Hi everyone … question … those of you that use a Chuck Style Rotary, how do you go about finding the Center on your piece … up till now I have been guessing but would like to be more precise if possible.
Looking forward for your ideas.
Take Care
BrianI’ve put a small diameter dowel in the chuck and nudged the device to get it in the ball park, then fired a pulse at each end, followed by additional nudges.
In the past, I created a 3d printed alignment jig, but the plastic deformed over time and has become unreliable.
Once I figure out a new alignment jig, I’ll make it more permanent. Until then, the skinny dowel (or pencil) is my tuning tool.
@Boomer, start with an alignment jig (mentioned by @fred_dot_u). The first step in good centering on the object in the chuck is a well centered rotary. A jig will ensure that every time you place the rotary on your bed, it is in the same spot consistently. This works well with having a saved position in the move panel:
Before going into more detail, am I on track with what you’re asking, or were you asking about suggestions on methods to chuck the object centered in a manner that it rotates without wobble?
As noted by the message posted by Stroonzo, the alignment jig references the gantry rather than the bed, as it provides a consistent distance from the gantry to the rotary, combined with the consistent distance from the gantry to the laser beam.
My jig was as simple as a pair of goal posts which rested against the gantry. The 3D printed part allowed me to adjust the distance to get it tuned in. Considering that the rotary is constructed from massively thick aluminum plates, a better way would use threaded holes, threaded adjusters, lock nuts, etc.
Another aspect of a good jig and my rotary in particular is that the goal posts have to be removable or retractable, as the jig gets uses laying on its side as well as the occasional upright position. A trip to the band saw may remove that requirement in the future.
Hi Fred and Jeff … Thanx for the replies … I guess I should have been a little more specific … I want to center the Head directly in the center of the Chuck Rotary … I make Pens and engrave on them … but I’m using my eyesight to Center … as I get older the eyes aren’t what they use to be 
… just hoping there might be something I can make to help in the process.
Thanx again
Take Care
Brian@Boomer, a chuck rotary is self centering and highly reliable at that. It is one of the advantages to a chuck rotary. There is one very important factor in this however --> proper jaw placement.
Each jaw is marked 1, 2, or 3 and each slot is marked 1, 2, or 3. You must make sure you have the jaws in their designated slot. If the jaws are in the wrong slot (even just one), you will never get proper centering on the chuck.
On my first rotary, I laser engraved the slot numbers on the chuck. 
I need to do that again on my new one too.
I don’t think the jaws need to match the chuck position, they just need to start in the right place and be consecutive. The number on the jaw and being consecutive is what’s critical.
If you look closely at the chuck, you can see the spiral that pulls the jaws in. Pick a slot that just has the beginning of the spiral visible and put in jaw #1, then move just enough to do the same for #2 and #3.
Maybe it is different on some of the chucks because on the two that I have owned, the jaws have to go in their designated slot for proper centering. It was one of those embarrassing realizations the first time after spending maybe two hours trying every way possible to do what you described. I mean, it makes sense… and I thought surely that’s all it would take.
See how my slots are also identified / numbered:
And to add one more detail to the jaw placement:
Slot one I have on the bottom so that once I have the jaws in their designated slots, I gently push up on jaw 1, reverse / loosen / outwardly move the adjustment screw until jaw one jumps in to the track. Then “tighten” / rotate the adjustment screw after jaw 1 slots into the track. Jaw one being slotted in first is also important on the chucks I’ve owned.
And with that, center is bliss:
I’ve seen the numbers on the jaws, I need to see if they are on the chuck, too. Like you, I’ve spent a lot of time trying to figure out why the jaws wouldn’t close properly. Maybe I’ve just lucked out with chuck position.
Hi again and thanx again for the responses … but I guess I’m not explaining properly … I want to be able to center the laser head exactly in the center of the piece on the Chuck Rotary.
Thanx Again
Take Care
BrianDo you mean center (left-to- right) or centered in order to burn at the highest point on the circle cross-section of the part in the chuck?
Some aspects have to be considered as fact as well. The rotary device should be running parallel to the gantry. If not, all suggestions are shot. Placement of the rotary along the gantry left-to-right is typically “unimportant” unless your request refers to centering left-to-right.
Hi Fred … I mean the highest part ( front to back )
Brian
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