GRBL Config

Discussion about the arduino based g-code interpreter, grbl
Post Reply
Shook
Posts: 139
Joined: Thu Nov 12, 2015 6:50 pm
Location: Downingtown, PA

GRBL Config

Post by Shook » Wed May 24, 2017 1:09 am

I'm adding an E-Stop switch that's Normally Closed with my Shapeoko 3.

Do I need to alter anything in the config other than uncommenting the line below?

#define INVERT_ALL_CONTROL_PINS
Shapeoko 3 (#1107)

chamnit
Posts: 376
Joined: Tue Aug 12, 2014 2:16 pm
Location: Albuquerque NM, USA
Contact:

Re: GRBL Config

Post by chamnit » Wed May 24, 2017 5:04 pm

E-stop should be wired to cut all power, if possible. If not, try wiring to the Arduino hard reset pin. That should prevent Grbl from running until the e-stop is released.

Shook
Posts: 139
Joined: Thu Nov 12, 2015 6:50 pm
Location: Downingtown, PA

Re: GRBL Config

Post by Shook » Wed May 24, 2017 5:12 pm

The stop switch is currently wired to the e stop pins, but the machine only runs if the switch is pressed. I have to release it to stop.
Shapeoko 3 (#1107)

chamnit
Posts: 376
Joined: Tue Aug 12, 2014 2:16 pm
Location: Albuquerque NM, USA
Contact:

Re: GRBL Config

Post by chamnit » Wed May 24, 2017 6:25 pm

Grbl does not have an e-stop pin, only a soft-reset, feed hold, and resume. None of these should be used to control an e-stop.

Shook
Posts: 139
Joined: Thu Nov 12, 2015 6:50 pm
Location: Downingtown, PA

Re: GRBL Config

Post by Shook » Wed May 24, 2017 6:50 pm

I'm confused. There's a set of pins on the shapeoko board labelled e-stop. If grbl doesn't do e-stop, what are those pins hooked to in the standard firmware?
Shapeoko 3 (#1107)

CrazyBillybob
Posts: 197
Joined: Mon Dec 16, 2013 2:09 pm
Location: Ohio
Contact:

Re: GRBL Config

Post by CrazyBillybob » Thu May 25, 2017 12:37 pm

most E-stop buttons have two sets of contacts a normally open and a normally closed set. Take another look at the switch and see if you can switch to the N/O set.
Chamit,

I don't have a Carbide 3D board in front of me, but I think that Edward has designed the E-stop into the board and is not relaying on the software for this function (a very good design decision imho). In this case you can not change the logic level of the trigger, you must have a N/O switch to have it work correctly. (please note this is only speculation on my part as I have not played with the board in question this way...)


CBB

chamnit
Posts: 376
Joined: Tue Aug 12, 2014 2:16 pm
Location: Albuquerque NM, USA
Contact:

Re: GRBL Config

Post by chamnit » Thu May 25, 2017 5:02 pm

If I remember right, the CarbideMotion board has an extra logic chip that disables the stepper drivers and overrides whatever Grbl is doing. In the sense of disabling Grbl, that's fine to use for an e-stop for Grbl and the steppers only, but there's a lot more needed for a proper e-stop.

I'm unsure if the CM board e-stop pins disable the spindle (and coolant). It might on the Nomad, but not a stock SO3, since it uses a separately powered trim router. You really want an e-stop to be wired into everything powered, so you don't have to stick your hand into the machine to turn off the spindle, especially when its still on and likely inside the workpiece. There can be other situations where this can be very dangerous, like the risk of a tool shattering or starting a fire. If you use a laser with your SO3, then the dangers are even greater.

I still recommend that you should just wire an e-stop to something to kill all power. This can be as simple as a using the toggle switch on a surge protector as your e-stop or just wiring a button into it. Or it can be more complicated and used to control a set of relays that power various machine components, along with the CM board's e-stop pin.

Post Reply