Engraved Acrylic Power Settings

[Russell Morgan]

Hi All,

Well, after a bit of soul searching and lots of good information from here at the Creek I went ahead and placed an order for the Trotec 100 w/ a 60W laser. I took delivery a few weeks ago and have to say this is an incredibly, well-built machine.

While I've been able to successfully tune my engraving and vector settings for wood, LaserMag, anodized aluminum, and most plastics I am having a difficult time finding the proper settings to engrave a nice frosted finish on acrylic. The engraving settings currently in use are Power 30, Speed 50, PPI 600, Air Assist OFF, and protective wrap removed. I have a 1.5" lens installed. Although the results are "passable", they are not the even, consistent, frosted look that I am after. My vector settings are Power 80, Speed .5, PPI 8500, Air Assist OFF and I am very happy with these results.

Could someone supply the engraving settings I would need to get the consistent, frosted look that I am after. I'd prefer to stick with settings for a 1.5" lens so as not to have to recalculate my vector settings.

Thanks...

[Jiten Patel]

Hi Russell,

Welcome to the Trotec club! look forward to seeing what you come up with.

I use 70% power, 80-90% speed depending on how fine the detail is and 500ppi, air assist on. I do have an 80w machine and use a 2" lens but these work well for my 1.5" too just turning the power down a little. So start with these and dial down or up the power until you get result you need.

[Russell Morgan]

Thanks for the settings Jit. I'll run a few samples through and let you know how they work!!

[Mary Geitz]

I also work with acrylic, and to get that nice frosty white look, you need to engrave on cast acrylic. Extruded acrylic (which is less expensive), give a ghostly look to your engraving. I use both depending on the look I'm going for.
Good luck!

[Mike Null]

Mary is making a good point about cast acrylic. You will not get a frosted white look with extruded such as you might pick up at the HD type stores.

[Russell Morgan]

Mary/Mike, Thanks for pointing out the possibility of the type of acrylic being the culprit. Is there a way to easily determine which type is which? Unfortunately, the sheet I'm looking at was purchased at HD. Aside from acrylic type can you let me know what settings you carve with. I'd like to do some testing with those values on the sheets I currently have. Thanks...

[Ross Moshinsky]

Cast acrylic you should be able to engrave at 100speed and probably around 50pwr. 500/600dpi for text. Photos you typically want 300dpi. I like to get it deep enough where I'm getting a bit of depth on the acrylic.

Extruded acrylic you'll probably use the same settings, if not a bit more power as you'd use extruded acrylic when color filling and engraving depth is important.

[Mike Null]

HD sells only extruded.

[Chuck Stone]

I wonder about using the 1.5" lens for this, although you mentioned why and i understand that.
But you're using a lens with a much finer 'kerf' or smaller beam size. This will allow you to go
faster, but at the same time it is less likely to produce the soft, frosted look you want. I would
have suggested trying the raster slightly OUT of focus, and here you have a lens that's HYPER focused!

[David Somers]

Russell,

You asked......"Mary/Mike, Thanks for pointing out the possibility of the type of acrylic being the culprit. Is there a way to easily determine which type is which?"

I had asked that in an earlier thread here. Folks advised me there was no real way of telling by sight, other than in their experience Cast always had a paper covering and Extruded had a plastic covering. They also advised checking on the covering to see if the details on it say what it is. And finally to check with the store and see if they can confirm the type. After that, the best insurance was working with a store who knows the difference and can order correctly for you, or directly from a supplier.

This was the starting point of that question in the thread. Hope that helps.
http://www.sawmillcreek.org/showthread.php?212809-Strange-Trotec-Problem-Help!&p=2221793#post2221793

Dave

[Mike Null]

Most of us buy our plastic from plastics distributors rather than retail stores. They have selection, sizes, colors and knowledge.

Many will not sell to the general public.

[Dan Hintz]

Mary/Mike, Thanks for pointing out the possibility of the type of acrylic being the culprit. Is there a way to easily determine which type is which?

Burn a piece (in a safe environment). Cast will burn with a crackling, smoky flame. Extruded will burn silently and drip.

[Chuck Stone]

Folks advised me there was no real way of telling by sight, other than in their experience Cast always had a paper covering and Extruded had a plastic covering.
Dave

And .. just to muddy the waters, I went and checked the sheets I have.
The ones that have plastic on them, I'd assume extruded because of the cost.
If it were cast, I'm sure it would be marked as such.

I have four sheets with paper on them.
Acrylite FF
Plexiglas MC
Plaskolite something or other with TG Masking
Optix

All four have paper on both sides.
All four are extruded.

Ah well..

[Mike Null]

Chuck

Well you just destroyed my method. But you are correct. In checking specs on Acrylite FF they state that it may be protected with either paper or plastic.

Peculiar that my suppliers have only paper on cast acrylic.

[Jiten Patel]

All my acrylic comes with plastic covering - cast and extruded. I get mine from Perspex.

