Rotary fill skewed, lines OK

[ConsummatePro (Steve Wong)]

Setup: OmTech 55W
Rotary: Mansfield Customs rotary (roller) metal version (https://www.mansfieldcustoms.com/product-page/co2-laser-rotary-attachment)
Rotary Setup:
Roller type rotary, Enabled (in both Rotary Setup window and in Laser window)
2224 steps per rotation, roller diameter 42mm – confirmed to properly rotate object 360 deg.
Speed: for fill and line: 100 mm/sec 10% power. File is Sent to the laser over ethernet and started at the laser, not via USB direct connect.

The filled images are really skewed compared to lines in a fill + line job. I had a similar misalignment issue in NON-rotary mode and fixed it by setting the “PWM Rising Edge Valid” settings in X and Y to “False”.

I figured this must be a variant of that and since the Y axis is replaced by a rotary with a different make of stepper motor, I figured just switching the PWM Y to True (and leaving X as before at False) would fix it but nope.

I’ve attached pictures of all 4 combinations, “PWM Rising Edge Valid” X and Y true/false, true/true, false/true and true/true - none seem to fix the problem and I’m not sure what else to try.

A pure line cut seems pretty good with a bit of distortion on the letter “S”.

Is this an acceleration issue? Y acceleration is the same as default (2,000 mm/s^2).

[Doug (Doug Fisher)]

Since nobody else has chimed in yet, have you experimented with dropping these two values?

FWIW, mine are both set at 10.

Also, since you might be dealing with multiple issues causing the problem, are you sure your metal tumbler is not slipping when held by the rotary?

[jkwilborn (Jack Wilborn)]

I have never been able to get a good vector cut on a mug or cup.

I see the same thing. Change them to scan and slow down the items indicated by @Doug and also the ‘start speed’ of that axes. All of mine are in the single digits.

I have a PiBurn…

PiBurn Rotary Attachment

Think about what you are asking the machine to do. During the ‘line + fill’ operation it will cut the ‘line’ out as a vector. It is likely impossible for it to go 100mm/s and turn, accelerate back to 100mm/s in those very short outlines. This is when the Min/Max power settings need to have attention. I really doubt that that cup can ‘hang on’ with it changing direction so quickly.

Don’t have the machine turned on, but I think there is also some other Y changes down in the Y axis group in the vendor settings…

Here is a cup I tried for a friend. It’s a vector with everything slowed way down…

You can see it has slipped. There is a boat load of little ‘leaves’ and it was twisting and turning…

Good luck

:smiley_cat

[ConsummatePro (Steve Wong)]

Thanks to both @Doug and @jkwilborn - I appreciate your tips - I’ll try them. Thanks to your suggestions and as well on the FB OmTech group I also learned you can only really do fills on rotaries reliably. Also, once I learned it really shouldn’t be rolling back & forth, and each step of the rotation should only be done once, I had a successful burn!!

For future reference, I learned that on a rotary, after configuring the rotary steps properly:

1. Use only Fill mode
2. Set scan angle to “0” - this ensures each step of the rotation is burned along the X (long) axis and only needs to increment once, in the same direction - if scan angle is “90” the object rolls back and forth for every scan line and this can cause slippage.
3. Choose “Fill all shapes at once”

I’ll try some of the start speed suggestions next to see if I can get even better results, but I’m happy now!

[jkwilborn (Jack Wilborn)]

Glad to assist.

Have fun…