Limit Switch configuration

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gstprecision
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Limit Switch configuration

Post by gstprecision » Fri Nov 30, 2018 11:12 am

Hey, I am very new to CNC building so please be easy on me...lol

I am about ready to put together my electronics, and I have no problem with that. However I am slightly confused with the limit switch. I did some research on here and I have found a few answer but still need clarification.

1- What ground do I use for the switch? Older version seem to have a GND pin with the limit switch connector, not the 2.60. Found an answer to use coolant GND, does that make sense?

2- Can I use 2 limit switch per axis, one on each end limit, or just 1 per? And do I connect them, in serie or parallel? Diagram or picture would help.

Thanks
GST

Bertus Kruger
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Re: Limit Switch configuration

Post by Bertus Kruger » Sun Dec 02, 2018 6:40 pm

gstprecision wrote:
Fri Nov 30, 2018 11:12 am
1- What ground do I use for the switch? Older version seem to have a GND pin with the limit switch connector, not the 2.60. Found an answer to use coolant GND, does that make sense?
Any of the GND's can be used for the switches.

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Re: Limit Switch configuration

Post by Bertus Kruger » Sun Dec 02, 2018 6:43 pm

gstprecision wrote:
Fri Nov 30, 2018 11:12 am
2- Can I use 2 limit switch per axis, one on each end limit, or just 1 per? And do I connect them, in serie or parallel? Diagram or picture would help.
You can use 2 per axis and they need to be connected in parallel... GRBL homes only in one direction though. Make sure to have a limit switch at that end.

Bertus Kruger
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Re: Limit Switch configuration

Post by Bertus Kruger » Sun Dec 02, 2018 6:51 pm

I have updated the Wiki with an image :
https://wiki.protoneer.co.nz/Raspberry_Pi_CNC#End_Stops
2xEndstops.png
2xEndstops.png (2.3 KiB) Viewed 74 times

gstprecision
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Re: Limit Switch configuration

Post by gstprecision » Thu Dec 06, 2018 12:29 am

Exactly what I was looking for.

Thanks
GST

StuartB
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Re: Limit Switch configuration

Post by StuartB » Thu Dec 06, 2018 1:01 am

You should also use NC (normally closed) switches.
They are standard in CNC machines and a lot safer than NO.

http://www.cnc4everyone.com/safety/limit-switches

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Re: Limit Switch configuration

Post by Bertus Kruger » Mon Dec 10, 2018 6:00 pm

StuartB wrote:
Thu Dec 06, 2018 1:01 am
You should also use NC (normally closed) switches.
They are standard in CNC machines and a lot safer than NO.

http://www.cnc4everyone.com/safety/limit-switches
The GRBL firmware recommends Normally open as in the diagram. We have added noise filtering to the board to take care of most noise issues.

StuartB
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Re: Limit Switch configuration

Post by StuartB » Mon Dec 10, 2018 6:18 pm

The GRBL firmware recommends Normally open as in the diagram.
That may be the case, but you want a safer method.

You want to break/open a connection when there is a problem, not close one and possibly make things worse.

This is helpful.
https://github.com/gnea/grbl/wiki/Wiring-Limit-Switches

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