Accurate pocketing?

Will GlowForge be able to cut a pocket into the surface of a material to an accurate depth? How smooth would the bottom of the pocket be?

This will not be cutting but engraving. With lasers in general “Cutting” means “to cut through” the material. (by removing the kerf in material). “Engraving” means “to remove a layer or layers of the material but not cutting through”.

You can engrave most materials but the depth of the engraving varies on every material and every setting of the laser (speed & power). Engraving is done in horizontal lines. (raster) I do not know if glowforge will be able to engrave on the vertical axe or even engrave diagonal. The engraved surface will not be silky smooth. If you are looking to engrave deep enough for something to slot in there you are looking at multiple passes at different speeds and powers as to achieve the acquired depth.

I do not have any practical experience with this so please anyone who has correct me. I only have experience in cutting and engraving grayscale.

Yes I am aware of what a normal laser can do, but doesn’t the GF have a camera that can measure depth accurately to allow it to do accurate 3D contouring?

@dan gave a good example of what the forge is targeted for accomplishing in regard to depth engraving. There are several threads that explore this:


@palmercr I do not believe that the glowforge will be set up in a way that you can tell it to cut to a certain depth, at least from the software demo’s I’ve seen on youtube. As long as the material is homogeneous and you use a consistent power and speed, it should be a fairly accurate pocket depth. If it is capable of measuring the depth, I’m not sure.

But that does make think of another question. The autofocus makes sure that you cut over a curve, but what if you want to make a flat pocket on a curved surface? Can you tell it to not follow the contour of a part?

1 Like

From what has been said in the other posts (including @marmak3261’s link) 3D depth cutting (read: engraving) will be a function of the Glowforge. From what I’ve read, the hardware is capable but they’re working to refine the software to do it more efficiently at the moment. All the demo videos have only shown stacked cross sections because the engraving feature hasn’t been completed to the point where a good demo can be shown.

The use of a grayscale bitmap will (unless they get a better idea between now and final production) be the means of calculating the depths for that kind of job, so… it’s not there but it’s definitely in the works.

1 Like

It can hardly be defined as a 3D laser printer if it can’t cut to a specific depth on demand, and not from a greyscale image, but from a normal 3D model file, like STL.

3D isn’t format dependent, so the claim to be a 3D printer just means that you can get 3D output. I work with 3DS Max and build files that can be exported various kinds of 3D model formats, but I also use Z-Brush, which includes 2.5D depth maping using grayscale images to create 3D topology (and from which, a 3D design can be exported as a grayscale Z-Depth map… which should be fun to play with once the Glowforge has that functionality smoothed out).

Depth will need to be calibrated based on the material being used, but then the black to white (0%-100%) map should give significant control over the depth. In most 3D apps, you can use a map like this as a displacement map. That should provide a decent way to get a preview of a map if you don’t have something like Z-Brush.

Granted, it’s not the same thing as a 3D extrusion printer, but 3D relief carving should be a very useful feature and is definitely 3D… not to mention the substantially broader materials list you can work with. I’ve got a number of things I’m looking forward to using that feature for.


Never been much of a fan of calling it a “Printer” as in the past, printers have always been additive process.
Laser cutter/engraver fits better. I think even the GF team has said that. It’s more of a marketing “buzzword” than actual fact.

But getting back on subject, it would in fact be 3D if it has any Z axis control, and it does. (0-100% power).

…not a laser expert, but the beam really doesn’t behave like a router bit with a ‘finite’ tip that can be located and guided precisely along the 1/4" Z-axis. Would be great if it did.

1 Like

From what @dan has said in the past, it sounds like rather than using a Z axis (with a mechanical motion along the third axis), the depth would be handled by adjustments to focus, duration (time on a particular point), and/or power will account for the Z depth.

The image that @marmak3261 linked to earlier in this thread shows a simple pyramid shape etched out of a single layer of acrylic. It’s obviously not the final product, but it makes the point that the hardware is capable of (and intended to) cut or engrave at variable depths.

While it will be capable of variable depth, it is perhaps important to point out that what you can control is POWER, not DEPTH.

There will never be a “cut this 1/16” deep" setting. Ever. That is impossible. (EDIT: Okay, I tried to be all final and harsh with my language but the scientist side won’t let me sleep with that in my head. Yes… you could get really REALLY tricky with specialized sensors or multiple cameras and actually monitor the depth, and have super awesome real-time controls which apply power in ultra-short pulses to fine tune the depth. But the need for real-time control means that in the cloud controlled Glowforge… won’t happen)

What there will be, is you personally doing numerous test cuts, and finally figuring out the exact power and speed combination which reliably gets you a 1/16" deep cut. Then being careful that your pattern doesn’t have any lines which cross the same area twice (as it will then apply extra power in that spot and cut deeper).

