[NSRCA-discussion] wing tube sleeve hole
Ted Sander
tedsander at comcast.net
Sat Nov 10 04:08:47 AKST 2007
Another variation on a theme - I too have gone back to built up, but in my
foam wing days..
Boring a hole - this assumes your root is at right angles to your wing
mid-line. Be creative if not - shim the jig, start with an oversize wing
that will be trimmed, etc. Build a jig consisting of: two pieces of scrap
lumber (1x3 or 2x4) that have holes bored in them big enough for your wing
tube. Use a drill press, get these two dead on aligned. Holes should be as
close to the OD of your sleeve as you can easily get, but do not have to be
100% exact. Cut a 2 small amounts off of your sleeve, and insert into the
bored holes to act as "bearings", do not glue yet. Find a plywood
square/rectangle sized appropriately for your wing and tube. Clamp one
support to the front edge of the plywood, one to the back edge. If you've
got excess socket tubing, you can just run it from front to back through the
holes, instead of making "bearings". Insert your wing tube through the
holes or into the socket, and just like aligning a plane, work to get the
tube exactly 90 deg. to the face of the front block and base (vertical and
horizontal). The longer your base, from front to back, the better, but it
all depends on how much tube and socket materials you have available.
Glue/screw the whole shebang - boards to the base, wing socket or "bearings"
to the holes, making sure the wing tube itself will be square to the face of
the front block while it all sets up.
Use: Cut about a 2-3" piece off of your wing socket. File teeth in it,
just as you would for brass tubing when boring smaller holes in balsa.
Phenolic sockets work great. You may have to harden other materials with
CA in order to get it hard enough to make teeth. Glue the "saw" onto the
end of your wing tube. Butt the face of the front block up to the wing
root, using spacers (more scrap lumber) to get the jig face firm against the
root, but allowing for clearance between the front support and the root for
the "saw". Shim the jig up or down to get the saw lined up exactly where
you want the hole to start. Support your wing tip as needed to provide any
dihedral you might need (if doing so, of course, make sure you start a
little "high" on the root). Clamp/weight everything down very firmly.
Start twisting your wing tube back and forth, boring into the foam with the
saw. You will have to pull it all out, and clear the saw of foam
periodically, but once started, using the existing hole to realign
everything is a snap.
Sure, use of scrap lumber, etc. may give some the willies due to lack of
extreme precision..so if you've got the capability to make it all more
precise, go for it. The concept is the same - use a long baseline to keep
everything in alignment as you drill. Use your wing tube as the drill
shaft, riding in sleeve bearings to keep tolerances close. Use the wing
sleeve as the drill bit, to get a really nice, close fit that requires a
bare minimum of glue.
Ted Sander
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Lance Van
Nostrand
Sent: Friday, November 09, 2007 6:37 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] wing tube sleeve hole
Thanks Karl, this is a good idea. It produces a hole that looks very clean.
My concern is how to get the template end that is inserted into the wing
into the precise location. I didn't used to be too concerned with this. As
long as the holes in the opposing wings were close they were good enough
because when I mount the wing tube in the fuse I would perfectly align the
wings. Even if the wing tube was tilted, it would not matter. However, now
that we sell kits and people order replacement wings, or use the wing tube
itself to align with the stab, I feel I must have a method that is
repeatable to a very accurate degree. Also, another difference from the
home builder to the production shop is time. Your method looks like it
would be quick to do, but not as sure about the setup (having to burn the
initial hole and feed the wire). I'm sure that with practice any method
becomes efficient.
--Lance
----- Original Message -----
From: Karl G. Mueller <mailto:kgamueller at rogers.com>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Friday, November 09, 2007 10:03 AM
Subject: Re: [NSRCA-discussion] wing tube sleeve hole
Lance,
I have cut the holes for the wing tube socket with a hot wire
and two templates mounted to the work bench at the proper
height to be on center of where the tube hole should be.
The socket hole is cut before cutting the core itself.
You need to make a slot in the core where the end support of the
tube is going to be to insert the template that is mounted to the bench.
I then burn a small hole thru the center of the templates in the
core with a hot piece of music wire held in a small machine vice
that is guided along a straight edge. Then I thread the wire for the
cutting bow thru that hole and start cutting following the two
templates. Start with a low heat and try the fit. If the fit is too tight
just increase the voltage a little and go around the templates again
until you achieve the proper fit. Of course you need a variable power
supply. Sounds more complicated than it really is. Now when you
cut the core, adjust your tip template to get the proper dihedral. Works
for me.
Karl G. Mueller
kgamueller at rogers.com
----- Original Message -----
From: Lance Van Nostrand <mailto:patterndude at tx.rr.com>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Thursday, November 08, 2007 10:46 PM
Subject: Re: [NSRCA-discussion] wing tube sleeve hole
That's a hard one, Mike. Both Terry and I use a similar method. We had a
machine shop make a jig for the cutter. The cutter is a length of 7/8" wing
tube with a ground sharp edge, but the jig to hold it has got to be made
presicely. I used to use a seemingly accurate jig made to the plans
provided in a KFactor several years ago, but my results were not good
enough.
--Lance
----- Original Message -----
From: Mike Miller <mailto:mgmiller54 at comcast.net>
To: nsrca-discussion at lists.nsrca.org
Sent: Thursday, November 08, 2007 7:08 PM
Subject: [NSRCA-discussion] wing tube sleeve hole
<http://www.mackrc.net/patternwings2/index.htm>
http://www.mackrc.net/patternwings2/index.htm
<http://www.nextcraft.com/foamwingsandparts.html>
http://www.nextcraft.com/foamwingsandparts.html
Terry Brox's web site on balsa skinned wings is very good and does show the
drilling of the servo lead hole with a tube and by hand.
Their is some great information on these sites on building foam core wings.
But a very important part of a plug in wing would be the wing tube sleeve
hole in the core, to be straight and parallel to the desired line centered
and at the right angle to set the dihedral. Is there a site that explains or
shows the process of set up and drilling of this hole? If this step is not
perfect looks to me like the wing is dead no matter how good the skinning
process is.
Thanks in advance
Mike
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