06-01-08 - Priming Aft Spar Parts & Wing Angle Parts
After much internal deliberation, internet reading and heated
discussions with engineer coworkers I've decieded that I am going to
prime all of the internal/inaccessable components. This is a
big change for me - originally I was not going to prime anything.
6061T6 is an "artifically aged" alloy that has good
resistance to corrosion. There is a chance my plane will be
tied down (at least while I'm on the hangar waiting list) and that
could allow some moisture to get trapped in the airframe. I
just cannot spend all the time and money requred to complete this
project without at least attempting some form of anti-corrosion
protection. I likely will also fog the airframe with
something like ACF50 or CorrosionX but that will be later down the line.
I decided to use Zinc Chromate primer to spray the parts. It
seems to be getting harder to find lately - Tempo doesn't make it
anymore (or at least none of the suppliers carry it) and I didn't want
to buy it by the quart or gallon - to messy and inconvient. I
got a case of 12 rattle cans from skygeek.com for $2.50 a can + $6
shipping. Quite the deal - the duplicolor primer popular with
the RV crowd is around 6$ a can for me locally.
Here's one set of unprimed aft spar parts.
I weighed the components before priming, just to get a baseline.
I'm curious how much weight a coat of primer could add.
The left aft spar parts weight 12.6 grams unprimed.
The right spar parts weight 12.3 grams.
My spray booth. It doubles as a driveway normally.
I've scotchbrited, washed the parts in hot soapy water and
wiped them down with MEK to get all of the oils off.
I threw together a spray rack from some old lumber I had in the garage.
To hang the parts I used some old SS electric fence wire hooked over
the boards.
To get everything spaced out for spraying I had to move it around a
bit, but it has all been coated.
I prefer the yellow over the drab green for the primer. I'm
likely going with yellow for the fiberglass so it'll match.
Moving along - on to the main wing spar angle pieces.
The first vertical stiffiner angle rough cut to size.
Two completed vertical stiffiner angles.
Marking the 1" angle to make the RH tie down fitting.
The completed RH tie down fitting.
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