Sorry if this has been asked before, but I was wondering about the engraving feature. All videos I have seen of the Glowforge engraving things has been a line by line horizontal engrave. That means that rounded edges end up looking like Machu Picchu farming terraces (even if you have to use a magnifying glass to see them).
I was wondering if there was any way of doing 3D printing style engraving. A 3D printer prints all the outer layers first, then goes and fills in the interior. This makes sure the outer surface looks as perfect as possible.
So question: Is that possible? And follow up question: Would it make a difference (would the edge error just be moved inside the engrave with overlap causing divots, etcâŚ)?
My end goal with this would be to do a shallow engrave of text and have the edges be âperfectâ, not have the steps on the outer edge of any curved area.
Easy workaround. Do your engrave, then follow up with a light âscoreâ around the edges. Searching the forum will show many examples of this technique.
Thanks for your answer. If itâs so prevalent of a request, why not make it a built in feature? I could see using that many times in what Iâm imagining to do. It would just be simpler if there was an option to âpreserve edgesâ or whatever the devs would like to call it.
Taking that a step further, you could do the same for 3d engraving. Do every intensity level edge first. Iâm sure that would increase engrave time significantly, but it might turn out a prettier thingy.
Difference in the requirements between an engrave and a score and the requisite graphics. The graphic styles process very differently, hence the idea of a âscoreâ around the edges to clean up if you wish that.
A couple things here if I understand your question fully.
I looked closely at @takitusâs engravings at Maker Faire. The edges of his engravings were much better than what I have been able to produce. Some of that is his skill with image processing but a great deal of it has to do with the machine he got, which while having some major issues did a better job at the edges of an engrave or engraving vertical lines to be straight. So yes, with a magnifying glass, you might be able to see where the engrave lines are, but at the highest lines per inch, it is amazing the crispness of the edge.
Seeing this engraving IRL doubled my excitement for a production Glowforge.
Once the lower power settings profile gets pushed, the scores will be able to clean up an edge even more at a lower resolution engrave. That is the feature you seem to be asking about to eliminate any aliasing at the edges of curves.
I think engraving is always in raster mode, but the low power vector score is always possible for edge definition.
Not sure what the tradeoffs will be if you are doing something like a six point or lower text engrave. But some insanely crisp detail is possible even at that small a text size.
I have seen a YouTube video of a laser engrave that does do it 3D printer style. I.e. if you send filled vector artwork it scores the outline and then does a zigzag infill. It would be nice if GF implemented that sometime.
Is that behavior of scoring the outer edge of an engrave before the engrave a default operation then in the UI of every closed vector fill? In the Glowforge it would be handled by the path color being one color and the fill another then you would do separate operation settings. Interesting.
As I understand it GF currently only raster engraves or vector scores. I.e. to fill an area it always does left right scans turning the beam on where it wants to engrave. The example I found did a zigzag only over each filled area with the beam presumably almost constantly on. That is more efficient with sparse vector artwork with filled areas than scanning a large, mainly empty, raster.
This is why I objected to the terminology cut, score and engrave. There is another operation in the wider world. GF engrave means raster engrave. Score means vector engrave but it can only do unfilled outlines. There can also be vector engraving of filled areas.
I think you get the same result by doing an engrave of the filled areas and a score of the outlines using different colours but it could be a lot slower in some cases.
Great explanation. Given that vector is so much faster than raster, Iâve been hoping to do everything possible as vectors. There are vector fonts specifically intended for CAM/Laser/3D Printing, an InkScape extension (http://www.evilmadscientist.com/2011/hershey-text-an-inkscape-extension-for-engraving-fonts/) - free and awesome - and commercial conversion tools such as FastCAM FontGEN. Because vector fonts are fast and come out clean. This is more of an issue with CAM, but is still a win for laser cutting, I think.
Iâve also been wondering whether (once my GF arrivesâŚ) if a dithering program like Texturing (http://ivan-murit.fr/texturing.htm) might be useful, in that you could convert a bitmap into line art, and if you could turn that into vector art (e.g. using Inkscape) the result might look cool and print faster than a grey-scale bitmap.
