Hello,
I hope i will get help about my problem which im having almost a year… so when engraving - i get missing lines of fill. No matter how power or speed i do. If you would closely look to engravings you can see that some lines are not enough power to engrave, but they are. So engraving is inconsistent. I’m tried this on leather, stamp rubber and plywood as i do these the most. Everywhere sometimes happens not power enough engraved lines. (And its not the grain of plywood).
And second problem is that when starting to engrave - few lines are engraved on the same spot at the start. I can fix it by draving a smal object like circle before the fill figure to engrave on 0% power. Then the engrave lines not overlap at the beggining. But the most problem is inconsistent engraving. Attached images. Seems i have cheecked everything from hardware like belt tension, beam allignment, all connections etc… but cant trace the problem for a long time. Please help
Attached lightburn interval test on plywood and rubber.
This is certainly Mechanical backlash. This can be confirmed by engraving a circle and seeing the gap. It’s most likely something is loose. Please test the motor belt drive sprocket with an Allen Key or hex key to confirm that the screws are tight.
With the amount of observed flattening in the Leading Zero in your engraving (after the traverse), this may be the cause of the inconsistent engraving. With the laser un-powered, physically move the engrave head 1mm left right and attempt to locate the cause of the looseness.
One of the idlers could have come loose and caused the drive belt tension to be lost.
The other thing that will behave like a backlash behavior is if the rail where the engrave head travels on the Gantry is sticking. I was told to keep the gantry clean and use sewing machine oil to ensure that the machine moves freely.
the screws are all tight, when moving head to X or Y a little bit - seems nothing loose. could it be those problems of the worn belts? also i have doubts on machine tension pulley design… There is only one screw to tighten pulleys of the belts and you can move a little pulleys even when the belts are tight. But when machine is working I cant see and feel with my fingers that they moves or wobble. So only i can see it can be tension design of machine or bad belt…
There are no “missing lines” in that pattern, but many of the lines are shifted slightly. As a result, the gap on one side is smaller and the gap on the other side is larger.
This is a mechanical problem, not a configuration or software problem.
Any looseness at all will cause the problems you see. All of the hardware between the motors and the laser head must be absolutely rigid.
It seems as though the laser was never properly adjusted, so it’s long past time for a complete mechanical examination and tuneup.
Because the lines are displaced throughout a pattern that should have the Y axis moving in a consistent direction, something is very loose. Start by removing the belts, figuring out why those pulleys are loose, making them secure, and then re-testing with the same pattern. If that doesn’t solve the problem, then you must continue looking for any mechanical looseness.
There are no shortcuts, but being methodical and fixing every problem you find will make the laser run better than it ever has.
today i fixed tension pulleys with additional screws drilled. Now they are rigid, but the problem is still there - not even distance between lines. Belt tension (loose or tight) not helps.So before changing to new Y belts - maybe I can set Y acceleration or shift speed between engrave lines to be slower? Wonder about results i would get
Did the machine work correctly at some point in the past? Have there been any hardware changes since purchasing the machine? Have you changed any configuration on the controller since purchasing the machine?
If all hardware is the same then the issue is most likely mechanical as @ednisley advises.
However, if the hardware or configuration has changed or this is a custom build and has never worked correctly then there’s a non-zero chance that you may be losing steps at the motor.
Do you hear a buzzing or whining sound particularly during Y-axis movement?
That seems unlikely, as the lines on either side of the displaced one have the correct positions. Lost steps would shift all of following lines after each glitch.
We’re still in loose mechanical bits territory.
With the pulleys snugged down, suspicion falls on the setscrews in those Y axis couplers buried deep inside the cabinet.
Woudln’t lost steps on Y-axis alone create the same apparent artifact?
This seems less likely to me only because I wouldn’t expect to see this multiple times in the same scan. Backlash would only be visible potentially in the first line. I’d expect subsequent lines to not show the backlash since the Y-axis is moving in the same direction.
Unless the shaft is nearly freely spinning in the gear or coupling.
I have bough a new machine. Maybe 5 years back. At first there was no problems only recent years and it went worse till this day. I havent done any hardware changes except new tube, fixing blown power supply mainboard power transistor, HV flyback transformer, changed few switches, light bulb… Then only daily maintenance etc…
when engraves - Y only ticking, like a clock, it goes ticking in small steps.
In that case I suspect @ednisley’s intuition is correct here about it being mechanical. And if my intuition is correct you’ll be looking for something that’s able to continuously turn, meaning it’s not strictly a backlash issue. It’s likely that a grub screw or something is providing some limited friction but that it’s allowing continuous rotation in the same direction when force is applied.
Try twisting every rotational component. Are you able to force slippage?
Perhaps back-and-forth over a limited range, if the setscrew bears on a a flatted section of the shaft.
As the screw works itself loose, it allows the shaft to rotate slightly in either direction until the flat hits the screw again.
These can be extremely hard to find, because the screw feels tight when the shaft is jammed underneath it. If you start by loosening the screw, it will turn easily; a truly tight screw won’t turn without some effort.
When you find an offending screw, tighten it while turning the shaft back and forth, so the screw will settle into the middle of the flat when it’s fully tight.
Then repeat that process for all the other setscrews!
