Rotary won't do a 360

I have a Red White 40 watt K40 with a cohesion 3d smoothie control board and a Randy Smith HM rotary. My setup is:
. Roller
. A axis
360 Degree Rotation < Greyed out
2.13" Diameter Roller Diameter
3.1831" Object Diameter
10" circumference

delta_steps_per_mm 17.77 # may be steps per degree for example
delta_step_pin 2.3!o # Pin for delta stepper step signal
delta_dir_pin 0.22!o # Pin for delta stepper direction
delta_en_pin 0.21!o # Pin for delta enable
delta_current 1.5 # Z stepper motor current
#delta_max_rate 3000.0 # mm/min
#delta_acceleration 500.0 # mm/sec2
delta_max_rate 800.0 # mm/min
delta_acceleration 100.0 # mm/sec2

WHEN I Issue a command from the console: G0 A360 on a glass jar marked with the begin point, the jar spins about 3/4 the way around about 270 degrees. When I Issue a G0 A0 it spins back to the begin point.

So, I’m not getting a full 360 degree rotation.
What have I got that is wrong?

I don’t know the correct measurement values for the HM rotary or your specific object. Assuming you have those correct, the only other thing to change would be the delta_steps_per_mm on the board. Try 23.7 steps / mm (that’s 17.77 x 360 / 270).

I have a question that relates to the rotary Steps per mm or degree in the delta settings in config.txt. You said that the value should be either 8.88 or 17.777 using the larger set of wheels on the rotary. I physically checked the wheel movement and it surely does turn a full 360 degrees when issued a G0 A360 command. The circumference changes every time I put something different into the rotary. I set the Circumference to the circumference of the piece that I put on the rotary. For this instance, I am using a peanut butter jar which has a circumference of 9.75 inches. When issued the G0A360 command, it turns about 270 degrees. I talked to the people at LightBurn and they said to change the delta setting from 17.77 to 23.7 by proportioning the rotation (17.77 * 360 / 270). I did this and it made no difference in the rotation. Got any ideas?

Any chance the inch circumference I entered is being mis-handled by LightBurn as a metric instead of inches?

No, that’s been fixed, and if it was an inch/mm difference it would be off by a factor of 25 times, not 25%.

If you changed the steps per degree value and it didn’t change how far the rotary moved when you told it to go 360 degrees then you may not have changed it, or written it to the card.

Ok did the test again and yes the peanut butter jar turned a complete 360 degrees. Success I thought.

So… I put in a tumbler with a larger diameter/circumference. The results was that it did not turn a full 360 degrees.

Does this mean that I must change the delta steps per mm every time I change a tumbler if the diameter/circumference changes? Shouldn’t the softwear be able to deal with this delima?

Maybe a stupid question, but what is the bed size of your machine? I think the bed size for many K40 machines is 8x12, so if your circumference is larger than your machine would allow if it were flat work, it won’t give you a full travel because it is limited to what your machine is capable of. Also are you beginning at 0 degees before you ask it to travel 360 degrees? If I’m way off with my thoughts, just ignore the post cause I’m just trying to help.

I have the correct focal length between the top of my target tumbler and the lens on the laser. The bottom of my K40 was removed and the k40 raised off the table it sets on. Thank you for trying to help.

What is the diameter of the tumbler?

Issuing the command G0 A360 moves the rollers 360 degrees, not the item, unless you have a chuck rotary (but you don’t).

Once you get the diameter values correct to turn the rollers, then you only care about object circumference after that, and only if you’re trying to make a seamless wrap. (And if you set the diameter of the object, LightBurn will tell you the circumference)

If you make a tall rectangle, where the height is the same as the circumference of your object, and run that rectangle, the top and bottom of the rectangle should land on exactly the same place. LightBurn figures out the correct angular amount to move based on the height you entered and the roller diameter.

3.10 " diameter tumbler

What I am referring to has nothing to do with the focal point or the Z axis in any manner. You say the diameter of the tumbler is 3.10". If that measurement is across the circumference and your machine is only capable of doing 8", you can never reach 360 degrees because your machine is not big enough unless maybe you manipulate your parameter settings so that your machine thinks it can do more than 8". When you take a 3" circle and measure it around the outside you end up with 9.5", 1.5" more than 8". In other words IF your machine has an 8x12 work space and you install a flat piece of wood that measures 9.5x12 it is still only going to engrave and area of 8x12. Hope this makes since but without the knowledge of your bed size all one can do is guess.

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That’s a great point, but I think in this case it’s just a misunderstanding about how it should work.

  • A rotary axis on a GCode machine doesn’t have limits in the way that it would on a Ruida where you’re swapping out the Y axis.

  • The user in this case was trying to use a 360 degree angular move, thinking it should move the object 360 degrees, but it doesn’t work that way - it only spins the roller by that amount.

The software knows only what you told it (for the peanut butter jar). The roller type unit deals with inches of roller to object, Yes, you need to recalculate for each diameter part you are engraving.
A chuck style rotary, once taught what 360 degrees is, will always turn 360 regardless of the diameter object.
Just make a crib sheet with the formula and do a quick calculation for thr new object.

You can change your bed size in the settings to accommodate the size of your tumbler to be able to get your full size design or 360 degrees.

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