The Murphy Builders Site

Craig,
There are tools that cut holes without the drill hole in the center but they are quite expensive. Check with your local avionics shop and they might have one and will do it for a minimal cost or borrow/loan/rent you the tool.
Good luck,
Keith

--- On Sun, 8/3/08, Craig Walls <snowyrvr@mtaonline.net> wrote:

From: Craig Walls <snowyrvr@mtaonline.net>
Subject: [rebel-builders] Here's Another Question
To: rebel-builders@dcsol.com
Date: Sunday, August 3, 2008, 12:49 PM

Does anyone have a good technique for making inspection hole covers? I've
tried carefully cutting a circle and filing to round but they aren't that
great and look unprofessional. Everything I have to make circles puts a
hole in the center which I'd be willing to fill with a screw if I had to.
I
like the bent edge, too. I've got one of the tools that form that edge but
am not sure if it'd work on a 5" disc AND I haven't made friends
with it yet
if you know what I mean! Thanks Craig





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Craig,

I used the MAM doubler, and put the covers on top of that (under wing, of
course) -- not flush, as the MAM drawing suggests. The doubler holes and
wing holes are identical. I used a large hole saw to cut the left, forward
inspection hole cover approx. 1.25" bigger in diameter than the doubler/wing
holes, in which I mounted the pitot. Because the pitot went into that one,
the pilot hole didn't matter. I used the circumference of the first cover to
draw out the other three, and cut and shaped them manually to the drawn
circle lines. I used Click Bond nutplates inside the wing for all four. I
have six machine screws in the pitot one, and four in the other three.

It took some care to get the pitot mount aligned perpendicular, etc., but
they all turned out pretty nice. I have several pics that were taken during
a period I wasn't keeping my site up-to-date. I'll try to get some of them
posted pronto.

Ron
254R
http://n254mr.com



On Sun, Aug 3, 2008 at 10:49 AM, Craig Walls <snowyrvr@mtaonline.net> wrote:

Does anyone have a good technique for making inspection hole covers? I've
tried carefully cutting a circle and filing to round but they aren't that
great and look unprofessional. Everything I have to make circles puts a
hole in the center which I'd be willing to fill with a screw if I had to.
I
like the bent edge, too. I've got one of the tools that form that edge but
am not sure if it'd work on a 5" disc AND I haven't made friends with it
yet
if you know what I mean! Thanks Craig





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At 09:49 AM 8/3/2008 -0800, you wrote:

Does anyone have a good technique for making inspection hole covers? I've
tried carefully cutting a circle and filing to round but they aren't that
great and look unprofessional. Everything I have to make circles puts a
hole in the center which I'd be willing to fill with a screw if I had to. I
like the bent edge, too. I've got one of the tools that form that edge but
am not sure if it'd work on a 5" disc AND I haven't made friends with it yet
if you know what I mean! Thanks Craig

I clamp the aluminum firmly to my drill press table and cut them with a fly
cutter that has the centring drill bit removed. My flanging tool is a piece
of 1" dowel about 6" long that I sawed a slit in one end. You could also
just buy the covers from aircraft spruce.

http://www.aircraftspruce.com/catalog/c ... tplate.php
Drew



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Some things are easy the low tech way. I've made many just by tracing
something round onto the aluminum with a sharpie pen. Cut out with tin
snips. (or trim around it a dozen or more times with a shear. You know
so that 4 cuts gives you a square, 4 more gives you an octagon, etc.)
Sand the last 1/16" to the line with a pedestal mounted disk or belt
sander and you have a surprisingly accurate round disk.

A very small edge bend is nice but none of the tools that are mounted on
a straight handle ever did work for me. The one that did work acceptably
was the one from Avery that has the two nylon wheels mounted in the
middle of a half inch thick x 3" diameter disk. Fits in the palm of your
hand and easier to control. Go around the disk lightly a few times til
you are happy. Probably even easier if you fastened any of these tools
in a vise and just moved the disk.

Ken

Craig Walls wrote:

Does anyone have a good technique for making inspection hole covers? I've
tried carefully cutting a circle and filing to round but they aren't that
great and look unprofessional. Everything I have to make circles puts a
hole in the center which I'd be willing to fill with a screw if I had to. I
like the bent edge, too. I've got one of the tools that form that edge but
am not sure if it'd work on a 5" disc AND I haven't made friends with it yet
if you know what I mean! Thanks Craig

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Find a wrecked Cessna. Their wings are covered with inspection plates.

Tim Hickey
R808
----- Original Message -----
From: "Drew Dalgleish" <drewjan@cabletv.on.ca>
To: <rebel-builders@dcsol.com>
Sent: Monday, August 04, 2008 12:10 AM
Subject: Re: [rebel-builders] Here's Another Question

At 09:49 AM 8/3/2008 -0800, you wrote:

Does anyone have a good technique for making inspection hole covers? I've
tried carefully cutting a circle and filing to round but they aren't that
great and look unprofessional. Everything I have to make circles puts a
hole in the center which I'd be willing to fill with a screw if I had to.
I
like the bent edge, too. I've got one of the tools that form that edge
but
am not sure if it'd work on a 5" disc AND I haven't made friends with it
yet
if you know what I mean! Thanks Craig

I clamp the aluminum firmly to my drill press table and cut them with a
fly
cutter that has the centring drill bit removed. My flanging tool is a
piece
of 1" dowel about 6" long that I sawed a slit in one end. You could also
just buy the covers from aircraft spruce.

http://www.aircraftspruce.com/catalog/c ... tplate.php
Drew



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Craig,

I just put several pics of this process in the "Wings" gallery at
http://n254mr.com/image/tid/8 They are not annotated yet but may give you
some ideas, especially about mounting the pitot bracket. The holes in the
wing and doubler are 3-5/16" dia., and the cover plates are 4.5" dia. As I
recall, the 3-5/16" wing/doubler hole size was chosen as the minimum needed
to mount the std. pitot bracket entirely within that diameter -- at least as
I did it. The cover plate size was chosen to be large enough for
nutplate/screw edge distances.

I hope this is useful.

Ron


On Sun, Aug 3, 2008 at 8:13 PM, Ron Shannon <rshannon@cruzcom.com> wrote:

Craig,

I used the MAM doubler, and put the covers on top of that (under wing, of
course) -- not flush, as the MAM drawing suggests. The doubler holes and
wing holes are identical. I used a large hole saw to cut the left, forward
inspection hole cover approx. 1.25" bigger in diameter than the doubler/wing
holes, in which I mounted the pitot. Because the pitot went into that one,
the pilot hole didn't matter. I used the circumference of the first cover to
draw out the other three, and cut and shaped them manually to the drawn
circle lines. I used Click Bond nutplates inside the wing for all four. I
have six machine screws in the pitot one, and four in the other three.

It took some care to get the pitot mount aligned perpendicular, etc., but
they all turned out pretty nice. I have several pics that were taken during
a period I wasn't keeping my site up-to-date. I'll try to get some of them
posted pronto.

Ron
254R
http://n254mr.com

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