This does not look right to me. Is there a way to adjust the alignment of the chucks? The piece is chucked tightly into place so there is no play. And the teeth are installed correctly. If you look closely you will see the entire head wobbles, not just the glass piece.
I focused my eyes on the shaft and backing plate. The jaws end is far enough away to magnify the effect, but there’s a significant deviation at the backing plate as well. Consider to remove the chuck by pulling the bolts at the backing plate and examining the rotation.
I think you’ll find that the plate is also out of true. Examine then the shaft as it exits the bearing. If it’s not out of true at the bearing, especially if it’s not out of true at the bearing on the outside, it’s pointing to a bent shaft.
I can see that this could happen if the mechanism was dropped on the chuck.
I believe you are correct. Thanks. I am returning this item.
I got taken on one of these too. If you don’t use the tailstock, whatever is in the chuck wobbles like a, like a, well - like a thing that wobbles a lot… It’s both the bearing and the shaft, tolerances are way out and they used cylindrical roller bearings instead of tapered so I think there’s no way to true the centerline of chuck and workpiece without the assistance of the tail piece center. I took mine apart and have been mulling over re-engineering it to help the chuck run true.
Well it is nice to know that I am not the only one. But I have learned something interesting. I tried to do an etch with the wobbly chuck and it worked just fine. I really could not understand this until I was going to sleep last night. Then it came to me. The laser treats light much the same way a camera does. The focal distance is not the only issue. There is also focal depth - that is, the space where focus is achieved. It is not a flat plane. It has depth. In the case of the laser, this focal depth could be up to 1/2”!
You can sort of demonstrate this to yourself. Hold your hand palm down in front of you and move it up and down about 1/2”. From the side, this is a pronounced movement. Now face your palm toward your face and move the palm 1/2” toward and away from your face. See what I mean? The movement is much less apparent. I believe the laser “sees” in a similar way.
So while I am still trying to get these Chinese vendors to make good o delivering a faulty rotary (good luck) I am delighted that I can actually use the thing. It works much better than the roller rotary I was using before.