And this will only work with 100% consistent material. Which doesn’t exist. With manufactured materials like plastics you can get pretty reliably consistent. But with natural materials like wood, the grain will foil you every time in your attempts to have consistent depth.

Variable power: Will be avialable
Selectable Depth: Never going to happen.

Well - actually, Z-depth has a precision level like anything else. With relatively homogenous materials like acrylic or Delrin, you can engrave to a specified depth - the precision of the Z accuracy won’t be perfect, but it will be good enough for “sink this magnet below the surface” for example.


Will it use the camera for feedback or is it just open loop that depends on the material and experimentation?


My first implulse was to respond exactly like you did. Even after Dan’s answer I’m thinking in a real world sense the answer is closer to yours for most materials including wood. My reasoning is, it has been stated before that should you loose connection the laser will finish what it is doing for small jobs. That means that there can not be an uber-tight coupling of z depth measurement and laser power in real time without significant onboard processing. And that doesn’t exist. I can see how the homogenous material like Acyrilc would work though. It’s primarily just power in, result out. If I carefully parse Dan’s post he really didn’t contradict what you said.

1 Like

This question popped in to my head today and this seems like an appropriate thread to voice my thoughts…

It’s two parts really so here goes.
Lets say I want to take a 5mm thick piece of acrylic, from which I will cut a triangle piece of material out of and from the triangle I want to engrave a 2mm deep round pocket for the purposes of gluing a magnet in there.
I take my final design and create a 3D CAD model (eg AutoCAD).

If I’m understanding everything correctly I can feed my CAD model in to the GF software, along with the material details (acrylic, 5mm thick) and it will do the rest for me?

Or do I first need to experiment to work out what settings are best to cut the depth I desire for the pocket?

@dan In either case, what sort of consistency are we expecting in the depth of the engraved pocket (assuming homogenous material to start with)?
That laser etched pyramid looks pretty darn good really. You can see the little ridges where the laser was making it’s passes, but they look pretty tiny and even.

1 Like

No, you’ll need to turn it into a greyscale where the color maps to thickness. You should get pretty good accuracy on depth with Glowforge-provided materials (and be able to get there yourself with some experimentation on materials you provide) - I can’t give you much more than a guestimate, but I’d say 0.05" depth accuracy or so.


If Glowforge is described as a 3D printer why doesn’t it accept STL files like any other 3D printer? Why do I have to encode Z information as greyscale?

Also, given that it is described as a 3D printer, why doesn’t it use the head camera get the depth accurate independent of material and not requiring trial and error?

Without these features it isn’t much different from any laser engraver that can vary the beam power, but they aren’t described as 3D printers.

1 Like

not to counter @dan but form what I’ve seen of the interface and the descriptions, I think once you’ve worked out the power and speed settings to get your 2mm pocket and a 5mm depth cut, you could just open up a basic drawing program, make a triangle with 1 color lines(say black), then make a filled circle with another color(say red).

then you send the image to the glowforge, align it on your material in the interface, select the power and speed parameters for each of the 2 colors and then forge away.

assuming of course like you a said a homogenous material.

1 Like

From Dan’s earliest interviews he explained that when trying to explain the glowforge people kept saying, “so it’s a 3D printer?” Most people don’t know what a laser cutter is, so eventually they just went with it. From a marketing perspective 3D is all the rage. As they pre-sold $28M worth it worked on that level at least.

Personally, I’ve run into the same issue (not with laser cutters) multiple times over my career at work, but with people who should be making an investment in understanding exactly what the company is producing. Eventually, I give up and go with whatever inaccurate descriptor has been bestowed upon some aspect of a new product. It is not really a 3D anything, and that may be misleading, but from personal experience my sympathies on this issue are with Glowforge.

Dan has posted that initially they wanted to use the camera to analyze how power and speed settings worked on a material so it could be automatically characterized. They gave up on that because they couldn’t make it work. So that is why the user is stuck with trial and error. Again, I’ve seen features dropped and projects cancelled because we couldn’t make something work that would have been awesome.

Yes, you are correct: it is a laser cutter/engraver just like all the other ones already on the market. The promise of the glowforge is that it will reduce the hassles common to all those other ones. They want to move the laser cutter from the workshop to the living room: laser power to the people (darn it, I should have posted that in the tagline contest thread.)