Foggy edges on Acrylic Vector cuts

[William Milligan]

Been working with a bit of acrylic lately...since I've worked with acrylic I seem to always have the same issue...I've tried a few different settings and get the same result....When I vector cut I get a kind of fog adjacent to the vector cuts so the acrylic isn't clear adjacent to the cut...it is foggy...I was working on a gift for my granddaughter today (a night light)..cut it out and sure enough...there was some fog adjacent to some of the vector cuts...overall theproject came out very well and I intend to post some pics tomorrow but i just don't like the bit of fog on the edge (though many folks wouldn't even notice it)....I would just like a clean edge..
For this project I used Epilog's recommended settings (50s/50p/2500f)...I had to run the vector job about eight times to cut all the way through the 1/4" acrylic I am using so I would assume I need more power but I am hesitant to do it as I don't want more fog on my edges...:(...
I have heard taping over the vector line might help...I haven't tried this yet but may give it a shot tomorrow...
Can any of you experts give me any suggestions on what to try?....As I say...it isn't horrible and some might not even notice it but it just isn't within my standards.

[John Noell]

Eight passes?!?!? Yikes! The best ways to avoid fogging on the edges (which apparently is vaporized acrylic settling back on to surface) is to use the exact right power for a single pass cut and/or cover the surface with transfer tape or something similar. Once you have it, it usually polishes off pretty easily with some Novus #2 but preventing it in the first place is best. FWIW, a higher frequency gives smoother edges. Most people use something like 5000. I'd up the power and slow the speed if necessary to get a single pass cut.

[Dee Gallo]

According to my manual, you should be using 8 speed/100 power/5000 freq. to cut 1/4" acrylic with a 75w Epilog. One pass. Try it and see if you get better results.

We all get that "fog" when cutting, which is easily cleaned off. Some people like to use alcohol, some plastic polish like Novus, some use a Mr. Clean sponge... I like to use a miracle cloth with water unless it's stubborn, in which case I use alcohol and wipe it off right away with my miracle cloth. You're going to buff off your finger prints anyway, so it's not really an extra step to clean off the fog.

cheers, dee

[Richard Rumancik]

William, I think you will always get fogging of acrylic if it is not masked. If you can buy paper masking on your acrylic, that is more friendly for laser cutting. If you can only get poly mask then you will have to remove it and replace it with paper mask. It is a pain to have to do that but it is really the only way to fully protect the sheet from both the vapor and scratches.

The fog is generated because acrylic cuts due to vaporization of the acrylic. It is rather unique in this respect; there are only a few materials that behave this way. The acrylic turns to gas and then tries to condense on the part. Since it is acrylic vapor it will tend to fuse to the acrylic. Dee has some luck in removing it but it is best to avoid it if possible. You also want to use air assist during vector cutting to blow the vapors right thru the material and allow the exhaust system to take over.

If you are raster engraving you pretty well have to engrave without mask, but light engraving does not generate all that much vapor.

[Gary Hair]

Some people like to use alcohol, some plastic polish like Novus, some use a Mr. Clean sponge... I like to use a miracle cloth with water unless it's stubborn, in which case I use alcohol and wipe it off right away with my miracle cloth.

How do you avoid crazing when you use alcohol Dee? I used denatured alcohol the first time I cut acrylic and it almost fell apart in my hands it crazed so bad. Since then the only time I use alcohol is when I want to show someone what crazing is all about.

Gary

[Gary Hair]

For this project I used Epilog's recommended settings (50s/50p/2500f)...I had to run the vector job about eight times to cut all the way through the 1/4" acrylic

I think Epilog was a bit off on their recommendation. I use 100P and 1.2 speed on my 30 watt (single pass to cut 1/4") and I can't imagine that you would use less than 100% power and anything more than 10% speed with 75 watts. There is no reason to use more than one pass to cut 1/4", I can cut 1/2" in mine with one pass - granted it's at .1% speed, but it does work... I'm not sure why they would have you use less than 100% power, that's a waste as far as I'm concerned. At 50% you are around 37.5 watts and your speed would have to be close to what I run my 30 watt machine at. As for the "fog", you can avoid it almost completely with masking and whatever is there comes off with Novus spray or fine scratch remover. Even though Dee says to use alcohol, you should know that it will craze if you do - maybe not immediately but it will eventually.

Gary

[Bill Jermyn]

William, the first thing I learned when I got my laser was to use the recommended settings in the manual as a starting point and then to test every different material to find my own settings of speed, power, frequency and focus that worked best. It involves some time and wasted material, but it's well worth it. Keep in mind that different thicknesses, manufacturers, manufacturing methods (e.g. cast vs extruded) and colors may need different settings.

[Mike Null]

Gary

I've been using dna to clean cast acylic for most of the 13 years I've been in this business. Never once have I had a piece of cast acrylic craze nor have I ever had a complaint from a customer.

Extruded acrylic is another matter.

[Dan Hintz]

If you are raster engraving you pretty well have to engrave without mask
Why? Bump up the power a few notches and engrave right through the mask. If you engrave from bottom up, as well, it's about as clean as you'll ever get it.

[Martin Boekers]

I have a 75watt Epilog, I cut at 5sp/100pwr/5000freq cuts right through .25".

Make sure to have air assist on.


Marty

[Dee Gallo]

Gary

I've been using dna to clean cast acylic for most of the 13 years I've been in this business. Never once have I had a piece of cast acrylic craze nor have I ever had a complaint from a customer.

Extruded acrylic is another matter.

