Z offset and Boss laser

Since ruida controller doesnt support relative z moves in cut files (from what I read), setting z offset for multiple pass doesn’t do anything.

Or does it move the z in other manners before each pass?

Am I missing something?

Sorry to be simple and basic but have you confirmed your machine utilizes a stepper motor and driver to move the Z axis versus just a basic DC motor with up and down switches? I know some Boss lasers have the stepper setup and others do not. I looked up your machine on the Boss website but its description page was not specific about this.

I’ve built other machines (didnt want to build another one) and so I’m familiar with both.

That said I’m fairly confident that it uses steppers but has limit switches. I doubt that there are encoders on the drive “motors”.

Ok then more I read the more confused I get as I set all the parts in LB send to laser, set origin, autofocus on a axis, and run…

Not parts… parameters…

Ruida controllers don’t support relative moves during a job, but as long as LightBurn can read the starting Z height (or you specify it) it can figure out what the absolute Z height needs to be for each pass, and that works just fine.

So reading other posts and doc…

So how do I specify the height… is material height the right place.

Or… tell LB the starting z height is 0 (autofocus) before sending job to laser and take a risk on head crash…

I see the pieces but can’t seem to put it all together…

The simplest way is to enable “Relative Z Moves” in the device settings, and then LightBurn will read the current Z height when you start a job, and make all moves relative to that. This assumes that the machine is connected to LightBurn when you start the job.

The alternative is to use the Material (mm) value to specify the Z height to use (material height + focus height).

I’ll say up front that Z moves aren’t generally necessary with CO2 systems, and the feature was primarily for diode users where power is low. It is useful for things like defocusing a line, but for straight cutting you won’t see much benefit.

Main reason I want to use this is to lower the focal point into thicker acrylic (1/2 inch).

So if I’m putting the pieces together…

  1. set material height to 12.7mm plus 5mm which is what boss programmed(?) to z plus after autofocus
  2. turn on relative z
  3. connect machine before sending file

When I run the job again later do I have resend? (Probably asked and answered in another post) I can reason that the answer to this question is no because the z focus offset (5mm) doesnt change (even with nozzle change) and the cut file wont need to change unless programming changes are needed, correct?

If you do 2 & 3, you don’t need 1 - You’re over thinking it. If you are connected to the machine and have relative moves enabled, the software will read the current Z height when you hit start, and all Z moves will be made relative to that number.

So you auto-focus on the top of the material as usual, your Z settings would only need to reflect the relative amount you need to move (6.35mm into the material if you want to focus halfway through).

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