Rotary slanting on photo images

[CX3 (Connor Hunkel)]

I’m super confused by this forums platform and how to put things in the proper categories so please bear with me, where ever this ends up.

I’m having some software issues with engraving photos using a rotary roller. My pulses per rotation is accurate, my belts are tensioned properly and in good shape, the roller is square with the gantry, and the machine itself is functioning as should. I’m using an OMTech 80w CO2 Ruida controller.

When I engrave a “fill pattern” such as a business logo image trace, I have no issues and the machine functions properly. However, when I engrave an image in newsprint or any of lightburns other dithering options the engraving slants. Almost as if the machine is losing steps while it rosters back and forth. I’m wondering if it’s a software issue either in my machine or with LightBurn because not all photos do it but the ones that do always do it. I also ran a test to see what would happen if I shut the rotary off on LightBurn (still leaving the rotary plugged in knowing the image would not give desired results) and the result I got was no slanting. Strange, right?

I did notice that sometimes the machine would roster back and forth as usual but let’s say my engraving is 3” wide… it would roster left 3” then right 3” then left 3” and then would only roster right 2.75” then would return left and then come back right 3” it seemed at this point the slanting would begin.

Any ideas helps, thanks guys!

I’ll try to attach some photos.

[ednisley]

@CX3

Almost as if the machine is losing steps while it rosters back and forth

Or, more likely, the cup is sliding on the rollers because they’re turning too fast.

Reducing the rotary speed by a factor of four will likely solve the problem. If so, increasing the speed in smaller steps until the slipping resumes will show how fast is too fast.

Reducing the acceleration may also help, but … speed kills.

[CX3 (Connor Hunkel)]

I’ll give it a try but the cup seems to end in the same position on the rollers. Also, wouldn’t I have trouble with engraving fill patterns too? It’s only photos that give me problems. I’ve also made a square that spans the width of the powder coating - 1/4” (1/8” on each end) and ran it at 200mms with a line interval of .08 no trouble.

[ednisley]

@CX3

It’s only photos that give me problems

Vectors, fills, and photos generally have different maximum speeds and definitely different movement patterns, so the forces they apply to the cup through the rollers will be different.

Think of reducing the rotary speed as a diagnostic test, rather than a guaranteed result. If a much lower speed produces a better result, then you have a data point to help figure out what’s going wrong.

You have a scrap cup or two, so the patient need not survive the operation …