Need some advice..
I am designing a small feed system for lumber grading. This feed system is part of a lumber grading system.
There is a motor drive feeding the individual boards along a horizontal surface using rubber wheels or rollers. The feed motor is started manually with a magnetic switch.
At a certain point the piece of lumber should activate a limit or proximity switch indicating the lumber is correclty against the horizontal surface of the grading component ( very important to correctly grade)
If the board rises above the surface , even as little as 1/3 in., the limit or proximity switch should shut the feed motor down using the same magnetic switch used to start it..(severly warped board, etc..)
I wish to use one limit/proximity switch to do this. The difficult part is that the switch is normally open while the board is being fed through, then becomes closed, then open if there is a problem.
The open switch then needs to shut the feed motor down...
I have been looking at metal roller ball type switches, preferably dust-proof and rugged.
How to perform this trickery?