This is my first time posting and pretty new to Lightburn itself, but not new to the world of designing/print and cuts. I work in a sign shop and we do print and cuts on the regular, but I cannot seem to get it quite right with lightburn.
I set up my file, and print it with the artwork and the registration marks. I then export the cut layer from illustrator as an SVG. I have tried printing on a desktop computer as well as our large format vinyl printer at work. The only time I have successfully completed a print and cut is from the desktop printer at home.
So after printing and applying to substrate, I import the SVG to lightburn and start the wizard. I move to my first position and test fire until I have found the center of my first crosshair and set the target point. I then jog to my second position until I am at the center of that and set the point. I then send it (both with scaling and without and neither of them seems to work properly). The single time I got it to work from the desktop computer I had to select “scaled” even though I had chosen do not scale on the print.
Before I print my files I draw a box from the center of point one and two and note the measurements so that when I need to jog to spot two I can simply enter the two numbers and not have to guess (represented with the red box in the image). Even with doing this, after moving from spot one to two, it has never lined up with the middle of the second position and when I go to cut, as the laser moves from left to right it gets progressivly more off. I have checked my mirror alignment from mirror 1-2 and 2-3. Is it possible this is a case of mirror 3 being out of alignment? or is it likely something else? Please help, as one of the main reasons I got a laser/lightburn was for the print and cut feature!
I am using a Monport K40 and Macbook Pro. I know the K40 isnt the best of machines, but I wouldnt think that a simple print and cut would be impossible on it.
Does your laser burn dimensionally accurately? Meaning that shapes burn to size?
Does your printer print to dimension? Check both of these first to make sure that 100mm indeed means 100mm
Are you homing your laser before operation and are you only ever using jog controls to move the laser head?
If you attempt to frame the job after alignment has been done, does the laser head move approximately to where it should be? This is made much easier with a red laser dot where you should be able to precisely determine position.
I wouldn’t expect laser alignment to play a major factor in the issues you’re seeing.
Are you jogging the laser to position it at the targets printed on the paper?
If you’re moving the laser to where the second target should be (based on the ideal coordinates), rather than where it actually is on the paper, then there’s no correction being applied and the offsets you see will occur.
A few other things stand out …
The “crosshairs” in the picture look elaborate. Is it possible they’re not a simple path, so that when you select them, the LightBurn selection is not centered on the center point of the crosshair?
It’s two lines and a circle, grouped so a single click selects the whole thing and it’s obvious the center marker of the selection lies at the right spot.
I’ve found millimeter-scale discrepancies between the digital image and the printed-on-paper image due to nonlinearities / inaccuracies in the printing process. Given the size of those tags, perhaps the laser is putting the cuts in the right place, but the printing is incorrect.
If that’s the case, then the linear translate-and-rotate applied by PnC can’t correct for nonlinear distortions in the printed positions.
Yes, as far as I can tell. When I cut a depth gauge all of the height measurements were within 1/1000 of a millimeter
It SHOULD be but I suppose I don’t know for 100% certainty. It is what we use in our sign shop and I’ve never noticed anything that would say otherwise.
Now that you mention it…I might not be? Seems like an easy one to try next time to make sure and confirm. If I understand what you’re asking correctly, I need to home the laser, start the wizard and then begin to jog my laser into position?
I’ve not actually framed after aligning a print and cut and will try that next time as well
My crosshairs are simply two identical rectangles that I united in illustrator. If you think using a simpler cross hair could solve my problem I’ll absolutely give it a shot!
In regards to the size discrepancy, it certainly could be the problem, but from my experience our printers at the shop are very accurate, but it’s absolutely possible some setting got changed or a scale applied without me realizing. Like I said in my original post, the only successful one I have done is from my home printer and even tho I had selected “do not scale” on the print, I still had to select “scaled” when sending it to print and cut.
It seems one of my next steps should draw a few specific size shapes and print them and confirm my printer isn’t scaling them and if it is, why it is, and to change my crosshairs and see what happens.
Is there a format that would be more suitable to go from illustrator to lightburn that have a higher likelyhood of not having issues like this or is SVG still the best format?
To be clear, I was referring to XY dimensions. Not sure if you were excluding that.
This is relevant for 2 things. 1. If the printer doesn’t print to dimension then you would need to use the Scaled option. If one one of the two axes is off, that would cause other issues that aren’t directly addressed in Print and Cut.
The part I was focusing on is to understand if you’re ever manually moving the laser heat at any point after homing. This would cause a situation where the controller is unaware of the manual movement.
Make sure you review this item from @ednisley. For the second target, are you explicitly aligning and verifying the laser is centered on the second target? Meaning you’re not relying on the jogging based on measured dimensions.
After mentioning homing my laser I think that may be the issue. I think I’ve been jogging to my first position before starting the wizard. Couldn’t say why I chose to do this, but I think that’s what I’ve been doing, and I’m guessing the one time I got into work correctly, was the one time I homed the laser and started the wizard and then jogged to position one.
I’ll also be adjusting my cross hairs as it seems I may have had not centered objects when I joined them together.
For sure if the geometric center of the machine does not correlate to the intersection of the lines then that would throw things off.
As for homing… as long as all motion is tracked after homing you should be fine. You can have jogged to the position of the target prior to starting the wizard. However, you shouldn’t home after positioning the target.
That is the correct sequence, because homing is how the controller establishes the relation between LightBurn’s workspace coordinates and the physical coordinates on the platform.
I’m somewhat surprised the K40 doesn’t automatically home when you turn it on. If it does, then that should be good for the rest of the day.
That’s fine, because the first step of the wizard tells you to jog the head to the target before reading out the coordinate: if it’s already there, you’ve done a jog of zero distance and the coordinate is just fine.
What will screw things up is shoving the head around by hand, which you should never do.
the k40 does home upon turning on. I did two tests tonight, one of which I tried from an illustrator file directly and it was off by nearly half an inch. I then imported an SVG, re homed my laser, started print and cut and moved to my first position with updated crosshairs. Set my point, and jogged to my second position and set it. I then chose scaled, as I had printed it on my home computer and knew from past ones it scaled ever so slightly. I had printed this one with the cut outlines as well to see how acurate it was and for the most part it was dead on. There were one or two that were fractions of mm off on the far right side but other than that it seemed great!
Ill still want to preform a few more tests with prints from our shop printers, as that is what ill be wanting to use for the final product.
one other thing I noticed, that I dont think is a lightburn issue is that when I jog from “home” by anywhere between 1-5ish mm, my laser doesnt jog at all. I seem to have to go about 10 mm which I know is too far past the point and then reduce my jog distance and back track. is that a common issue with lasers or more likely a k40 issue on account of it not being a top of the line laser?
This is a major problem and unrelated to K40 being lower end. You should have no unaccounted controller function. Meaning all requests to move should result in a move… and any move should also be accounted for in the controller.
I would think this would be a mechanical issue but for something this dramatic I would expect this to manifest in other ways.
Does this occur only on a single axis or does for both?
