Thanks Doug, but the hardening is not at all
the problem here. The tubing can be re-hardened
at any time by heating and cooling at the correct
rate etc.

I'm more interested in finding out if it is better
to drill a lot of small holes, (like a honeycomb)
or a few larger ones, and what will give better
strength for the same final weight of tubing. :o)
-Roman


Douglas Butler wrote:
>
> If the aluminum is tempered the edge of each hole will lose some of its
> tempering when drilled.  That means each hole will have a ring of weak
> soft aluminum around it.  This leans me towards fewer bigger holes.
> Also drill slowly with a sharp drill.
>
> Sherpa Doug
>
> > -----Original Message-----
> > From: Roman Black [mailto:fastvid@EZY.NET.AU]
> > Sent: Monday, October 15, 2001 11:07 AM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: Re: [EE]: Drilling a square tube??
> >
> >
> > Hi, I know this is more of a mech engineering
> > question than an EE one, but here goes. :o)
> >
> > I need to drill a square tube, hardened aluminium,
> > to make it as LIGHT as possible. The square tube
> > is 25mm across each edge, and used on a racing
> > motorcycle for a non-critical purpose, ie it's
> > not part of the drivechain!! It's about 1.2mm
> > thickness wall (25mm x 25mm x 1.2mm) if that
> > helps.
> >
> > From my rather "fuzzy logic" examination of the
> > stucture the square tubing is not stressed under
> > flexion, but it will be exposed to compression
> > and expansion forces, so there is nothing to bend
> > it, but it needs good strength for compressing
> > and stretching forces... ;o)
> >
> > I'm not after formulae as the problem is slightly
> > more complex than what I have posted, but any
> > general ground rules and "reasons why" will be
> > really appreciated.
> >
> > Do we drill the tubing with large diameter
> > holes, or lots of small holes, and why/how
> > will each method give the BEST STRENGTH for
> > the MAX amount of weight lost???
> >
> > Thanks guys! :o)
> > -Roman

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