Newbie here with lots of questions

Yes, I’ve gone over these instructions several times.
Keep in mind that I don’t have a dedicated laser, my laser is attached to a CNC machine.
My laser will never come from the lower left corner of my machine bed.
My origin will always be the lower left corner of the material that I place on the machine bed.
That being said, When I do that and then call that corner X Y zero, then move away from the zero, then click on the go to origin button, the machine takes off in a completely different direction.
What am I missing?

You have not said much about how you have this CNC setup configured, technically (I can’t see your settings until you share them :slight_smile: ), so I would look to the following;

Have you set your machine status reporting to be relative to the workspace origin, not the machine origin ($10=0)?

If your machine uses negative workspace coordinates you’ll need to apply a workspace offset (G10 L2 P1 xx yy).

Could these be issues you are experiencing?

In LightBurn, the zero point of your machine is never altered - On your system, it will always be the front-left corner. Set Origin just records where your machine is when you click that button, and running a job in User Origin mode will start with a jog to that coordinate.

@Rickx
My machine is an X carve with a J Tech 7 watt laser attached.
I don’t know anything about negative workspace.
I simply do not have any problems when I use the CNC and set my X Y zero anywhere I want.
I can jog away from that position, set in a new piece of wood, then tell it to go to X Y Z zero and the machine will move to that position.

OZ,
when I set the the origin, and then move away from it to set another piece of wood.then click the go to origin, th machine goes to a completely different area of the bed.
It doesn’t even try to go to the lower left hand corner of the machine.
It actually wants to go to about the center of the bed and almost all the way to the front edge.

these are my settings

The issue you’re having is likely two parts:

  • $10 needs to be set to zero, so LightBurn can read the position of the machine in workspace coordinates, not machine coordinates.

  • The zero point needs to be set to the front-left corner. This is done with a GCode command after homing that shifts the origin by the size of the X and Y travel values. (for example, G10 L2 P1 X-750 Y-750 would be what you’d use if the machine had a 750mm square working area)

Once those two things are done, everything should work as expected.

All of this is covered on this page in the docs: https://github.com/LightBurnSoftware/Documentation/blob/master/CommonGrblSetups.md#common-grbl-setups

And I think the link above that Rick posted to the J-Tech site covers all of it as well, with the exception of the $10 setting.

LightBurnOz

16h

JVL:

Is this not a positive coordinate machine?

Correct, it is not a positive workspace machine. If you run a homing cycle, and the machine homes to the rear-right corner, and sets that corner as zero, you will need negative coordinates to jog into the work area. This is common for CNC machines, and uncommon for lasers. Read here for a bit more info:
https://github.com/LightBurnSoftware/Documentation/blob/master/CommonGrblSetups.md#common-grbl-setups

JVL:

(I never use homing as I always home from my work piece)

This is easily most of your trouble in LightBurn. You are using it like CNC software, and it isn’t written to work that way. By zeroing to your workpiece you are eliminating the ability for the software to jog within the machine envelope safely, because you moved it. LightBurn enforces its own soft limits. By changing your zero point, the software can no longer know where the actual bounds of the machine are.

The ‘Click to position’ feature, for example, uses absolute coordinates, relative to the machine zero. If you move the zero, that feature won’t work, and neither will anything else that uses the location of the machine to figure out if you’re going to go out of bounds.
image

Zero the machine to the front-left corner (the origin) and leave it there. Then use the ‘Set Origin’ feature in the software to set the job location, and ‘User Origin’ mode when running a job. It behaves the same as what you’re used to, but doesn’t require changing the coordinate system.

1 Like

Good morning OZ,
So to better help me understand.
In the CNC world, my X carve is in positive coordinates.
But in the laser world my X carve is in the negative coordinates.
Is that a true statement?

So I’m out in the shop and going through the directions line by line under the section “other machines”

  1. I started the machine, went to the “move” tab and hit the “home” button.
    got an error:5 message
  2. followed the directions to enter G0 X0 Y0 and pressed enter
    the machine moved toward the front of the machine and to the right.
  3. followed the directions and entered G0 X10 Y10 and hit enter.
    the machine moved to the right and to the rear (into the work envelope)
    If I’m understanding the directions correctly my machine is in positive work space?
    So then I moved the machine to the left front of the bed and hit the “set origin” button in the move tab.
    From there I moved the machine to someplace about the center of the bed.
    At this point I’m lost again as the machine behaves the same as before.

If you hit the Home button and got error:5 it means homing is disabled on your controller.

I’ve mentioned a couple times now that the $10 setting must be set to zero, but you haven’t confirmed yet if you have done this.

And again, “Set Origin” does not zero the machine, or change anything at all. It simply records the position that the machine reports when you hit that button, and it relies on the $10 setting being correct. When you hit “Set Origin”, LightBurn sends this to the controller:

?

