Switch

[beeg]

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.

DRMCRobert

I hope you've read this post.

[dusty]

I have a SS 510 that I bought it in Dec of 2004 but did not put into service until January of 2006 (bought it and then waited to use it until I retired in '05 and moved to Nedada). It has been used intermittently up until the past six months and now is being used a couple of hours two to three days a week for turning pens and other small items. I have installed a duplex outlet on the right-hand leg of the base and that is connected to a 20A circuit by a modified extension cord from Lowes. The extension cord has a molded plug with a heavy-duty, 12-ga 25-foot cord that I removed the end from.

That's my current setup and it has worked great for the past six months without any problems.

As of the past couple of weeks I discovered I was intermittently unable to turn off the SS with the switch. It has now gone to a solid condition and I have to unplug the SS plug to cut the power. The power switch on the SS headstock does not get hot nor does it appear to be warped or over-heated. I have ordered a new switch from SS but they are on back-order and are expected to be back in stock the end of this month (Jan 28, 2009).

I just can't figure out why a switch that is designed to turn a unit on and off can't handle this minimal amount of usage. Based on the comments in this thread it appears to be a more common problem. Has anyone contacted SS to see if they are aware of the problem and are they doing anything about it?

Is this a new Mark V that you should rightly expect to have the 20a switch or is this an older model that may have the 15a switch. If it is an older model (or a newer model with a 15a switch)...what has just happened is what would should have been expected. A 15a switch is under rated.

Then there is the power source. It has been stated that the unit is running on a 20a circuit and that a 12ga power cord is being used.

A couple thoughts on this.

To say that the unit is being used on a 20a circuit means that the power cord is 12ga and not 14ga as was/is the case with the cord provided with a new Mark V. The new equipment power cord is 14ga (thus 15a).

Having a 20a breaker in the wall panel does not necessarily mean there is a 20a circuit. What gauge wire is used in the power run from the outlet clear back to the power companies input (the main service circuit breaker). It has to be at least a 12ga wire to be rated at 20a.

[W3DRM]

Is this a new Mark V that you should rightly expect to have the 20a switch or is this an older model that may have the 15a switch. If it is an older model (or a newer model with a 15a switch)...what has just happened is what would should have been expected. A 15a switch is under rated.

Then there is the power source. It has been stated that the unit is running on a 20a circuit and that a 12ga power cord is being used.

A couple thoughts on this.

To say that the unit is being used on a 20a circuit means that the power cord is 12ga and not 14ga as was/is the case with the cord provided with a new Mark V. The new equipment power cord is 14ga (thus 15a).

Having a 20a breaker in the wall panel does not necessarily mean there is a 20a circuit. What gauge wire is used in the power run from the outlet clear back to the power companies input (the main service circuit breaker). It has to be at least a 12ga wire to be rated at 20a.

My 510 Mark V was brand new in Dec of 2004. It has been used for perhaps 20 hours or so over the past six months and very little prior to that, as I noted in my original post. My garage is an over-sized 3-1/2 car garage specifically built to have my shop in the third car side. Overall size of the garage is 28' x 40' with a 11 foot ceiling. It is also completely insulated and I have a REZNOR garage heater model UDAP45 which does a beautiful job of keeping it comfortable in the winter here in northern Nevada.

As to the wiring, I have 400-Amp service to the main power panel in the house. There is then a separate 200-Amp power distribution for the garage. From there I have a dedicated 110V - 20A circuit with 10-gauge wiring just for the SS. Additionally, in the garage, there are numerous outlets for other parts of the shop all on separate 15A circuits. There is also a separate 220V/20Amp circuit for my compressor. As I mentioned, I use a 12-gauge cord that goes directly from the 20A circuit wall outlet to the Shopsmith. Nothing else except for the utility lamp on the SS is on that circuit. I am still using the original power cord that came with the SS. It is marked with "coleman - 14-3" which would be a 14 gauge three conductor cable. Perhaps someday I will change out the internal wiring with 12-gauge but that should not make any difference with switch performance. The small voltage drop in the short lead is realy insignificant.

How can I tell if the original switch on the SS is 15 or 20amp rated? Is it marked on the switch. I have not tried to remove the switch as yet but will do so once the replacement one I ordered comes in. It's a bear to get into the switch so I don't want to try until I am ready with the replacement part. Any hints on the best way to get the old switch out would be appreciated...

BTW, I've been in electronics all my life and am familiar with voltage drops and power distribution systems. I'm also an amateur radio operator (W3DRM) and know my way around radios and electronics pretty well.

