"Clare Snyder" wrote in message
...

It's not so much that the rods are stiff - if you use BOLTS and
tension them against the shelf you mightbe able to significantly
increase the bending strength of the shelf - but "gun drilling" a 4
foot shelf is going to be something of a problem, me-thinks.
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The metal rods under the steps of a wooden step ladder are good examples of
this.