Laser Etching Painted Plastic


#1

I’m trying to create Instrument Dial Faces by Laser Etching off the top layer of Black paint to expose the White paint layer below. The clear plastic (acrylic) I’m using has been painted with 2-3 coats of Krylon 2X White Primer to provide a White under coat and that was followed by 1 coat of Krylon Flat Black paint.

I have tried setting the Raster Speed to 100% and the Raster Power down to as low as .001% and yet the Laser still seems to Etch through all paint layers and into the plastic several .001’s. (See below.)


It is more obvious when viewed from the back as you can see right through the White.

I don’t know if more layers of paint will solve the problem given how deep the Raster Etching seems to go. I may also try applying a masking layer through which I Etch (and thicker paint layers). Using that I can always spray the dial face with White and then remove the mask to (re)apply White paint into the Etched Face.

So at this point I’m looking for advice as how best to accomplish this Etching without burning through the White Layer.

Beau


#2

You can purchase two layer plastic, black on the outside, white on the inside that you can etch to remove the black part and reveal white.

I think you can find it locally at johnson plastics and royal plastics?

The other possibility is to use straign white plastic and just paint the surface black as your doing. Or you could use the plastic you have and paint one side white and the other side black.


#3

The plastic needs to be clear so that the dial face can be illuminated. I have several items like this made by someone else (non-DMS, non-local) but that person has disappeared so I’m now trying to learn how to do this myself.

Is there some magic about power settings in Raster mode such as the system will only accept power values down to a certain value and will not go any lower despite what you have set in the software?


#4

In that case I would purchase a translucent white plastic and give it several coats of the black paint.


#5

Something like this


#6

I did this on a CNC router once to back-light some buttons (see below). But that wouldn’t work with a raster file. I would be very interested in using the laser to do this as well since getting the engraving bit to work right was tedious.

I like @wanderson suggestion of the diffuse plastic. I was looking to use an acrylite product.
http://www.acrylite-shop.com/US/us/sheet/acrylite-led-3rb9eum8heh.html

https://dl.dropboxusercontent.com/u/8122313/IMG_0742.jpg


#7

Yes, that diffused white translucent plastic is certainly an option. However, the guy that disappeared that used to make these dial faces managed to do this with painted clear plastic to maximize illumination. So I’m pretty sure this can be done.

I’m seeing some details on DPI values in the Retina3D manual. Apparently having too high of a DPI setting can result in poor resolution/burning as the Laser is on for to many “dots”. Unfortunately, they don’t really discuss how to make those changes in DPI.

I also hope to get some guidance from a commercial firm over in Euless that also does this sort of work. They have been very helpful in the past. Maybe they will tell me how they make their dial faces.


#8

My guess would be that he used some combination of ‘special’ paints and a much lower power laser then ours.


#9

Probably not the answer, but it strikes me, so I’ll toss it out there.
Paint front in black, etch, paint back in white. This will make the clear between the paint layers, with the white layer providing backing color…
I have 0 experience, so I could be way off, but it seems sensible in my head…

Another idea: paint black, masking tape on top, etch tape & black, then paint white, then remove mask…


#10

Well, I’m pretty sure I’m using the same paint. He told me he used the Krylon 2X White Primer and Krylon Flat Black. However, how many coats and thickness is unclear.

As to his laser, it has to be powerful enough to cut through the plastic so it can’t be too wimpy.

As for putting White on the backside, that won’t work. Back side needs to be clear as that’s here the illumination comes from. Also, when the back lighting is off, you must see White lettering on the front.


#11

Well, I think I’m onto something wrt the DPI setting. I just saw a video on YouTube that shows the menu in Retina3D that has the “Raster @” and then a DPI window where I think you can change the DPI. I may also have to create a raster .bmp file of the image that has the desired lower (250dpi?) DPI setting of the image.

Forward, fiddle on! (Tomorrow)


#12

When rastering you set the power level with the slider bar not with numbers…


#13

Actually, I’m pretty sure you can do either. Move the slider or click on the power and change the number to get the exact value you want.


#14

Also, I found in the manual that there “is” a value below which the laser just wont fire. It will differ with each laser and its age if I understood what I was reading.

(I wish the manual showed examples of the windows in the software so we could reference them offline. Then I could include a picture of what I’m talking about on the screen.)


#15

I submit it will still work. After all, you’re relying on the light shining through the white with the current approach, unless I’m misunderstanding your method.
It seems to me that trying to etch through only one layer of paint is going to be tough and hard to replicate in our environment. This makes my secondary proposal sound even better to me.
No matter. I can accept being wrong. I WOULD like to hear about what you get to work, though.


#16

No, I think we have a disconnect on this. When the back lighting is on, then you would be correct and you would be using transmitted light to read the face. However, most of the time, the dials are read in the daylight and in that case you are using reflected light which is why the White on the front surface (just under the black) is what is needed. It happens to be the results that the professions get when they build dial faces.

It may be the case that we just can’t achieve those same professional results with our resources but I’m not willing to give up just yet.

Thanks everyone for your proposed solutions. If I figure this out, I’ll make a post here as to the results and how I got them.


#17

I just want some right seat time in whatever this dial goes into. :smile:


#18

There isn’t a “right” seat.

:wink:


#19

Nice!
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#20

Have you tried etching it with vector? You can set vector current to 1% and then power to 1% and then speed to 100% and see if that gives you better results. I “etch” paper this way.