Laser burn color tile issues/success?

Hello Longmill peeps,

I am trying to get into using the Longmill Laser to burn 4x4 white tiles using the spray paint method. Painting the first layer in the color you want than the black layer on top.

I am having issues with the laser changing the power levels to get the different layers of color.
This is my test file:
ColorTest1200_50.lbrn (90.8 KB)

I have tried to burn a yellow tile and a red tile. The red tile is a lot more promising than the yellow but, it is still not right.

I tried to burn with the limiter switch at 4 and these are the results:

The yellow only seems to show through the 1200 mm/min text.

I thank tried to change the limiter switch to 2 and three and these are the results:

The yellow was still not showing through. The red is sort of working but is still very dark.

These are the spray cans I am using:

I don’t know if there are settings that I have not set in LB to get the results I was hoping for. The reference video I was using was this:
How to Create Amazing Color Tiles on a Portable Laser Engraver - YouTube

If anybody has any advice or assistance that would be greatly appreciated. I really want to use my Longmill to its fullest sooner than later.

Thank you

I’d try increasing the speed, even at the low power setting the laser is still burning away too much of the paint it seems.

Burning is a combination of power and speed, so if it is too dark/deep of a burn either decrease power (you really can’t here) or increase speed (I think the longmill can go upwards of 3000, so you have plenty of room to increase.

One problem I have with the JTech laser, is when you get to around 30 ipm the burn starts becoming a dotted line. I don’t know if the Longmill Laser suffers from this method of operation. You could easily make a test burn.

JTech explained to me that the laser is actually pulsed on/off at about 1000 pps (by design), and this is what is making the dots show at faster speeds.

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I guess you could try to lower the power more. You’re starting at 8 on the lowest square, make that a 1 and try going up from there.

There is a setting in GRBL for the precision of the PWM (my words), basically a number value that = 100% on the PWM. Some people set that to 100, others (and I think by default) it is set in the 30k range. If yours is set to the larger number you should be able to use fractional power settings also (1.5, 1.6, etc) I think. I’ve never tried it, but it would be worth a test if you find the right value is between two integers.

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I did not know you could do this with a laser setup…
I want a laser now