The controller responds with a status report that includes the current position, reported in either absolute machine coordinates, or relative to the workspace zero. You want the latter, which is what setting $10=0 gives you. If you don’t set that, the ‘Set Origin’ function will record the wrong coordinate, and when you start a job it will go to the wrong place.

If you don’t have homing enabled on your machine, your system is in no particular coordinate space at all.

Normally, an X-Carve has homing switches in the rear right of the machine, and when you home it in CNC mode, it sets that position as zero, which means you get this:

Since that rear-right location is zero, and +X goes right, and +Y goes back, it means you would need to jog in the negative direction to move the head into the usable work area. This is all that is meant by “negative workspace” - The workspace, by default, after homing, is in the negative coordinate area.

With dedicate laser systems, they’re usually set up so that, after homing, the coordinate system looks like this:

The directions are identical, but because the origin is in the front left, the workspace coordinates are all positive numbers.

Homing is the key here. Since your machine doesn’t have it enabled, when you power up, the actual machine origin is going to be wherever the head was when you applied power. Everything else you do from there will be a workspace offset applied to that (completely arbitrary) location. This is why you need to set the machine to report its position relative to the workspace offset, not machine space, because you can’t have a machine space without homing enabled.

OZ,
I only stated that I don’t use homing.
How do I check if homing is disabled or not?
How do I change it.
These are my settings.

$0=10
$1=255
$2=0
$3=4
$4=0
$5=0
$6=0
$10=0
$11=0.020
$12=0.002
$13=1
$20=0
$21=0
$22=0
$23=3
$24=25.000
$25=750.000
$26=250
$27=1.000
$30=1000
$31=0
$32=0
$100=40.000
$101=40.000
$102=50.024
$110=8000.000
$111=8000.000
$112=750.000
$120=1000.000
$121=500.000
$122=200.000
$130=540.000
$131=540.000
$132=100.000

$22 is the homing enable setting, and yours is off, which is why when you click the Home button you get an error.

You also have $13 set to 1, which is “report machine coordinates in inches”. You will also need to change that, as LightBurn expects mm from the machine, so that would be another reason why things are wonky for you.

For using the laser, you also need to enable laser mode ($32=1) so the machine doesn’t pause with every power level change, and will automatically turn off the beam for travel moves. When you want to use the CNC again, just set $32=0 again.

OZ,
I made the changes you suggested.
When I hit the home button on the move tab, the only thing that happens is the Z axis goes all the way to the top ans bottoms out.
(at least something is happening)
$$

$0=10

$1=255

$2=0

$3=4

$4=0

$5=0

$6=0

$10=0

$11=0.020

$12=0.002

$13=0

$20=0

$21=0

$22=1

$23=3

$24=25.000

$25=750.000

$26=250

$27=1.000

$30=1000

$31=0

$32=1

$100=40.000

$101=40.000

$102=50.024

$110=8000.000

$111=8000.000

$112=750.000

$120=1000.000

$121=500.000

$122=200.000

$130=540.000

$131=540.000

$132=100.000

ok

For that, you might be out of luck, at least if the Z axis doesn’t have limit switches on it. Z homes first, then X/Y. The only way to turn off the homing for the Z as far as I know is to disable it when compiling GRBL from the source code.

I don’t think you can do it otherwise, so you might not be able to use homing with your hardware unless you can find a pre-built version of GRBL that has Z homing disabled, or install a switch for the Z limit.

You are correct in that I do not have a homing switch for the Z axis.
It got broken very early on and I never replaced it because I realized that I would never use homing anyway.
So maybe I have to install a Z homing switch for the laser only. (not a big deal)
Thank you for the learning lesson today.
I will pick this up again when I get a homing switch installed.
But for now, I have to get on the John Deere and mow the grass here in sunny Ohio.
Sorry for all the dumb questions but I really want to get this software to work for me.
Thank you again

OZ,
I have an aftermarket (CNC4newbies) Z axis.
Right now I don’t see a simple way of mounting a homing switch to it. (doesn’t mean it cant be done though)
I was reading the other thread (lovesnapped) and saw this response.
Could this be a work around in my case?

BlakeBlake BartlettRegular

10h

LightBurn:

To fix it, move the laser head to the front-left corner (or wherever you have your origin set), before you power it up, so that’s where zero goes, OR, jog the laser to that corner, and issue this command:

G92 X0 Y0

Did you follow these instructions?

Yes, that could work as well - if you turned off homing, issued that command, have $10=0 set, and $13=0, yes it should work.

Cant easily install a limit switch on my Z
So I made the changes and now my laser works exactly the way that I want it to.
Thank you for all your help.

So currently when I click the “fire” button and then jog the laser, the beam turns off and then I have to click it twice to make it fire again.
Is there a way to fire the laser (obviously in low power) and have it stay on while jogging the machine to the target and then click it off?

There is no way to jog the laser with the low power beam enabled in LightBurn. It is explicitly turned off when you move the laser. You can frame at low power though:

Rick fixed the link - try it again.