Help - Slate

[Arthur Nagel]

Hi Folks,

I really could us some help!! Not sure what I am missing...

So I have been through Russ's Slate Videos and youtubes etc.. but I still seem to be missing something when it comes to etching on Slate.

I have done the typical testing etc with various power settings with the inverted "Totem Pole" picture and not getting anything worthwhile.

This is what I have tried:
I am using CoralDraw, and following the std process of 1. Convert to Greyscale, 2. Adjust the contrast, 3. unsharpen the pic, 4. Convert to Black and White then 5. Invert the Pic, 6. Save file for RDWorks

I bring the inverted photo into RDWorks, Set DPI anywhere from 100 to 600 DPI, Dot, Black and White, Grey Scale Dither, Scan with Power settings High/Low being the same or setting Low power to 5 high between 10 - 20, Output Direct, Interval between .002 and .0015 and speed any between 100 and 300mm/sec. I have tried on both a 2" & 4" Lens with no luck.

My results have all been a blank etch (all grey) with little or no discernable image...

I am hoping I am missing something simple and someone can help me.

Cheers!

Art

[Gene Uselman]

I am not sure what the pict represents [if you created this, I love it], but if you are looking for a darker color I think that as the stone will not burn, it will not get darker. I have Corian and it being mostly mineral reacts the same. I can engrave, even deep 3D engraving and the color does not change.

[sebastien laforet]

I am using CoralDraw, and following the std process of 1. Convert to Greyscale, 2. Adjust the contrast, 3. unsharpen the pic, 4. Convert to Black and White then 5. Invert the Pic, 6. Save file for RDWorks

I bring the inverted photo into RDWorks, Set DPI anywhere from 100 to 600 DPI, Dot, Black and White, Grey Scale Dither, Scan with Power settings High/Low being the same or setting Low power to 5 high between 10 - 20, Output Direct, Interval between .002 and .0015 and speed any between 100 and 300mm/sec. I have tried on both a 2" & 4" Lens with no luck.

slate is a hard material, so it does NOT take levels of grey... either you mark (and you have a blank point) or not (slate stays black).

the key is in the dithering, as it will NOT convert half-tone to half-tone (it may work on paper or wood, not on slate). in your picture, you have low contrast, more or less all the totem is greyish-white so it is not surprising that you lose all the details.

i suggest you first try to create a very basic image with just panels of grey (from black to white) and use different dithering options until you can get a correct result.

also, setting the DPI too high will do no good : our machines have a dot resolution of at most 0.1mm (probably more in fact) so if you try to engrave at more than 256 DPI (=0.1mm per point) the points will overlap each other. so, if you have a blank point near a black one, the black one is probably overlasered by the white.

if you have a flat mid-grey panel, the dithering should give you a batch of white and black points, large enough so that they can be lasered individually. you will only get black and white dots, but at a distance the result will be grey.

i'm not familiar with rdworks dithering... Lightburn has better options, and you can choose different ditherings. the solution might be to do the dithering outside of rdworks and directly with the good DPI setting. maybe start with relatively low DPI like 100, so that you will have bigger chunks of white/black and at least get some contrast on the slate

[Arthur Nagel]

Thanks Gents for the advise, I will give it a try and report back.

Cheers!

Art

[sebastien laforet]

i just made a quick test. i took your image, cut a part, and used "atkinson" dithering (+ invert black/white) on it in Lightburn.

you can see on the attached file the original image, and the preview (computed, not sure of the "real" result)

the result is not greyscale, but patches of black/white. provided you have the correct DPI, you should have a better result with this method.

i do not know the DPI you use and the size of your design, but i suspect that your image is WAY too much detailed to get a good result on a small scale.

[Arthur Nagel]

Hi Folks,

Thanks for your help, I was able to get a fair picture out on granite. What I did was revisited my dot size and realized I was printing over my dots which was causing me my problems. I did adjust my interval; by a fair bit, and was able to get the image on the granite.

I could not have done this without your help, thank you so much!

Cheers!

Art

[Arthur Nagel]

Hi Folks,

I guess I should provide some of the details of the settings in case anyone is interested.

Image size was 2.5x12 inches, DPI was 353
Power was 5 min and 10 max
Speed 200

This image was one of my fathers last before he passed over and is from an ancient Native Tribe found in British Columbia. These totems no longer are standing and most have eroded away.

Thanks again everyone for your help. If you have any further thoughts on how to make this better I am all ears!

Cheers!

Art