Yes, I have been reading the other posts in this thread and did see the article about the suggested replacement switch but I would much rather stick with the switch SS has for the time being. Rockler also has a safety switch (p/n/: 20915) that was reviewed in the March '09 Wood magazine as being 5-star (page 28). Unfortunately, it is only rated at 15A and uses 14-gauge wiring. I have also thought about installing a relay-operated master ON/OFF switch that would mount somewhere within easy reach of the SS. That way, I would never have to worry about the SS switch going bad again. But, that may be overkill...

[dusty]

My 510 Mark V was brand new in Dec of 2004. It has been used for perhaps 20 hours or so over the past six months and very little prior to that, as I noted in my original post. My garage is an over-sized 3-1/2 car garage specifically built to have my shop in the third car side. Overall size of the garage is 28' x 40' with a 11 foot ceiling. It is also completely insulated and I have a REZNOR garage heater model UDAP45 which does a beautiful job of keeping it comfortable in the winter here in northern Nevada.

As to the wiring, I have 400-Amp service to the main power panel in the house. There is then a separate 200-Amp power distribution for the garage. From there I have a dedicated 110V - 20A circuit with 10-gauge wiring just for the SS. Additionally, in the garage, there are numerous outlets for other parts of the shop all on separate 15A circuits. There is also a separate 220V/20Amp circuit for my compressor. As I mentioned, I use a 12-gauge cord that goes directly from the 20A circuit wall outlet to the Shopsmith. Nothing else except for the utility lamp on the SS is on that circuit. I am still using the original power cord that came with the SS. It is marked with "coleman - 14-3" which would be a 14 gauge three conductor cable. Perhaps someday I will change out the internal wiring with 12-gauge but that should not make any difference with switch performance. The small voltage drop in the short lead is realy insignificant.

How can I tell if the original switch on the SS is 15 or 20amp rated? Is it marked on the switch. I have not tried to remove the switch as yet but will do so once the replacement one I ordered comes in. It's a bear to get into the switch so I don't want to try until I am ready with the replacement part. Any hints on the best way to get the old switch out would be appreciated...

BTW, I've been in electronics all my life and am familiar with voltage drops and power distribution systems. I'm also an amateur radio operator (W3DRM) and know my way around radios and electronics pretty well.

Yes, I have been reading the other posts in this thread and did see the article about the suggested replacement switch but I would much rather stick with the switch SS has for the time being. Rockler also has a safety switch (p/n/: 20915) that was reviewed in the March '09 Wood magazine as being 5-star (page 28). Unfortunately, it is only rated at 15A and uses 14-gauge wiring. I have also thought about installing a relay-operated master ON/OFF switch that would mount somewhere within easy reach of the SS. That way, I would never have to worry about the SS switch going bad again. But, that may be overkill...

With your extensive background in a related field, there is little or nothing that I can tell you about resolving your problem. It appears that you must be the victim of premature component failure (infant mortality in the component test and evaluation world).

As for the markings on the switch, it is not in a position that can be read until it is removed and they can be very difficult to remove. You are wise to leave it in place. Both the power rating and the location of manufacture should be marked on the body of the switch. In the meantime, I know you will utilize a proper and safe method to apply and remove power.

You might want to contact Shopsmith regarding your switch failure. They might want to have a failure analysis performed.

[W3DRM]

dusty, et all,

I hope my replies haven't been taken as being smart-a$^ in nature. I was only attempting to describe how my shop area is set up and what I have done to hopefully make it more usable and without major shortcomings, such as power. My background was meant to give you an idea of my expertise level, or lack therof. I am by no means an expert in woodworking.

I will contact SS later this afternoon and see what they say about the switch problem I am having. Will post here in this thread afterwards.

Thanks to all for the ideas on this forum!

Happy woodworking to all...

[JPG]

dusty, et all,

I hope my replies haven't been taken as being smart-a$^ in nature. I was only attempting to describe how my shop area is set up and what I have done to hopefully make it more usable and without major shortcomings, such as power. My background was meant to give you an idea of my expertise level, or lack therof. I am by no means an expert in woodworking.

I will contact SS later this afternoon and see what they say about the switch problem I am having. Will post here in this thread afterwards.

Thanks to all for the ideas on this forum!

Happy woodworking to all...

No you were not a smart as-! You came across as one who was frustrated by not being able to use your SS after going to the detailed and knowledgeable preparations come to a halt by a funky switch. I hope SS can give you some solution. (i.e. a durable working switch):)

P.S.I just noticed (not good news) on the blog thread. SS ain't got no switches today! Let us know how call to SS goes!!!

