Router Safety Switch

Below you will find photos of a safety switch that I recently constructed for my table mounted router. Following were my requirements:

§ Easy to switch the router off during use
§ Inability to cause accidental starts
§ Guard against accidental starts after a possible but unlikely loss of power
§ Quick disconnect near the router because the power receptacle is not in a convenient location

A couple of years ago I built a magnetic starter switch assembly for my jointer-planer using components from AutomationDirect. It seemed to me that a similar setup for my router would meet all of my requirements.

Photos 1 & 2 show the assembly prior to installation. I removed the router power cord and replaced it with a Festool “Plug-It” quick connect pigtail that I picked up on a business trip to Europe. Of course a twist-lock plug will accomplish the same thing and can be purchased at most home or hardware stores. The original router power cord now supplies power to the switch contactor assembly (relay) in the larger box. I did not modify the cord in any way so it can be refitted to the router should I desire to return it to stock condition. A separate smaller box is used to mount the large mushroom stop switch (with twist to release) and on the side a green start pushbutton. It would have been easier to mount the switches in a standard 2-hole box but I liked the idea of having the start switch in a place that required intentionality.

Photo 3 shows the “guts” inside the boxes

Photos 4 & 5 show the installation. Now I have a higher degree of safety with my router setup. If I want to disconnect the power I just reach under and twist to disconnect. More importantly the router cannot be started accidentally even after loss of power and I can easily turn it off by bumping the red switch with my hip allowing me to keep both hands free.

Is this overkill? Probably! The switch assembly cost me about $100 for all the parts but it does make me feel more comfortable in the shop.

This is a very elegant solution and I would not consider it overkill. This may encourage more of us to do the same.

Greg

Is that an AEG switch setup, John? Looks identical to the switches that I have in my MM equipment...

Very nice setup. I really like those big, red kill switches and wish all tools came with them.

Very nice set up. It looks like a very smart way to go.

Richard

Hi John,

I really like the switch. $100 vs. a finger???? I don't see any overkill. The less safe (not a magnetic switch, possibly easier to start when not planned) switch I have on my table, from a major company, was $35.

If you had just posted the pictures, I would have asked where you bought it. Great job!! Now, we all need a parts list and instructions for assembly. Pictures of assembly optional, but would be very very helpful..;-)) Jim.

Hi John...

I dont understand? It looks like a standard type of setup. Ohhhhh yahhhhh, that router thingie is a single phase uni-motor. Cool! Now I get it.

Joking aside, this is how its supposed to be. One more suggestion however. Your using an IEC class contactor in there and not the older nema style. These have to be mounted on a rigid mount. If your mount has any flex in it, there is one condition that can cause issues. Certain types of bumping can turn the machine on if not mounted ridgid.

As good as the general SS-32 shaper is, they did not mount the danfoss box on all four corners. So when I was adjusting stuff, I used to wack the back of the box with a rubber screw driver to start up the machine. This saved me having to go around the front to do it.

What happens is the spring on the main contact bar is a bit bouncy and if it makes contact, it closes the hold circuit which then keeps the machine on until the hold circuit is interrupted. Your choice of a safety cutout mushroom was a good idea here. You have to twist the mushroom to get it to reconnect the hold circuit. Otherwise, you can start the machine but you have to continously hold the start button as only the start circuit is working.

By the way guys, this **IS** a mag starter. If your looking for a cheap fix, go onto ebay or where ever and snag a three phase contactor and a two button start/stop switch. You could use two switches as well. Just remember that the start switch is open til pushed and the stop switch is closed until pushed. You can use one of the three phase legs through the three phase relay/contactor to make the hold circuit while using the other two legs to support a 220 single phase circuit. Just note the voltage needed by your pull in coil and work it accordingly.

Looks great. To bad you don't have it set up so you can stand next to the router table instead of behind it. That for me is more of a safety problem than the switch because you don't have near the control that you would standing beside it. Think of it like you would operating a shaper or stand alone router table.

