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Skin blemishes

Converted from Wildcat! database. (read only)
Jesse Jenks

Skin blemishes

Post by Jesse Jenks » Sat Feb 18, 2012 10:59 am

Thanks mike, good tips,
I was using a dowell to roll up the plastic. The blemishes started about
halfway down the skin, so for 5' or so it went fine. The blemishes don't
look like they were caused by the force of the plastic as it was being
pulled off, but more like there were some bits of crud, metal ships or
whatever, that got rolled up on the dowell and then imprinted in the skin
every time the dowell rolled over them. I was using a lot of pressure on the
dowell just to keep it rolling, ie the plastic was really stuck on. I think
your idea of removing it in strips is good. That would take less overall
pressure on the dowell to roll it. Also I will try to make sure there is no
foreign material in there. Maybe just ditching the dowell and going slow by
hand is the way to go too. If it took half a day to get the plastic off
without damaging the skin, that is still better than the alternative.
Jesse

From: Mike Kimball <mkimball@gci.net>
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: RE: Skin blemishes
Date: Thu, 01 Sep 2005 19:05:26 -0800

I would find it harder getting the plastic off on a soft surface such as
carpet. Use your table, go slow and careful. Put a lot of pressure on the
uncovered skin with one hand very near to the plastic where you are pulling
on it. Keep the hand that is pulling on the plastic moving to stay close
to
the skin. In other words, don't get a hold of the plastic and keep pulling
until your hand is a foot or more from the skin. Pull a couple of inches
then grab again right at the point it's stuck to the skin. Keep the hand
that's on the uncovered skin moving too to stay close to the plastic you
are
removing. Don't pull straight up. Pull close to parallel to the skin.
Another thing you can try is to split the width of the plastic you are
removing into strips, say about 12-18 inches wide. Start pulling and when
you get it going, grab the part that is separated from the skin and split
it
so you aren't trying to roll off a four foot wide piece. Pull at an angle
on the left side of your strip, then follow with the right side. Keep
going
back and forth like that instead of pulling straight down on the strip you
are removing. Hope this helps.

Mike Kimball
044SR




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jtpackard

Skin blemishes

Post by jtpackard » Sat Feb 18, 2012 10:59 am

Jesse:
I agree with Mike's recommendations on film removal. It doesn't really take
that long by hand if you follow Mike's instructions.
One idea I got from Kent White at one of his seminars at Oshkosh this year
for dent removal (shrinking metal in small areas like hail damage) is to
heat the area around the dent (about 6" DIA) with a hair dryer to about 220
deg F and then placing a piece of dry ice on the dent itself. The
contraction in the area under the dry ice is supposed to shrink the metal in
the dented area and therefore remove the dent. He also said that liquid
Nitrogen will really shrink it.
Has anyone else heard of this technique or used it successfully?

Tom Packard
SR043
----- Original Message -----
From: "Jesse Jenks" <jessejenks@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, September 02, 2005 11:55 AM
Subject: RE: Skin blemishes

Thanks mike, good tips,
I was using a dowell to roll up the plastic. The blemishes started about
halfway down the skin, so for 5' or so it went fine. The blemishes don't
look like they were caused by the force of the plastic as it was being
pulled off, but more like there were some bits of crud, metal ships or
whatever, that got rolled up on the dowell and then imprinted in the skin
every time the dowell rolled over them. I was using a lot of pressure on
the
dowell just to keep it rolling, ie the plastic was really stuck on. I
think
your idea of removing it in strips is good. That would take less overall
pressure on the dowell to roll it. Also I will try to make sure there is
no
foreign material in there. Maybe just ditching the dowell and going slow
by
hand is the way to go too. If it took half a day to get the plastic off
without damaging the skin, that is still better than the alternative.
Jesse

From: Mike Kimball <mkimball@gci.net>
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: RE: Skin blemishes
Date: Thu, 01 Sep 2005 19:05:26 -0800

I would find it harder getting the plastic off on a soft surface such as
carpet. Use your table, go slow and careful. Put a lot of pressure on
the
uncovered skin with one hand very near to the plastic where you are
pulling
on it. Keep the hand that is pulling on the plastic moving to stay close
to
the skin. In other words, don't get a hold of the plastic and keep
pulling
until your hand is a foot or more from the skin. Pull a couple of inches
then grab again right at the point it's stuck to the skin. Keep the hand
that's on the uncovered skin moving too to stay close to the plastic you
are
removing. Don't pull straight up. Pull close to parallel to the skin.
Another thing you can try is to split the width of the plastic you are
removing into strips, say about 12-18 inches wide. Start pulling and
when
you get it going, grab the part that is separated from the skin and split
it
so you aren't trying to roll off a four foot wide piece. Pull at an
angle
on the left side of your strip, then follow with the right side. Keep
going
back and forth like that instead of pulling straight down on the strip
you
are removing. Hope this helps.

Mike Kimball
044SR




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Mike Kimball

Skin blemishes

Post by Mike Kimball » Sat Feb 18, 2012 10:59 am

Yep, I've heard of the technique and tried it on my hail damaged Cherokee
180 a few years back. I used dry ice, not liquid nitrogen. Didn't work.
Not a bit.

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
jtpackard@usfamily.net
Sent: Friday, September 02, 2005 9:50 AM
To: rebel-builders@dcsol.com
Subject: Re: Skin blemishes

Jesse:
I agree with Mike's recommendations on film removal. It doesn't really take
that long by hand if you follow Mike's instructions.
One idea I got from Kent White at one of his seminars at Oshkosh this year
for dent removal (shrinking metal in small areas like hail damage) is to
heat the area around the dent (about 6" DIA) with a hair dryer to about 220
deg F and then placing a piece of dry ice on the dent itself. The
contraction in the area under the dry ice is supposed to shrink the metal in
the dented area and therefore remove the dent. He also said that liquid
Nitrogen will really shrink it.
Has anyone else heard of this technique or used it successfully?

