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View Full Version : Stop switch advice please.



piping-hot
03-26-2004, 06:00 PM
Hello all, I have recently modified a 1959 Weiler lathe to single phase using a new 3 ph motor (1.5 kw) and a Nordac vector frequency invertor. This is a super setup but the only thing that worries me is the only way I can turn off the machine is by pressing the small button on the control panel...... What is the best way of building an emergency switch? I was thinking of something opperated by foot (the frequency inverter has a provision for the wireing) but cannot find a sutable plan or switch. I play the bagpipes and need to retain all of my fingers http://bbs.homeshopmachinist.net//smile.gif thanks.

ibewgypsie
03-26-2004, 06:12 PM
I hope you have a manual.

I have a Toshiba inverter on my machine, I had to change the inverter program to match the screw Terminals on the inverter so I could use a external switch. "A two wire flip switch is easiest to wire up", a 3 wire (start-stop button) control makes you have a relay to lock the start button in. One "Hot" wire goes to stop, wire off back side of stop feeds both start switch and hold contact in the relay, on other side of start Normally open switch goes to relay coil, once coil closes, the hold circuit coming from the stop button holds it powered up till you push the stop button..

By standard, the start button must be a normally open contact, the stop must be a normally closed. 3 wires are required. and a starter or relay..

With a two wire control such as a toggle switch or a selector switch you really don't even need a relay, just take it to the two terminals your manual tell you..

I have dual relays, one is a enable from the computer cnc program, the other is a run relay for the inverter also fired by the computer. If the first enable/estop is out, the inverter won't run. YOU can by Code standards lock a control for saftey, But I always lock the brake on my machine before I grab the mill and change it.

I also mounted a ten turn speed pot on the front of the machine. Makes it easy..

Hope this helps and did not confuse you too bad, communication is my worst skill.

Ohh, and if you go with the two wire switch for the estop, you can use a foot switch if you like, www.grainger (http://www.grainger) sells one that I used to use for a tattoo pedal.. costs about $8.. BUT, a problem probably exists, a lot of times you can't use both the terminals and the panel mounted start-stop buttons.. (hence the explanation above)

David


[This message has been edited by ibewgypsie (edited 03-26-2004).]

J Tiers
03-26-2004, 11:42 PM
I don't know if a foot-operated one is best.

I find that when there is trouble, I tend NOT to want to pick up a foot and balance while finding a switch. Even stepping OFF one is hard for me to remember. I must remember the jungle too well, trouble equals both feet on ground ready for it.

One of the best I have ever seen is the knee operated stop switch for table saws. Big button 8 x 12 inches right there, almost automatic to hit it.

ibewgypsie
03-27-2004, 07:34 PM
I installed one on a carpet roll up... It was a limit switch with a cable across over the carpet..

Problem was I installed a brand new VFD drive, the roll up-inspector would go around and walk down the carpet while inspecting it.

He set it up to a fast walk, went around and was walking down the carpet.. fell.. and tumbled on the incline to the rollers about half a mile before someone ran over and hit the estop..

I put a cable across the carpet, it'd hit the estop circuit and break it out. I used a relay.

David