I didn't get quite that fancy I bought the $25 switch from Sears.

It has a red pad that you push to stop it & you lift the pad & reach underneath to push the rocker switch to start it & pull out the knob on the right to make it so it can't be started & there are 2 plugins on the back. Works great. In the picture the red pad is flipped up so you can see the switch underneath it.

John,

Looks like a great modification! To shut off my router, I have to reach under the table and find the switch. I am sure yours is much much safer!

Quote:

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Originally Posted by Jim O'Dell

If you had just posted the pictures, I would have asked where you bought it. Great job!! Now, we all need a parts list and instructions for assembly. Pictures of assembly optional, but would be very very helpful..;-)) Jim.

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Jim - Here are the parts I used:

AutomationDirect
GH15DN-3-10A Contactor 16A $25.25 1 ea
GCX1102 22mm Metal PB NO green $ 5.50 1 ea
GCX1136 22mm Metal PB NC Twist 60mm red $13.25 1 ea
SA105-40SL 2 Hole Box Grey Reg Depth $ 7.00 OR
SA103SL 1 Hole Box Grey Ext Depth $ 6.25 1 ea

McMaster
7360K32 Polycarbonate NEMA 4X enclosure $21.16 1 ea
69945K21 Metal Panel for enclosure $ 1.80 1 ea
7310K23 PG-13.5 Cord Grip $ 2.46 5 ea

Prices may be higher now than they were when I bought all this stuff in Februaury. AlliedElectric may be less expensive than McMaster now that they have eliminated their minimum order. You will also need 2-conductor wire the same gauge as your router power cord and some 3-conductor cable (smaller size OK) for running to the pushbutton switch box. A very short section of DIN rail is useful but not necessary for mounting the contactor in the NEMA enclosure. I used the schematic from my table saw which uses a similar magnetic switch setup (except that I did not ise an overload module). I don't have a scanner so I cannot post it here. Send me a PM if you are interested.
In order to use the one hole extra deep box I had to drill a second hole for the green switch (easy) but mounting it was not easy due to the small size of the box. It would be easier perhaps with a different box, such as the usual 2-hole version.

Quote:

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Originally Posted by Jim Becker

Is that an AEG switch setup, John? Looks identical to the switches that I have in my MM equipment...I really like those big, red kill switches and wish all tools came with them.

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Jim - the contactor is a generic house brand version from AutomationDirect. One of these days I am going to run another of the red switches from the starter for the table saw so I can also kill it from above. That will be real easy because it's just running another button in series with the stop button already there.

Quote:

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Originally Posted by Dev Emch

...You('re) using an IEC class contactor in there and not the older nema style. These have to be mounted on a rigid mount. If your mount has any flex in it, there is one condition that can cause issues. Certain types of bumping can turn the machine on if not mounted ridgid....I used to wack the back of the box with a rubber screw driver to start up the machine. This saved me having to go around the front to do it.

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Dev - I enjoyed the story about the hammer.:) Inside the NEMA box is a metal plate which is screwed down to posts within the box. I then mounted the a short piece of DIN rail to the plate by screwing into two other posts in the box. The contactor snaps onto the DIN rail (alternately can be mounted by screws). The NEMA box is then mounted to the underside of my router table (the back of the box is screwed on all four corners to the underside of the table).

Hi John...

Sounds good. The key is to deaden the shock that can "bounce" the contactor spring. Enclosed is a photo of my old SS-32 shaper so you can see what happened. The box is one of the nema classes. But it attached by only two bolts ans hung. Note that there are many different nema boxes including explosive proof boxes. For those looking for generics, look to the homann box enclosure. You can get these at your local electrical supply house and they come with either a bolt on cover or a hinged cover. I loved my SS-32 and was sad to see it go in exchange for the big german. I even designed and machined a router bit spindle using ER collets for this baby.

Nice job John. Let me guess, you also made that overarm blade guard for your saw. Ceiling mount?