On Sun, 26 Mar 2006 13:37:03 GMT, "Karl Townsend"
remove .NOT wrote:

I'm building my latest contraption. Its a large metal plenum for directing
the air from an air blast sprayer down onto three rows of strawberries.
Think of an air duct for heating with three registers, only use a forty
horse power fan and very small openings.

Strawberries? What happened to the apples? ;-) I go through
Oxnard regularly, right past the pro pesticide places (AgRX for one)
that own these blast sprayers. And they're put together to be rugged.

I made the whole plenum out of sheets of 1/8" steel, and 1/8" round tubing
of different sizes. Its all tack welded together now. I'm going to finish
welding for strength this afternoon. I'll stitch weld with a three inch or
so gap between every one inch of weld.

I'll have yards and yard of places where the metal meets that I need to
seal. It needs to hold up to vibration and high air pressure. And be
paintable. What would you use?

More weld. Seriously - go back and fill in all the blank spots
between the stitch welds, an inch at a time so it doesn't warp on you.
Then get out the angle grinder for the pre-paint clean up.

If this blast sprayer is to be mounted on a tractor and bounced
around regularly by hired farm workers who don't care about being
gentle on the equipment (they just want to get done and go home) you
have to build it bulletproof or it will crack and fall apart. And
they won't say anything about it when the crack appears, only when it
fails totally.

(And they get the afternoon off while you fix it.)

Put X bracing anywhere it might twist, brace all the register
opening arms, triangulate the arms mounting it to the tractor
three-point and the fan unit. Stiffen any large flat metal areas so
they don't "oilcan" on you. Then go drive it around and have someone
watch and videotape while you hit bumps - you may be able to see where
it needs more reinforcement before breaking it.

After that, you can get spot putty and urethane based seam
sealer/filler (to make your welds look good) from an auto parts with
an auto paint department, use stuff that is meant to be painted.
They'll also have the 'tractor paint' for the finish coat.

And you might want to paint the inside so it doesn't rust as fast.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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