[Jim Dawson]

depending on the plexi, we typically start at 25% power and max speed with the air assist on. We are using a 100watt Vytek w/ 4" lens

[Chuck Stone]

Newest addition to the family.... 60" x 120" flatbed UV printer. 4" max part height.


...drool...

[Russell Morgan]

Thanks to everyone who has replied to my requested regarding settings for engraving acrylic. After several samples and attempts at the real job I have settled on 80 power 100 speed and 1000 ppi for my 60 watt Speedy 100. I think what helped the most was increasing the ppi to 1000 due to the fact I had a 1.5" lens installed. Seems as though I most likely am using extruded acrylic instead of cast for all the reasons given above. I normally pick up many of my engraveables at Johnson Plastics but wanted to be able to fulfill the job quickly; next time I know better and quote a delivery time based on the proper product.

Now, does anyone have any ideas on how best to remove the smoke haze that has deposited itself on the finished acrylic?

[Ross Moshinsky]

1000ppi/dpi will result in double the engraving time vs 500ppi/dpi. I'd try to drop that number if possible.

[Chuck Stone]

Now, does anyone have any ideas on how best to remove the smoke haze that has deposited itself on the finished acrylic?

Naptha should take it right off. I'd keep some handy, as you can use it for other
things as well. And it's cheap.

[Mike Null]

Ross
On Trotecs ppi and dpi are different settings. PPI has no bearing on speed.

[Mark Ross]

We do graphics and logos on extruded with no problems with good definition, but anything like a picture never turns out well for us on extruded. It seems to get all "melty" no matter what settings we used.

[Russell Morgan]

Hmmm, hadn't thought of Naptha. I'll have to add it to the list of items that I have tried such as Goo Gone, Krud Kutter, DNA, and another product that escapes me now but recommended on a different thread. None of the products I have worked as I had hoped; I think too much time has gone by since engraving and the haze has set. I've decided to redo the job on cast acrylic and will switch to the 2" lens and get the results that I know I should, and can, get.

Thanks again for all the valuable input from everyone...

[Khalid Nazim]

I am just in the middle of quoting a job for engraving acrylic invites. I tried engraving on the acrylic I had at hand for a sample and its not coming out frosted white which leads me to believe I have extruded acrylic. I was checking my suppliers site and they have listed on the products as "Premium, architectural grade, cell cast. Best optical quality" . Is this what I should be buying. Vendor is Piedmont Plastic and product is Plexiglas® G.

Regards
KN

[Andrei Georgescu]

I've ran a few tests on mine. I think I'll do this kind of sampling on every material I'll come across.
http://i62.tinypic.com/28ix3eb.jpg

[Khalid Nazim]

Hi Andrei,


I am guessing these are power/speed numbers. What is the meaning for the top row where you have 25/30 for example. What are these two numbers? I ran a few tests couple of days ago on my 80W Shenhui and I was getting great results at 24 power / 300 speed with 0.04 scan gap (which is making the total time to engrave too long).

Regards
Khalid

Regards
Khalid

[Andrei Georgescu]

Hi,

The two numbers are min/max power. I did not figured out yet how to adjust those, I just wanted to have a starting point for the future tests. I will play with those later and see what they do. The rest of the settings were the Laserworks standard settings. I will also adjust them also on the next samples. I want to assemble some sort of a machine's own catalog with different settings on as many materials I could use. Maybe I'll figure out the easiest way to test a Chinese laser. So far I've discovered that at above 600 mm/s it's not engraving neatly enough to be worth testing.

[Chris J Anderson]

Just adding to what Chuck Stone said regarding focus...

try it with the focus out by say 1/16 ", you might be surprised how it 'frosts'.

Cheers,
Chris

[Michele Welch]

Help me here please, when you say "try it with the focus out by say 1/16", how is that achieved, by bringing the lens closer to the material or further away? I know, newbie question....

[David Somers]

Michele,

Either direction will do it. If you think of your laser beam as it comes out of the lens as being shaped like an X, with the crossing point in the X being the point of focus. If you raise or lower the surface of the object you are focused on above or below that point it will go "out of focus." So focus it, then either raise or lower the item 1/16".

And just so you know, when you hear folks talk about depth of field? Think of that as being the height above or below the crossing point where you still get acceptable work out of the laser for your purpose. That is not really a hard number since what is acceptable for one use may not be good enough for another. But you get the idea.

Dave

[Chuck Stone]

That is not really a hard number since what is acceptable for one use may not be good enough for another. But you get the idea. Dave

While that's mostly true of a lot of things, focus is something
that's closer to universal among people except for those with
vision issues. Acceptable color can vary widely.. acceptable
density or contrast.. much of it is preference and taste.. even
imaging professionals have different ideas about what is "correct"
(although they're smart enough to avoid that word) But not usually
about focus. However.. differences in materials can mask focus
issues. Some materials aren't able to show sharp lines, so there
is a much wider range of 'acceptable' in low res materials.


Not being a 'know-it-all' .. just thought I'd throw in my $.02

.
. ok, I was being a know-it-all