Some minor Engraving Issues

[Andrew Nuckols]

Hey everyone,
So I am still new to the whole engraving world and I had some questions. I have an Epilog Zing 24 30 Watt and have absolutely been loving the machine. I cut acrylic basically all day for our shop and have been running into a couple engraving issues. Here are some images of a couple pieces I did that have a bit of a moire effect which is not what was intended. I have gone through and cleaned the entire X-Arm where the carriage rolls, and even removed the carriage and cleaned the wheels and spring arm. I helped it to be a bit more consistent but still does it. What else could be causing something like this? I am doing 500 DPI at 85 speed and 100 power. Thoughts?
13499989_10154014354034760_2054098602_o (2).jpg13499711_10154014361274760_1595346251_o.jpg

[Mark Sipes]

I would try two tests. 1) take the table 1/32-1/16 " out of focus. This will widen the beam and spread the power over the image area. 2) raise the DPI to 600+....

.

[John Noell]

What is the resolution of the artwork (and is it a bitmap)? Does it match the resolution you are engraving at? I've seen it more in photos but a mismatch in resolution sure can cause moire patterns.

[Andrew Nuckols]

I am using Vector based images, All out of Illustrator CC so There should be no difference in resolution, and the 500 DPI used to work just fine on these same files. Been cutting essentially the same stuff everyday since February.

[Kev Williams]

how low will your resolution go? My LS900 will run at 50 lines per inch, which is great for testing the beam path--

Here's some of my results. I love this machine but it's Achilles heel is banding. These pics show how the beam wobbles as it moves from left to right. You can see areas where the beams are quite far apart, then get pretty close together. Now, imagine this at 400 and 500 lines per inch-- the areas where the beam paths overlap more than others are going to make for more or less burn in those areas, all the way down vertically, and that leaves ugly bands!

Here's the funny part about my machine- most of these samples were run at least twice, some more. The beam wobble follows the exact path every time. Why? No clue-- New Hermes only answer is it's 'on purpose', something to do with getting better photo engraving. Faster speeds result in more wobble. But, notice in the pics with 4 test paths, the bottom test lines are nearly dead straight- those were done in vector mode at full speed. No wobble. Full speed vector on my machine = 27% raster speed, which is what I ran the tests above the vector tests. So with the gantry moving the same speed, the raster test wobbles, the vector test doesn't.

So while the wobble may be on purpose, I wish there was a way to counteract it. The only way I've found is to experiment with gray colors and let the machine dither the burn. But because of my testing, I know the wobble isn't a mechanical issue...

ANYWAY-- you might run these same tests, clear plex works great. These pieces were 4" long... Run some tests at different speeds, and see if you get any wobble, how much it varies- THEN repeat and see if the wobble exactly repeats itself like mine. If not, your problem may be a loose or damaged belt, guck in the belt or cog teeth, the gantry is dragging for some reason...

banding1.jpgbanding2.jpgband3.jpgband2.jpg