Shopsmith Forums

I recently purchased my third SS as it was too good of a deal to by pass. It was a 520 50 year anniversary addition. When I looked at it, the seller said he had installed 3 switches over time that he purchased from SS and that all burned up soon after installing, so now he has (I have) a regular toggle switch hanging from the wires out the front of the SS. I have just ordered a new switch, but would like to know what to do to keep from burning up any more switches. Any help will be appreciated.

Tom

I have replaced one switch in about twenty years and was not burned up. It was broken.

If the switch is "burned up" (that is melted or distorted from heat, I have absolutely no idea.

If the contacts on the switch are pitted (like from arcing), I would check all connections in the 110vac power circuit to make certain they are good and tight.

In fact, I would probably completely rewire the 110vac power cord and the switch with all new connectors.

The switch in my Mark V is a double pole, single throw and originally it was wired using both poles. That is to say they switched both the hot and the neutral wires. In accordance with more recent changes, Shopsmith only switches the hot wire. I have chosen to keep mine wired as done originally.

This does NOT affect the amount of current drawn by the Shopsmith and in no way should cause the switch to heat up (burn out).

I would recommend that you install a 12 gauge power cord on your Mark V. The original was 14 gauge. I recommend that you power your Shopsmith using a 12 gauge home run (from wall outlet to main breaker panel) and to use a 20 amp breaker (NOT the normal 15 amp breaker typically used in home and garage wiring).

I think it is odd that the switch needed changed so many times. Perhaps (and hopefully for your sake) the problem was with the seller's electrical system and knot the Mark V switch. Like dusty recommended, make sure you have a 12ga power cord and hopefully you have a 20 amp circuit available for it.

I have been buying my 20 Amp rated heavy duty motor toggle switches from http://www.delcity.net
7300001 - DPST On-Off Toggle Switch - .250 flat terminals (1 MIN)
Details Price: 4.51 Qty in package: 1

I have replace many shorted/open toggle switches on the 500s in the past 6 1/2 years. Since I have spent most of my life as a trouble shooter/problem solver, I will offer my ideas why the toggle ("B" headstock) and rocker ("C" headstock) switches fail. The original Greenies with the 3/4 HP motor had a 15 Amp rated switch. When the switch was made to the 1 1/8 HP motors, a regular 15 Amp rated toggle switch was used. Shopsmith finally switched to a better 20 Amp rated switch in the late 80s. When they went to the "C" headstock, they went with another 15 Amp rated rocker switch. I believe they are using a 20 Amp rated rocker switch now. I have been using a HF motor rated rocker switch for the "C" headstocks.

Big Box stores and hardware stores sell a 15 Amp and sometimes a 20 Amp toggle switch rated for light/regular use, not for motors. The contact points on a motor rated switch are larger and heavier than the regular switches. When the Shopsmith 1 1/8 HP motor starts, both the motor and start windings are energized drawing 18-24 Amps just for a very short time until the start windings are deenergized. I believe this heavy current draw will cause the regular contact points to burn over time or weld together. Since switching to the above motor rated switch a few years ago, I have not had any failures with the above switch.

a1gutterman wrote:I think it is odd that the switch needed changed so many times. Perhaps (and hopefully for your sake) the problem was with the seller's electrical system and knot the Mark V switch. Like dusty recommended, make sure you have a 12ga power cord and hopefully you have a 20 amp circuit available for it.

I wholeheartedly agree with what Bill has presented here; however, he described the failure mode as being either a short or an open. He did not indicate that the switch would overheat.

In the original question asked here, the term "burned up" was used. If "burned up", in thebears' mind, means that the switch either burned open or arced shut then this discussion is really over. Bill has given us an explanation.

If "burned up" means what I first read it to be (overheated and melted) then I believe there is a much more potentially serious problem brewing.

Only thebear can tell us whether or not his concerns have been settled.

Sorry Dusty, I did not say anything about burned/melted switches as that is what happens some of the time. The plastic housing can partially burn and/or melt resulting from the heat generated which causes the switch to fail. This causes the open or welded contact points. I only find one side of the DPST switch would have this problem. I have not found any switches that shorted the hot wire (black) to ground (white) which would hopefully trip the breaker. I have found a couple headstocks with lots of sawdust inside but only the switch got burned or melted. No burnt sawdust or any other burn indications inside or outside the headstock. I have not found any switch where the electric power was shorted to the metal toggle or metal housing. Of course, everyone should have/use a grounded (3 wire) power cord, plug and outlet to protect themselves if this was to occur. The wires have always remained connected to the switch terminals when this condition happen and did not drop into the headstock.

The first indication of a switch problem is no power when the switch is turned on or unable to turn the power off when the switch is turned off. Removing the switch from the headstock was the best way I found to see if it was the problem. I always use 20 Amp switches in my rebuild headstocks.

I might as well post what happened to my switch. The first symptom was a mere touch on the switch when running would cause the machine to turn off. After putting up with that for about a year, the switch failed and it was internally burned. The plastic on the quill side had burned so the plastic was bulged out in two places.

I have the brown and gold Shopsmith with a 3/4 Hp motor. When I got it home I took the headstock apart and I found loose wires on the switch. I thought that the power cord looked kinda of lightweight at that time. Now after reading these posts I would like to change it to the heavier cord. Is the a place that I can get a new cord with the plug molded on it or do I just buy the wire and make my own? When I change the cord will I have to put a heavier switch on it also? Sorry if I Highjacked the thead Thanks Ivan

There is no hijacking here.

I don't know where you can get a cord with a molded plug except to buy an extension and cut the other end off. I sort of prefer the removable plugs my self because I can get a hold of them better (they are bigger) and I am not so inclined to pull on the cord.

At one time, the power cord on my Mark V had Shopsmith written on it. I was sort of protective of that cord but then one day, I know not when, I lost track of it. It is no longer in the shop. Oh well.

Bill; with the experience you have had, do you see burned (overheated) 20a switches?

I believe startup current is too short term to melt switches. If the contacts get pitted or are inadequate in size for the current being drawn through them they would heat. This heating would more likely occur during a run period than during switch closure. Run current would normally, in my opinion, not be enough to melt a switch.

Whatever.

I appreciate all the help on this question, as I stated in the initial post the seller told me he had burned up 2 or 3 switches and reverted to a regular toggle switch. I didn't ask him what he meant by "burned up". Wasn't smart enough to ask till I read the other posts on here. But I will tell you that his shop was older and maybe the wiring was a little weak. My shop is a little newer and I have never lost a switch on my other SS's. Again thanks for the help.