Re: Looking for a better way to make carbon torque bars...

From: Tapio Linkosalo <tapio.linkosalo_at_iki.fi>
Date: Thu, 28 Feb 2013 13:15:29 +0200

On Wed, Feb 27, 2013 at 9:22 PM, Jake Palmer <82.jake_at_gmail.com> wrote:

> **
>
>
> When I drill the holes I put the bit in a pin vise. I only expose about
> 1/16" of the bit beyond the tip of the pin vise. I then mount the pin vise
> in my drill press. In my experience this prevents the bit from wandering.
> It will either drill the hole where you want it or it will break. I've
> tried using bits with 1/8" shanks, but as you said they tend to wander and
> they're much easier to break.
>
>

I use a 0.3mm drill to make a row of holes that I then open up for a slot,
to the bottom of a 0.3mm ID 0.7mm OD pultruded carbon tube used as the prop
hub centre piece (the prop hangers go into the slots). I used to have
similar problems using bits with a thicker (3mm) shaft on a drill press,
the tip just wondered away from the tube centreline. I even broke a few
drills. But then it turned out that these broken drill bits work better!
For drilling the carbon tube it does not really matter that much, what
shape the drill bit is, the broken tip has some sharp edges that cut
through the carbon tube. And with a bit that is broken just a millimeter or
so off the thicker shaft, the bit tip is stiff enough not to wander aside.
I use ordinary tabletop drill press for drilling, but a "adjustment table"
from a small milling machine helps to get the holes in just the right
position and in a nice row along the tube.
Received on Thu Feb 28 2013 - 03:15:35 CET