Atomstack S10 Pro - engraving/cutting mirror/clear acrylic & S max

Has anyone figured out the correct settings to engrave/cut mirror/clear acrylic with the Atomstack S10 or X7 Pro lasers? The settings originally sent from Atomstack are way off. I am working from the back, and blackened the front to no avail. I reached out to Atomstack and here is the response they sent:

I just asked our technical team for a test data, they have tested another one laser engraver 2.8mm acrylic cutting parameter before.
They say this data also applies to the S10 pro. Please refer to the following data.
Material: acrylic Thickness: 2.8mm

Number of passes:1

Number of passes:2

Number of passes:3

Besides, under normal circumstances, it is not necessary to blacken, but it is still recommended to paint black for materials with strong reflection.

I also question what exactly does the S max do? I’m a total newbie and am learning a lot from Youtube but have been unable to be successful with this after hours upon hours of researching/trying. Any help would be greatly appreciated!! Thank you!

S max is a number that does a couple of things. This is fun.

The laser power is controlled by PWM (Pulse Width Modulation). It’s a fancy term for a turning a switch off and on several times a second (usually about a thousand times a second for most diode lasers).

Because the on/off is so fast you can’t tell when the laser shuts off and comes back on - so this works like a light-dimmer but it doesn’t dim the laser out of the operating range because it’s on/off.

LightBurn takes a number in the Cuts / Layers window that is a percentage of the max power and converts it to g-code on/off and sends the g-code on/off to the laser in a cutting / engraving instruction. Instead of a percentage (some number out of 100) it becomes a fraction of S-max. LightBurn instructs the engraver in the fraction of S-Max (10% becomes S100 when sending g-code if S-Max is 1000 and 90% becomes S900 when sending g-code if S-Max is 1000)

When $30=1000 in the Machine Settings the engraver will understand the S=900 or S=100 correctly.

So, S-max and $30 are the way the amount of max power is communicated which is why they really should be the same number.

If these two numbers are not the same, the G code can all too easily call for maximum power or not enough power.

Like an accelerator pedal, you want the mostly-off state at one end of the scale to be mostly-off and you want the full-blast end to be full blast. If this leverage is messed up in software it won’t make for a great time.

The mostly-off end at zero or one lives in the definitions in the software but the S Max can be 100, 255, 1000, 10000… anything really, as long as those two numbers match.

S-Max seems to be a term left over from CNC (Computer Numerical Control) milling machines. I believe that the S Max originally referred to Spindle speed (like a dremel only much bigger) in the original intent of the milling machine software. Since that type of motor could be PWM controlled it was easy to repurpose for the laser diode engraver.

If I didn’t write this clearly enough or if you’d like to pick at the ideas here I’ll be more than happy to elaborate and clarify. I want people to have an appreciation of how this process works and why it’s kind of a big deal in motor/laser control.

I think simplistically that when $30 is 256 and the S val is 1000, lightburn figures a 50% value based on 0 to 1000, which is 500.

Grbl expects (because of $30=256) 50% of 256, or 128. 500 would indicate full power.

It is the same as the machine being in inches and Lightburn in mm, there will be a problem… They need to ‘speak the same language’, so to speak…

Make sense…?

Don’t know how Lightburn handles it exactly, but this gives you an idea of the reasoning.


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