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]

403012

Does a magnetic switch like this one (link (https://www.amazon.com/Big-Horn-18823-220-240-Volt-18-26-Amp/dp/B002LVUWHM/ref=sr_1_1?ie=UTF8&qid=1549597901&sr=8-1&keywords=delta+unisaw+switch)) 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]

403012

Does a magnetic switch like this one (link (https://www.amazon.com/Big-Horn-18823-220-240-Volt-18-26-Amp/dp/B002LVUWHM/ref=sr_1_1?ie=UTF8&qid=1549597901&sr=8-1&keywords=delta+unisaw+switch)) 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-125V-250V-230V-Universal-Plastic-Saftey-Switch-Emergency-Stop-Part/142369749121?hash=item2125e5f881:m:mQThrcYuZFHptPx rMphPUKA: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:6:pf:0

This is what I put on my lathe to control a contactor ahead of the vfd.
(https://www.ebay.com/itm/SQUARE-D-START-STOP-CONTROL-STATION-BG-201-SER-A-600Vac/302985296092?epid=1023007820&hash=item468b54b8dc:g:w8cAAOSwNTNcCD2x:rk:6:pf:0)h ttps://www.ebay.com/itm/Light-1-NO-NC-AC-LED-22mm-Momentary-ON-OFF-Start-Stop-Push-Button-Switch/323113772493?epid=6015909629&hash=item4b3b14e5cd:g:lOwAAOSw2EhamqBz: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?

[andrew whicker]

The transformer was reading odd outputs (40v+) when the sticker on the transfer says 24. The momentary remote switch seems to be acting properly (N.O. and N.C.).

For a while, the motor would start after plugging the machine in and the motor would run at low speed. I let it run at low speed for a minute, it tripped my breaker.

Some friends and I were looking it over, trying to understand how it works (one of my friends used to diagnose locomotive electrical issues) and it started working flawlessly. However, we didn't actually touch anything. Yesterday, i tried starting it and it wouldn't start.

I think the solution is new magnetic switch to replace the old Unisaw components. Is there a reason for not doing this?

[Jeff Heath]

Something is certainly awry. If you don't have the diagnostic equipment to trouble shoot the starter you have, they are usually cheap enough to buy. Frequently $75 or less on the OWWM forum. I probably have 6 or 7 of them sitting in my rathole, from restorations. I buy them for future use at swap meets. You'll find one.

[Curt Harms]

The transformer was reading odd outputs (40v+) when the sticker on the transfer says 24. The momentary remote switch seems to be acting properly (N.O. and N.C.).

For a while, the motor would start after plugging the machine in and the motor would run at low speed. I let it run at low speed for a minute, it tripped my breaker.

Some friends and I were looking it over, trying to understand how it works (one of my friends used to diagnose locomotive electrical issues) and it started working flawlessly. However, we didn't actually touch anything. Yesterday, i tried starting it and it wouldn't start.

I think the solution is new magnetic switch to replace the old Unisaw components. Is there a reason for not doing this?

I think it depends on how concerned you are with authenticity. Some people treat Unisaws as collectibles which is fine. I have a G1023 with a Tian magnetic starter (https://www.grizzly.com/products/Grizzly-Magnetic-Switch-Single-Phase-220V-Only-3HP-21-25A/T24101) and it does what it's supposed to do. The difference between the paddle switches and magnetic switches is that magnetic switches include overload protection. If a motor is designed to work with a starter, I wouldn't bet on its having overload protection built in.

[Jeff Davies]

Forgive me if this is redundant.... I 'm gonna bet your low voltage circuit (LVC) relays are dusty. Not at the push button switch in front , but in back or where ever , are the high voltage switches . these are operated by elctro-magnets that are activated by the low voltage small switch in front .
Pull the cover off and blow the dust out of it with compressed air . Now I can't tell you to blow on them while 'hot ' and cycle them while blowing, but that is what I have done, to clear them out.... Yeah, Yeah, I was sitting in a tub of gasoline too...... just don't be stupid and become part of the circuit.
I reassemble these boxes with calking. It is amazing where the dust can migrate . Regards, J J Davies

[andrew whicker]

Yeah, I definitely want a magnetic switch. Was interested to find one with a paddle switch, but I guess that's asking for too much.

[andrew whicker]

I've blown out everything. I still need to figure out what the issue is.

[andrew whicker]

could I keep the magnetic switch 'on' full time and have a paddle switch control power to the switch? So in other words, have a paddle on the 220v line before the mag switch? I'm not sure if the mag switch can stay without power, since they are momentary switches.

[Dan Hahr]

Sounds to me like a capacitor issue.

Dan

[Curt Harms]

could I keep the magnetic switch 'on' full time and have a paddle switch control power to the switch? So in other words, have a paddle on the 220v line before the mag switch? I'm not sure if the mag switch can stay without power, since they are momentary switches.

I don't think you could add a paddle switch before a magnetic switch and expect it to stay on. The unpowered state of a table saw starter is "off" AFAIK. I guess you could put a paddle switch after the magnetic switch but I'm not sure what that would gain you beyond the ability to turn the saw off with a bump of your leg. People have hinged small vertical boards above a magnetic starter with a piece protruding so that when the wooden board is bumped it pushed the magnetic starter's "off" switch.

[Bob Vaughan]

I think like others do. The contacts are likely corroded or dirty. This is a very common problem when those switches get some age on them. Take the switch apart and clean the contacts. Air won't do it. Its likely your switch is a Furnas-made unit. Those units made for Delta had a little longer plunger than the standard Furnas plungers because of the push button design used by Delta.

Here's how to clean it.

http://owwm.org/viewtopic.php?t=32071

[andrew whicker]

Ooooo.

Thanks for the link

[andrew whicker]

That's an interesting idea. thanks

[andrew whicker]

A follow up for those of you on the edge of your seats with anticipation:

I temporarily wired up a new magnetic switch (bypassing the Delta magnetic switch entirely) and it starts and stops fine. The Delta transformer was giving odd voltages. I otherwise didn't dive into the Delta magnetic switch. I took apart the remote switch and cleaned the contacts (they weren't dirty) also.

cheers,