I'm trying to make an index marker for my CNC lathe spindle. I need one signal per revolution and it should be "on" for about 1/4 of the time on my three inch diameter shaft.
I'll be using a hall effect proximity switch by Cherry Corp.
OK, I'm trying to figure out how to make a permanent bar magnet. I'll use a piece of cold rolled steel 1/2" thick by 2" wide. Then cut a 1 1/2" radius on both ends. This can be mounted to the end of the aluminum 3" timing wheel. The prox switch would then be mounted so the end of the magnet bar lines up with the end of the prox. switch.
I'll make this bar magnetic by imbedding 1/8" diameter permanent magnets in it. McMaster Carr rates the force of one 4" magnet at 0.4 lbs. (I'm planning on cutting them up - maybe 1" long?)
OK, I have NO CLUE how many little magnets to imbed and where.
Ideas?