Acrylic not engraving as "white" or "high contrast" as it used too

#1

Not sure if this belongs here or Beyond the Manual… feel free to move it if need be.

Glowforge Pro

I have seemed to run into a bit of a snag getting high contrast with my clear acrylic lately and I am not sure what has changed. It has been a bit since I did any acrylic engraving but my previous engraves were an opaque white and very high contrast. Now they are more or a transparent white and not as high contrast.

I have tried my luck with both Proofgrade and non-proofgrade acrylic. Both are cast, not extruded. I have tried nearly every combination of settings I can think of. I have tried raster images, vector images, vary power, and they all seem to produce the same results. Anyone have any ideas?

Here are a few pictures…

This first picture is how the engraves used to turn out.

20180620_221441
20180620_221441.jpg2268x4032 2.35 MB

And here is a comparison between the numerous tries I made on my GF and a quick burn my buddy did on his GCC 30w CO2. His is the eagle in the middle of the frame, which is the contrast I need to create.

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20180620_195550.jpg2157x2600 1.77 MB

Close up… the shield logo next to it is close but not near as clean or vibrant as his.

20180620_195604
20180620_195604.jpg2268x4032 2.56 MB

Any help would be much appreciated. Thanks in advance!

#2

Are you now using a different lpi, by any chance ?
John
:upside_down_face:

#3

I have tried lpi from 225 to 675. The setting my buddy burned at are 100% speed and 40 power @600 dpi. His LPI is set to auto so I am not exactly sure what it is.

The weird thing is, when u look at the acrylic up close, the burn resembles more of that frosted glass look u see in bathrooms. It has texture to it like little dimples rather than smooth lines. My buddy’s engrave on the other hand is smooth and his depth is minimal.

#4

I noticed something similar yesterday while etching some acrylic. I’m glad to know it’s not just in my head.

#5

Defocus the beam. It smooths that out. :slightly_smiling_face:

#6

Which you can do by setting the focus height for the Engrave operation only, to some number higher (maybe start with adding .1 inch to the material height).

#7

just don’t defocus too much or it ends up clear (great for reverse painting though)

#8

I am giving that a try now. We will see what happens. However, that still doesn’t explain what changed with the laser. I didn’t have to defocus the laser in the past.

#9

They did mention making the autofocus better in a recent patch. Perhaps it was slightly out of focus before and now it is more in focus?

#10

Are you using the same type of acrylic? Looks like the difference between cast and extruded acrylic to me.

#11

Yep, same acrylic and all cast. I had the same thought, which is part of the reason I took the acrylic and tried in my friends. In doing so, his laser produced the results we knew it would and also confirmed it was cast not extruded. His burn is the nice white eagle in my original post which I am trying to recreate.

#12

Perhaps this is the case. However, the eagle in my original post that I burned using my friend’s laser was in focus. So if the changes are more accurate then it should produce the same results as his, I would think.

#13

Thanks for letting us know about this.

I’m looking into it, and I’ll update the thread when I have more information.

#14

Thanks for your patience.

I extracted the logs to investigate the issue, and I was able to find your design file. I printed the design on Medium Clear Acrylic using the Draft Graphic, SD Graphic, and HD Graphic settings respectively.

20180629_170525
20180629_170525.jpg2986x1721 523 KB

Do any of these prints show the outcome you are looking for?

If so, please try ​​the corresponding Proofgrade setting on Proofgrade acrylic. If the outcome doesn’t seem to match what I’ve printed here, please send me a photo of the print and the date and time of your print.

Thank you in advance.

#15

Awesome. Thank you!!!

I am looking for opaque white look of the draft but with the definition of the HD graphic. If that makes sense.

I will see if I can give it a try Sunday and compare the results.

#16

It’s been a little while since we’ve seen any replies on this thread. Have you had a chance to perform some test prints? If so, please let us know how it went. Thanks!

#17

Not yet. Work has kept me fairly busy. I did some quick none proofgrade stuff today so I didn’t get an accurate comparison. It will be about a week before I have the chance to do the comparisons now sadly.

#18

It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email support@glowforge.com.

#19