Do a bit of investigating here. Chuck up your arbor and check if it is
running true without the chuck on it. if not then note the high spot.
Grab the reamer blank with the chuck on one end and the mill on t he other.
Check the run out on the taper in the chuck, note the high side. Assemble
so that high sides cancel. You may find that your chuck is truly wonkey.
Have you had the chuck apart and cleaned and inspected? I went through a
similar situation with a 14n and had the arbor and chuck together and apart
a few times until I lucked on the orientation that worked. What I suggested
above is a bit more scientific.
lg
no neat sig line

"JK" wrote in message
...


When I first started fooling around with metal working 9 years ago, I
bought a Jacobs 14N chuck and stuck it on an Enco 5/8 ths straight
shank to 3JT arbor. It has ALWAYS wobbled. I figured that it was the
cheap shank and recently removed to replace it with a genuine Jacobs
shank since my machining skills have progressed a little bit beyond
the "mark with chalk, cut with axe stage". Appropriate chuck wedges
wouldn't work but the Enco shank was soft so I threaded it and use a
chunk of ¾ inch dia tubing and a 5/8 ths nut to pull the Enco straight
shank off with minor effort. Cleaned up the chuck and brand new
Jacobs 5/8 ths straight shank to 3JT arbor and gently pressed into
place. A reamer blank chucked in the mill has zero run out. Same
reamer blank chucked in the newly shanked 14N drill, 25 thou runout.
Damn. I must have mistreated the chuck badly over the past 9 years.