry a lot of mains connected small motor repair stuff. Maybe also try an electricial contractor? Or do you have a handyman guy in town who fixes all sorts of broken stuff for people not so inclined?

Cheers Phil
 
HARV shops too. Large AC units have start caps and you can also order them on Ebay cheap too. If you will take the cover off of the side of the motor and write down what is on the cap we can direct you to a suitable replacement in no time at all. Before you swap the motor, did you try to start it like an old rope start lawn mower? If the start cap is bad you can do that and the motor will spin up and run, it might just save you some money. Or you could get the new motor, repair this one and have a ready spar handy for the next machine that lets you down on a Sunday... Just some thoughts.
Bob
 
I've seen wood chips or sawdust get between the contacts of the centrifugal switch. When then can't come together, the main windings just hum and heat up. Try a good blow from a compressor all around the motor (outdoors). There's probably lots of dust in there anyway.
 
Rbeckett said:
. Before you swap the motor, did you try to start it like an old rope start lawn mower? If the start cap is bad you can do that and the motor will spin up and run, it might just save you some money.
Click to expand...
That's one of the reasons I think the windings are the problem,not the capacitor - I did try to give it a helping spin but it didn't work. (The other reason I think the capacitor wasn't the problem is that the motor housing was very hot to the touch all the way around, but the capacitor wasn't.).

It may all be working out to some sort of warped karma. I bought the tool a couple of years ago because it was so much bigger than the little 6" benchtop one that I had. I put the tool it replaced in the shed until last month when I listed it on Craigslist. It didn't sell until this morning. The guy said he was on the way before this one broke, and got here just after I'd finishe dismounting the broken motor. And the money he paid for the old one will cover most of the cost of the new motor and pulley.

I'll get the new motor on - that's my focus right now because I've got rough lumber piled all over the shop. Then I'll take the old one apart to see if I can find the problem, or get enough info to track down replacement parts for it.

Thanks for everyone who responded.

Joe
 
Rbeckett said:
... did you try to start it like an old rope start lawn mower? If the start cap is bad you can do that and the motor will spin up and run, ...
Click to expand...

Some motors are also cap. run. So if the cap is bad it wont keep going i am led to believe.

joe_m said:
...the motor housing was very hot to the touch all the way around, ...
Click to expand...

If the motor isnt spinning it will heat up pretty quick.

Cheers Phil
 
As I mentioned in the OP, I did try to crank it by hand and it didn't start. I also bypassed the on/off switch so that wasn't the problem.
New 2HP motor is on the way so in the meantime I started playing with this one. I took off the capacitor cover and found this on the capacitor:
LTW 34010 340-408 MFD 110VAC 60 Cycles Cornell-Dubilier FC.

The first thing that struck me as odd is the 110VAC. The motor is 110/220 currently wired for 220. Is it possible someone swapped the original out for this one, and then a future owner rewired it for 220 but didn't change the capacitor? Or are capacitors wired to just pull from one leg of the 220V circuit? I can't tell if the capacitor is original or not - it was very clean but so was the inside of the housing.

I went looking for a replacement and I can see the 340-408 110V/60A with the same external measurements as mine will be less than $10, that's good. I also found a link online on how to check a capacitor: http://www.wikihow.com/Check-a-Start-Capacitor so I'll do that when I get the time.

Joe
 
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