Sumtor Control Board - homing/limit switches

[Roy-J]

Hi JAZZCNC,

You have made that all very clear for me to the extent that I feel ready to undertake this project one all the parts have arrived.

Can I just clarify that although your diagram shows 3 limit switches I can protect both ends of all 3 axis travels using 6 switches?

I wish to use your suggestion of using separate limit and home switches, if I do how should they be mounted to prevent hitting the limit before hitting the home switch, or vice versa? Or can I mount a home switch and limit switch on top of each other and Mach 3 sort out which switch is activated when either homing or hitting the limit? I hope I have explained this question correctly here.

Thanks and Regards

Roy

[JAZZCNC]

Can I just clarify that although your diagram shows 3 limit switches I can protect both ends of all 3 axis travels using 6 switches?

Yes I only used 3 as an example, you can have as many as you want in the chain within reason.

I wish to use your suggestion of using separate limit and home switches, if I do how should they be mounted to prevent hitting the limit before hitting the home switch, or vice versa? Or can I mount a home switch and limit switch on top of each other and Mach 3 sort out which switch is activated when either homing or hitting the limit? I hope I have explained this question correctly here.

Well if your using separate switches then HOME will always be before the LIMIT SW, which is the main reason for having them separate, so if when HOMING the switch fails and the axis doesn't stop then eventually it reaches the LIMIT SW.

So you'll need to place the HOME SW so that it's before the LIMIT SW. When placing the switches you don't want the SW so they get hit HEAD-ON, so to speak, ideally you want them to get RUN OVER when triggered so if something does go wrong or you hit them at high velocity the SW doesn't get wiped out.
Often this is done using ramps to trigger the switch, then if axis goes too far the ramp just rides over the SW.

There are several ways to do it and often the machine and space dictates which works best.