The Murphy Builders Site

The amount of stress at a corner is inversely proportionate to the radius. The smaller the radius, the larger the stresses. Drilling a hole gives you a fixed radius. If you just make a relief cut you will end up with a small radius and much higher stresses. A nick has a very small radius and will concentrate stresses as well. That is why stop drilling a crack works. The end of the crack has a very small radius and causes concentration of stress. Stop drilling the crack increases the radius and reduces the amount of stress so the crack does not spread. Drill the holes as directed and make sure you deburr them so there are no stress risers.

Dave Jackson

Date: Mon, 5 Nov 2007 08:39:38 -0500> From: klehman@albedo.net> To: rebel-builders@dcsol.com> Subject: Re: [rebel-builders] To Drill or Not to Drill...> > Craig> The holes are just an easy way to get a round corner with no nicks at > the corner. A straight edge or a rounded corner is desired when bending > metal. A sharp corner or a nick is not wanted.> Ken> > Craig Walls wrote:> > >I thought I read somewhere in the archives that when MAM has you drill holes> >at points where you'll be bending channel/metal, etc, it's just another> >place where a tear could start. In the fin section when you build ribs, the> >directions say to drill holes in each side and then fold them up around a> >piece of wood. Is that a good way or is it better to just make relief cuts> >and then bend? Craig> > > >> > > > > > -----------------------------------------------------------------> List archives located at: https://mail.dcsol.com/login> username "rebel" password "builder"> Unsubscribe: rebel-builders-u

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Craig
The holes are just an easy way to get a round corner with no nicks at
the corner. A straight edge or a rounded corner is desired when bending
metal. A sharp corner or a nick is not wanted.
Ken

Craig Walls wrote:

I thought I read somewhere in the archives that when MAM has you drill holes
at points where you'll be bending channel/metal, etc, it's just another
place where a tear could start. In the fin section when you build ribs, the
directions say to drill holes in each side and then fold them up around a
piece of wood. Is that a good way or is it better to just make relief cuts
and then bend? Craig

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Craig,
I find it faster and easier to just cut the channel or whatever without drilling first, then use a round chainsaw file to make the radius and deburr with a fine half-round file.
Jesse

Date: Mon, 5 Nov 2007 08:39:38 -0500
From: klehman@albedo.net
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] To Drill or Not to Drill...

Craig
The holes are just an easy way to get a round corner with no nicks at
the corner. A straight edge or a rounded corner is desired when bending
metal. A sharp corner or a nick is not wanted.
Ken

Craig Walls wrote:

I thought I read somewhere in the archives that when MAM has you drill holes
at points where you'll be bending channel/metal, etc, it's just another
place where a tear could start. In the fin section when you build ribs, the
directions say to drill holes in each side and then fold them up around a
piece of wood. Is that a good way or is it better to just make relief cuts
and then bend? Craig

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