Iâve been thinking about engraving times. Since almost all of my engraves are closed path vector fills, I can combine and group and do efficient engraving. Yesterday I did some engraving of multiple rulers each with a bitmap on the piece, same bitmap. Because I imported one bitmap and copied and pasted it in to get the resolution I needed, that broke up the engraving into discrete sections. Trying to think through this fully, but having vector filled engraves really can speed things up. However, you lose gradients at the moment.
Iâm confused. âClosed path vector fillâ means doing a vector score around the perimeter of a closed area, right? Or does it mean doing a raster engrave over a closed region defined by a vector curve? Or does it mean a raster engrave with a fixed power/speed, so itâs a region with a uniform level of material removal?
Vector engraving a fill means zigzagging within the boundary, just like an FFF 3D printer draws an outline and then fills it with a zigzag. A raster engrave scans a rectangle turning the beam on and off, like a CRT monitor. Theoretically the results are the same when engraving a monochrome image but vector can be a lot faster than raster if the image is sparse.
Neither are right because you say raster engrave. A raster engrave is what Glowforge calls engrave where the head scans a rectangle and creates a picture in that rectangle by modulating the beam. You can raster engrave raster images (they are bitmaps resampled to the LPI) and you can also raster engrave vector images where vector fills must be rendered to a bitmap at the correct LPI.
There are two more combinations in the laser world. You can vector engrave a raster image, that is tracing. You can also vector engrave vector artwork. The laser doesnât scan a rectangle, it follows the vectors. I think GF then only supports unfilled shapes and that is cut and score in their terminology.
Other machines can also handle filled vector shapes and zigzag within the bounds of the shape with the beam on. Yes that would most likely be a uniform removal. Care would need to be taken to prevent over burn at the edges where the head reverses. It may needs some overshoot and then it becomes a bit more like a raster engrave. The difference is it would scan each feature separately rather than doing long horizontal sweeps
I understand there are apparently various terminologies that some laser cutter manufacturers have adopted, which are at odds with the GF terminology, and you are describing those. I was going back to more basic terminology.
I relate the term ârasterâ to mean a process that performs a task in sweeping parallel motions. A raster printer doesnât sweep out a rectangle, but stops at the end of the last character on each line, thus sweeping over a non-rectangular region.
âVector engrave of a raster imageâ you call tracing. To me, tracing is a process of creating vector shapes at transitions in intensity of a bitmapped image. This produces a bunch of vector outlines, and would not be related to any engraving process, in my mind. If I had to define something called âvector engrave,â it would be a bastardization of âvector fill,â which would be the act of scoring a 2D space filling curve within an arbitrary boundary.
Yes a raster scan can be optimised to have non-rectangular edges when mechanical motion is involved but always covers all the features in the image in one horizontal sweep, although you can have several raster engraves run in a sequence.
Yes tracing a raster image creates a vector image.
Yes you could use any space filling curve but horizontal zigzags are the most efficient for Glowforge. Spirals probably involve the least change in direction.
Thereâs definitely a case to be made for optimizing sweep paths to eliminate time spent sweeping over empty areas that arenât being engraved.
Itâs hard to imagine doing the zig-zag approach without overshoot though, and once youâre overshooting youâre back to doing ordinary raster engraves.
It would be interesting to prepare a design with two thin vertical lines on the far left and far right sides of the work area. How much time would it take to raster both at once compared to rastering each one separately? If one line takes one minute and doing both at once takes 16 minutes, optimizing the rastering areas would shave 87.5% off the total job time. With these times, time could be saved all the way up to doing 15 lines individually instead of all at once.
I suspect the faster the machine can accelerate, the more helpful optimizing the raster areas would be. Since the Glowforge UI has such accurate time estimates, someone with access to the UI could accurately answer these questions with regard to the Glowforge without needing to waste any material. Any volunteers?
I could check the time estimates with my Trotec, but I donât know how accurate they are.
