Stray Marks

[David Sabot]

Hi folks, have a weird problem that I could use some help with. I have a PDF file of a logo that I am engraving. I am engraving it onto a piece of wood and the best way to describe my problem (since I can't photograph it) is that when engraved it is producing stray marks the same place each time on the wood. These marks are very faint, almost look like a scratch on polished wood. I have checked the file and see nothing on it. It is not close to the logo, about 1/2 inch away. It almost looks like the autofocus pin or air assit cone is scartching the wood, but those aren't even touching. I cleaned the lens (which has a small discoloration on it), cleaned all the mirrors, etc.

Could it be the lens? Could it be casting a reflection of some sort? Any ideas? Using a M-25watt with Corel Draw.

[Mitchell Andrus]

Have a look at ALL of the layers in the file you're using. Stray errata is easily overlooked there.

Try selecting a small part of the image, then all of it, and print "Selection Only" and see what happens.

If you're really stumped, post the file so we can have a look.

Mitch

[David Sabot]

Here is a copy of the PDF file
http://www.cheaphumidors.com/HCGLogo.pdf

[Dave Jones]

Also, assuming you are using Corel Draw, try setting the view mode to wireframe. That sometimes shows things that are otherwise hidden.

[David Sabot]

Tried wireframe, tried top to bottom and bottom to top, same results. When I enlarge the image the marks are larger, when I reduce they are smaller. It almost seems like the lens or mirror is creating a stray mark, is that even possible? I cleaned the lens and mirrors, the lens had a mark/dot on it that I can't remove, it is faint, but never caused problems before.

[Richard Rumancik]

David

Have you watched the laser while operating? Is the "scratch" within the bitmap itself or is it a "vector" problem? See if you can tell if it is embedded in the bitmap or a phantom vector.

If you have a scanner maybe you can take a "photo" of the workpiece and post it.

[Joe Pelonio]

Try this. Locate the area on the file where the spec is printing, and
cover it and the area around it with a white box with no outline. If
there's something under there you can't see on screen that should block it
so that it doesn't etch. If it's still there it may be the lense.

Also, if it's the lense, it should show up on other files that you engrave.

[Dave Jones]

If you enlarge the image and the problem enlarges, it's unlikely it's the laser. It's most likely something in the image.

[Mike Null]

I have experienced this issue.

If the problem is not apparent with the solutions offered earlier I would guess that your file is corrupted.
I would delete the job and re-send the file. If the mark still appears I would re-do the file and re-send it.

To clarify, the file is possibly being corrupted in transmission not because there's anything wrong with the PDF.

BTW, check your printer cable connections.

Lastly, re-boot the laser if necessary.

[Tom Cole]

You might also import it into photoshop or photopaint as a bitmap and do a

1. remove noise
or
2. select the background (and the dots) using the magic lasso and cut the background out
or
3. Jaggy Despecle

[Shaddy Dedmore]

I opened the PDF in Draw X3 and it looks fine, it's vector and there's no extra dots. Stepping throught he Object manager is how I varified.

Maybe post the CDR that you're using and we can take a look and see if anyhting extra shows up.

Shaddy

[Barbara Buhse]

I've encountered this problem before, always with PDF files.
Now what I do is if it is something simple and easy to outline, I use the procedures for manually converting a bitmap to a vector, and that solves the problem. If it is a complicated graphic, maybe some else has a better idea.

Barbara

[Mike Mackenzie]

David,

If none of the suggestions work above Then I would suggest that the tickle signal from the laser tube needs to be adjusted.

Are the marks on the left and right sides of the material?

Does this happen on other jobs as well?

If the tickle signal needs to be adjusted I can help you to do it, However I will be out at a show until Monday Oct 2. If you need help before then give the service dept. a call or perhaps your rep can help.

let me know.

[Mike Mackenzie]

David,

I just re-read the post I want to clarify is this the Universal M-25 or the GCC?

If it is the Universal I can help you if it is the GCC model then hopefully someone else will chime in if I recall there was some discussion on this subject a while ago.

Maybe you can do a search for "Tickle Signal" or something like that.

[Bruce Volden]

Are you engraving a bitmap file? (TIF, JPEG, ...) I have had this happen before only it didn't appear as a "scratch", more as a wider mis-engraved? area. I believe it was called banding.

I solved this problem by resampling the graphic larger than what I was going to engrave, bringing it into Draw, and sizing it to the actual size I needed! It has yet to fail me~I only wish it didn't take so long for me to figger out.


Bruce

[Frank Corker]

My personal thoughts are that it is the pdf file itself. When I import this one into Corel x3 the two main shapes are missing! Now that is something I have never had problems with before

[Barbara Sample]

maybe you could just copy the logo, and paste it into a new doc in corel.
This has worked for me in the past when something showed up on the engraving that was not seen on the screen.
Sometimes things are left on the screen that we thought were deleted, and they are still there.
Good luck.
Barb

[Mark Singer]

My mother used to call me that..."Stray Mark"....can't hear you Mom (wish I could now!);)

[Joe Pelonio]

My mother used to call me that..."Stray Mark"....can't hear you Mom (wish I could now!);)
If that's the worst she ever called you I'd have to guess that you were a good kid!

[David Sabot]

Wow, thanks for all the wonderful suggestions. I will be up all day trying them all. I really don't think it is the file because I recreated it and the same problem exists, the more and more I do this I think it is the lens or something else.

[Mike Null]

David:

I've had precisely the same problem and it was always a corrupted file. Check the cable connections and create a new file and send it. Be sure the lasers memory isn't stretched to the limit.

I could see nothing wrong with your PDF.

I'm assuming your machine is a ULS M25.

[Mitchell Andrus]

How about deleting the elements you expect to engrave and send the file to the laser. If the marks show up, they are somewhere in the background. Another: Select and send one element of the design at a time and see if the marks show up with any of them.

This isn't rocket science. Process of elimination with a little clicking around will eventually lead to a fix.

Mitch