Chinese laser RD Works engraving accuracy issue

[Mario Kozic]

Hi guys,

I'm a complete newb to engraving. I use a typical chinese laser 40w tube and RD Works 8.
I've mostly figured out everything I need except for one issue that's killing me.

No matter what I do the laser beam always engraves outside the vector lines. You can see what I mean in the images.
It shouldn't be a focus problem because I always pay attention to aligning the head. For my machine its 24mm from work surface.

The issue is not a big deal with simple art but I can't do precision stuff and it's hurting my business.

I would be very grateful if someone with experience could point me in the right direction because RD Works is a pain in the ass.

Thanks.349384349385

[John Lifer]

Are you just using rdworks as the program for your artwork? I.e.,import graphic into rdworks and then do prepwork in just that program? If so, you need coreldraw or another program to set up and then then just transfer to rdworks to laser. You can only do so little with rdworks on preparing. And frankly, I haven't learned, nor care to lean to draw in rdworks. Corel would let you engrave on top of your cut lines or just short of them. You just need to draw your lines that way.

[Mario Kozic]

I'm doing all my work in Corel before importing it in RDWorks. But I'm not sure I understand what you're saying.
No matter how I set my vector lines in Corel once I import the artwork into RDWorks it imports the exact outline of the vector lines.
And even that shouldn't be an issue because as you can see from the preview image the lines in RDWorks look ok. But the laser beam crosses the lines by as much as a half of mm.
For the life of me I can't figure out why it's doing that.

[Bill George]

Those lines are too wide to be Vector lines unless you have two as = side by side with engraving inside. If they are being engraved you control that by the width of the line in the art work. Vector lines can only be hairline.

[Mario Kozic]

Well, yes, you're right. It appears I used a wrong term to describe it. Those are two vector lines with engraving inside between them.

As you can see by the picture, when I use normal scan settings the laser engraves what is set but also outside the lines and I get that thick right side.
When I do the same thing but doing a "negative" I get that left side where the laser has again went across the line and basically engraved too much empty space.

Theoretically I could fix it by fiddling with dimensions on one side until I get it approx the same size but that's more "applying duct tape" approach than actually fixing the problem.

[Matt McCoy]

Try expanding the stroke on the image or convert it to a bitmap.

[Scott Marquez]

I would suggest going back to the basics and determine if there is a problem with the machine or how it's interpreting your file.
Using RD works, can you create some small (10 mm) squares and circles, and then engrave them on acrylic? When completed, measure them for accuracy.
Scott

[Mario Kozic]

I took your advice and tried converting it to bitmap.
Much better result. Thanks!349398

It will work for now. It doesn't fix the general issue but it's an improvement.

[Mario Kozic]

Thanks for the suggestion. I probably won't have time for it today but will try to test it tomorrow.

I did test the laser when I started running it and it was doing nice accurate rectangles but it doesn't hurt to test it again. Maybe something is misaligned.

[Bill George]

Looks pretty good to me. I am thinking its more user error with the RDWorks but this looks very nice.

[Bill Carruthers]

I took your advice and tried converting it to bitmap.
Much better result. Thanks!349398

It will work for now. It doesn't fix the general issue but it's an improvement.

What you have to do in RDworks is select the parts of the image you want engraved and make sure the colour selected is set to Scan not Cut as it appears to be doing in your first sample.

[Kev Williams]

349420

- I enlarged your photo so I could see if you were having backlash issues- Nope.
What you're engraving is a 96 dpi (or less) basic 2-color Windows bitmap.
If you have nice smooth outlines in Corel, then somehow during the transfer to RDworks the Corel vector file is being converted to a bitmap.

Dithered bitmaps are okay, and basic 2-color bitmaps aren't too bad if they're at 300 dpi.

The absolute best is to engrave the vector graphic Corel creates...

[Mario Kozic]

Hi guys.

Sorry, it's been a couple of crazy days. I've haven't had a chance to test the machine or check the forum.
Hopefully I'll find the time to run some tests during the weekend and I'll get back to you with results.

[Mario Kozic]

Finally gotten around to running some tests and I figured it out.

Bit embarrassing to admit but it was really simple. I've been using too much power while engraving. Basically I took some wrong advice. It said I should be running it with high speed and high power for optimum results. It didn't even cross my mind to reduce power significantly because I assumed a 40w machine is pretty weak as is.
When running the machine on 15-20% power and speed 80-120mm/s it doesn't go across the vector lines and everything turns out great.

Thanks for your help guys. I appreciate it.