I've been using rubbing alcohol, which is diluted alcohol so it works but is very mild. I also wipe it off right away, and have never had any crazing. I have pieces in my shop that were done 2-3 years ago and they have not shown any signs of crazing.

- dee

[Larry Bratton]

According to my manual, you should be using 8 speed/100 power/5000 freq. to cut 1/4" acrylic with a 75w Epilog. One pass. Try it and see if you get better results.

We all get that "fog" when cutting, which is easily cleaned off. Some people like to use alcohol, some plastic polish like Novus, some use a Mr. Clean sponge... I like to use a miracle cloth with water unless it's stubborn, in which case I use alcohol and wipe it off right away with my miracle cloth. You're going to buff off your finger prints anyway, so it's not really an extra step to clean off the fog.


cheers, dee

I cut 1/4" with 40 watts at 6s/100p/5000f. The fog is being caused by all that heat being applied over and over. I had that happen the other day when I raster engraved a piece of black cast. I accidentally reversed the settings -I used 35s/100p and it should have been the other way around. (It was nice and deep though!)

[William Milligan]

Thanks for all the suggestions...I'll give them a go tonight when I get off of my day job.

Looking back at what I did yesterday I do remember I went to the Epilog suggested settings for 600dpi acrylic...they have a recommendation for vector and rastor...I guess, though, when I am vector cutting I need to make sure and use their recommended settings for cutting which are a little lower down on the list....live and learn...:)....at least acrylic is fairly cheap.

I had been trying to run this as a combined job but perhaps I will run the raster job and then mask with some painter's tape and do the vector cuts...

OR...I'll just run them both and use DNA or Novus to clean it up...I'll experiment with them and see what works best....

Thanks for the suggestions...they are quite helpful for someone just learning this gig....

Cheers.

[Richard Rumancik]

Why [not mask when rastering]? Bump up the power a few notches and engrave right through the mask. If you engrave from bottom up, as well, it's about as clean as you'll ever get it.

Yes, it can be done, but then you need to strip off the mask that might break into a lot of little pieces, and you have to pick off the centers of some characters one by one (like centers of a, e, o, g, etc). I never really found it necessary when rastering and the extra effort in removing the mask discouraged me. But in some cases it might be warranted such as when deep engraving.

[Dan Hintz]

Yes, it can be done, but then you need to strip off the mask that might break into a lot of little pieces, and you have to pick off the centers of some characters one by one (like centers of a, e, o, g, etc). I never really found it necessary when rastering and the extra effort in removing the mask discouraged me. But in some cases it might be warranted such as when deep engraving.
If you use a light-tack mask, everything comes off with a brush of a cotton towel... no need for any real pressure. I find it useful for keeping stains away form the non-rastered areas, but if you're rastering the entire piece, well, it's kind of pointless.

[Robert Walters]

Yes, it can be done, but then you need to strip off the mask that might break into a lot of little pieces, and you have to pick off the centers of some characters one by one (like centers of a, e, o, g, etc). I never really found it necessary when rastering and the extra effort in removing the mask discouraged me. But in some cases it might be warranted such as when deep engraving.

Some have suggested that you can just use water to soften and remove transfer tape remains.

Else there is always plastic razor blades or plastic scraper:
http://www.amazon.com/6-piece-Plastic-Razor-Blades/dp/B0038ZGS9Q

[Larry Bratton]

Thanks for all the suggestions...I'll give them a go tonight when I get off of my day job.

Looking back at what I did yesterday I do remember I went to the Epilog suggested settings for 600dpi acrylic...they have a recommendation for vector and rastor...I guess, though, when I am vector cutting I need to make sure and use their recommended settings for cutting which are a little lower down on the list....live and learn...:)....at least acrylic is fairly cheap.

I had been trying to run this as a combined job but perhaps I will run the raster job and then mask with some painter's tape and do the vector cuts...

OR...I'll just run them both and use DNA or Novus to clean it up...I'll experiment with them and see what works best....

Thanks for the suggestions...they are quite helpful for someone just learning this gig....

Cheers.

William,
For sure you entered your settings incorrectly.(happens to the best of us :)) If your manual is set up like mine, they show the recommended settings for raster engraving in the first 3 columns (300,400 and 600) and your vector settings are in the last column. I cut acrylic all the time and I don't get any foggy edges. I rarely mask acrylic either. If I am going to fill it, I use Winton's artist oil paint, rub it in the engraving, wipe off excess with a card, let dry and then buff.

[William Milligan]

Thanks for the help everyone!...ran the job again last night and it ran perfectly...used 100p/12s/5000f on my 75w Epilog. No foggy edges at all...I made two of these night lights, one for each of my granddaughters for their birthday. Haven't finished mounting them. I should have that done tonight and will post pics of them...

I DID try the DNA on some older acrylic pieces I've done which had them and the DNA cleaned up the edges fine with no cracking at all.

Thanks again!..It is great to have a place to go and get some good advice. Have a wonderful day SMCreekers...

[William Milligan]

Thanks again everyone for your help on this...I believe my granddaughters will be happy with these!180889180890

[Larry Bratton]

William:
Sweet! Those are really cool. Glad you got it sorted out.

[Jim Dawson]

I have actually noticed a better edge finish when cutting acrylic with air assist off. It seems to cool the edge too fast and not let the acrylic flow.

[paul mott]

How do you avoid crazing when you use alcohol Dee? I used denatured alcohol the first time I cut acrylic and it almost fell apart in my hands it crazed so bad. Since then the only time I use alcohol is when I want to show someone what crazing is all about.

Gary

I think you may have had a bit of polycarbonate there Gary :D

Paul.