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Got a new motor for my 700 wards

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rambin

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#1
my lil 1/2 horse motor on my 700 has been loosing power for awhile and when taking a heavy cut it would buck and slip making a mess so ive had my eyes open for months looking for a cheap 3/4 horse... well it finaly happened 25bucks got me an older but I'm told unused 3/4 general electric motor.... shaft turned freely so I cleaned it up and installed it... the big capacitor just cleared the mounting bracket but I got it installed flipped it on and it runs like a charm... my question is when I got my lathe I replaced the missing power switch which is on the gear box as most on here would know... well with this being a 3/4 I would like to run a dedicated 220 circuit to it which means the switch wont work anymore its st/sp and would only turn off one leg of the power... room is really tight in there is there a dpdt switch that would fit? the reason I want to go dedicated as the outlet im in now is shared with prbly half a dozen other outlets in the garage, I havnt popped a breaker yet but it could happen if something else is being used in there at the same time.
 

Dave Paine

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#2
A picture would help folks like me who do not know what the present switch looks like.

I have some 240V dpdt switches which fit in the same space as 120V spst switches, but these look the same as light switches.
 

T. J.

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#3
There are double pole toggle switches that will fit. I have a 3 phase motor on mine, so I have a triple pole switch in that space - it really is a tight fit!
 

markba633csi

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#4
It's not really imperative to break both sides of the 220 v power unless it makes you nervous not to do so. The motor won't know the difference. As long as the machine is well grounded there shouldn't be any hazard. Obviously you wouldn't do any major electrical work on the wiring without flipping off the main breaker
mark
 

wa5cab

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#5
If it is as tight as you-all imply, regardless of what the NEC says, I'd question whether or not any switch that would fit would be safe. On a lathe, the motor switch should be capable of breaking the circuit to a stalled motor in case of a crash. And yeah, I know that most early lathe manufacturers who put the motor switch in the headstock didn't use a switch large enough for that. We had a long argument on the Atlas-Craftsman list on groups.io over meeting local and NEC rules versus being reasonably safe. Personally, if I had a lathe with the motor switch in the headstock, I'd remove it.
 

Bi11Hudson

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#6
I have never trusted the OEM switches on any machine tool. The simplist fix is to use a Chinese drum switch. Yeah, they look flimsy, but the one on my Craftsman 12X36 has stood up for several years. Mounted along the front of the machine anywhere convenient. Mine is on the drip pan. (home-made) Reversing would be an issue, it could be done but you would need to get creative. The big issue is to break both lines on 240. Do not try to run it with one leg hot anytime. That's a no-no of the highest order.

I have, and use regularly, a number of 2,3, and 4 pole switches. Probably half would physically fit your situation. But for a machine tool of any sort, they just won't stand up. Use something with large contacts. As stated above, the switch has to interrupt locked rotor (stalled) current. A lightwieght switch just won't do it.

There are a number of switches from W`W Grainger and the like that will handle motor currents. But the size is out of the question. They require at least a 2X4 box. They have a "heater" to time rate the starting current. And they get real expensive real quick. The Chinese drum switches are pretty cheap.

Bill Hudson​
 

rambin

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#7
the bull gear is dangerously close to the back of the switch and wiring..and every switch ive eve seen the wiring comes out the tail end of it.. **** poor design. I guess I will have to search amazon or someplace to see if I can find a very low profile dpdt. if I get a chance later i'll take a pic of my present switch it will prbly make some of you cringe its that close. not sure what the original one looked like it was long gone when I bought the lathe
 

markba633csi

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#8
In your case I would add a beefy relay/contactor to the circuit to do the actual heavy lifting, and control the relay's coil with your light-duty switch. Problem solved.
mark
 
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