Other lasers have a PPI/PPS/frequency setting in addition to power, why not us?

When I look up materials settings I often see references to a frequency input in addition to speed and power. Is a frequency setting something that’s unavailable to us because of the Glowforge design, or something that is manipulated behind the scenes?

Recently for the first time I actually wanted to change that value as it’s said to be handy in the material I am working with, so it made me wonder.


Look at the manual engrave settings. The item you’re referring to is labeled “Lines Per Inch”.

I think LPI is in the front-back direction. That is, how many lines or back and forth passes per inch. The gantry moves from front to back 1/LPI of an inch after each right to left or left to right pass.

PPS/PPI on other lasers are pulses per inch or pulses per second and means how many ons/offs in that time or distances during the scan from left to right (or right to left). It’s a little like horizontal resolution.

I think the idea is that the Glowforge software wants to figure that out for you.


Is it? I see references to changing Pulses Per Inch in cut operations on other lasers. We don’t change LPI for cuts.

You may find this of interest


Good find! It’s worth mentioning that other laser technologies (solid state/YAG and RF-excited CO2) are sometimes operated using extremely quick pulses instead of continuous being on or off which may be what you’re seeing.


Memory like an elephant - a blessing and a curse.


No kidding.


Yep. The conventional laser cutter/engraver actually uses a series of dots that are supposed to meld together. The GF can simulate that if you want, but you can also do the continuous, which gets you certain effects that are difficult to achieve with a bunch of pulses.

How would I simulate changing PPI on a Glowforge? Cut a dotted line?

You would most likely have to do it in your design program.

AFAIK, Glowforge won’t recognize the dashed lines created in Illustrator using the Stroke palette. You would need to create a pattern brush with a single dash, then expand the object’s appearance.

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Correct – as of March '18 (hey, things change over time) the GFUI will display a warning, then render “dashed” lines as solid.


Did you find an answer to your question about ppi? I have the same question and have yet to find an answer. If you can help me out would be amazing!

There are two posts above that should answer it - one from me and one from @aeva (she’s pretty smart, so I just linked to her words in another thread)