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1. 09:53 AM - Rounding The Bottom Flange Of Baggage Door... (Matt Dralle)
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Subject: | Rounding The Bottom Flange Of Baggage Door... |
For the RV-8 Rebuild I decided to build a new front baggage door for a
number of reasons. The main reason was due to the less than stellar job I
did with the bottom flange that intersects with the top of the fuselage.
On the Ruby 1.0, when I finished the baggage door, I found that the bottom
flange of the baggage door was sticking out away from the fuselage by about
3/16" and just looked stupid. At that point the door was already built, so
the only option I really had was try to put a bend in it using the bending
brake. The bend came out fine, but from the first flight to the mishap, I
always hated the way that crease looked since it didn't match the rest of
the fuselage.
So, on Ruby 2.0 I decided I was going to make a new door and hoped that the
first one was just a fluke. Unfortunately, after I finished door #2 I
found that I had exactly the same problem with the 3/16" gap at the bottom!
Rather than using the brake, this time I clamped the flange between two
1/4" thick pieces of oak wood and tried to bend and stretch it so as to not
leave a crease. The good news was that I did get a better fit and the
crease was much less, but the bad news was that I didn't use enough clamps
and the bend came out inconsistent front to back and, frankly looked a lot
worse that the original one. Rats. Another one for the scrape pile.
So, I ordered up another pile of parts to build a third baggage door. But
this time, before I did any building, I decided to try to get the fit
better right out of the gate and while I still had just a single flat skin
and no bulkhead structure underneath. I worked though in my head a dozen
different ways that I might put a creaseless bend in the bottom 1" of
flange on the door, but nothing seemed like it would really work. Then I
remembered that my piece-of-crap-Chinese-made combination shear/brake also
had a roller on it! But I didn't get too excited, because I'd never really
used the roller because they just seemed like a bigger piece of crap than
the rest of the tool. Today, I decided to take a closer looks and figure
out just what tweaking I'd need to do to get the rollers working.
The first thing I discovered was that the rollers still had the anti-rust,
shipping compound on them which made them very uneven and not too
consistent for grabbing. I broke out the Acetone and some paper towels and
gave them a good cleaning. Turns out, the rollers were pretty well made
and smooth, once all the gunk was removed. Next, I fiddled around with the
adjustment arms that vary the distance of the rear roller from the front
rollers. This distance gives you looser or tighter bend radii depending on
their position. But you have to make sure that the distance is exactly the
same left-to-right if you want a consistent bend radius. I used a digital
caliper and got things dialed in pretty well and used a few sample pieces
of .032 2024-T3 to test. In the testing, I found that I could get just the
right amount of bend that seemed like it was fitting nicely along the
baggage door mounting. So, next, I grabbed the real piece of metal for the
top baggage door skin and ran the first 4" or so though the roller from the
front. Then I took it out and put it in from behind and ran it though the
rollers again which seemed to even the bend out nicely. A trial fit on the
fuselage and lo' in behold it was a lot closer that it had been. I
adjusted the rollers again for a little bit more bend and repeated the
bending process. Even closer this time. One more tightening and the fit
was literally perfect! Best of all, from the outside of the baggage door
skin, there is NO crease! The natural bend of the door that matches the
fuselage top skin simple accelerates evenly over the last 1-2" of the skin
which is just right for making a perfect fit and seal with the top of the
fuselage.
So, I'm happy to report that I think I will finally have an acceptable
baggage door for the RV-8. 'Course, I now I have to build this new one
using the freshly rebent skin, during which time there is always lots of
opportunity to slip with the rivet gun or whatever and cause a catastrophe
that would require a forth attempt. But, let's not focus on that... :-)
-
Matt Dralle
RV-8 #82880 N998RV "Ruby Vixen"
http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log
http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 172+ Hours TTSN - Rebuilding Fuselage After Landing Mishap...
RV-6 #20916 N360EM "The Flyer"
http://www.mattsrv6.com - Matt's RV-6 Revitalization Log
Status: 200+ Hours Since Purchase - Upgrades Complete; Now In Full Flyer
Mode
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