Tom Packard
SR043
----- Original Message -----
From: "Jesse Jenks" <jessejenks@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, September 02, 2005 11:55 AM
Subject: RE: Skin blemishes

Thanks mike, good tips,
I was using a dowell to roll up the plastic. The blemishes started about
halfway down the skin, so for 5' or so it went fine. The blemishes don't
look like they were caused by the force of the plastic as it was being
pulled off, but more like there were some bits of crud, metal ships or
whatever, that got rolled up on the dowell and then imprinted in the skin
every time the dowell rolled over them. I was using a lot of pressure on
the
dowell just to keep it rolling, ie the plastic was really stuck on. I
think
your idea of removing it in strips is good. That would take less overall
pressure on the dowell to roll it. Also I will try to make sure there is
no
foreign material in there. Maybe just ditching the dowell and going slow
by
hand is the way to go too. If it took half a day to get the plastic off
without damaging the skin, that is still better than the alternative.
Jesse

From: Mike Kimball <mkimball@gci.net>
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: RE: Skin blemishes
Date: Thu, 01 Sep 2005 19:05:26 -0800

I would find it harder getting the plastic off on a soft surface such as
carpet. Use your table, go slow and careful. Put a lot of pressure on
the
uncovered skin with one hand very near to the plastic where you are
pulling
on it. Keep the hand that is pulling on the plastic moving to stay close
to
the skin. In other words, don't get a hold of the plastic and keep
pulling
until your hand is a foot or more from the skin. Pull a couple of inches
then grab again right at the point it's stuck to the skin. Keep the hand
that's on the uncovered skin moving too to stay close to the plastic you
are
removing. Don't pull straight up. Pull close to parallel to the skin.
Another thing you can try is to split the width of the plastic you are
removing into strips, say about 12-18 inches wide. Start pulling and
when
you get it going, grab the part that is separated from the skin and split
it
so you aren't trying to roll off a four foot wide piece. Pull at an
angle
on the left side of your strip, then follow with the right side. Keep
going
back and forth like that instead of pulling straight down on the strip
you
are removing. Hope this helps.

Mike Kimball
044SR




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Wayne G. O'Shea

Skin blemishes

Post by Wayne G. O'Shea » Sat Feb 18, 2012 11:24 am

Sounds more like MAM shear damage. All the SR flap/aileron skins I put
together have nice round dents just back from the edges, from the shear hold
down pads. Maybe that sheet had some junk under it on the punch or
shear...unless you had some dirt wrapped into the plastic as you removed it.

Blank sheet placed underneath the original "pattern", as Jim suggested, on
top of a smooth piece of plywood/press board. Hold down tightly while you
transfer the holes and cleco down tight to the board as you work from the
middle outwards in all 4 directions.

Wayne

----- Original Message -----
From: "Jesse Jenks" <jessejenks@hotmail.com>
To: <rebel-builders@dcsol.com>
Sent: Thursday, September 01, 2005 1:03 AM
Subject: Re: Skin blemishes

Thanks for the replies guys,
I would like to have hope that it would be all OK once riveted in place,
but
I really don't think so. I don't want to cringe every time I look at my
right wing. There is a pattern of small dents about 6" long that repeats
with even spacing for about half the length of the skin. It may be
possible
to burnish them out or something, so I guess I should ask around as you
say.
It looks pretty bad to me though.
The skin is already drilled to #30 along with the ribs, stringers, and
spars. If I started over with a new pre punched skin then would I just
drill
it out to #30 while off the structure and hope the holes line up? I would
be
worried that the holes I already had drilled in the structure might be
slightly misaligned with the new skin because they would have not been
enlarged from #40 to #30 at the same time. That's why I thought it would
be
better to start with a blank sheet and use the original skin as a
template.
Although I would have to drill to #30 on the first go, the holes should be
accurately located by the original skin. Also the holes around the tank
area
where the tank skin joins to the main skin are not pre punched, but where
added by me, and would not be easy to locate without using the original
skin
as a template.
Jesse
From: Jim Cole <jcole@rangroup.com>
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: Re: Skin blemishes
Date: Wed, 31 Aug 2005 22:27:34 -0400

Hi Jesse,

I wanted to extend my tanks to 5 bays from the original 3 bays so I
ordered a new piece of 6061 from a local supplier in Toronto and used
the old skin as a template. They cut it to size and I had a large table
and a piece smooth press board underneath so that I could drill through
with out worrying about it. It worked fine - especially after I bought a
cobalt #40 drill that was sharp and stayed sharp but certainly was time
consuming. I used clecos and clecoed it to the template and the table as
I progress in a sequence from one end to the other.

I'm with Bob though - check with someone with experience locally because
you just might be surprised at what can be done.

Good Luck
Jim (now rebel 333)
Hi Jesse !

Maybe you could find a nearby builder to have a look at that
skin -
it might be fixed, or not as bad as you might think ...
(optimistically
!)
Perhaps someone from the RAA chapter might have a trick or 2 ...

Hard to imagine that you'd be better off drilling your own - I
think
the CNC punch has a tolerance of less than one thousandth of an inch in
the 12 feet !!
.....bobp

-------------------------------orig.-------------------------
On Wednesday 31 August 2005 09:47 pm, Jesse Jenks wrote:

rolled
half of
but
I
the LE
duplicate
it.
to
that.
I
go
to
better
off

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