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Unlock Gantry, Manually Set Origin/Position


I would like to place the carriage at a start point by manually moving the laser head/gantry.

How can I unlock the steppers to do this?
I am using Lightburn.


Hi Eric,

If by manual, you mean pressing a button and changing the gantry position as you need it, LB provides a few different options:

1   In the Move tab, you can press the 4 > characters which jogs the gantry step by step as defined in the 'Distance' field.

2   In the Move tab, you can enter in a destination (eg. x=100, y=100) and press Go and the gantry will move straight there.

If by manual, you literally mean with your hand:

Firstly, remember the K40 doesn't have limit switches to turn off the laser when you open the door, so you need to be very careful the beam isn't operating if you're putting your hand in there.

Secondly, it's a misunderstanding that the gantry should be able to freely move between positions when not actually running a cutting/engraving operation.  G-code systems like the K40 don't have real-time positional feedback, so a controller loses sight of where the gantry is once it's been moved by hand.  For this reason, controllers deliberately keep some current running through the stepper motors to ensure that the gantry does not accidentally drift off position, for example, due to tension from a air-hose, or a hand brushing against it.

So if you really want to go ahead and move the gantry by hand, the details are below, but be clear that manually moving the gantry can confuse the controller, and result in crashing the gantry into the end of the machine etc.  Once again, take care.  Instructions below:

In Lightburn's console screen, set up a macro by right-clicking on the Macro1 button. Enter in



G0 x0.1

G0 x-0.1


and rename the macro label to FREE MOVE ON

After clicking OK, now right click on Macro2 button and enter



G0 x0.1

G0 x-0.1


and rename the macro to FREE MOVE OFF

Now, whenever you want to move the gantry by hand, simply click the FREE MOVE ON button, manually move the gantry, then clock FREE MOVE OFF and it will be back to normal.

LB's macro settings are very handy.  In the above, the $1 setting is what turns off holding current to the stepper motors, but it's only active after the next command.  For that reason, I use G91 to go into relative mode (so you don't lose your position as you might want to keep it), perform a trivial movement, then back to normal absolute mode.

Hope this helps.


Your a life saver!

I have had the ability to do this for so long I was really missing it with the new controller.

So many times I just need to test or cut a circle or something and with my machine 8 foot behind me this makes life 10x easier.


dancolwp1974 has reacted to this post.

You're welcome!

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