I think I am going to just do rocks. No smoke and great results. Won’t burn the house down either. This is my very first try and it looks great. Starting up a paperweight business is on the horizon.
Sculpfun iCube Pro Max 10w.
1000mm/m
80% power
1 pass
No coating or burn assist material on the rock.
Average 3" rock.
Can you engrave names at it?
I’m thinking about training my aim. I know some cool targets but I wanted to personalize them, taking into account the size of the stone and the name to be placed on it. 
The result we see is just the passage of the laser. No paint job? What kind of stone is that?!!
It turned out really well!!!
Nice result, especially for first go. Seems like that work suits your situation and focusing on a speciality will teach you a lot.
Could be the cornerstone of a niche!
Yes, but do not mention my name when they haul you away! 
No paint, just raw rock and laser. I was surprised by how black it is. There must be variability in rocks just like wood (DOH!). A second rock did not turn out so well. My granddaughter liked it because it had a weathered look. One rock was a light grey (good) and the second was a medium tan (not so much). A QR code on the second was a dismal failure.
Got the rocks from Amazon, who got them from Kentucky, who got them from China. They are listed as bag of paintable rocks 3" - 4" with a count of 20. No matter what size you order, assume they will all be the smaller of the two measurements. The bag weighs about 10 pounds and I have no idea why I ordered two. I am currently at son’s house and can’t throw them in the carry-on.
If you mean I can make money selling rocks, I am all for that. Maybe I can draw customers that do not like slate or white tiles? I live in a town notorious for weekly art fairs, so we will test the market.
Thanks for your feedback!
UPDATE:
Sorted, there were 4 types of rocks in the first bag.
Light grey
Dark grey
Granite
Dark tan
The first two carve pretty good at 1000mm/m, 80% (10w), and one pass.
Granite has white spots that are hard to remove (yes, it actually removes material). It appears 250mm/m, 80%, and multiple passes are requited to get a somewhat continuous path. Blast enough material around them and the white ones will pop out too.
Dark Tan had only one rock in the batch, so no more testing with that color.
Observation:
Save the rock’s cash and buy a shovel!!
Do you have a local beach or river bed…that would save a ton and you can QC as you go.
The one in the picture has nice crisp lines and the inconsistencies give it a nice aged look…that will work well if you pick designs suited to the patination.
If the time taken is as reasonable as the possible material costs, its looks like a winner.
“Go MH”!
Had to look that up. Did not notice the root word was patina.
Few rocks in my part of Florida, but plenty of sand.
Depending on the design or text, the time takes 5-10 minutes. @thelmuth says slate can be done at 6800mm/m, 90% but that is much softer. I am seeing speeds of 500-1000mm/m, but that is not bad.
Thanks!
I would never think of buying stones on amazon but these are remarkable results! such high contrast.
How would you describe the hardness of this stone - compared to slate for example?
I have never done slate, so I cannot say for sure. But I do know slate is a much softer rock. I think slate is clay before it turns into rock (or coal?), so I suspect it is relatively consistent.
The bag of rocks has a variety of compositions. I sorted them into 4 groups of similar color. I found that two of the same group can be dramatically different. The rock you saw was from the Light Grey group. Another from the same group had almost no contrast at all.
But I turned it from a fail to a win. I noticed when I got it wet, the rock got dark, but the lettering stayed light. New plan, instead of tossing the fails, I coat them with something. Turns out all I had here was my Granddaughter’s clear nail polish. I worked, contrast restored, rock saved from the garden.
When I get back home, I will spray the fails with clear water-based urethane (Varithane).
By the way, have you ever found anything you could NOT buy on Amazon?
I had some rocks I bought at Lowe’s that were called Mexican beach rocks. All were gray. I was able to lase some text and even an image on it that looked great. But when I tried to repeat the same image and text I could not duplicate the results on at least 5 other similar looking stones. I never figured out why unless the first was dirty, or just the right crystalline structure, shade of gray or whatever. Can’t easily sell to people if you can’t get consistent results. I have marked sea shells and some sanole rocks I bought at a rock shop, but didn’t get some to even mark at super low speeds and full power Hope you can figure out the secret to getting consistent results.
Google did not help me here. Describe in words a Hillbilly can understand.
Already know the secret —> Get consistent rocks.
Here is an image to show the variety of rocks and results. You probably guessed granite is off the table. The one to the left of it is the same symbol. The weak burn on that one was due to going out of focus. I wonder if I can order some “parallel top and bottom” rocks.
By the way, that top left one is my best yet. No, it was just plain luck.
Footnote: I just had an idea. What if I paint them and burn through that?
I’ve been shimming my rocks to get the top parallel, but I just had the idea this week that I should just use a small storage box (as would fit a sandwich) with some dry play sand in it. That would let me just press the rock in with my selected flat-ish area top center and level.
(I had considered Playdoh or blue tack, but I was concerned they’d leave residue on the rocks.)
Great idea. Will adopt this when I get back home.
Here in New York we had someone selling stone from the Brooklyn bridge.
My play sand was damp, so I baked it at 250°F for half an hour to get it nicely dried out and free-flowing. After it cooled down, I poured it into my new laser sandbox and tried it out with a wedge-shaped rock. Worked like a charm.
Here are some demo rocks:
I hit them with two sets of parameters. First layer engraves down into the rocks but leaves the engraved area basically the same color as the untouched rock. Second layer goes back over the engraved areas and slightly melts the surface to give a much darker and slightly glassy result.
I don’t know what they are, but they came in a big bag from the garden center.
60W JPT Mopa (175mm)
Deep engrave:
3000mm/s
70% power
80kHz
200ns pulse width
0.05mm interval
45° bidirectional cross hatch
8 passes
Darkening meltish:
2000mm/s
70% power
800kHz
100ns pulse width
0.05mm interval
45° bidirectional cross hatch
2 passes
If it is like my authentic stone piece from the London Bridge, it is granite. That stuff is better handled with a diamond tip tool in the CNC.
I need to scale the sandbox to fit my iCube, but it is a superb idea! We will now officially call this the “Clay-Jar Sand Box Method”.
Can also use it on other odd shapes, or round objects that do not require the rotary. I see placement repeatability being a problem with this idea. Maybe I could make Plaster of Paris molds as fixtures to do the thing.
I’ve only used the sandbox for irregular natural objects, so it’s already a given that I have to do the three Fs (frame, focus, fire) on every piece. I’ll often even rescale each if there’s lots of sizing variation.
Regular things usually get jigs. In fact, in the bottom right corner of the sandbox image, you can just see a 3D-printed block for holding and registering a d12 die.
I played with hieroglyphics on rocks. Sometimes the laser pecked away the “desert varnish” exposing lighter native rock underneath. Sometimes the rock turned black - think I was melting it into a very thin layer of volcanic glass.
Nice rock’s
Just thinking…if the play-dough was mixed with fine sand, would it still allow to level the rock but not stick to it so much.
Are any of the examples above ‘sandstone’, the ai said slate is best but sandstone is good too cause of small particles.
Pitty about the inconsistancy but I think the less than perfect examples could look good with the right design and filling with paint ect. Just though about gold leaf with a clear resin overcoat or such.
Im wonderin if the 2wIR or 20w diode would make much of an impression.
