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Thanks David. Yeah it would be great to know the history and design considerations that Shopsmith went through. Just speculation, but I can think of at least a couple of possible reasons for their decision. Sometimes DPST switches are cheaper than their SPST counterparts. Depending on shipping volume and customer demand sometimes you'll see a more complicated electrical component like a DPST sell for less than a SPST switch. Another reason might be that the engineer wanted to fully isolate the Mark V internals from the input line voltage, e.g. to mitigate any leakage currents, etc. They also may have had concerns about Shopsmith owners doing their own repairs and wiring the switch wrong. Having both hot and neutral switched eliminates this concern. With a product like this that can be open to product liability concerns it may have been more a legal decision than a design choice, i.e. safer to fully disconnect from line voltage than leave the neutral connected. Just some opinions based on my experience, but I am open to hearing from others on it as well.DLB wrote: ↑Sun Feb 07, 2021 7:48 pm This is one of those threads where it would be great if Shopsmith Engineering weighed in. Only they are going to know what rationale supported the change from switched to unswitched neutral. Without them, I think the debate is useful. I'm very much on the fence about it and would like to hear from others.
- David
Green wires are normally(in the USA) ground.stgabby617 wrote: ↑Wed Aug 25, 2021 9:23 am I'm replacing the head stock lock assembly. My 1995 mark has a two terminal switch. I disconnected those from the switch. One is black and the other green. Does it matter on this single pole switch, which wire goes on which terminal? K have the 1/1/4 up motor.
Are you sure one wire is green? It'd be very unusual to use black, red, white, or green for anything other than their standard meaning in AC wiring. Green is normally ground / chassis. In my experience I'd expect to see two blacks or, more likely, a black and a blue. If you have a green wire I'd suspect that the headstock wiring has been modified at some point. But that ain't what you asked...stgabby617 wrote: ↑Wed Aug 25, 2021 9:23 am I'm replacing the head stock lock assembly. My 1995 mark has a two terminal switch. I disconnected those from the switch. One is black and the other green. Does it matter on this single pole switch, which wire goes on which terminal? K have the 1/1/4 up motor.
I'm 'almost sure' I've seen SS Headstocks this way (SPST). The unswitched Neutral variety, obviously. I'm 'almost sure' my shorty was like this, but the switch failed and I replaced it with a standard (no safety key) DPST rocker. "C" headstock, circa 2003. I probably kept the key and tossed the switch, so no evidence. But I'm thinking my PowerPro donor was also unswitched N and I kept some of its parts, so I will search for the old switch for it. Since it was good I would have kept it. Somewhere...