Line accuracy with Kentoktool LE400Pro?

Does anyone know how to improve line cutting accuracy on a Kentoktool? I’ve checked my belt and all set screws, and everything seems solid and not slipping, but LightBurn’s accuracy cutting SVG files with it is unusably horrible. Using PNG is much better, but those take forever to cut.

I tried cutting these two files, perfectly aligned on each other:


rosette3-holes

but when it cuts, they don’t line up, and there’s a lot of wobble and overshooting at the corners, like the head’s not completely stopping:

I cut the holes with 5mm/sec at 90% power, and the lines with 5mm/sec at 0.07% power.

I’ve tried slowing it down further, but that doesn’t seem to improve accuracy.

Why is the result so misaligned?

Looks to me like the laser module itself is wobbling around during travel. This is typically from the laser module either not being well secured to the mount or from module assembly not being properly tightened against the gantry itself.

If the assembly can be easily lifted from the gantry then that is typically adjusted by rotating the eccentric nuts that are on the wheel axes. Take away any slack between the wheels and the railing. You want it secure enough where there’s no play but without any binding.

It seems pretty solid. No screws loose are anything. If that was loose, why would it only effect SVG files and not PNG file quality?

Here’s what my laser module setup looks like:

There are four screws attaching it to that L-shaped bracket, and I’ve tightened them as hard as I can.

Is there any flaw in this design that would simply make it inherently too wobbly to cut SVGs?

Did you also review the wheels that connect the assembly to the gantry? Are you able to push the assembly forward and back at all toward and away from the gantry?

Because you are moving rapidly in 2 dimensions vs a repetitive linear scanning operation.

It seems you’re incredulous as to the cause so suggest you take a high-speed video of the laser in motion and look for movement of the laser module in along the Y-axis.

This would be a challenge due to the many small cuts requiring rapid, sudden, and continous changes of direction.

You could also test this by running a fill operation with a large interval size of around 1 or 2 mm. If you run this horizontally you’ll likely see the starts and end of each line with a lift or drop in the burn. You will get a different artifact if you run a vertical burn.

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