Why is my x0-y0 17" past home position?

Ready for this??? I’ve had Lightburn for more than a year now and just opened it up after upgrading to 1.5.6. I know, Crazzzzzy right. Well, Since I also use Vectric V-carve, I finally decided that it’s time to figure out how to use Lightburn. I’m going through the tutorials however because my machine wants to home -15+ inches behind what Lightburn has decided to call X0-Y0, I need help. After several days of trying, I’m permanently stuck and need some expert advice. Can anyone help???

Just a wild guess, sounds like your machine is set to -x,-y and lightburn wants to work in the positive +x,+y quadrant.

Do you have limit switches?

Post screen shots of your machine setting and the program settings. The kool kids™ here will be able to help you (I am not a kool kid ™)

Yes I do Have Sensors

Do the sensors stop the machine during the home cycle or does the machine crash on the rails?

it stops where it’s supposed to.

Ok, now the Kool Kids™ have some workable information to chew on. Again, I am not any kind of expert at anything, besides sleep and eating.

There are hundreds of different combinations of laser, controller, operating systems and customer experience levels. The more information you put into your forum post, the less questions have to be asked to get your problem worked out.

Good luck, I will be watching to see how this plays out.

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Need more input. Not a Kool Kids™ either, but I will try to help.

The Sienci appears to be only a laser head. What machine has this been attached to? Is it a leadscrew or gantry machine? What controller is used on this machine?

To help us help you, enter $$ in the Console window, then follow it with $#. From the Console window, copy the results and paste them in your Reply.

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Does sound like an offset for sure
in console would show also Mpos and Wpos, they should not be matching if the offset is there

That was next if others looked good.

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:pray:, thank you for your support.

I’m using Sienci Labs Longmill 48x30 CNC machine. The actual working surface is 50”x33”. It has a gantry with lead screws and I’m using their longboard controller.

Currently the machine is in use using the v-carve, so as soon as it completes its task, I’ll attach that photo.

Ok, one of the large ones! Envy here…

I know nothing about that controller, and my questions were based on it being a GRBL controller. If the $$ does not produce the expected results, I will have to turn this over to someone with experience using the Longmill machines.

No worry, we (the Lightburn community) will help get you to a solution.

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I just did a Longmill search in the forum and see the $$ and $# commands should work.

Here are the results of the $$ & $#

This morning I saw something strange happen. When I first access, Lightbourn, the coordinates were X=0 Y=0 and Z=0 at the homing point, However, as soon as I move the machine, the coordinates changed. I’ll include pictures. Maybe this means something?

I moved the Y axis back two clicks and got this.

Now the homing position is showing -7.9 as opposed to -15+? And a similar situation with the Y axis however, the axis hasn’t changed.

Curiouser and curiouser🤔

Okay, I see you are using work coordinate offsets G54-G59.

Do the ? in the console window and paste here. This will report machine and work position numbers.

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It looks like you are G54, G10, and Current Position confused. With those settings, it would be hard to predict where it is going to end up. You are still in the CNC mode.

Make a note of your current settings, and then do this:

  1. Set $10=0 (from =3). This tells the controller to report workspace coordinates rather than machine coords.
  2. Home the machine.
  3. In the Console window, enter G10 L2 P1 X0 Y0 Z0.
  4. In the Move window, click on Get current position.
  5. Record the X & Y positions reported. Post those numbers here.
  6. Jog the machine to near the corner opposite of the Home position.
  7. Record the X & Y numbers and post those here too.

Once we see those numbers, we should know what we need to change in GRBL.

I also recommend you use Absolute Coordinates for positioning.

Might go through the Lightburn grbl setup… Many of these settings are described there…

Such as the relationship between $30 value in your controller and the S-Value Max set in your device settings. They should be equal, Lightburn defaults to 1000…


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:pray: thank you. I’m going to go through this later today. This is good stuff.

Also, a new revelation on the subject. By way of Sienci Labs support, I was just informed that they’ve located a glitch in the system regarding touch screens where it will double the x and y movements, but only when using the touch screen.

I’m going to test this out today. This may be part of the problem,

Either way, I can’t share enough gratitude for all of you who came to my rescue. :pray::pray::pray:

I’ll bring back my findings after getting through all of this stuff.


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