JK wrote:


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.

Got a new Jacobs 14N chuck with new Jacobs 5/8ths SS cleaned
appropriately gently pressed into chuck and tested with reamer blank
today. 12 thou run out on new chuck and shank. Zero run out when
reamer blank chucked into mill collet. WTH???

As an aside, a new Rhom chuck pressed onto cheap HF drill press has
zero run out.

Any insight on either what I'm doing wrong or how to fix it would be
appreciated.

Regards,
Jim


There is more than a chuck different here.

1. different insertion
2. different arbor or at the very least different arbor insertion
at the very least.
might try rotating the arbor to a different engagement angle...

Martin

--
Martin Eastburn
@ home at Lion's Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

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