Time for engraving granite

[Scott Shepherd]

I'm just playing with some black granite for the first time, engraving photographs and since I have no reference point, I'm not sure if I'm on the right track or if I'm way off base.

Assuming you're engraving a 10" x 10" photo on a 12" x 12" piece, about how long does it take? With/without photograv?

Is something like that a 10 minute job, a 30 minute job, or a 45 minute job? (run time only)

I'm still trying to get my arms around what settings look the best, so I'm just experimenting at this point. I'm also curious to see if using photograv is faster than using the 3D feature for photographs for our new laser.

Using the 3D mode for photographs, it looks like it takes about 24 minutes to do a photo. In the ball park?

[Brian Robison]

I was going to guess 20 minutes, depends on wattage and dpi too.

[Dave Jones]

The time it takes is going to be based on the speed and dpi settings you use. I'm surprised to hear you using 3D mode with stone. It's meant for softer materials like wood, where you can get a varying depth in the material based on varying power.

Photograv won't save time over using the normal photo or clipart settings on a laser. But may give a nicer looking image. I have no idea if the 3D mode on your laser goes at the same speed as the normal photo/clipart modes on your laser.

[Scott Shepherd]

Thanks guys. Dave, on the Universal, the 3D mode says it can be used for several things, one being photographs. It's got a calibration scale you pull up, and you have about 15 or 16 adjustments you can make. You run the calibration image, and then adjust it, run it again until it matches a graphic in the book. Once you do that, you save it for that material and you're all set.

It says in the manual that you can get very high quality photographs this way. In trying it, they look quite good, that's why I was curious.

I've done it a with a variety of settings and still trying to find what looks best. Just curious if I was in the right time frame. Looks like I am. I'll keep playing with it.

[Dave Jones]

3D engraving can give a decent photo, but I would expect it to be better on materials like wood that change color with power levels (higher the power, the darker the wood gets). It just doesn't seem like it would give as nice a photo on stone as the regular photo/clipart modes, or Photograve processed images. I haven't done much stone, but it seems to do most of it's color change at a certain power level and then only change a little more as power is increased. That's why I would think 3D mode wouldn't work so well on stone.

[Joe Pelonio]

I'd say longer than that, for a decent quality photo that large it's going to be more like an hour. The power is not as much a factor, it's the speed at which the head travels on the x axis, and the dpi which affects how fast it moves on the y axis. I did a 1200 dpi image of a woman's head on an 8"x8" tile for someone, set at 600dpi, speed 100 and it was 50 minutes.

[Scott Shepherd]

Dave, in the manual, it actually says doing photograph quality images on harder materials is part of what their 3D option is made for. It's very different than the standard Epilog driver.

Thanks Joe. At least I know now that I'm in the range or on the low end. I'll go back to playing. Once I get it all set right and get a good image, I'll post a photo of it. First I have to find something worthy of using as an image!

[Mike Mackenzie]

Scott,

The 3d engraving mode for photographs will only work well for materials that can give you 16 different shades of Grey.

Unfortunately Granite is not one of those materials to do granite and get good results you need to use photograv.

That method works great on anodized, black marble,plastic engravers material, alumamark, and some others.

When you run the scale you must be able to see 16 separate shades.

[Scott Shepherd]

Hi Mike, I'm pretty close to that. Can't see all 16, but can see about 10 of them. I thought it actually turned out well so far. It might not be granite. The box was open and I only bought a 1/2 dozen of the them, so I don't know exactly what they are. Guess I'll look for some more materials to play with. I did one image using the method Rodne explained about how to manually make the adjustments to come close to photograv results and that worked quite well.

Still playing with it and trying to figure out what it will do. What a powerful machine. Amazing driver.

[Darren Null]

Granite, like most igneous rock won't vapourise at the kind of wattage most of us are talking about- you either melt a hole or you don't. Even if you give it some on a single spot, you're not going to get a much deeper hole and you're essentially just surface engraving.

Have you tried using halftones to get the light/dark effect? (Halftones are like B/W newspapers and get the light/dark shades by using different-sized dots). Halftones are excellent for surface engraving and you may well see a significant speed difference over a 3D attempt.

[Scott Shepherd]

I'll quote out of the manual :

"Using the appropriate materials and settings, the end result is an engraving that looks more like a photograph than a halftoned or diffusion dithered image does."

I have very limited time this week, but if I get a minute, I'll try and get a piece of black marble and give it a try.

[Dave Jones]

It's very different than the standard Epilog driver.

It does sound like you have a bit more control over 3D mode than with an Epilog engraver. I have done a lot of 3D laser engraving, and have used Photoshop and Corel to adjust the shades of gray to get similar non-linear shadings in the photo to give linear shades in the engraving, like your driver gets you. The fact remains that 3D mode works by removing depth in material and some materials do not change depth like others. PhotoGrav doesn't get shades of gray by different depths like 3D engraving does. It gets them by grouping pinholes or dots in the material. So it's a fundamental different approach that works well on virtually any laser engraveable material.