Layer alignment problem when doing multiples with Chinese laser w/laserworks.

[Jeffrey Michael Wilson]

• I'm having a problem with layer alignment... I'm using laserworks. RDcam2 I think. I never have a problem if just doing one item with multiple layers, but if I'm doing many, the further I get from the original, the bottom layers start getting offset a little to the side..the greater number of copies, and the further from the original...the more offset. It doesn't matter where on the bed I begin.. .the laser is aligned, just did that yesterday. Sometimes I can do just 4 pieces and get by, but any more and the offset is just too great. I usually have a final layer that's a cut, so it cuts out areas that shouldn't be cut, and leaves areas that should. This really cuts into my productivity if I have to sit there and do pieces one at a time. I'm wondering if there is some setting in the software that will fix this...the book, translated from Chinese into....gibberish, doesn't help at all with this. Please advise OH Master Laser Gurus.
• OH, ALSO, I have the raster layers set to Independent output...if I don't select this option and do it as a single graphic, the alignment problem is mostly gone, BUT the image quality becomes Pixelated... So maybe is there a solution to this pixelated problem. Either way, (independent or as one piece) if I just do one single one, it's fine...the problem is with multiples.

[Keith Winter]

I don't fully understand if you are stacking items and trying to cut through multiple or what. If you are I'd stop that practice a little vibration will make them move.

If the question is regarding increased thickness then it's likely due to your lense bring too small. On thicker items the line would appear to curve toward the bottom if this was the issue.

Can you simplify your question and maybe post some photos so we can see what you're talking about?

[Jeffrey Michael Wilson]

I'm burning designs on various woods, small..like 20 -30mm diameter. These are for earrings. Thin wood, 1/4 in. or so thick. I'll have one layer be a tree with deep background, another layer will be embellishments on the tree itself,(bark, knotholes etc. The final layer is a vector cut out of the piece. I run my images at 600 dpi, seems to work the best.with speed of 80 or so and power 20 or so..all depending on the wood. If I do multiples of the piece as independent graphics, each piece done separately, then the further I get from the original piece, the subsequent layers get offset, each additional one, a little more... (the embellishments and final cut shifting to the right). If however I do it all as a single graphic, I do not have this problem of offset of layers, even though each layer is still done separately, BUT the graphics on all but maybe the end, (first or last) piece are very pixelated.

[Ray Scott]

Many of the import laser machines have machine configuration settings that control the acceleration, rapid speed, ... Most laser operators will adjust the cutting speed, but they forget about the accelerations and rapid speed settings. The laser machine may have originally setup for some aggressive configuration. After a year or so of speedy work, the laser machine might have resistance in the bearings... and so the stepper motor steps might slip. You would be better off to adjust the machine configuration and live with a slightly slower laser machine that stays accurate.

Thank You,

[Jeffrey Michael Wilson]

Thank you.....OK, I found possibly where that is.. I have cut and sweep Parameters ... under cut I have min, and max acc, (mms/s2)
Min.Acc (mm/S2) 400.000,
Max Acc./S2 3000.000,
also Idle speed 200.000,
Idle acc. 300.000....
start speed 20.000
normal cutting, S mode (slower stedier...

.UNDER Sweep parameters
x start speed 10.000
y start speed 10.000
x Acc 10000.00
y Acc. 3000.00
line shif speed 100.00
scan mode common


Home speed 20.000

Are any of these what you are talking about, and what would you suggest...I don't mind slowing things down a bit..
Thanks

[Rich Harman]

I know the problem you are talking about, it used to happen to me. That was a long time ago and I honestly do not know what I did to fix it. I do know that I made no changes to accelerations or other similar parameters and my steppers have never missed a step - not even once (excluding experiments to find the max rastering speed). If the stepper was missing steps it would offset everything, not just things further away from the origin.

I did upgrade my controller early on, that may have solved it. I also found a loose pulley.

[Jeffrey Michael Wilson]

Here's some more info. Last night I decided to try doing the multiples in a vertical line instead of horizontal...it works just fine like that....Any ideas anyone?

[Dave Sheldrake]

Backlash due to change of direction I would suggest

[Jeffrey Michael Wilson]

Thanks, but I have no idea what that means

[Ron Gosnell]

Backlash due to change of direction I would suggest

To test what Dave is saying, you should have a setting that will engrave in only one direction.
Mine is called unilateral but yours may be called something else. Look for anything related to bidirectional engraving in your settings.
If it engraves nicely in one direction that lets you know if it's a belt that needs adjusted.
Backlash takes up the slop in the belt or other symptoms via the software.
It will give you a starting point for troubleshooting anyways.

Gozzie

[Rich Harman]

If I understand the problem correctly, I think it must be a software issue and not mechanical.

A row of objects to be engraved then cut out. Each engraved (rastered) individually. As the objects get further away from starting point the engraving moves further from where it is supposed to be. When the object is then cut out, the cuts are in the correct locations - meaning there is a difference in the coordinates of where it is rastering vs cutting, and that difference is greater as it moves further from the start point. The difference happens only during the raster, not the vectoring.

[Jeffrey Michael Wilson]

Thanks I'll check these things out.

[Ron Gosnell]

If I understand the problem correctly, I think it must be a software issue and not mechanical.

A row of objects to be engraved then cut out. Each engraved (rastered) individually. As the objects get further away from starting point the engraving moves further from where it is supposed to be. When the object is then cut out, the cuts are in the correct locations - meaning there is a difference in the coordinates of where it is rastering vs cutting, and that difference is greater as it moves further from the start point. The difference happens only during the raster, not the vectoring.

Aha, I understand now. So it would be a layout problem of sorts. I think Kev Williams has the answer to that.
He likes to (and it works) put all of his work inside a larger box drawn in corel. Set the box so it doesn't raster or engrave. The items to be
engraved are set inside the box and will stay aligned inside the box I could have probably explained that better.

Gozzie

[Rich Harman]

Aha, I understand now. So it would be a layout problem of sorts.

In my case it was not a problem with the layout. The rastering and cutting were done in the same job - not a matter of needing to line things up in different runs. It was the laser drifting further off the mark the further it got from the start point - but only during the rastering portion of the job. So when it goes to cut, it cuts where it is supposed to but the rastering isn't where it is supposed to be - hence the part is ruined. It's as if when the job is sent to the laser it scales the rastering part, but not the vectoring. It is a mismatch of the rastering to the vectoring that happens proportionally as you move away from the start point. I can't come up with any mechanical problem that would cause this and I haven't had the problem since swapping out my control board.

[Jeffrey Michael Wilson]

Yep, that's pretty much my prob. I do multiple layers, some raster and some vector...BUT, the Raster layers are also offset... like there will be embellishments on a tree that are a different layer than the tree itself, and they will shift over....as well as the Vector cut out layer...