Electric Motor Starter

Years ago when quite young there was an old man who worked on tractors in an old shop with really old tools and a dirt floor.His most popular tractirs were the old McCormick standard treads. He had a huge drill press that had two switches. He told me to be careful with it and use both switches to start it and then just run the larger switch. This worked fine.

I have a 10 inch tool grinder with a broken centrifigual start switch. I had it worked on one tome and the repair shop could not get the right switch and repaired the switch with epoxy.the repair did not last long
I was wondering if I could wire up this grinder like that and possibly use an automotive Ignition / starter switch.

A automotive switch isn't going to be able to handle the current required to start a motor like your wanting to do. That said the best way to do what your needing is to use two motor starters. The best way to explain it is this is that it's wired as a push to start/push to stop circuit. In other one starter is wired with an auxiliary contact so it pulls in and stays in when the start button is pushed. The other contact is wired to where it only pulls in when the start button is pushed. You should be able to do a search online to see how it's wored.

Doing it this way gives you a momentary switch (as long as the start button is pushed) that pulls in and engages the capacitor start, and the second starter that pulls in and holds to keep the motor running.

I wired a 10HP 3 Phase motor this way to use as a rotary phase converter and it works great. In my case the 3 phase motor needs the capacitors tied in on the third leg to get it started spinning, similar to the way a single phase, capacitor start motor needs the capacitor to get it spinning. Once spinning the capacitors are dropped out of the circuit, in most cases by a centrifugal switch, but in this case simply by releasing the start button and letting the starter wired for momentary operation open and drop it out.

Like I said I did mine awhile back and it works great so I don't see why it wouldn't work in your application also. The only drawback is the starters aren't usually cheap if you have to buy them new. I got lucky and got a few from the place my Dad works that came off pump controllers that they had removed from service. That said if you don't have the starters on hand try calling around to some places that do municiple type well and sewer equipment repair. If they are like where Dad is they pull at least one controller or two a week that has a good contactor in it but another bad part that keeps the whole thing from working properly.

Good luck...

I have done it using a momentary contact push button for the start circuit, worked fine, but it was a 1/5 hp motor.

Wayne, I don't know, but would one of those starter switches off an old Oliver tractor work????

Toss the obsolete old mech start switch in the trash can.

Go to a refrigeration parts supplier, commercial overhead door opener co., or possibly Grainger, and ask what they have in the line of universal replacement solid-state motor start switches. Info on ONE brand is at the .pdf file linked below, including selection info and installation instructions.

Problem solved.
Untitled URL Link

Some, maybe all single phase submersible pumps use a timed relay to switch from start to run. The relay must be matched to the motor/pump.
Perhaps your motor shop could do that, I don't know how to match them, other than matching part numbers.

Dusty

I just got a new "SURPLUS CENTER" catalog in the
mail yesterday. They had new,(industrial surplus)
motor starters. Not being an electrical person,
I don"t know about brands, price, or value. Over
the years I"ve bought lots of hydraulic and
mechanical stuff there, with no problems!

As Bob says get a solid state switch put in I used to replace a lot of switches but then my motor guy found out about the solid state switches and he put those in for us. It is a pretty much permanent fix and pretty much one size fits all. He used "Synpac" brand. Call them and find out who in your area puts them in.

I can't say 100% for sure wether it would work or not, because any switch that would handle the current flow would work, for awhile. The life expectancy would be determinded, I believe, mainly by the time it took for the contacts to burn out. I say this because an A/C motor stater is designed with the contacts being somewhat of a snap action to reduce the burning of the contacts as they open and close. If the contactor your talking about doesn't have that snap action the contacts will burn out fairly quick in relation to the right kind.