[Jewelry making - Article 00410] - Re: [Orchid] Drill press - drills don't clamp in exactly straight

[Marty]

========[ Invite a Friend - http://www.ganoksin.com/invite.htm  ]========

    50 years experience with drill presses and the like at yr service 

    First thing - I recommend strongly against keyless chucks. Unless
    you are willing to consistently exert extreme two-handed torque to
    the chuck and locking collar, they are unreliable. Drills are likely
    to slip and come loose unpredictably either in forward or especially
    in reverse mode. Of course, you can use pliers and vise grips and
    then you'll have to look for those instead of for the chuck key. I
    have two newish keyless drill chucks I bought to eliminate the
    lost-key problem. They ain't worth the trouble. Much easier in the
    long run to invest a little time in fixing the key so it cannot get
    lost. I usually use a length of brass plumber's chain to keep the
    key with the drill press. It looks spiffy and professionally
    elegant. It is worth the trouble because you can really lock a bit
    in the chuck with a key and trust it will stay put. I can't wait to
    wear out (or throw out) the keyless wonders and go back to the real
    thing. 

    Second - if your drills are truly not turning on center and you are
    sure that you are not putting them in the chuck wrong, (like getting
    them caught between 2 jaws before they are centered and gripped by
    all three jaws), then there is something wrong with the chuck or
    spindle of your drill press (take it back where it came from) or
    your drills are bent (unlikely) 

    Or, if your problem is the drills don't start drilling but instead
    walk all over the surface, leaving tracks behind them, perhaps you
    don't know about using a center punch to mark the spot where you
    want the center of the hole to be. Cheap tool - put the point on the
    spot - tap it with a hammer to make a small dent - then drill.. 

    Third - Different materials have different drilling and machining
    characteristics - too many variations to list here. In general, the
    speed of a cutting tool is described in terms of the speed at which
    the cutting edge encounters the material (officially known as
    "surface speed") So, in the same material, a larger diameter bit
    should revolve at fewer RPM's than a small diameter bit. So it is
    not the RPM's but the surface speed you want to be aware of. It is
    vanishing rare that you need to do this precisely or else you'd have
    to have an infinitely variable speed drill press. But that's the
    general rule. Get a machinist's handbook and it will show you best
    surface speeds for various materials and maybe even will have a
    table of how to approximate the desired surface speed for various
    diameter bits. In general you will be able to see which materials
    can be cut better at higher or lower surface speeds. You will learn
    how to tell if your drill bits are sharp and cutting correctly by
    the nature of the shavings that come out of the hole. 

    Fourth - Different materials require different lubrication while
    cutting, or none at all. This is not intuitive or common sense.
    Lubrication is to keep tools cool and prevent loss of their temper -
    also helps chips clear out of the hole. Some materials will sound
    terrible while being drilled no matter what you do. Brass, for
    example, squeals and screams famously but that is just how it is.
    You can't fix it. But you should know about that so you don't think
    something is going wrong. Some materials benefit from grinding drill
    bits in non-standard ways, changing rake or point angles etc 

    Good luck. Do a little machine tool research. Nobody can give you
    the whole story on email. 

Marty Hykin in Victoria BC where I won't mention the weather

 
____________________________________________________________________
T h e   O r c h i d   L i s t
Open Electronic Forum for Jewelry Manufacturing Methods and Procedures
____________________________________________________________________
Orchid FAQ:
~ http://www.ganoksin.com/orchid/faq.htm
Orchid Archives:
~ http://www.ganoksin.com/orchid/archive
Orchid Galleries:
~ http://www.ganoksin.com/orchid/gallery.htm
Invite a Friend:
~ http://www.ganoksin.com/invite.htm
____________________________________________________________________
Tips From The Jeweler's Bench - Article Archive
~ http://www.ganoksin.com/borisat/tip_sear.htm
The Jeweler's Selected Bibliography List
~ http://www.ganoksin.com/jewelry-books
Buy Orchid Jewelry:
~ http://www.ganoksin.com/shop
____________________________________________________________________
-Unsubscribe:
-Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank
____________________________________________________________________