"Leon Fisk" wrote in message ...
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A patent here that uses wedges or teeth on plates and beams that would
transfer stress over a broader area:
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I don't have the shop space to clamp one end of an 8' beam in my mill vise
to accurately drill a hole pattern. All I can do is hang the opposite end at
an angle in a doorway and locate a punch mark or pilot hole under the
spindle to drill it larger. The splice plate will have to be match-drilled
to beams on sawhorses out in the driveway. Either a Portalign or clamped-on
bench drill press will keep the bit, hole and tap square to the surface. I
use an adjustable hand reamer to give bolt shanks the minimum of clearance.

That's how I spliced 8' sections of 3" channel into the sawmill track and
overhead gantry, but those splices have to sustain only the dead weight of
the channels while I'm setting up and leveling them, they are supported at
the splice in service. I'm trying to splice the 4" channel strongly enough
that it doesn't need a center support although it will normally have one.
The problem is designing a tension-side joint that gives the full strength
of the channel without blocking the trolley.
https://www.harborfreight.com/1-ton-...ley-97392.html

If I just weld them together or buy a suitable 16' beam the assembly is too
large to store under cover and too heavy to carry and lift into place. One
8' section of the 4" channel is hard enough to support and align with one
hand while inserting a bolt with the other, on a stepladder. When possible I
turn a taper and a root-diameter pilot on the ends of machine screws to help
align tapped and clearance holes in things I repeatedly assemble and
disassemble outdoors, like my 50' TV antenna mast, but there isn't enough
clearance for that between the trolley wheels.

The problem could be worse. I had the chance to examine and ride in a Beech
18 whose original wing spars had been stiffened with a similar-sized steel
reinforcing strap underneath. It makes an un-aerodynamic bulge in the lower
wing surface.
http://www.twinbeech.com/sparstrap.htm

"Other manufacturers kits resemble bridge trusses and can protrude more than
10 inched from the skin of the Beech. Not only is this unsightly but it is
enough to make an aerodynamicist sick. I heard one owner say that one good
thing about his bridge truss spar strap was that if he ever had to belly
land his Beech at least the props wouldn't hit the ground!"