Air assist off for engraving?

Anything to do with air assist, vacuum tables, fume extraction and related...

Air assist off for engraving?

Postby naPS » Mon Aug 15, 2011 8:55 pm

So I've been doing a little bit of engraving in wood and in acrylic, and I'm noticing that especially with the acrylic the air assist condenses the acrylic fumes, and it ends up leaving a powdery residue on the engraved portions of my material. I can only assume that this material is the condensed acrylic vapors, since the acrylic sublimates, and I'm assuming the air assist is causing a temperature drop and subsequent condensing of the vapors to the powder I'm seeing. Also, it appears as if it's actually causing some ghosting outside of the engraved areas, like it's pushing the vapors down onto the non-engraved surface, and it's leaving a shadow of sorts that I am unable to get off with anything.

When I'm engraving in wood, the only wood I've had a problem with so far is beechwood. I really like the high contrast I'm able to get with it, but again, the air assist seems to be pushing the dust down onto the portions of the engraving that are already completed, and they somewhat stain at that point. It actually doesn't seem to get much better with the air assist off though, so I'm thinking about developing some sort of vacuum attachment, possibly using a venturi or something located inside the extraction duct to produce the localized suction. It's fairly weird.

Is anyone else noticing this? Is leaving the air assist off during engraving a pretty standard practice?
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Re: Air assist off for engraving?

Postby BenJackson » Mon Aug 15, 2011 10:39 pm

One trick I heard was to use water soluble PVA Mold Release. You can smear it on any kind of plastic before engraving and engrave right through it and after you can wipe it off with a wet cloth. It keeps the white film from condensing on the acrylic (or whatever you're engraving).

Tap plastics sells it. I actually have some (based on the recommendation of the above trick) but I have not tried it. My 2.x laser still isn't set up for engraving (the perils of being a DIY'er -- perhaps I should just buy the damn DSP...)
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Re: Air assist off for engraving?

Postby naPS » Tue Aug 16, 2011 12:43 am

Hmmm... interesting. I'll have to check it out. I've been getting good results lately leaving it off for acrylics, not sure I want to introduce something else that I have to clean off, although, I'd have to try it to make an actual informed decision. Looks cheap enough, I'll order some and see how it works.

I've had really good luck with the Mach3 engraving plugin. There's definitely some drawbacks to it, but overall, it's been pretty solid for me. I just engraved a bunch of stuff on the rotational engraver this afternoon using it, and it came out great!
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Re: Air assist off for engraving?

Postby TLHarrell » Tue Aug 16, 2011 5:34 am

When engraving plexiglass, I just leave the paper on and add a few % to the power. It's easy enough to peel off afterward.

Made some really nice signs on milk white plexi, shot flat black Krylon on the paper after engraving, then peeled off immediately. Came out very crisp.
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Re: Air assist off for engraving?

Postby StigOE » Tue Aug 16, 2011 5:59 am

Something else that's been recommended, is "Fast orange" hand cleaner, especially for wood. I read that over on FS forum and, I think, on one of the big laser companies' site.
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Re: Air assist off for engraving?

Postby TLHarrell » Wed Aug 17, 2011 2:33 am

I've read that using Fast Orange is great on wood. I haven't found it in a store yet but I'm still looking. I'm assuming it's the variety that looks like a tub of grease?

With plexiglass, on my FSE 40 watt, it seems to redeposit the hot gases from cutting plexiglass which fuses the dust to the surface. I can't simply clean it off like with a cleaner. It'd need to be polished out. So I stick with the paper on trick for now.
40w Full Spectrum Engineering 5th Gen Hobby 20"x12" w/ Rotary Engraver
South San Francisco Bay Area - Sales and Support Representative for Full Spectrum Engineering
408-47-LASER - Skype: whitelightlaser-thomas - Facebook: White Light Laser
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Re: Air assist off for engraving?

Postby gene » Wed Aug 17, 2011 10:50 pm

TLHarrell wrote:I've read that using Fast Orange is great on wood. I haven't found it in a store yet but I'm still looking.

You will usually find fast orange in car parts stores. I know for sure that autozone carries it
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Re: Air assist off for engraving?

Postby macona » Fri Aug 19, 2011 3:34 am

BenJackson wrote:One trick I heard was to use water soluble PVA Mold Release. You can smear it on any kind of plastic before engraving and engrave right through it and after you can wipe it off with a wet cloth. It keeps the white film from condensing on the acrylic (or whatever you're engraving).

Tap plastics sells it. I actually have some (based on the recommendation of the above trick) but I have not tried it. My 2.x laser still isn't set up for engraving (the perils of being a DIY'er -- perhaps I should just buy the damn DSP...)



Yeah, Tom Brandt came up with that at TechShop. I have used it and it does a very good job. Just runs the parts off in the sink after you are done.

Always use air assist. It will make your lens last a lot longer between cleanings.
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