Can we change raster engraving to go top-down, to avoid smoke discoloration?

Not sure if this really belongs in Q&A, but it is a Q looking for an A, so…

I’m trying to figure out why the Glowforge etches raster images bottom-up instead of top-down. Or if there’s some way I can make it go top-down. My reason is pretty simple… smoke damage. The air-assist sits above (y plane, not z) the head. As such, it blows the smoke straight down as the machine etches. Therefore, as it’s etching, all of the smoke hits the areas you’ve already etched. Where if it went down instead, it’s blowing smoke only onto your masking, leaving all of your etches pristine.

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It has been mentioned here before. I can’t remember if it is “in the hopper”.

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The question was asked here in another thread as well. I thought I remembered @Dan answering the question before, but couldn’t find anything.

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Well… Not the answer I was hoping for. That hopper won’t be emptied for months and months, but we’re engraving today. But I guess it’s better than “It’s never going to happen.”

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I have found that scrubbing with rubbing alcohol and a toothbrush cuts the ‘tar’ pretty well and doesn’t raise the grain of wood like water does.
Just don’t use too high a PSI when drying with air pressure, you can blow some of the dissolved stuff into the woodgrain on the edges of the engrave.

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Thanks. Yeah, I’ve been using a toothbrush as well and it does a pretty good job. But it doesn’t do much of anything on extremely thin, delicate details. In my most-recent adventure in engraving I have some very fine detail lines that I was expecting to be nearly untouched since they’re white. But it all got smokey and I can’t scrub them much at all in fear of breaking them. Makes me wonder how it would have come out top-down.

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Since you can’t change the machine, change your work piece and the art.

You control the orientation. Turn things so that you’re getting the engraving in the direction you want.

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No it’s the head direction relative to the fan direction, so you can’t change it.

It seems an obvious and easy change. I don’t know why GF did it that way and why they can change it in an instant.

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That is s good answer, and would certainly help for simple things. Maybe though you want to engrave some, switch directions, and engrave some more. In that case programmatic control would be helpful.

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i mean, no offense to either of you, but that’s not an answer that would do anything to fix @Tom_A’s problem. this is really something glowforge needs to change.

to be honest i suspect this is something that never really occurred to them might be a problem. i think it’s easy to overlook until you start really encountering it.

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Ya, that’s my point. It is something you would like to be be able to set in the ui.

(And no offense taken, which should be an emoji)

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We’re dealing with a machine limitation that may or may not be “fixed” at some point.

I don’t expect that reorienting the work piece or the art will work in every situation, but it is something we can control or adjust to our advantage most of the time. Once we understand the limitations we either work around them or find a different solution.

@Tom_A pointed out he had some things that were thin and engraved at the wrong end in this case. I think rotating the art might have fixed that problem (although I haven’t seen it so may be way off).

sure, but the big problem he’s pointing out is that no matter what your design or rotation, it’s blowing smoke in the direction of previously engraved material. nothing you can do will avoid this. having it changed in software instantly would.

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True enough, we can only orient for “least damage”.

We saw a lot of this with every stamp that has been posted so far since so much material is removed and redeposited.

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I find it interesting just because Trotec, Epilog, etc tout the benefits of their bottom top raster engrave - though I do believe it’s switchable in their interfaces.

Thanks, but the rotation of the piece doesn’t do it for me. At least not in this case. Think shape with complex pattern. Mandala, let’s say. No matter what I would do, bottom-up would smoke up the whole piece. Now I’m not sure if top-down would be perfect, but I imagine it would be significantly better.

As a far distant 2nd place to allowing us to go top-down, being able to disable the air assist might allow the smoke to rise, rather than pass across.

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You can’t pre-mask whatever the item is?

unforunately this is an issue regardless of masking. since the air is blowing down, and your engrave starts at the bottom, as the engraving proceeds upward, the air is constantly blowing smoke and debris into the engraving you just made (through the masking, if you were using).

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Then brush it off with a soft brush?

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i guess, though i’m not sure how well that works for smoke deposition. but there’s a completely simple way of avoiding the problem entirely, which is to reverse the direction of the engrave. this isn’t my problem and i’m not like railing on glowforge for it, if there’s some arcane technical explanation, i guess we’ll need to be satisfied. but i really think this was just overlooked.