[Jewelry making - Article 00236] - Re: [Orchid] Replace the chuck on a low end bench drill press?

[Don Rogers]

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Hello Christine

    As an old Machine Repairman, Machinist, as well as a life long tool
    freak (ok jeweler, and lapidary and , for a living once, main frame
    computer repairman, how is that for a ten word resume), the chuck
    replacement may not give you what you want for fine drills. 

    First, find out if the quill, the mechanics which carry the chuck,
    warrant any further improvements. This is not a question of the
    brand of drill press, but rather the drill press you have.  The
    tolerances of the off shore produced drill presses are not very
    tight.  That means the you may have a very good piece of machinery,
    or a dud. 

    The first test is, with the machine turned off, grab the chuck and
    push, pull, move it side to side.  Do you feel a lot of movement, or
    just a slight amount of shift, or none.  It things seem quite tight
    here, you have a candidate for improvement.  If you end up with a
    lot of movement, then there is not much you can do to improve your
    machine.  I have a bench drill press that has enough wobble in the
    quill to cause it to drill oversize holes.  This isn't  to bad if
    you are drilling 1/2"  or larger holes, but for the jewelers, it
    would never work, regardless of the chuck you would install. 

    There are a number of different mountings for chucks.   Some mount
    with a Morse taper "MT", others with a Jocobs Taper "JT",   These
    will have a number before the JT or MT to designate the size of the
    taper.  IE,  a 1JT is a small version of the JT than say a 3JT. The
    taper is the same angle, but the number designates the big end, and
    small end sizes.  A 3MT shaft will not fit into a 4MT socket. 

    Some of the drill chucks mount on a threaded shaft, usually a 3/8-24
    thread, or a 1/2-20 thread, but some of the smaller ones will use a
    5/16-16 thread.  These threaded chucks sometimes have a lock screw
    which is a left handed screw that you can access through the opening
    of the chuck.  This prevents the chuck from unwinding when turned in
    a reverse direction.  These are usually used on reversible hand
    drills. 

    There are some other low cost chucks that use a different mounting
    arrangement, but these are not desirable. 

    There are also some other taper shaft types the you might encounter. 

    The point here is that you need to find out what chuck mounting you
    have before you can determine what you could replace it with.  Once
    you have found the mounting type for your machine, you then can
    chose between keyed or keyless chucks, and between the capacity of
    the chucks.  The keyless are easier to use, but come with a big
    price tag.  The important thing is to get a chuck with a "0" min
    cap..  You will seldom if ever need a high capacity of over 1/4",
    unless you are doing other work on the side. 

    I have two drill presses, a 1/2 tall bench unit which wobbles
    something awful, that I use for large end work.  I have a 3/8" small
    bench unit which is really nice that I use for the more precession
    work.  In addition, I have a couple of small drill presses, for
    Lapidary use, in addition to my Fordom drill.  All get used at
    times.  None of them have the same chuck mounting. 

    You might also look at www.use-enco.com for chucks and such.  They
    have some lower priced machine tools and supplies. 

    Don 
 

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