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Michael James Smith
01-05-2008, 12:06 AM
Hi everyone, Thanks for all the great posts. I'm new to engraving and have a 30watt laserpro spirit. Been surviving the learning curve but I'm having extreme difficulty with photographs on black marble. I've seen some fantastic marble pics on here and other web sites with amazing clarity and detail, but I've been through cases of marble withvery little satisfaction of the quaility. It really seems to be a lot of hit and miss. I am including a few pics for critique. The first photo is the first I tried in my machine aboutfive months ago but don't remember the settings. The second is a photo I'm working on for a customer who wants more detail. I used 28 power 65 speed. I am using lasersketch marble, rendering greyscale at 300dpi, inverting and bringing into photograve using lasersketch params for black marble and mostly autoprocess, I am not altering the picture whatsoever once back in draw. I have used every possible combination of speed and power setting under the sun but not I'm sure where I should be at now. Does anyone have any recommended settings for a 30 watt laser? The other problem I've been having is sparatic banding throughout. I've talked to my sales rep and he thinks it is a power issue. We've tested the power with laser running and not noticing any fluctuations that would cause the banding. Has anyone else had this kind of thing happen? I'm not sure if it's my settings, but I would like to get clearer photos without the banding and the washed out look . I would deeply appreciate any advice or help from anyone would have suggestions on this subject.

Steve Chalmers
01-05-2008, 11:33 AM
In my experience with black marble, the best way to eliminate banding is to focus the lens. . .then put the table out of focus by .20. In other words, drop the table .20.

If your power and speed are correct, you'll not have a problem with banding again.

Steve

Michael James Smith
01-05-2008, 12:31 PM
thanks Steve, I'll give that a try.

Curt Stallings
01-05-2008, 1:02 PM
If you use the Black Marble parameter in Photograv you shouldn't have to invert it before sending to Photograv.

Curt

Larry Bratton
01-05-2008, 1:33 PM
James:
Also, just remember, marble is a natural material and you can get pretty wide swings in the physical properties of it. In other words, it ain't consistent. A trick that works on it is to use Armorall on it before lasering. For some reason it makes the whites brighter and gives you more contrast.
Good luck with it.

Scott Challoner
01-05-2008, 4:20 PM
Hi Michael

I have the exact same lser as you and although I'm no expert, I've had good sucess with 80% speed and 20% power. I also use the Armorall and put the table .020" out of focus although I raise the table instead of lowering. I also engrave at 380 dpi wich may also help reduce your banding. One poster here processes through Photograv at 300 and runs it at 600. I've never tried it, but it might be worth a try. One thing you should remember is that the hit and miss results reflect more on variations in photographs than your abilities. One thing I do is, once I import the Photograv file into Corel, I zoom into an area that should be relatively light like someone's nose at 1600%. If you can see individual dots, it's usually OK. If there are a lot of dots that run into each other and make chains, it will likely be washed out or overpowered.

Michael James Smith
01-05-2008, 9:19 PM
Thanks all for the replies and suggestions. Come to think of it the first few pieces
I ran at 380dpi came out great. My sales rep told me to try 300dpi and many
folks on the creek recommended nothing over 300. So naturally I just figured
300 was the number. I have also tried running at 600dpi with not good results.
The big issue I am having with the power and settings is finding the fine line
to be visable on the marble without overkill on the power washing out and
losing detail I don't really have any basis for comparison except for photos on the web and I know that some add color fill to make the picture brighter. I also have been
using armour all. I will definately try the out of focus method and keep experimenting
with the settings. If I can eliminate the banding that would help me out a lot. Just
don't know if one piece to the next will band or not. Thanks again for the replies.

Dennis Solomon
01-06-2008, 4:32 PM
sometimes i will process the photo thru photograv at 1000 dpi and run it at 300dpi and get great detail on marble!

Rags Alan Ragland
01-06-2008, 5:43 PM
Guess I am the odd ball here. I am not that big a fan of Photograv. I never use it on marble, wood yes but never on marble. I do invert it and clean it up a little as far as contrast, but get good results. I have an Epilog 36EXT/ 75W. I keep the speed to 30 and the power from 6 to 8. Yes, it takes longer but the results are what is important to me. I know someone is going to say send them a file so they can show me how wonderful Photograv is but I just don't seem to need it that much.

Tom Cullen
01-07-2008, 11:59 AM
Just wanted to add my fiddy cents, I was also having issues with banding and found that when using black marble it was way more prominent than with other materials. My conclusion was that dust from the work area was lightly covering my #1 mirror and throwing the beam off. Believe me , it doesn't take much. So what I do now is remove ALL mirrors one at a time before starting a marble job and clean them with the recommended process. I do this at the start of my job and will run maybe three marble tiles before doing it again. The number 1 mirror below seems to attract way more dust than the others, even with a blower on. Take a look at my marble tiles on my web site , the settings for mine are : laserpro explorer II 30 watt, speed 24 Power 100, I have had great results from those settings, although I do not invert the image ...never have, even in Photograv.

Hope this helps you?
Tom

Michael James Smith
01-07-2008, 11:46 PM
O.K guys here we go I have tried running at suggested settings from Scott and Tom, by the way Tom beautiful work, If I could get those kind of results I'd be in buisness. Well any way I ran at both settings and could not even get a mark. I had to run at 30 power and 40 speed to even get a picture to show and a lousy one at that. I cleaned the lense and all mirrors, which leaves me to believe either something is out of alignment or I am losing power somehow. As far as I can tell it is impossible to put a mirror in the wrong way. I also replaced the maincircuit board about 3 1/2 weeks ago think it could have been static electrcity that fried it. As far as I can tell nothing else seemed to be damaged. I'm not sure whats going on here.I would assume if my laser was functioning at full power it should be at least making a mark at those settings. Does anyone know of a way to test the power. I think I'll be contacting my sales rep in the morning.

Dee Gallo
10-23-2008, 10:26 AM
Just wanted to add my fiddy cents...... Take a look at my marble tiles on my web site , the settings for mine are : laserpro explorer II 30 watt, speed 24 Power 100, I have had great results from those settings, although I do not invert the image ...never have, even in Photograv.

Hope this helps you?
Tom

Hi Tom,

I am trying marble for the first time and looked at your site. Fantastic work! What I do not understand is your statement that you do not invert the photo. How does that work? Wouldn't that give you a negative effect instead?

Thanks for your comments, dee

Frank Corker
10-23-2008, 4:34 PM
Dee the image for a black background (granite or marble) has to be a negative that you engrave. For wood and lighter background pieces it is a positive image.

Dee Gallo
10-23-2008, 5:11 PM
Thanks, Frank, that's what I thought after reading the posts here from you and others.. so how can Tom be getting such nice results on Black Marble without inverting? I'm so confused!

cheers, dee

Martin Boekers
10-23-2008, 10:01 PM
Hi Tom, I too wonder how you get a positive image without inverting.

Say in a photo I am wearing a white jacket if I run it straight the area that is showing up as white wouldn't burn, thus leaving the black to show.

I think I may be misunderstanding something.

I saw you website nice work!


Marty

Martin Boekers
10-23-2008, 10:08 PM
Michael, one thing I would recommend since you are just starting out and working with photos is;

When you get one that really looks nice save the photo that you used to make your conversion (the 8 bit greyscale you sent to Photograv)

Then save one that doesn't look good engraved.

Now you have your benchmarks. You can look at the photo that you liked and try to get the new one to fit similar tonalities and contrast. This isn't perfect, but it will help as you start out.


Marty