Image position off center

Having an issue with my workflow. I set up a template to engrave metal lids. The template is perfectly centered.

However, when I engrave a lid, the logo is off center. It is perfectly engraved, but off center. I was able to tinker with it a bit, but I ruined 3 lids in the process.

Any thoughts?

Using an xTool D1 Pro and MacOS


Photographs will be much more informative than a diagram, because we need to know the direction & orientation of the results to help find the cause.

Do this debugging on cardboard …

Generally this sort of problem comes from mechanical backlash, so give the machine a detailed checkup. Although this is for Sculpfun machines, you’ll recognize many of the parts and the sequence of checks will help you find the problem:

Run this pattern at a high speed to find problems, then again after fixing them to verify it’s OK:

BacklashTest.lbrn2 (197.6 KB)

Ed,
Thanks for the Wiki. I did most of this successfully last night (in some fashion).

I will get some pictures when I get home tonight. The weird thing is the engraving is perfect (no warping, etc.). It just isn’t in the correct spot based on the absolute coordinates. However, when I ran it a second time last night, it worked perfectly. I just cant seem to get it right on the first try.

That tells you there’s a mechanical problem in need of fixing, because the machine is not putting the laser head at the position commanded by the controller.

Loosen all the setscrews you find, starting at the motor pulley, and retighten them while wiggling the shaft to get the screw tightened on the flat. They can appear tight, because they’re snugged down off-center on the flat, just waiting for enough motion to shake them loose and move to the other side.

Understood.

I am new this, so I will make (what is likely) a noob statement. If a set screw was loose, I would have thought the image would have been warped or botched. This was definitely not the case. The lines were perfect.

Nope, it’s only loose under duress. Until enough stress arrives to knock that screw loose from where it’s stuck, the whole machine works fine.

That’s only slightly made up; there are other things that can (and do!) go wrong to produce those symptoms. However, if you spend enough time around here, you’ll find plenty of folks who were absolutely certain their machine couldn’t have a mechanical problem, until we exhausted all other possibilities and they found, yeah, a loose screw.

Or a stripped screw socket. Or a shredded belt. Or a maladjusted eccentric wheel. Or a completely missing screw.

And so forth and so on …

Well alright! Guess I have some screws to check.




Here is what I am talking about. I tightened all the bolts and belts. Still off center. Is is better though.

How are you locating the cap? I would run in absolute coord, home properly, and burn a pocket in a waste board jig to hold the cap. Framing something like that cap will be tough.

Beautiful work, btw.

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When the machine can run that backlash test without any problems, “centering” comes down to aligning LightBurn’s coordinates with the platform and the material with the platform.

The Atomstack A5 Pro doesn’t seem to have home switches, bu they may be doing something more clever. The simple test:

  • With the laser power off move the laser head to the middle of the platform
  • Turn the power on
  • Does the laser head move to one corner of the platform?

If so, then the machine has home switches, then the controller can automatically align LightBurn’s coordinates with the platform.

If not, then you must manually home the machine every time you turn it on, so the controller knows where it is:

Once you get that settled, verify the accuracy of the homing process by repeatedly burning that backlash test on a single sheet of cardboard.

  • Set the machine to Absolute Coordinates
  • Put that pattern in the middle of the workspace.
  • Set the layer speed & power to lightly mark cardboard

Then do this five times:

  • Turn the machine off
  • Move the head a few inches by hand in any direction
  • Turn the machine on
  • Connect to LightBurn
  • Run the backlash test without moving anything

If the five patterns overlap exactly and they’re all perfect, then we know the hardware will let you hit a target with good repeatability. Show pix of the results!

Then we can work on aiming & accuracy …

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