Rastering small details | in-depth trial-and-error

Or spent the same $ as an Epi and gotten 3 GFs. :slightly_smiling_face:

sorry, I’ve been fighting the issue for a while and am rather frustrated :confused:

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I’ve got some other stuff going but I’ll try to defocus and see how my settings work with that.

One trick that might work is lower your LPI to like 240 and then run a score around the edges to make them smooth

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Thanks, I once tried scoring but it almost cut through at a low power. I’ll try with the lowest power to see how that works.

how thick is your material?

it’s 1/8"

At 500 speed 1 power I managed to score without burning through. Maybe the first scoring setting I tried was no good, I didn’t explore it further, oops

How are you getting your artwork into the Gfui?

Wanted to come back to this. I never did get a chance to play more with settings on the glowforge but I got an Epilog and I now understand why you are frustrated/fighting the lack of detail in small items on the glowforge. My items with tiny text come out way better on the new laser compared to the glowforge

Yeah I started to use an Epilog when I need the crisp details

Why do you think that is? Do you imagine that the GF is incapable or just not set correctly? I would think that the beam size is the same.

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I would say that having a better motion system probably makes a difference but the dot size is for sure smaller on the epilog than the glowforge. My cuts have less kerf on them.

This isnt even on materials like dual layer acrylic which can be weird; this is just on things like veneered MDF I see a night and day difference.

I wonder if this is perhaps related to the steps that the Glowforge uses on the focusing mechanism for the lens. I believe the GF lens moves in steps just under .03” (something like .0278” from previous discussions, which I guess could mean beam focus could be up to .0139” out of what would be considered perfect focus). I wonder what the focus resolution is on the Epilog.

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I don’t have autofocus so my focus resolution is bassically how quickly I can tap the jog up and down buttons on the table. I take my time but I don’t spend forever doing it so it is probably a bit better but not incredibly so.

Right. But it’s still mechanically driven so it presumably has increments that it can adjust the lens by to achieve focus.

I’m no expert in the mechanics behind all of it. I know you have a fixed focal length/point and you are adjusting the lens up and down to achieve that optimal point of focus that matches where your material is (in our case, that is 50mm from the lens). That up/down motion in the Glowforge occurs in steps. But, say a ring gear on a camera lens, could/would have much finer increments of change (depending on the teeth of the gear).

Do you know what lens is in your Epilog? I know they offer a 1.5” as well as the standard 2”. The GF would basically be 2”. The 1.5” Epilog lens is basically 38mm. You’d have finer details for engraving but it would reduce your cutting ability somewhat.

Yea but the stepper motor on the glow forge isn’t directly connected to the lens either so it should have pretty accurate positioning as well I would think. Assuming they have a good controller in there as well it should microstep. It’s been a while since I looked at the explode image of the head so ill have to refresh myself on it.
Standard 2" lens in my machine.

Very interesting discussion!

Here’s some discussion back in the day, partially related at least:

The real question is, what’s the impact on the end result? As mentioned, splitting the difference between focus steps give you a max potential distance of .0139” away from the actual point of focus. Using other internet info, a beam is considered in-focus with up to a 40% divergence in beam width. And the setup for the GF should have an in-focus (by the above standard) distance/depth of about 0.1”. So I’m not sure what the deviation would be for .0139”. I guess one could extrapolate it out and get a ballpark. Or make some small risers and test material at a few different heights around the focus steps.

And then you also have crumbtray variability which could be a couple to a few hundredths. :slight_smile:

And in the end, we aren’t even really measuring spot size, but kerf (a correlation between the two exists, so they aren’t independent, but they also aren’t fully dependent).

Either way, just thinking aloud more for the sake of thinking aloud than anything else.


yea I am curious what makes the quality difference as well.

Now the epilog applies dithering to all engraves no matter the source so perhaps that is it? I work 99% off vectors so if the glowforge handles them differently perhaps that process combined with the increased precision in the motion system is what makes they quality. The precision of the closed loop servo motors in the epilog will be higher than the servos in the glowforge so perhaps being more consistent from line to line is what makes the difference?

I know that the Trotec I also use has a 1 inch focal length lens in it which I use for engraving - and a 2 inch which I usually use for cutting thicker stuff. On the occasion I forget to change lenses, the engraves end up about as blurry as on the GF, which has - if I’m not mistaken - a 2’’ lens. I haven’t been able to achieve the laser-sharp focus (pun intended) of the Trotec (with the 1’’ lens) on the GF, closest I got was with very low speed, low power and high LPI. I did my trials on black anodised aluminium, which shows up the detail really well. I’ve posted on the subject before - before I knew about the focal lengths: Here’s the post

Hey… maybe that would be an option for a replacement head… An “Engraving head” with a 1in lens. Before you start working on that one though, @dan, finish the snapmarks rollout! I find I’m frustrated using the machine when everytime I do something I have to sacrifice time and material to cut yet another bl… jig.