Engraving Very Small

[Russell Ludwick]

I have a customer that needs conductive film removal from glass on very small areas, say .050" x .050" squares or .005"x.25" cut lines. My problem with the squares is when I set it up and laser it, the output looks like a hounds-tooth pattern instead of the normal solid. Basically the driver sends a pixelated pattern instead of the solid because it can't pulse fast enough to remove all the film in these small areas. Does anyone have any tricks to get all the material removed? Maybe going over a 2nd time or some trick to spread the pulse out?

Russ

[George M. Perzel]

Russ;
Not sure what settings you are using-slow it down, max out your dpi, and cut your power as required. You can also set it up as a vector burn with high ppi, slow, and low power.
Best Regards,
George
Laserarts

[Richard Rumancik]

I'd probably set it to engrave at 1000 dpi (this is a nice setting if you are working in Imperial units as 1 dpi - .001"). That way you would get 50 lines on a .050" square. Since the lines are .001" apart and the spot size is probably .003" or more you would get quite a bit of beam overlap so I would not think you would need to plot twice. Also, I would use a 1.50" lens for this. Focus must be done very accurately.

Are you letting the laser do the vector-to-raster conversion? You could convert the image to bitmap and plot the bitmap directly and see if that improves the result. Or if it is already a bitmap examine it at high magnification in PhotoPaint and see if it is a solid black box. Make sure you have 100% black RGB (not CMYK).

Keep in mind that when you laser fine items like a .005" wide line you can get roundoff error if the dpi is too low or not a good multiple. For example, if you used 300 dpi on a .005" wide line, each pass is 1/300" = .0033. If the driver decides it can't fit 2 passes of .0033 into a .005"wide line it might do only one pass. If you use 1000 dpi, then 5 passes fit nicely (although your line might end up wider than .005 due to beam width). So you might need to do 4 passes to compensate. With finer features you have to look at them carefully and do what is appropriate.

If you use low dpi and a 2" lens (with .005" diameter spot size) it will be difficult to create such features precisely.

[Russell Ludwick]

i forgot to mention I am already maxed at 1000 dpi and I am using about a 10in/s feedrate with a 1.5" lens. Any slower and I start burning the film. I think I have maxed the dpi, that's why I was thinking someone might know of a trade secret. If I can't improve it, I will probably just turn the job down.

I will check the 100% RGB, because i might have my default at CMYK.

[Rodne Gold]

In your software , perhaps overlay another copy of the artwork on itself , however shift it a TEENY bit to overlap the "missing" dpi , run the job , will engrave the first artwork then shift a bit and re engrave taking away any remenants from the first pass.

[matthew knott]

Find someone with a fiber or yag laser, i suspect it will be much better as the spot size is much smaller and it wont affect the glass and to get a solid area of removal is much easier. I know this doesnt really help you much but if you know someone with one you could sub it out to them and still make some $$$

[Richard Rumancik]

Is this a conductive ink on polyester film like a membrane circuit? (You say that if you slow it down you start "burning the film" ).

Perhaps the problem is that there are metallic particles in the conductive film that are reflecting the beam. Conductive films for membrane switch circuits often use silver additives - don't know how small the particles are but they may still have the tendency to reflect the beam.

Since you are already doing max dpi and using a 1.50" lens I can't really think of much more that will make this job run better . . .

[Dan Hintz]

For the thin line (0.005"), I'd use a 2"FL lens and draw a single line in the drawing program... you'll get a near-perfect edge on the line (assuming you're focused properly).

[Scott Weinstein]

I have tried removing dichroic from small glass discs in the past and it is very tricky. The speed and power settings are very crucial so that you remove the film, but not etch the glass. (https://www.google.com/search?hl=en&client=firefox-a&hs=fEE&rls=org.mozilla:en-US:official&sa=X&ei=JuSfT5eVJYqFtgeCgcncBA&ved=0CIgBEL8FKAE&q=dichroic+glass&spell=1&biw=1079&bih=560)

[Joe Hillmann]

Since you say the film is conductive, I assume there is metal in the film which may be causing the rough edges. I would also suggest that you find someone with a yag to test it because a yag will be able to vaporize the metal and it will leave the glass unaffected.