I true every shaft with a dial indicatorthen you'll know if it's the shaft or the chuck. You'll have to SHIM the shaft one way or the other, to get it perfect...JER
That's true and the best way to do It, dial It in beforehand, and keep It locked down through all of the steps until the tip is on. I have to be honest though in saying that I indicate on just about everything else in a cue, but have been fortunate enough to be able to eyeball ferrules pretty well. I just keep the back chuck locked down, loosen the front chucks and spin the collet to a different position on the shaft, then lock back down and check for runout. I do that until I get the shaft running true, then the rest of the job is a breeze. If the collet was bored out on the same spindle then marking these points to make them easier to return to would save even more time. Most of the time I don't even need to do any file work, although with a very small % it may still require a small amount.
For the poster: You want that shoulder right behind the ferrule running perfectly true if you want to reduce the fore-mentioned issue. Like Chris already said It does not take but the smallest amount of runout to create a lip, and since in many situations the ferrule material sands away slower then the wood does, sanding them flush is not always an option, that's why sometimes the file work has to be done if you can't get them running dead nuts.
One issue with ferrule work is a lot of It is dependent on how the tenon was turned before. There are occasions where You can dial the shoulder in, but that doesn't mean that the tenon will run true to it, unless you turn It down to match, but then You loose diameter. In some situations as with taper downs or just a shaft that has lost diameter over time, It may not necessarily be a bad thing if the ferrule walls are getting too thin anyhow due to a large tenon, but we would prefer not make those changes with all shafts, as to keep them as original as possible. Sometimes It makes the most sense when you consider all of the options though. The other option would be to replace the tenon If you need to keep the diameter, and/or there is too much of a difference in runout between the shoulder and tenon. I have seen some where the shoulder can run dead nuts, but the tenon flops around so badly that even reducing the the size is not an option because you would have to remove too much material making the tenon too small to be within reason.
