A woodworking forum for woodworking hobbyist and woodworking projects related and unrelated to the Shopsmith MARK V
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Is that your attempt to "rectify" the thread?garys wrote: Sun Jul 18, 2021 9:41 am It seems to me that the original post was looking for suggestions on getting the machine running again. How did we get so lost in stray discussion?
CHECK THE SWITCH.
(someone had to say it) 
Only problem is, some are half wave.RFGuy wrote: Sun Jul 18, 2021 11:33 am Now forum members have become "rectifiers" as well....will the re-definition of technical terms ever end?
I think there's a relevant message hidden here. Or maybe only hidden from me. When I think of Marks using the two sets of switch contacts in series, I'm thinking of Hot and Neutral both being switched. That is the only way I've seen it. It is a fairly easy feature to add to unswitched neutral headstocks, just requires a couple of long-ish jumpers. But it would be much easier to switch the Hot only in series through both sets of switch contacts. Cuz it would only require one short jumper and you don't have to worry about wire routing through the moving mechanical bits. And you'd get the same benefits in terms of increased switch life and performance.(?)BuckeyeDennis wrote: Fri Jul 16, 2021 1:43 pm When I replaced my failed switch, I wired both contacts in series, like Shopsmith used to do. When you open the switch contacts (i.e. turn off the switch), the inductance of the motor windings forces the current to continue arcing across the open contacts, just like the coil in an old-fashioned engine distributor forced an arc across the spark-plug gap. The arc continues until the inductive energy is dissipated, mostly as heat in the contacts themselves. So I figure that with two contacts sharing the energy-dissipation duties, they should last much longer than if using just one contact.
I saw a switch specification the other day that tends to support that theory. It was rated for 1 hp if using just one contact, but for 2 hp if both contacts were wired in series.