Switch for Old Unisaw

[Thom Porterfield]

Sorry to all of you who offered good advice. My grand plans on upgrading my shop took second place to other endeavors, some of which were not so grand, and some that were very grand indeed. But now I'm back to it, and just this week finished revamping the switch on the saw.

I found this: http://powertecproducts.com/71007-11...paddle-switch/ and devised a way to mount it below the Bies fence, similar to the solution posted above by Scott Schwake but using existing bolts. It works fine. . . . But I don't...I keep reaching for the now non-existent switch under the table. I'll get used to the new location, and I really DO like the panic paddle to turn the saw off.

One of the problems with the modification my friend made was that the oval hole for the original bullet motor was now huge, and had no cover. Needless to say, the result is that almost as much sawdust wound up outside the saw as piled up inside the cabinet. So I made a box of some scrap hardboard as a test for a future sheet metal solution. But the hardboard works great, if somewhat ugly, so the sheet metal solution may not happen for some time.

Anyway, guys, thanks again for all your advice. It's good to have sawdust in my hair again and Titebond under my fingernails.

[Jacob Reverb]

You could use a Grizzly H8242 (they are on sale for $10 right now), or put a magnetic switch on it, or go with a vintage thermal overload switch/motor starter.

I put one of those on my Powermatic and love it. It's nice to have the paddle you can hit with your knee (or whatever) when you're wrestling a sheet of plywood or whatever and need to shut the saw off in a hurry without looking for the switch.



I had considered fabricating something along the same lines, but it was so cheap that it'd be stupid to waste my time.

[Don Jarvie]

Nothing wrong with a “light switch” as long as it’s rated amp wise for the motor. Some find the paddle more convenient so it’s up to you.

[Bob Vaughan]

When switch shopping, don't forget the unavoidable condition called inrush current. "Experts" won't agree on how many times more amps the inrush is than the rated running amps, but three times is conservative. Say you've got a 3 HP single phase motor that's rated for 14 amps at 230 volts. Inrush will be 42 amps if not significantly more. The switch's contacts need to be sized to sustain that kind of arcing during power on and off cycles. For a single phase motor, there's also the added draw to charge the capacitors.
Light switches are for resistive loads and not inductive loads like motors. Using a light switch will work for a while but it doesn't do the components any good and those tiny contact points of a light switch get corroded quickly and let less and less electricity flow over time. Fortunately single phase motors have capacitors that fail before the windings burn out when one is using a switch with tiny contacts.

The optimum motor starter size for that motor would be a NEMA size 1. The contacts in those plastic box mag starters from Asia aren't a whole lot bigger than light switches. They just play fast and loose with what amp ratings they print on the labels.