Ask Grbl CNC questions here.

I have built a corexy drawbot like the axidraw but i am having a few problems getting grbl to work correctly. Everything is working but after homing when i send a g code file it is going to the opposite ends of the axis instead of starting from its home position. I have it setup so that + is away from the endstop and - is towards the endstop.Any help you can give me will be much appreciated as i have been struggling with this for a few days now and not made any headway.

Thanks Nikki

 

Hi Nikki,

Can you explain what you have done to set up the direction ?

Also what happens if you don't home , but move to the home position , then run the g-code ?

I also note that that there are some comments regarding HOMING and COREXY in the config.h file ,ie the default
homing is incompatible with corexy , have you changed this.

Hope this is of some use.

Regards

Dave

 

Hi all, a very basic question. Which boards are compatible with GRBL? I know of one, its name is "woodpecker CNC GRBL 0.9 . I like this board, it controls 3 motors very easily, but I would like to know if I have options. Thanks!

 

Hi i have changed the config.h file for homing corexy. when i don't home it and send the g-code it is still moving to the maximum extremes of both axis. Ive attached my config.h file and my grbl $$ settings.

Thanks Nikki

 

I have found my problem. because i am use to using octoprint i forgot to check if the g code sender was at zero when i reset it to zero it works perfectly

thanks nikki

 

I have done this

a dozen times keeps takin me to a video .. where are the files ???
this site is frustrating

 

Hi ,

I'm currently working on controlling a VFD spindle over its RS485 interface . I note that it takes about 20 seconds to run up to speed, So I assume , the M3 SXXX command should block until the spindle has run up to speed , Is this the expected behaviour .

Many Thanks

Dave

 

Well, it used to be there... As we both pointed out, those versions are getting a bit long in the tooth anyway, the newer versions are much better. Thanks for the links, David.

BTW, I use Xloader to load GRBL into the arduino, much easier and faster than using the Arduino IDE.

XLoader

MG

 

Today I have started to have a problem that when started homing it seems that the machine resets the machine coordinates BEFORE it finish the homing procedure just before homing debounce and gives me negative coordinates. Does anyone know what is going on?
Machine coordinate goes like this:
X axis limit - 1mm (in my example -879),
Y -1 and
Z -1.
Earlier today it all worked fine
Any ideas?

 

@Sonny Jeon Hi. I've run grbl primarily on the Atmega328p and I was wondering if it is possible to run this on a 32-bit processor running at much higher clock speed (near about 100Mhz) than the AVR at 16MHz. If it indeed is possible, is there any benefit to doing this?

 

So after three frustrating days and after numerous trials and errors it seems that the problem solved uncommenting #define HOMING_FORCE_SET_ORIGIN in config.h
Hope it helps someone with the same problem.

 

Yeah, I tried to use that define as well, and had no luck with it. As you pointed out, the Y axis set to zero as expected, but the X axis still shows a large negative number. They are both supposed to set to zero. Perhaps put in a bug report on the GitHub page for GRBL, Sonny might fix it.

MG

 

Thanks David. I didn't know there was a version in the works. Are you aware of an ETA? Also where can I find more info on the kind of hardware it'll run on?

 

Hi all

As I have previously mentioned , I'm implementing the control of a Huan Yang VFD over RS485 for use with grbl-Mega.
I now have the basic system running, I'm able to start, stop and set the speed of the VFD , blocking any further commands from being processed until the requested speed is reached.
Also if It fails to reach the required speed, with in a time limit , it will set an alarm and attempt to stop the motor, At the moment , all the parameters for the drive have to be set up on its control panel .
I've yet to cut anything but air but I will set it to work next week.

If anyone is interested in having a go , with this, please let me know , and I'll make it available once I've cleaned up the code. I'll probably be able to make this available as a patch to grbl-Mega.
It is mainly additional files with additions to spindle.c and a call to initialise the serial comms in main.c , I've also used a second serial port for logging /debugging purposes , but this will not be required after setup.

Hope this is of interest to someone out there

Best Regards

Dave

 

Hi All. Having a bit of a strange issue here. My Z Axis ignores my settings and does as it pleases. What I mean buy that is if I set the Z Axis to invert via the tick box or the invert mask and use the jog buttons it does as required. However when I load my G-Code, if it reads Z5 it will push into my stock rather than retract up 5mm. So I invert the axis and it will do the same. If I manually edit every Z line in the code it all works well. So it seems that when it reads the Z line in the G-Code it is ignoring my settings.

I am about to pull the last strands of hair out and any advice would be appreciated.

I have not included the settings as it seems to make no difference what i set my invert mask to.

 

Beautiful I will give it a crack to night and let you know. I will also make sure to upload said examples. Thanks for the Quick reply.

 

Well. I fairly certain I manged to download the GBRL equivalent of a knock off star wars figurine that you bought from a guy round the back of a pub. It says official but was not. Any woo a few large glasses of wine and full reload of GBRL and a new Arduino UNO and she sings like that kid from the Voice, you know the one the one that is actually good.

I very much appreciate the help.

Matt

 

Hi,
I have been trying to configure a simple and reliable wireless cnc plotter setup. Basically need to take bmp, svg file from android to plotter for outline print like with a vinyl cutter. As a matter of fact our original proto was controlled from a stepper board out of a plotter/cutter and worked well but now needs to be off-the-shelf electronics (for the most part), reproducible and wireless.
Tried a MakeBlock app XY-Plotter Application for Andoid that looks perfect for our application but no evidence that the app even works.

Any ideas? Also, how can I find someone to work on these type of projects on a regular basis for compensation?

Thanks Much!
Charlie

 

Hi Sonny,

Many thanks for all your effort with GRBL, I think its such a great project!

I've got my GRBL 0.9 running on an Uno and then I have a cnc shield on top of it, for easy plugging in of stepper driver boards. The shield is here: Arduino CNC Shield V3.XX – Assembly Guide | Protoneer.co.nz

What I would like to do is switch my spindle on and off through a relay when the gcode sends an M3/M5 command. No PWM or anything, just drive a relay through a pin going high and low at the beginning and end of a gcode file.

The spindle enable pin and the spindle direction pin seems to be staying high, regardless of whether I send an M3/M4 or M5 command through Universal G code sender.

Is there some setting which I need to change in the grbl configuration before I can get this to work?

 

Hi Asterix

try specifiying a speed after the command , I found I had to do this for the relevant functions to be called , even though I was ignoring the speed at that time.

eg:

M3 S1000
M5 S0

Regards

Dave

 

You'll need to connect your relay using a transistor as described here. If you are using grbl v1.1, you need to specify a S value along with the M3 command to turn the PWM pin HIGH. If you've not tampered with the default values then its M3 S1000 to turn ON and M5 to turn OFF.

 

Thanks HPB, I have a board like this, which can switch 10A at 220V, off a 5V signal. So all I need is the 5V, 0V signal.

 

Thanks Dave, I will give this a try. I am also uninterested in the speed commands; but if that is what is required then that is great.

 

Yep that would work. Good luck.