Run your indicator as close to the jaws as possible and then out maybe 2". Try using a different chuck key hole to see if things change. Some chucks have the chuck key position marked that was used when tested.
I will look at them to see if they are marked.
Those arrows are simply the direction you turn the chuck key to tighten or loosen. The tick mark aligns to show when the chuck comes free.
This could very well be. I am sure I have the manual somewhere around here....I would like to know for sure.
Three jaw chucks can be all over the place as you are finding out. They vary because of the scroll that works the jaws can have variations that will transfer to the jaws. Was the runout consistent with the different diameters? If so, I have seen where the jaws were trued up with a grinder attachment on the lathe.
When I first got into machining it was all three jaw because of the convenience. Now, the four jaw is what mostly lives on the spindles of my two larger lathes. Really doesn’t take that long to dial in a piece and you have the advantage of more gripping power.
I would venture to say this ......."Both seemed to be pretty consistent in their runout errors"
The only time I had a Yuge swing was when I tested a "skinny" piece of mystery metal, and I think the piece had a "bend" in it. Both chucks saw "larger than normal" swings.
So I chalked that up to being an "outlier".....
The one "solid thing" I learned was that this " M_______F______g spring" had to go.
That damn spring would shoot that key about 5 feet. I had to pick that thing up off the floor so many times, I was starting to see a "6 pack" develop in my ab's........
Much better now........
I certainly don't want the Mrs. getting used to that "6pack" look. Too hard to maintain. This is a modeling gig I could apply for though.
