3 –On/Off Switch (No Volt Release Switch)
It is a good safety feature to have a so called ‘no volt release switch’ on your lathe. Basically this switch will start from a push button but if there is a power cut for any reason, it will not automatically restart when the power is restored. This is important – say there is a power outage, you do not want your lathe bursting into life unexpectedly (when your not around or leaning against it) when the lights come back on.
This feature is fairly standard on most decent sized power tools. You can buy them ready to fit off e-bay or make your own if you have a good high current contact relay and a push to make and push to break buttons in your scrap box. See circuit diagram.
S1 = On button (push to make)
S2 = Stop button (push to break) – if you make it this way S2 must be a very robust button as it will carry all the power going to the lathe. It should also be big and conveniently situated for quick stopping.
K1 = Heavy duty contacting relay.
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January 26th, 2019 at 10:43 pm
If you put S2 between the A1 terminal and the joining point it would only need to be a light duty button with no loss of safety.