How do I set z-height correctly with SnapMaker?

Hi all -

I’m using LB with a SnapMaker2 A350.

I ran the autocalibration via the screen to get the correct bed height (set material thickness, run calibration, etc.). So the machine knows where it should focus above the material.

If I start a laser job on the device touchscreen, I can specify the material thickness, and it will adjust z-height automatically.

How do I set the z-height in LB? So far I’ve been manually moving it until the dot looks as small as I can get, but that seems inefficient.

I believe there’s a gcode command for getting the z-height focus length that the machine has stored, but can’t seem to find it on the SM g-code reference sheet (or am not seeing it).

What’s the correct workflow for using the autofocus height + material thickness with LightBurn & SnapMaker?

Thanks!

I don’t have a SnapMaker and have no way to test this, and all SnapMaker support so far has been incremental, making changes after user feedback, so tread carefully here - I can’t guarantee this won’t do something bad:

If you enable Z moves in the Device Settings, the Z height will be set to whatever value is in ‘Material (mm)’ on the main panel. If you know what the focus height is you should be able to add that to the material thickness and it should just work.

Z moves are a rarity with lasers, so the Z support in LightBurn is pretty minimal. When using an Emblaser machine, the Z control is pretty good, but they specified exactly how it should work for their specific hardware, and sent a unit so I could verify everything and test incrementally. I would likely need SnapMaker to do the same in order to fully test and verify proper operation for their machine.

Hi @GameMaker,
I was in the same situation with my SM2.
My solution was to make the laser calibration in Luban. Then I measured the empty space between the laser hood and the surface of the material to be laser engraved/cut. 4mm in my case.

I designed a small cylinder of the same height (4mm) and 3D printed it. For calibrating I place the cylinder over the surface of the material to be engraved and I gently place the laser hood over the cylinder’s surface with small increments by the Lightburn Move menu.

In this way the positioning is war more precise than the laser spot observation.

Hope it helps!
Gianluca

Yeah, I’m going to do something similar, but without the cylinder.

Luban to calibrate, then use Lightburn to move the laser down until the hood just touches the surface, and keep track of how far it moved. That’s my focal length.

Then from now on, I calibrate by placing the material, adjusting the laser so it barely touches the surface, then move it up by my (now known) focal length, and I’m done.

How does the measured space you found correlate with the Snapmaker’s own “Laser focus” reading? Mine, for example, after doing the built in laser focal length procedure (with the included wood) reports a “Laser Focus” of 23.000 mm - which is way more than the 4mm you’re seeing.

I’ll measure mine after the current burn job is done, but I was curious to see what the correlation was.

I’m just starting my laser experiments with my A350 and found Lightburn in my searches for better apps than Luban. From what I can see so far, Lightburn looks terrific, if a bit complex (I’m willing to learn!).

Good question. In my case Snapmaker’s own “Laser focus” reading is 22.20mm but it consists on the distance between the emitter and the material’s surface. 4mm in my case is the empty space between the base of the hood and the material’s surface. Being the distance between the emitter and the base of the hood constant, you just need to measure the difference.

I jumped to Lightburn exactly for the same reasons you mention. Moreover price is affordable and the developer willingness to support users makes the difference.

At the moment there are still some issue to solve in the software, mainly with the M7/M8 function, but this should be solved in the next software release.

@LightBurn - I have the Snapmaker working nicely with Lightburn now, Thanks. As you suggested I have to set the material height as the sum of material height + the focus distance. This is fine when you remember to do it, but if you forget you crash the head into the work peice :frowning:

Thanks to @Voidoids for the setup info.

Any chance you could add a “Focus Distance” setting somewhere that is automatically added as an offset to the material height? If it had that feature it would be perfect!

I’m planning to write up a new setup guide for Lightburn with Snapmaker, building upon what @Voidoids did with some other settings and explaining the Z height more.

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@Chapmaker - I’d be willing to collaborate with you on that. I’m trying to write a “Second Book of Snapmaker” - like, the book you need if you’re new to all this, and you just received your SM2. It covers all the pitfalls you can run into - like head crashes and stuff.

Right now it’s just a bunch of notes and stuff, so I’ll cut it into parts (3D printing, laser, cnc), and share links, and anyone can contribute. I’ll post here when I get it ready.