larry(at)macsmachine.com Guest
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Posted: Mon Aug 17, 2009 12:09 pm Post subject: Securing J-nuts from "floating"...? |
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Patrick,
The J-nuts are easy to position if you've sized the holes that hold the
retaining edge of the J-nut.
There are a few still finishing the forward tilt canopy and I thought
perhaps this information would be useful for those wanting a removable
forward top skin. It’s easier than trying to make a hole in the skin
work around the canopy etc., and it costs lots less.
For peripheral fasteners, I used clip nuts better labeled as J-nuts for
screws. I used a 6-32 J-nut from McMaster-Carr their part number #
94809A102 and 94808A401. These can be seen on the McMaster site
http://www.mcmaster.com/
I used round head 6-32 screws 3/8-inch long and spaced them about the
same as you'd do for A4 pop rivets.
Believe I used about 80 of these on the forward top skin and I use a
$9.00 battery powered screwdriver to remove them.
The clips were about $9.00 per 50 pieces. These do not raise the skin at
all. Much easier than nut plates and the half dozen that you might over
tighten or damage each year are just lifted from the hole catch, slid
off and replaced. These just slide over a hole and a very small
retaining edge captures it to keep it from slipping or being wiped off.
I'm terribly keen on these things, because they're cheap, refuse to let
go and never allow screws to come loose.
The forward top skin has to be modified to eliminate the wide segments
on each side and the wide segments have to become separate pieces that
stay on the plane.
See links below.
The fastener hole normally used should be 7/32 diameter for the clips.
The top skin holes should be 9/64 inch. I purchased about 300 of both
types and have used them elsewhere. See links of clips placed,
originally clecoed, finished install and access.
http://www.macsmachine.com/images/canopy/full/uclips.gif
http://www.macsmachine.com/images/canopy/full/xlfwdtopskin.gif
http://www.macsmachine.com/images/canopy/full/flash&rubber.gif
<http://www.macsmachine.com/images/canopy/full/flash&rubber.gif>
<http://www.macsmachine.com/images/canopy/full/flash&rubber.gif
<http://www.macsmachine.com/images/canopy/full/flash&rubber.gif>>
http://www.macsmachine.com/images/canopy/full/electricaccess.gif
The method for removing the forward top skin begins by removing the
forward most 6 side screws before opening the canopy.
Two 3 x 5 rectangles of deburred aluminum are slid between the rubber
trim near the hinge to prevent the rubber from catching on the edges of
the top skin. When the canopy is lifted, these screw holes are covered
by the canopy arms. The rest of the screws are removed progressively,
the gas cap is removed and the skin is lifted out toward the cockpit and
set aside. The gas cap is then reinstalled.
The canopy should be raised to replace the forward top skin and the
reverse assembly is the same.
The removable forward top skin allows an easy removal of the forward
tilt canopy when it's time to paint. I've had the skin off half a dozen
times the past two years for wiring, gage replacement, checking inside
engine mount integrity, etc.
I hope this is useful for you and as you have questions, don't hesitate
to ask.
Larry McFarland 601HDS at www.macsmachine.com
PatrickW wrote:
Quote: |
I'm working on my forward top skin. Want to be able to easily remove this panel in the future, so I'm going with J-nuts.
Question: How are you guys securing the J-nuts so they stay in place long enough for you to place the top skin and screw it down? Are you crimping them down somehow? By the time I got my first screw secured, many of the remaining J-nuts had "floated" so they were no longer accessible through the holes in the top skin.
I'm using "Spring Nut Type J" (part number 214883 from McMaster) with AN526-632R6 machine screws.
What works for you guys who are using J-nuts...?
Thanks,
- Pat
--------
Patrick
XL/650/Corvair
N63PZ (reserved)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 58229#258229
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