Switch question for an 90's Unisaw

[andrew whicker]

Okay, I feel dumb. Maybe I'm not, but maybe I am. I don't know.

My Unisaw switch is starting to fail. I bought a replacement Powertec Paddle switch (I run 220v). I am confused because my Unisaw uses a 1NO1NC switch (SPDT) and I think this Powertec switch is something different? I think this switch is intended for a situation when power comes from the wall, to the switch, to the motor. My Unisaw is more complicated. Power goes into the machine, into a control box, I get a few wires out that go to a switch. I measured the power on these a long time ago and they low current, low voltage (if memory serves me).

So I go online to look for 1NO1NC switches and I am not coming across a lot of options (especially on Amazon) and it has me doubting myself.

Is there a way to wire the Powertec Paddle switch with 3 wires that I'm not getting? It looks like I'm going to have to go thru Grainger, etc to get an actual (not Chinese dillywacker thing) switch.

Confused in Utah,

[andrew whicker]

Ah, it's a magnetic switch for the LCV (?) starter. I'm starting to understand what I was seeing during my Google searches..

[Bill Orbine]

On LVC system, the existing switch are momentary switches with on normally open and off normally closed. However, you stated your system is "starting to fail"! Perhaps you can elaborate more about this malfunction just starting?

[andrew whicker]

tablesaw.jpg

Does a magnetic switch like this one (link) replace the wiring in the red squares?

[andrew whicker]

I just have to keep pushing the red button in, push the green button in and so on until it finally starts. Tonight it seemed to be more of an issue than normal. But you are right, the more I am researching these switches, the more complicated this 'simple' problem becomes.

I did read in one forum that someone was having similar issues and it was the magnetic switch failing. There are also Amazon reviews for new magnetic switches that seem to tell a similar story.

[andrew whicker]

Okay, so Delta has a 'Remote Switch for a Magnetic Starter' and the link above is for a full on magnetic switch. That is interesting. From my quick googling, finding a remote switch may difficult, but finding a full magnetic switch is easy. That sounds like a fun wiring project...

[Bill Orbine]

tablesaw.jpg

Does a magnetic switch like this one (link) replace the wiring in the red squares?

That magnetic switch will replace the whole LVC system assuming you have single phase 220 less than three up motor. BUT....Your "starting to fail" problem really sounds like a dust problem that may just need a little cleaning and keeping a fat wallet. Diagnose the problem first!

[Jeff Heath]

Your LVC "starter" (not called a switch) sounds like it has low voltage controls. If you open it up (power disconnected) you will find a small transformer inside, with control wires running to and from. That is your momentary contact circuit, which goes to and from your start/stop button. These are magnetic controls.

[andrew whicker]

I will try that. Tried it already once and now I'm way from the shop.

[Brice Rogers]

I've got a lathe with a 220 volt magnetic momentary switch. It has a momentary green button and a momentary red button and a cover that - when struck - pushes the red stop button. Grizzly correctly referred to it as a KDJ178 switch. This may be an error and perhaps the correct number is KDJ17B. When I looked on eBay I saw a listing for about a dozen emergency stop switches. Take a look and see if you can identify the model that you need. Alternatively get a mirror and a flashlight and see if your switch has a model number on it or perhaps the owners manual ? Here is the link to ebay for identification purposes:
https://www.ebay.com/itm/10-Types-12...PUKA:rk:3:pf:0

[Bill Dufour]

I suspect the stop button is not making good contact. The stop button is NC. If it is dirty and not conducting the motor will not run. The start button is NO.c. If it is dirty the circuit will not start when pushed. I would blow out the switch box to remove saw dust.
Look for start/stop pushbutton controls. Personally I like to use Illuminated stop switches. look for mushroom switch. Make sure they are non latching/momentary contact type.
22mm is the standard industrial switch mount hole
Bill D

Like this one on ebay
https://www.ebay.com/itm/SQUARE-D-START-STOP-CONTROL-STATION-BG-201-SER-A-600Vac/302985296092?epid=1023007820&hash=item468b54b8dc:g :w8cAAOSwNTNcCD2x:rk:6f:0

This is what I put on my lathe to control a contactor ahead of the vfd.
https://www.ebay.com/itm/Light-1-NO-...mqBz:rk:6:pf:0

[Ron Citerone]

I wonder if you have tried blowing the switch out with compressed air or using a powerful shop vac? I ran four labs as a teacher, and many time switch problems were solved that way. The district electrician always started with that and many times it was that simple.

[Tom M King]

Blow it out with compressed air, and with the power disconnected, spray contact cleaner in it. If you can easily take the cover off, it would be better to do so. If not, it probably still should work. I have done this many times, including this week with a 1/2" right angle drill that was bought new in the mid 1970's. It's almost always fine sawdust in those switches that causes trouble.
I used CRC QD electronics cleaner, but any contact cleaner should work. The QD is for quick dry.

[andrew whicker]

Thanks. I was looking at the mushroom heads. I was trying to remember how they worked the last time I used them. You pull to start and push to stop?

[andrew whicker]

Also, this wiki article helps a lot:

https://en.wikipedia.org/wiki/Magnetic_starter

It's cool to finally take the time to understand what the box of components is actually doing. I didn't take the time before. All new cabinet saws must have magnetic starters, right? It's weird to me that so many people buy the generic Paddle Switches. They must have saws without magnetic starters. Does this mean motors less than 3 HP?