[Amps] Another metalwork question

[Will Matney]

Martin,

On bending steel, you use 1/2 the material thickness to figure how much to add in length. In other words you divide the material thickness in half where there would be an imaginary center line (its neutral axis) going trough it. Then when the steel is bent, a radius is formed on this imaginary center line even though the inside bend is a sharp 90 deg bend. So whatever the distance is around that small radius in the middle of the steel is the material to be added. Now aluminum is a different story and there is a formula for it too. What happens in aluminum, there is a shrinkage on the inside radius and a stretching on the outside different than steel. For aluminum see the formula and example below;

BA = (0.0078 * T + 0.0174 * R) * No. of deg. in bend

14 Ga = 0.0641"

For 0" radius, 90 Deg bend in aluminum;

(0.0078 * 0.0641 + 0.0174 * 0) * 90

(0.00049998 + 0) * 90 =

0.00049998 * 90 = 0.045" or about 3/64" or for ending pieces of flanges make it 1/16" from bend line to end.

BA = Bend Allowance
R = Radius of bend on the inside, not the neutral axis.
T = Material thickness

I have a pic with this and a drawing if needed I can e-mail it to you. Hope this helps.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 8/2/05 at 2:46 PM Martin Sole wrote:

>Well it is actually amp related, or will be at some point I hope but
>seeing
>how there is a great wealth of resource here it seems a good place to
>start.
>
>Some time back I recall seeing an article, might have been in Radcom, might
>have been in QST. Think it had to be either one of those two though. It
>addressed the process of marking out metalwork for making enclosures and
>explained how to allow the correct amount of material for bends etc. Was
>within the last year or two I think.
>
>Just hoping that somebody might recall where this was or maybe point me to
>another resource with similar information.
>
>Tks
>Martin HS0ZED
>
>
>
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