From my measurements, it appears the shaft is not perfectly true and creates
runout. The problem occurs when a regular PCB drill bit is used in a rotary
tool. Because the drill bit tip is an inch from the collet, 0.002" of
runout at the collet yields .006" at the drill tip. With a 0.006" diameter
bit and 0.006" of runout, the bit doesn't stand a chance.
I would like to drill holes to bring balls of 0.5mm BGAs to the board
bottom. The hole goes between the balls which is why the holes are small.
Jeff
-----Original Message-----
From:
Homebrew_PCBs@yahoogroups.com [mailto:
Homebrew_PCBs@yahoogroups.com]
On Behalf Of Todd F. Carney / K7TFC
Sent: Tuesday, March 12, 2013 1:38 AM
To:
Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] drill for micro drill bits
Jeff,
One problem I've had in the past is trying to figure out what the source of
the runout is with drills and drill presses. In this case, it could be the
shaft of the motor tool, or its collet, --or-- the drill bit itself. On a
drill press, a dial indicator can be used with a precisely-ground "know
bit" to measure runout. The 'know bit' eliminates any runout of a drill bit
itself. Runout that left is from either the chuck (or collet) or the "quill
shaft." Here's a page with some background:
http://www.precisebits.com/tutorials/spindle_runout.htm
I'm just curious. You'd need a 36 gauge or smaller wire to even go through
a 0.006 hole. What is your application? Are you drilling "pin holes" for
photography or some other optical application?
73,
Todd
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K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
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QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design
On Mon, Mar 11, 2013 at 8:36 PM, Jeff Heiss <jeff.heiss@...> wrote:
> **
>
>
> I am drilling holes with #96 (0.006 inch) drill bits. However, not one
hole
> has been drilled because the bits are so small compared to the runout of
> the
> tool, they break in half when they touch the workpiece before any drilling
> begins. Copper clad is my workpiece.
>
> I tried a Dremel, Dremel flex handpiece, and Marathon 35k RPM micromotor.
> All three have too much runout and the bit breaks in half. Has anyone
> successfully drilled holes this small before? Are there any suggestions
for
> a drill or rotary tool that has low runout?
>
> Jeff
>
> [Non-text portions of this message have been removed]
>
>
>
[Non-text portions of this message have been removed]
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