My first tiles My first tiles

JVL · May 10, 2020, 1:44pm

I have done a lot of reading about laser tiles and the technique.
My understanding is to use low power < 1 watt, slow speed, and a relatively high DPI.
My first attempt was as following. (using a 7 watt laser)
Jarvis, 350 DPI 40 IPM 10% power.
It just barley turned the paint a light grey that washed off with acetone.
My second attempt was again with Jarvis, 350 DPI, 40 IPM and 80% power.
This is the result. (as you can see, its horrible)

So then, I changed to Greyscale (because, well the the preview looked very good) with the other setting remaining the same.
This is the result, (better but still not good)

This is the picture.
IMG_0731001.jpg cropped

Any thoughts???

raimondo.squitieri · May 10, 2020, 2:36pm

Ciao, forse si è attivata cambiando modalità scala di grigi la funzione “negativo”

JVL · May 10, 2020, 9:51pm

Geeze,
I was kinda hoping that Bulldog or Sasquatch would also weigh in on my dilemma,

Sasquatch · May 12, 2020, 6:58am

@JVL did you spray the tiles with the white paint that @Bulldog suggested?

Have you done a test pattern burn And Focused your laser beam properly? The diode lasers are very touchy when it comes to focus.

Also subtract the background it’s too busy and some of the background blends in with the hair especially when color is converted to black and white

Cheers

Sasquatch

Bulldog · May 12, 2020, 10:47am

Sorry been off for a bit…taking care of grand Daughter while Daughter in Hospital giving Birth…Proud GrandPa of Little boy

Bulldog · May 12, 2020, 10:51am

Nortons method for etching white ceramic Tile or Glass or Cups or Plates(for Diode Laser)

NICKY NORTON·FRIDAY, MARCH 6, 2020·

AIR ASSIST… will reduce “Blacks” (but on some Co2 Lasers you will need air assist to keep lens clean)

DO NOT USE GREYSCALE

1…Prepare Photo with a photo Editor…(LightBurn now has photo prep under shape properties)

2…set size of photo to size you will laser on tile

3…set DPI to around 300 (this really depends on the size of your Laser Beam)

4…clean white tile with Lacquer thinner

5…paint tile / Glass Flat White…allow to dry (one light coating should do)

6…fine focus Laser beam

7…pick Image Mode to use ( I prefer Jarvis Dither and have had some success with Stucki Dither…Available with LightBurn software…this preference takes some trial runs and documentation …if preDithered use LightBurn “Passthrough”

8…for my 2.5 watt diode…speed 1200 mm/min…power 85% (my S-value in LightBurn =255) Line Interval = 0.085

9 takes approximately 50-70 minutes to complete

10…clean off all paint with Lacquer Thinner…

11…place felt pads on bottom to prevent scratching

Video

How to Focus Diode

Prepping Photos to Laser

Basic Steps

Dithering is done when converting to 1-bit black and white from either greyscale (8 bit black and white) or color. Dithering is one of the last steps. Here’s a typical flow

usually resize for your DPI and finished engraving dimensions. DPI is based on your beam size and burn radius (upgraded optics usually as small as 0.08mm, stock optics more like 0.10mm) anything more you will be overlapping lines and quality will actually get worse
convert from color to greyscale
Unsharp mask (to give it pop)
Adjust tonal curve (because mid-tones do not process well in engravings
Brightness/Contrast
Convert to 1 bit (dither)
Process in Lightburn as passthrough

These are the basic steps, and each photo is different, you need to develop the laser “eye” and know what looks good when finished. It takes time and practice. Some photos just won’t engrave well, due to limited quality.

Comments

Bulldog · May 12, 2020, 10:55am

JVL · May 13, 2020, 11:09am

Sasquatch,
Yes I did use the the Rustoleum flat white paint.
As far as focusing, my J tech is pre focused for 1.5 inches and I don’t have access to the lens.
It comes with a .125" spacer to set the correct Z height.
I’m guessing that I may be able to change it by adjusting the Z ??

Bulldog,
Congratulations on the new grandchild.
Their great fun aren’t they?

I think I’m going to take a step back and see if I can play with the focus using the Z height adjustment.
One question though.
Why not use greyscale?
I did this one the other day, and it appears to be the best that I’ve done so far.
(although still not as good as what you are producing)

dkj4linux · May 13, 2020, 2:52pm

Since it appears you have a fully-implemented Z-axis, best focus can be easily determined with a simple script… engraving 10 lines, 1mm apart, and each 2mm higher than the previous. Start “too close” in Z and run the script. The final Z height will be 20mm above the starting Z. Count the number of lines back to “best focus” and multiply by 2mm… then lower Z from its final position by that amount. You are now focused on the surface of the material.

In the following photo, the thinnest/finest line (lower-left of material) is about 8 lines back… so I lowered Z by 16mm for best focus and set Z=0 at surface of material. IIRC I cut this 3mm corrugated cardboard in a single pass with a 2.5 watt (might have been 3.5watt… I have both) Banggood/Eleksmaker diode laser at 100 mm/min feed…

I use this focus script any time I switch material and/or thickness. Here, after finding best focus, I used a second script (10 lines at different feedrate) to determine the fastest feedrate which fully through-cut the cardboard… this gives clean, uncharred cut edges.

My thanks to Ryan Zellars (creator of MPCNC/LowRider/etc) at V1Engineering for demonstrating the focus method and some initial scripts.

Bulldog · May 13, 2020, 4:59pm

Grey scale use variable power,depending on photo…some of the “greys” don’t produce enough power for the paint fusion to tile to fully “take”…as for focusing pin point is a must…https://www.youtube.com/watch?v=AuhHsIySGlo

JVL · May 14, 2020, 2:39pm

Thank you gentlemen for your input.
Today I will be in the shop doing test burns.
At what power level do you adjust the focus?

DougL · May 14, 2020, 2:44pm

as low as you can go and still see the dot

JVL · May 14, 2020, 6:24pm

What power setting do you use when you run the test?
I currently have my 7 watt set at 50% and cant see the difference no matter where I set my Z height.

JVL · May 14, 2020, 9:21pm

Dropped my power down to 25%
It appears that the focal point is within .005" - .010" of the stated focal point. (the Z height)
I am measuring using gage blocks.
What is the acceptable tolerance of the focal point?

DougL · May 14, 2020, 11:46pm

I run mine at 0.8% 15W Ortur Laser Master. Dot just becomes visible at .8% on mine.

JVL · May 15, 2020, 12:47pm

Doug,
8 tenths of one percent???
Or do you mean 8 percent?
My JTech 7 Watt wont even come on until 5%
If in fact you are correct with .8%, then I’m starting to wonder if I have an issue with my laser.

DougL · May 15, 2020, 5:28pm

Jan, it is a different laser and different laser driver so the point should be understood as, you focus your laser point with the least power possible for your laser setup. This is because it’s hard to see the dot of a very bright light.

Bulldog · May 16, 2020, 12:49pm

12% on red paper

Bulldog · May 16, 2020, 12:51pm

under x30 lens…left not focused…right focused…about 1/32nd of a turn of lens

not focused vs focused

JVL · May 16, 2020, 1:29pm

I will play with the focus some more today and use a magnifying glass to check the quality.
Here is a coaster I made for my wife yesterday. (Its ok to spend your anniversary in the shop isn’t it?)
7 watt laser.
Jarvis
200 DPI
60 IPM
50% power
So far, this is the best I have done.
Critique welcome.