Homing In GRBL

Mach3, grbl, ect.
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wmgeorge
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Homing In GRBL

Postby wmgeorge » Wed Jun 22, 2016 4:49 pm

I see a lot of discussion but not finding answers I need. Have a Chinese 6 watt laser and took out the POS controller and changed over to a Genuine UNO R3 and a real GShield V5. Purchased Pic Sender and its a god sent once you get it figured out. Ok up and running test files ran, no power to the laser diode yet, getting motion control done first.

On my commercially built ULS 50 watt CO2 laser, Home is top left, Y-X Zero. On my Plasma CAM CNC I think it was lower left. In Inkscape .91 it seems to be 0,0 lower left.

So where do I mount the NO Homing switches for X-Y?

How do I get the machine to find those switches?

On one other question, my laser diode is TTL control, can I just use the PWM signal 0 = off and 255 = On? I know it does not need the full 5 vdc to turn on the TTL but you get the idea. Someday when JTech gets the 6 watt controller ready and for sale I will go to that. I have seen the work people have done with Pic Laser and that's very impressive.

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Picengravertoo
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Re: Homing In GRBL

Postby Picengravertoo » Wed Jun 22, 2016 5:39 pm

Hi William,

The Homing for grbl is normally upper right, but you can set them at any corner. Look at the $23 - Homing dir invert mask, int:binary.

https://github.com/grbl/grbl/wiki/Configuring-Grbl-v0.9

You may run into a problem with no Z axis though. Are you using a custom branch of grbl?

If your driver is TTL, it should be able except PWM for variable intensity & on/off control.

Jeff

wmgeorge
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Re: Homing In GRBL

Postby wmgeorge » Wed Jun 22, 2016 6:03 pm

Ok Kind of got it. So positive is the same direction that my UP arrow key on the keyboard takes the Y axis, toward the top of the screen if it was a computer. And positive for X is to the right? Since I have not mounted or wired the N.O. switches I can put anywhere. No I am using the Plain Jane .9J version, pretty sure anyway.
So what your saying is the built In Homing looks to take the Z up and then moves to upper right side of table.
If the Z is not there, it will wait forever?
I don't suppose I could just jumper out the Z?

What I had assumed is that I would have to write something in gcode and somehow get it into the controller for Homing.

Thanks for taking the time to reply!!

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Picengraver
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Re: Homing In GRBL

Postby Picengraver » Wed Jun 22, 2016 6:18 pm

William,
I have full limits and homing switches on my Shapeoko2, and I home to the front left corner of the machine. I did have to change the $23 as Jeff advised. I'm not at the machine now, so can't tell you what setting I used. If it is a problem for you, post back and I will reply with my settings.

As to the Z axis, if it is a problem for you, you could connect a push button switch to the Z limit input and manually simulate a Z axis switch. Not ideal, but should work.
John

wmgeorge
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Re: Homing In GRBL

Postby wmgeorge » Wed Jun 22, 2016 6:26 pm

Well I am headed out to the shop after supper and just confirm the directions. What I may do is just move the carriage to the middle of the table, change the $22 or 23 to enable the Homing and see what happens. Slowing down the homing speed to allow me to switch it off when needed. I have worked with CNC for a number of years, but never the Arduino and I can see the potential already. Thanks for taking the time to reply.

Added: The arrow keys confirm I have the direction correct and I enabled the Homing and set the Seek and Feed settings, but Duh when I try the Homing the Z axis board lights come on.... so now its time to mount the switches (per standard upper right) and a cheater switch for the Z... for now anyway.

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Picengravertoo
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Re: Homing In GRBL

Postby Picengravertoo » Wed Jun 22, 2016 7:00 pm

Yes, you correct about the keyboard keys and axis directions. GRBL 9J will not execute the S commands in real time when raster laser engraving using S commands on every line of gcode. It will work fine if vector engraving/cutting though.

Yes, the Z axis homes first, then the X&Y. You could use a momentary switch on the Z axis limit switch pin on the UNO. Start homing, then push the switch, the X&Y will then home.

The $H button does the homing with grbl. No gcode required.

wmgeorge
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Re: Homing In GRBL

Postby wmgeorge » Wed Jun 22, 2016 7:31 pm

Picengravertoo wrote:Yes, you correct about the keyboard keys and axis directions. GRBL 9J will not execute the S commands in real time when raster laser engraving using S commands on every line of gcode. It will work fine if vector engraving/cutting though.
Yes, the Z axis homes first, then the X&Y. You could use a momentary switch on the Z axis limit switch pin on the UNO. Start homing, then push the switch, the X&Y will then home.
The $H button does the homing with grbl. No gcode required.


The funny thing is, the Chinese software for engraving allowed you to change the power setting in the set up. I had my Fluke set up to monitor the voltage on that yellow control wire and I could see the voltage change and the dot get brighter or dimmer.

I just need to purchase the Laser program here and see what it outputs. Learning a lot, thanks guys!

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Picengravertoo
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Re: Homing In GRBL

Postby Picengravertoo » Wed Jun 22, 2016 7:46 pm

On the main page of our forum here, there is the J-Tech LaserMode grbl 9g hex download. It executes the S commands in real time without any dwelling. However, it does not support Arc or G00 rapid commands. It was branched for raster engraving photos with a laser diode.

wmgeorge
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Re: Homing In GRBL

Postby wmgeorge » Wed Jun 22, 2016 7:48 pm

So I did have the Demo program and it outputs the M03255 command for spindle On CW full 255 speed in this case full output of the laser diode control. The rest of the commands follow more or less the same syntax. So without a true PWM controller like Jtech sells the Pic Laser will not work with my setup. I need something for now that just turns the laser on and off.... like TTL with M03 and M05 commands only, no speed or power.

wmgeorge
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Re: Homing In GRBL

Postby wmgeorge » Wed Jun 22, 2016 7:52 pm

Picengravertoo wrote:On the main page of our forum here, there is the J-Tech LaserMode grbl 9g hex download. It executes the S commands in real time without any dwelling. However, it does not support Arc or G00 rapid commands. It was branched for raster engraving photos with a laser diode.

Ok I was over to J-Tech site and was looking for his grbl file, I know I saw it there in the past? So the Pic Laser software will work for now, but I need to test first. That's great news. Thanks again.


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