Hello everyone, my name is Francesco Bravi and I am writing to you from Italy. First of all I wanted to introduce myself and share with you what I do, I am 34 years old and for 11 years I have had a business that deals with printing on objects, engravings, millings and much more, Last month I broke a board of a desk engraver, I promptly replaced the controller with in arduino and GRBL, all smooth until I stopped for the limit switches, basically when the machine touches the limit switch then it no longer moves too pressing the "abort" key on openbuilds. I can't figure out how to fix this problem, I recognize that I'm self-taught and some things I don't know especially in the software part, I'm better at getting my hands dirty: D Not knowing how to do it I decided to see if there was a forum on openbuilds, and so here I am writing to you for help. Sorry for my English too but I used automatic translator because I was afraid of writing something wrong. I hope someone can help me, thanks a lot to everyone and good evening
Hi GRBL regards a hit on any limit switch as a hard limit and will then stop with an ALARM. This is mainly because the Arduino Uno does not have enough pins to have separate switches for home and limit, so it must share limit and home on 1 pin for each axis. The only time it must hit a switch is during the homing cycle, after that, never go to machine coordinate 0 on any axis. For this reason our Fusion360 post has offsets that you can set, the default is -10mm,. At the start of a job you will see a G53 G0 Z-10 which means "raise Z as high as you can, but don't hit the switch" The user can reduce the offset to a value that still avoids triggering the switch, say -1mm, whatever suites your switches and is 100% reliable.
Cheapie? Or decent controller with optoupled and filtered endstops like an docs.openbuilds.com/blackbox running Xtension Limits
Thanks so much for the answer, so could I customize some macros to do the home loop? If I used a different card with more pins, would the problem be solved? do you have any advice for me regarding the purchase? thanks and good job!
hi, the controller is original, and the limit switches work perfectly, they worked for 10 years with the previous electronics, then also in the openbuild serial communication screen I see when the limit switches are activated or not.
no, you do not need to change boards, it won't help. The total solution is to NEVER go to machine coordinate 0. Most of the postprocessors already support this, it is not a big problem. The GRBL command for homing is $H OpenbuildsCONTROL and other GUI's for GRBL will send this for you, it is not normally used within a Gcode file. The homing cycle is automated and uses values set in the GRBL setup. The defaults will most likely work but you can fine tune them after reading the Wiki github.com/gnea/grbl/wiki I use a macro on my machine (under bCNC) that safely moves to 'near home' so I can switch off the machine with it in a known position and after turn on the homing is quick because it does not have far to go. something like G21 G90 G17 G53 G0 Z-10 G53 G0 X-10 Y-10 moves the tool up and away to 10mm short of the switches. When to home? always after power up/power cycle/reset/software reconnect.
