Drilling holes in steel tubing

In article .com,
"wright1902glider" wrote:



Epoxy doesn't offer enough strength.

If you're paralleling the tubes for six inches or more, and you filled
the notches between them top and bottom with a fillet of serious
industrial epoxy, (not the five minute stuff) I'd think you'd be able to
support more of a cantilevered load before the glue sheared, than you
would before the tubing folded at the bolt holes. (EMT isn't very
strong, and you're going to need a 0.187" hole for a #10 bolt.) But
that's just a feeling. I was the guy who built the weakest cardboard
bridge in high school physics, so I'm probably wrong.

Anyway, I can see you like the bolts. You could make your own clamping
fixture, a combination of the V-block idea and the two by four idea. If
you have a table saw, you could cut stepped grooves in two 6 or 8 inch
long wood blocks. The inner step has a width and depth of 1/2". The
outer step has a width of 1" and a depth of 1/2." Drill some holes for
drill bushings, available at the industrial hardware store, press them
in, clamp the two halves around the three tubes, and drill.