From: "McHatten, Shawn" 
To: "'Dwight K. Elvey'" , atm{at}shore.net
Reply-To: "McHatten, Shawn" 


Hey Dwight
        Hmmm? Interesting. I was wondering about that when you said it before.
I was always taught to move up through the sizes as Bill mentioned below.
Especially for larger sizes in metal (above 3/8in). I kinda remember
something about it was to save the larger bits from wearing as fast but
can't honestly tell you why or where I heard it.
        However I have definitely noticed the vibration and 3 or 5 sided hole
that you talk about. I've had to drill a number of 1/2in holes in 1/4in
truck frame using a portable hand drill. Started with 1/8 moved to 3/8 and
then 1/2. The vibration is noticeable on the 1/2in.
        Have you ever heard of "moving through the bit sizes"
before or do you
know where it started? Anyone else heard of this? And is the pilot hole
just for guidance. It definitely seems to make the larger holes drill
faster with a guide hole (1/8in). Maybe the wedge on the larger bits are
just too big to start the hole properly?

Thanks
Shawn

-----Original Message-----
From: Dwight K. Elvey [mailto:dwightk.elvey{at}amd.com]
Sent: Thursday, April 17, 2003 1:31 PM To: atm{at}shore.net
Subject: Re: ATM drilling aluminum


>From: "William Thornley" 
>
>Hi Eric,
>
>You'll find aluminium soft enough to mark your drilling point with the push
>of a sharp scriber(easier to line up your markings) . Centre punch this with
>a centre punch and hammer. That will get your first drill right where you
>want it. Hammer across the drilling point (hold the centre punch at an
>angle) if you missed slightly, to bring the drilling point back to your mark
>and repunch.
>
>Next, start with a small drill 2-3mm (1/16"-1/8"). Increase
in increments of
>3 or 4 drill sizes between drilling until you reach your wanted size. That
>way you will ensure your final hole is dead centre.

Hi
 As I stated in my previous post it is best to not step the
drill sizes. If the hole is a large percentage of the drill size you intend
to end up with, the dill will virbrate. This often makes a hole with three
or 5 lobes as the drill steps around the hole. It is better to make only a
small pilot hole about the size of the wedge part of the final drill size
you intend to have.
Dwight

>
>Hope this helps
>
>Regards,
>
>Bill Thornley
>Sydney, Aus.
>
>>Eric wrote:
>>Thanks, everyone, for your input on this.  Think I'll get a drill
>press :)
>>
>>Regards,
>>Eric
>>
>>
>
>
>_________________________________________________________________
>MSN Instant Messenger now available on Australian mobile phones. Go to
>http://ninemsn.com.au/mobilecentral/hotmail_messenger.asp
>
>
>

--- BBBS/NT v4.00 MP