[beeg]

I didn't take your replys that way drmcroberts. "WE" now know about your background and know that everything should be wired up okay.

[reible]

I find it interesting that these engineers who have done such a great job on designing our shopsmith but can't seem to design there way out of a paper bag when it comes to power cords and power switches?????

Guy's the 14GA to 12GA cord change is a myth as far as I can see after doing the math.

As far as switches go if the design were bad then my 1976 model should have gone through lots of switches.... but here it is still on the original.... mmmmm I'm also guessing I'm not the only one who is still on an original switch.

Just for the fun of it... Do you know about the word "arcing" well on each cycle of the switch you have arcing. Kind of like what happens when arc welding. The two(or more) contacts can only take so much of this before they start loosing material.... the less material makes it even worse until they fail... They no longer make contact or the fuse together... sometime along the way the lack of material might cause the switch to heat up then fail to provide the power needed for operation often resulting in the switch material melting which will cause even more problems between the contacts...

The arcing is due to the load (motor) being a large inductor, well at least in the case of a shopsmith. In the moments (1000's th of a sec) between the contacts getting close enough to arc and the time the are in physical contact does most of the damage. Once in contact and if the contacts are in good shape they will not heat up nor will they fail from heat. It is very unlikely they will be come the fuse (yes it could happen if the contacts are warn or if the "spring" has weaked from other causes... but if the switch is in good shape then very unlikely). The same is true as the switch opens, between being closed and getting out of range of the arcing doesn't take long but that is where the wear is in the switch.

When you do a design like this you can't spend weeks on it so you make some guesses. You might say I want this switch to last 20 years, people shouldn't mind replace them in that long. They you might say that if someone were using a shopsmith at home for say 20 hours per week and turns it on and off say 8 times an hour or 160 times per week that comes to 166,400 cycles. Now all I have to do is look in the switch hand book for something will handle the load (15A or 20A) (inductive motor load) (good for 200,000 cycles). You might look to see if it is rated at 100C or 105C because it will be in an enclosed enviroment and have an external heat source (the inside of the shopsmith). And since you are in a dusty enviroment perhaps one that fits that bill too. Maybe you have two suppliers you work with so between them you now go for the lower cost one that meets the requirements. Job done, on to the power cord....

Now who ever you order from could have change manufacturing locations to who knows were or change materials, or changed specifications to 50,000 cycles or... well an endless number of things could happen all the way down to a single batch having a problem and shopsmith having purchased 500 of them. If the problem were to wide spread I would think that being the wonderful company they are shopsmith would do a recall of those switches or give free replacements...

Ed

[W3DRM]

Well, it's now 2:07pm PST. That means it's 5:07pm EST and SS is closed for the day . Guess I'll just have to wait until tomorrow morning to make the call.

One thing about my switch problem is that it is stuck in the "ON" position so I can still get work done. Am currently sanding and finishing a cigar pen for my brother-in-law. My ON/OFF switch is now the power cord to the SS itself. Not very handy but it allows me to continue working.

As to arcing - yes that is the reason a switch will eventually malfunction. Based on the physics of current flowing through a wire and/or switch, when you break that connection, the current will try to keep flowing. That's what causes the spark or arcing. When you close the switch you start off with no current flow at all. It will only start flowing the instant the contacts meet each other, not before. So, there should be NO arcing on contact closure, only when the circuit opens up. There may be some initial heating of the contacts due to startup current through the motor windings but any well-deigned switch (assumption being made here) will handle that start-up current easily and without any damage being done to the switch. A capacitor can be placed across the connections to absorb and minimize some of the arcing but I doubt that SS uses that method for their switches.

Opps, that's my electrical engineering background speaking this time...

Ed - we were both making entries at the same time. You are correct about the switch design. If SS is using switches rated at 15A then they will deteriorate faster than one rated at 20A. Both, over time though, will fail due to contact arcing. The higher the current rating, the longer they will last.

[W3DRM]

Well, my problem is fixed and I'm a very happy SS camper!

Here's what I did. The power switch used in the newer models is still double-pole, single-throw (DPST) BUT, they only switch the hot-lead to the motor. That means you have an "extra" backup switch built-in to every newer model SS! So, all I did was reach in and move the two wires from one side of the switch to the other. I now have a "new" switch that should last me for who knows how long. I also have a replacement coming (some day) that I can then use two more times, if necessary.