One limit switch per axis

[Ulsterman]

Usual CNC setup with homing required machines
Move to Zero
Plus soft limit--- where the servo is stopped or held mode is plus 5mm and comes from the axis control
Hard limit activated by a switch linked to the Estop circuit is plus 10mm
The same goes for the Minus side
Wither its two switches or two position dogs really doesn't matter but they are there to protect the machine and zones
For recovery from these usually needs an over travel release button on the operators panel and sometimes keyed so proper- questions are ask to why its there in the first place

[JAZZCNC]

Normally wired open given you a warning if the switch is sticking or failed --remains in Estop with alarm

Not being pedantic here but it's Normally closed switches not open.! Then if wire breaks you get warning, switch gets broke when it's triggered.

[Ulsterman]

The failure is usually caused by the switch never being used and then they stick down in the on position not the wire being broke ---------So when you release the machine off the switch it is stuck on the on position -so normally open would be a good idea ?

[EddyCurrent]

Just ignore, I seem to have posted twice.

[JAZZCNC]

The failure is usually caused by the switch never being used and then they stick down in the on position not the wire being broke ---------So when you release the machine off the switch it is stuck on the on position -so normally open would be a good idea ?

No that's unsafe and it's very common for a wire to break or come disconnected in which case the machine E-stops.
Doesn't matter if the switch is stuck after being tripped because E-stop is still affective it just means you have to find the faulty sticking switch which you would want to do anyway.

Regards the Limit over ride then I use Momentary button with Buzzer warning it's overridden.

[Ulsterman]

Thanks jazz your right should be that way so always a break in power detected for these and Estops -sorry for the mix up

[JAZZCNC]

Thanks jazz your right should be that way so always a break in power detected for these and Estops -sorry for the mix up

No problem understand and like said was being pedantic but it's small things like these that new folks pickup on and see from other post's that your knowledgeable so take that it's correct and use it.!!. . . I see it often with helping new users so it jumps out at me and wasn't trying to put you down just clear it up.

[manofgresley]

Hi

Yes there's 2, but very easy to install

Something like this ?

Ray

[EddyCurrent]

If I was using servos and encoders I would be using the absolute type and as you say soft limits would be my choice with hard limits providing final limits. As I'm using stepper motors this is not an option so while I could fit encoders I've decided to just fit switches. As you say, once these switches have been activated there must be a way to recover and I admit I have not investigated this aspect yet but I'm sure there is a simple solution such as an override button as you mention. With regard to limit switches these are always in the normally closed mode and are opened upon activation, this means that if the wire is broken or the connection fails the system will stop.

[Ulsterman]

Removed by me