help with engraving granite

[anthony jude]

long time lurker. finally have something I need to ask the more experienced users.

I own a 60watt hurricane laser-co2 one. acrylic and such is no problem for me. I have been asked by someone to do a photo on black granite. I went down to HD and picked up a pc of black granite 12" x 12" to do some trials on.

Checked the recommended settings and such. I am using photoshop to edit the photo. and then importing into laser cut.

speed of 200 power of 65, scan gap of .05 roughly 500dpi.

No matter what combinations I try, I really don't get anything except a blob of etched granite. All it looks like I am doing is exposing more of the grain.

What am I doing wrong? do I need a different editing software? scan gap too much?
Any help would be appreciated.

[Bruce Volden]

I would lower the dpi setting first off! My experience with granite and glass is it needs little power and lower pulsing.

Bear in mind I was using my LMI 25 watt machines, IIRC 35 power, 50 speed, 150 dpi.

Bruce

[Jon Sollee]

I do alot of big granite memorials. I always have a standard 200DPI setting at run it at 75p and 50s on my Vytek Machine. The more mica in the granite, the harder it is to etch. SO..lowering the DPI helps alot with stone when dealing with that. All my stuff is run through photoshop. Stone is all over the place, I dealt with HD "granite" before and it gives different results than lets say Indian Absolute Black Granite. Test, Test and more testing till you get your right combination.

[Bill Stearns]

Anthony -
Hopefully, I can add helpful info. I laser engrave black granite, too. Purchase mine at Home Depot, 12 x 12. BTW: Bought an expensive tile-cutter at HD - works great; use it to cut smaller sizes. (i.e. 8" x 10.) The helpers at HD all know I engrave photos; suggest you make friends with 'em. While it is kind of a pain, they help me find tiles that are way less speckled than others. I have found that the top tile in each box tells the story. Started out using more costly granite thru one of our vendors, but there is 'lot more profit to be had if you can use HD's. I have found finding the right settings for each project 'matter of trial and error. So, keep your scraps. Originally thought more power would produce better results; not the case. One huge issue I had: getting photos and text bright enough. Be sure to check out my earlier thread - think I called it: Losing my marbles, marble business". The fellas had all kinds of really helpful advice! i.e. I learned that I could apply white oil based paint to the tile, wipe it off, the result an incredibly brighter image. - Busy day - got' a go. Will check back later ... Good luck.

Bill

[anthony jude]

thanks for all the help.

Bill, will look for that thread.

Lowered the settings for the power and it came out a lot better. Kept the speed at 200 and lowered the power down to 20. I did order some of the fills thru laser bits to see what that does aswell.

bought the tile at HD just so I didn't spend a lot of pcs to test on. I know not the best way of getting settings , but it will help nail them down somewhat. And still playing around with dpi settings and picture resizing aswell to get a base of settings down. As with a lot of others here, I try to keep notes on how I do something... Will post some pics up after I get the fills in and try out.

[Bert Kemp]

There are less expensive fills out there, try white oil paint or rub and buff, they work well and cost less.

[walter hofmann]

hi there
first rule for granite the laser should only scratch the surface, second with a lower speed and the right focal distance you get more detail, third always put papermask on it and remove it after the whiting is done.
greetings
waltfl

[Bill Stearns]

Walter -
I have een engraving black granite tiles for some time now; don't think I remember anyone suggesting masking 'em. I've learned speed 'n power settings are key, But, what do you achieve by masking them? - the advantage? Oh, and what is it that you mean by "whiting"? (always learning something new.)

Bill

[Ross Moshinsky]

I'm confused why your speed is so low. Granite is a high speed engraving process at low power. Chinese machines are slow to begin with. You should have your speed as high as you feel comfortable running and then adjust your power to match. You only need about 10-15W to mark granite.

On text, 500dpi works. Photos you want a maximum of 300dpi.

[walter hofmann]

hi bill
sorry was a typo ( whiting)should mean whiten. I use the masking because I fill lots of the engraving with colors and it makes it easier and not so messy with cleaning after fill.
greetings
waltfl

[anthony jude]

I'm confused why your speed is so low. Granite is a high speed engraving process at low power. Chinese machines are slow to begin with. You should have your speed as high as you feel comfortable running and then adjust your power to match. You only need about 10-15W to mark granite.

On text, 500dpi works. Photos you want a maximum of 300dpi.

I was just going with the base setting recommended.