Uneven engraving, fluctuating power?

[Riki Potter]

Lately I've been noticing some uneveness in engravings. Attached is a scan that show's what I mean, it's engraved on black laminate with a white cap. It's not a big issue for us yet but in the red circles you can see lines of white in areas that should be smooth black, I've looked through the forums and seen this attributed to low tube power and alignment among other things, I've found the instructions to align the beam and will try that on monday but I'm doubtful for some reason. We've had the machine for around 5 years and it's normally only in use 2-3 hours each day, any help is appreciated :)

[Mike Tavares]

Hi Riki,

I know this might sound mediocre, but have you tried cleaning the optics and strip?

If your image is correct than it may be an optics situation.

Ask your self this,---How often are you cleaning your optics?

Just because you use your machine 2-3 hours a day, it doesn't mean they need to be cleaned less often!

I would check that out primarily first, before touching any alignment.

Hope I helped?

Good Luck!

[Riki Potter]

Thanks Mike. I routinely clean the lens and the mirrors never seem to get very bad when I do clean the occasionally, is there anything else I should check and/or clean?

[Rodne Gold]

The servo motor encoders , disc's in the motor covers , can get dirty. Also clean the rollers and rails especially well and check the belt tightness on X and Y axis.

[Frank Corker]

Well from someone who hasn't experienced that phenom I would have said that you have a moire pattern that you are contending with, in other words your graphic. Is it happening in the same place with different pictures or is it just this one.

[Riki Potter]

Rodne, thanks for the info, I'll look into those things.
Frank, I'm almost positive it's not the graphic. I prepared the pic in Photoshop in a way similar to the gold method, these patterns weren't in the final file and I kept the dimensions and dpi consistent while engraving it so I wouldn't get any surprises (as I know corel likes to do). It happens on all pictures in varying places depending on the picture, though most of the time it's unnoticeable.

[Mike Mackenzie]

Riki,

Did this problem start after you adjusted the tickle?

[Riki Potter]

Mike, it's hard to say. I believe it's something that's been happening on and off for a while before I adjusted the tickle voltage, although I can't be sure as I've never taken much notice of it until now.

[Mike Mackenzie]

I do not know how difficult it is to adjust the settings however you may want to test this by switching it back and running the exact same file, settings, etc. if the problem goes away then the voltage might be to low. If it stays then you will know that changing this did not effect anything else.

[Bill Cunningham]

If this picture was originally scanned from a 'printed page' then processed using any method, Frank is right, it's a moire..

[Riki Potter]

Mike, I'll give it a test. I'll get a chance on saturday to do some maintenance and testing on the machine so I'll add that to the list.

Bill, I got the image from a stock image site so not a scan as far as I can tell. It was already professionally retouched and I modified it more using basically a customised gold method. I'm not ruling out moire patterns but it doesn't quite seem like that's the problem, are moire patterns fairly common when engraving photos?
I will report back in the weekend to let you know how I get on.

In other news I just got my first order for a half dozen wooden photo coasters with holder woohoo!

[Bill Cunningham]

Mike, I'll give it a test. I'll get a chance on saturday to do some maintenance and testing on the machine so I'll add that to the list.

Bill, I got the image from a stock image site so not a scan as far as I can tell. It was already professionally retouched and I modified it more using basically a customised gold method. I'm not ruling out moire patterns but it doesn't quite seem like that's the problem, are moire patterns fairly common when engraving photos?
I will report back in the weekend to let you know how I get on.

In other news I just got my first order for a half dozen wooden photo coasters with holder woohoo!

A moire pattern is more common with a image that was scanned from a halftone print such as you would see on a printed page. The other cause can be scanning or using a photo that was sampled at say 150 or 300 dpi, and engraving at 400 or 500 dpi if it was 150 or 300 you can engrave at a multiple like 600 or 1200 but a odd number like 400 or 500 may result in a pattern as well. Also a web image of 72 dpi will almost always result in a substandard engraving.

[Niklas Bjornestal]

The first thing i would try is to move the engraving to another place on the table, for example down 1". If the result is identical its the image, if its on the same place on the table its the "hardware".