LumberJocks

New guy. Need a new switch for my Unisaw

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by Airspeed posted 03-17-2013 02:30 AM 931 views 0 times favorited 7 replies Add to Favorites Watch
View Airspeed's profile

Airspeed

425 posts in 598 days


03-17-2013 02:30 AM

The 4 hp Leeson motor in my Unisaw recently let out its smoke, found a great deal on a new one but not sure if I should reuse or replace my mag switch. My saw came with a 4hp leeson motor and mag switch but I just found out the switch is rated for a 3hp motor. It’s rated for 20 amps and the circuit breaker it runs on is 20 amp and never blew until the motor burned up. Should I replace the switch or will it run my 4hp motor without damaging it? The saw is 1ph, 220, 4 hp running on its own circuit through 10 gage wire. I have a 20 amp on/off switch on hand but I’m wondering if it would be a mistake using it since it has no overload protection. Any suggestions would be greatly appreciated!

-- http://smg.photobucket.com/albums/v655/aaronhero/


7 replies so far

View Grandpa's profile

Grandpa

3190 posts in 1371 days


#1 posted 03-17-2013 02:59 AM

Topamaxsurvivor is one of the best when it comes to motors and controls. I would try to private mail him and see if he responds. I haven’t seen him on here in the last few days.

View TorxNut's profile

TorxNut

58 posts in 593 days


#2 posted 03-17-2013 03:24 AM

Your 4 HP Leeson should draw 17.6 full load amps so the 20A magnetic switch circuit should be just fine. I have a Unisaw with a 3 HP (13A) Leeson and the mag switch setup. The controller has heaters and an overload relay all built in. Are you sure yours doesn’t have the same?

Incidentally, I was originally going to put a 4 HP Leeson in my saw but I decided against it because I would have had to rewire the dedicated circuit to the saw (it’s 12 ga.) and people kept telling me that 3 HP would be plenty. People were apparently right as I’ve always had more than enough power to run a full kerf blade through anything I’ve thrown at it.

Bill

View TopamaxSurvivor's profile

TopamaxSurvivor

14905 posts in 2372 days


#3 posted 03-17-2013 04:35 AM

Thanks for the confidence GP ;-))

I would assume Unisaw used the proper starter for the motor when they manufactured the saw. With that said, your overloads should have tripped before the motor burned up. Hard to tell what you have and what the problem is or was from here. A 20 amp switch is not rated to operate a 3 or 4 hp motor.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Airspeed's profile

Airspeed

425 posts in 598 days


#4 posted 03-17-2013 01:36 PM

The 4hp motor that burned up and the mag switch werent original to the saw, the previous owner installed them. I bought a new Leeson 4hp because the 3hp was only a few bucks less, I just couldn’t settle for 3 hp after having 4hp for so many years. My mag switch didn’t protect the motor, when I opened it up there were broken chunks of plastic rattling around in it, the dial that sets up the amperage as well as the one for temp were adjusted to their max settings. I really need a new controller. I’m using the old one right now only because I’m working with pine right now and I’m not doing any heavy cuts but I want to replace it as soon as possible, as soon as I decide on a new controller. I found one for a 5hp motor and am wondering if it will work? Seems like all the controllers rated for 4hp are a couple hundred dollars, the one I found for a 5hp is only $50. If anyone can suggest a controller let me know! Thanks for all the replies! I appreciate it!

-- http://smg.photobucket.com/albums/v655/aaronhero/

View TorxNut's profile

TorxNut

58 posts in 593 days


#5 posted 03-17-2013 03:37 PM

Griz offers this 5 HP magnetic switch: http://www.grizzly.com/products/5-HP-Magnetic-Switch-Single-Phase/T20551 I have no idea of the quality. Oddly, the 3 HP version costs a little bit more.

TopamaxSurvivor makes a good point about amperage vs. motor HP capacity of switches. A switch that’s meant to control a motor should have a HP capacity on it.

Bill

View TopamaxSurvivor's profile

TopamaxSurvivor

14905 posts in 2372 days


#6 posted 03-17-2013 06:34 PM

Motor starters an not cheap. The Grizzly looks to be a bargain. 5 hp will work fine on 4 hp motor. You want it rated at or above your motor hp rating. Follow the instructions for setting the overload. They are worthless if set even a little bit too high. Most of the motors I have seen burned up were ”protected” by improperly set and sized overloads.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Airspeed's profile

Airspeed

425 posts in 598 days


#7 posted 03-20-2013 12:35 AM

Thanks guys, I ordered the 5hp starter from Grizzly. I was boycotting Grizzly for awhile, I bought a spindle sander from them recently and was less than happy with its condition and operation when I recieved it, The box looked like it had been in a flood, the cast iron top was scratched and the spindle vibrated like nuts! I just received a replacement today and am very happy with the new one so I lifted my boycott. Thanks again!

-- http://smg.photobucket.com/albums/v655/aaronhero/

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase