Technical GF question

Just a random technical question.
is there a reason why engraving takes SO long?
is it a hardware limitation, safety concern, software limitation?

I think it is my only true complaint of this machine.


It is a hardware limitation. You can only move the gantry so fast. There are units that use a moving mirror that are much faster. Start at around $25k.
Try score. Much faster and in some applications looks great.


Plus, the Proofgrade settings optimize for quality at the expense of speed. I’ve found you can get really decent results at 225 lpi and that cuts the time in half.


Engraving is slower than cutting or scoring because the laser has to touch every part of the engrave. From that point, the main consideration is the quality of the engraving. As noted above, right now we optimize for quality. We have some work in the hopper to give you more options in the future.


Compared to what?

Not CNC or 3D printing :slight_smile:

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I used a Universal laser cutter and it has done the same engrave in 8 minutes compared to 40min on the glowforge.

Glowforge does need to continue to optimize but you are comparing apples to pomegranates. I just looked a Universal in the same size and power class is thirteen grand so…


Have no doubt that the Universal is much faster. But for clarity in quantifying the difference, was the image used exactly the same? Most important, the same lines per inch? The GF default is quite high. Not talking about the resolution of the image that’s irrelevant to the time, but the number of LPI the laser steps. Half the line per inch almost equates to half the time.


Also it’s been discussed elsewhere but when engraving try to orient the piece so it’s “horizontal”. The Glowforge has to accelerate and decelerate at the end of each horizontal scan, which is “wasted” time. Orienting horizontally minimizes the amount of scan lines, and maximizes the ratio of lasering time compared to the starting and stopping time.

Also, manually engraving at higher speeds makes a huge difference in time, seems to be roughly linear by the speed, though I can’t guarantee that. That is, if you do engrave at 300/20 versus 900/50, it takes about a third of the time.

Anyone actually done a quantitative analysis of this yet? Has Glowforge officially commented? @jules would know, she knows all :slight_smile:


Thanks everyone. I am very much a rookie and have zero technical knowledge on laser cutting.
so sorry for my rookie question, but the responses were great!

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That’s really something! I don’t know anything about the Universal you used. I’m guessing it’s 40W CO2? Personally I’ve nothing to compare my Glowforge to. But this is the first time I’ve heard of such a big disparity between similarly-equipped lasers using the same artwork and comparable settings. So, and I’m not doubting you here, but are you sure everything was actually comparable when you tested? If so, seems pretty dramatic.

Most likely not similar… like i said, i am a rookie with the technical details.

so probably user fault in comparing the two.

ROFL! Actually, I believe @dan was the first one to point that out.
(And he probably does have the stats on it.) :smile:

Ah. Well, that’s cool. I mean, there are certainly a wide range of lasers out there. Some considerably better and some considerably worse. And, like I said, I’ve nothing to compare it to, so it seems like a perfectly reasonable speed to me. :wink:

Caveat: wild speculation follows, beware!

Ignoring all other factors like quality, material choice and effective LPI, I think this turns into a physics/thermodynamics thing. I’d suspect that to get similar results you’ve got to put a similar amount of energy into the material to ablate the engraving. Thus, you’d expect to need a much more powerful laser to work that quickly.

I mean you might be able to optimize scan algorithms to make it faster but there are diminishing returns there. You could try to reduce gantry/head mass as much as possible and/or increase the stepper motor specs (thus reducing acceleration losses) but again, diminishing returns. In the end I don’t see how to get around the overall energy requirement, so I bet the machines were quite different.

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My inquisitive side wonders if there are any restrictions with the laser and/or power supply - not with the GF specifically, but with lasers in general.

I’m curious if the slew rate of power adjustments may not be fast enough to allow for high horizontal resolution at high speed. That is, the zooms may have to be lowered to allow the pews to catch up.

I imagine the tube acting like a big capacitor, and that it takes a measurable amount of time for it to change from one power level to the next.


It’s the “comparable settings” thing. Hard to do that comparing zooms & pews to mm/sec & watts or % power. The Redsail is much faster than the GF for a top speed (1000 mm/sec). Heck, the K40 can be faster too on some operations.

It’s the results that matter and the other lasers I use are faster - often much faster - than the GF. Dan has pointed out before that they err on the conservative side of things. The GF is focused on improving the whole process of design to finished product. So I still prefer the GF when the project can fit :slight_smile:


Thanks for that insight!

BTW, the K40 remains unpowered and the Redsail has only been used a couple of times (last time I could have done it on a Pro with the pass-through but the PRU is a Basic so no go). The GF is a 99% machine for me :slight_smile: