I am back again. Trying to make a printing plate on the glowforge. We used to do these on our epilog the growforge replaced and it was easy. Select stamp mode when sending to the laser and it would automatically engrave the white and leave the black. On the glowforge I can manually invert the colors.
Now for the issue. The other option that got enabled when you turned stamp mode on was shoulders. What this does is give some meat to any protrusions. Without shoulders your tiny dot is a weak column. With shoulders the same dot is essentially a pyramid. Still the same size tip but much stronger overall. How would I go about doing this in say inkscape, coreldraw or illustrator? I was thinking a uniform gradient around everything but I can’t figure out how to do it.
By an astounding coincidence I just this minute finished making a clear art laser stamp that incorporates the features you seek. I was sitting down to write up a step by step tutorial for it. If you give me some time I’ll do that and send you the link. I’ll put it in Beyond the Manual since it will include settings.
Edit: forgot to mention, I did it in Photoshop. It may be possible in vector programs as well but I found it easier to do in Photoshop.
Just a note: I did not do the two-part thing with final cutting of the outline on the Glowforge because the polymer stamp blanks I use are backed with what I think is a PVC sheet. I didn’t want to cut through that in my laser so I hand trimmed after engraving.
There is a super simple way to taper the features on your stamp - Gaussian Blur.
These instruction are based on GIMP (gimp.org), but should work with any advanced graphic editing program.
If the art is not already a raster file convert it into a raster file.
Open the art in the graphic editing program.
The black portions of the art will be the deepest portions of the engrave. Invert the art if necessary.
Create a duplicate layer of the art above the current layer. Hide the new top layer for now.
Measure the narrowest detail of the art in pixels.
Apply a Gaussian blur. The blur value should be half the distance measured in the previous step.
Turn on the top layer and set its mode to “Lighten Only”
Flatten the image and the art will be ready for processing.
Use the vary power based on gray scale option when engraving and the resulting engrave will have a nice taper up to surface that is inked.
If the taper needs to be steeper or shallower, use the levels tool to move the white point of the blurred layer before flattening the image. A white point value between 190 and 160 usually works well.
I use this technique when I’m making my wood block printing plates with the GF. Very small details have a nice tapered base that prevents them from breaking off during pressing.
I’ll have to try the Gaussian Blur method. The method I used was based on Outer Glow but the results were probably similar to what you get with Gaussian Blur.
I like the Outer Glow as well, but with the “More Precise” option, rather than “Softer”, which seems to make a more distinct “ramp” as the gradient forms a more consistent ring around the image to be stamped.
Depending on the size of the stamp though, I’ve found the SIZE and RANGE sliders need to be played with a little, but not much. The 3rd image is the settings i used on the inked stamp image with the shoulders highlighted below.
@aj_stewped, your second picture is the money shot. It is the best illustration of the technique we are working for. Thanks so much for the instructions and good posts.
I think you might be right—I’ll try Precise next time. Actually I did try it and for the particular size of image I was working on it didn’t seem as good. I guess the takeaway is that you need to fiddle with the settings a bit to optimize for your use case.
I wonder if you would mind posting your note in my tutorial thread so it is captured?
Added - and added a bit more because I realized my files are maybe higher res than most people are used to working in, but it helps a bunch with the final results.
I found the outer glow option in Affinity Designer, but haven’t found any way to duplicate the “elements” and “quality” options yet. Are there any AD aficionados out there who know how to accomplish this in AD?
The Gaussian Blur behaves differently depending on if you apply it before or after inverting the image. If the blur is applied before inverting, the resulting taper is wide at the base and narrows quickly. If the blur is applied after inverting, the resulting taper only narrows near the top resulting in almost a domed profile.
In the picture below the left most sample was blurred after inverting. The middle was blurred before inverting and had its gray point shifted to widen the base of the engraved features. The right was blurred before inverting, but its gray point was not altered.
Ill give it a try monday if I can. Had to put the old laser back up friday to try and get it done. Should be able to put the glowforge back in place monday.
