Page 1 of 1

Chromate/Building questions

Posted: Fri Feb 17, 2012 5:26 pm
by Ryan Amendala
All,

Just picked up our kit (Rebel #669) this weekend (can you see the huge smile
on my face) and have been reading ahead in the manual with some questions:

1: Chromate. Apparently an overlooked item by us. We were surprised not
to see it in our kit. Can you buy this form local auto paint shops or do
you have to order it?

2. Salt Water application. I have read some archives on this. Seems as
though some people dip every rivet and spray the inside of panels with
chromate for heavy salt water use. My question is then, Do you spray the
inside of EVERY panel before assembly including the entire inside of the
wing (excluding tanks), ailerons, elevators...? If so do you spray say the
top skin before you put in on and then let it dry or do you apply chromate
and immediately install top skin? We do not plan on painting the outside at
this time we are trying to save on weight.

3. Elevator/stab construction: Reading this I was wondering if it is a
good idea to build the stab before installing the elevator tip? The
instructions say to make sure that the leading edge of the stab should be
even with elevator tip but if you follow instructions you do not have a
leading edge to reference to.

All parts have been inventoried, building starts as soon as we get our tools
from ATS.

Thanks in advance

BB&R Amendala
Rebel #669
Long EZ N666BA

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

Chromate/Building questions

Posted: Fri Feb 17, 2012 5:26 pm
by Bob Patterson
The fun begins !!

I'm surprised ! I thought the epoxy chromate was included with the kit.
I know that they now ship the Pro-Seal later, when you are ready for it -
just ask.

You should use Polyfibre Epoxy Chromate. DO <NOT> use spray bombs of
"primer", etc. - You will find LOTS of comment about epoxy chromate by
searching the mail archives at www.dcsol.com/murphy-rebel by subject !!
The epoxy chromate is available from Murphy, as well as Aircraft Spruce,
and most aircraft supply houses.

Salt water or not, the proper construction method is to brush the
epoxy onto both sides and put together while wet, whenever joining 2 pieces
of metal. Spraying the whole sheet can be done afterward, but can add a
LOT of weight unless you are very careful. Most people spray 'way too
thick -
the film of spray should be thin enough so you could read the lettering on
the aluminum. Any more, and it can crack & flake off.

There are several other, easier and less toxic, ways to protect the
large surfaces later, if you need to. Boeing D-25, or Northern Shield,
are both protectors that you can spray in as a mist AFTER construction.
They both spread out to cover all surfaces, and then harden into a waxy
permanent protection. (The D-25 is a 2 part effort, requiring a spray
of hardener after a day or so ...) And there are others. I wouldn't
worry too much about the large surfaces, as long as the joints are safe.

All of the rivets are dipped in epoxy before installing them - just
a bit (1/8") at the bottom. This seals around the rivet & pulls up around
the mandrel as well. Too much epoxy will glue up your rivet gun ! :-(

Most people don't install elevator or rudder or wing tips until
final assembly time - prevents damage, among other things. You are on the
right track !! Generally, don't rivet until you're SURE that all steps
have been completed. Generally, leave one side open - especially on the
fuselage, until you really are ALL done ! It makes it so much easier to
get in there later...

If you haven't already seen them, consider buying the tail & wing
tips from Dave Fife - they look great, will save you at least 40 -60 hours
of work, and will improve performance ! (over 20% reduction in takeoff
distance, and about 2 mph on both ends of the speed range !).
Dave is at: 3D Composite Aircraft Parts Inc., and his email is:
Aircrafttips@yahoo.com

Have fun !!

.....bobp
-----------------------------orig.--------------------------------------
At 08:31 AM 9/27/99 PDT, you wrote:
All,

Just picked up our kit (Rebel #669) this weekend (can you see the huge
smile
on my face) and have been reading ahead in the manual with some questions:

1: Chromate. Apparently an overlooked item by us. We were surprised not
to see it in our kit. Can you buy this form local auto paint shops or do
you have to order it?

2. Salt Water application. I have read some archives on this. Seems as
though some people dip every rivet and spray the inside of panels with
chromate for heavy salt water use. My question is then, Do you spray the
inside of EVERY panel before assembly including the entire inside of the
wing (excluding tanks), ailerons, elevators...? If so do you spray say the
top skin before you put in on and then let it dry or do you apply chromate
and immediately install top skin? We do not plan on painting the outside
at
this time we are trying to save on weight.

3. Elevator/stab construction: Reading this I was wondering if it is a
good idea to build the stab before installing the elevator tip? The
instructions say to make sure that the leading edge of the stab should be
even with elevator tip but if you follow instructions you do not have a
leading edge to reference to.

All parts have been inventoried, building starts as soon as we get our
tools
from ATS.

Thanks in advance

BB&R Amendala
Rebel #669
Long EZ N666BA

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
*----------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*----------------------------------------------------*



Chromate/Building questions

Posted: Fri Feb 17, 2012 5:26 pm
by David Ricker
Hi Ryan

Welcome to the "Rebels in progress" clan!

Corrosion protection is a key issue with many Rebel builders and leads to
plenty
of spirited discussion and even differeing opinions, I'll toss mine out here
to
start the thread and let the others join in. When we started our Elite we
faced
this issue and eventually settled on a paint system from Dupont availible at
your local auto part jobber. Our road to this choice is outlined below.

CHEMICAL TREATMENT:

According to best information, aluminum parts should be treated by a
"chromic
conversion coating" process. These are chemical processes
which leave a gold tint (actually a thin oxide layer) on the bare aluminum.
It
is more resistant to corrosion and paint sticks better. These are
known by trade names such as "Alodyne" and "Irridite". These materials are
availible in bulk, unmixed (airplane size) quantities from industrial
distributors and premixed in smaller quantities from automotive body repair
supply dealers (UAP, Autopro). This treatment is then covered by some
primer/paint treatment.

When you talk to the industrial distributors for bulk chromic conversion
coating
materials they do not really want to discuss the material if you are not a
licensed facility because handling the chemicls and disposal of the waste
products is regulated. This is a clear indication that it is not worth the
trouble to do this process in the home shop. We eventually found a shop who
offered this process to the "public". We had some parts treated but since
that
time they have closed the business and moved. Because they have closed and
we
do not want to do this process in our shop we will not treat any more parts
this
way.

PRIMERS:

Traditionally, aircraft manufacturers used zinc chromate primer for
aluminum.
This zinc chromate primer is said to be carcinogenic (!) and some
have said now that newer epoxy paints are better. I spoke to a facility
which
repairs military aircraft who said they no longer use this type of
product due to the health and environmental hazzards. I spoke to a
manufacturer
of floats who does not use this material either.

The favored materials seem to be epoxy primers, some with and some without
chromate in the paint. The military aircraft repair facility uses
alodyne then the epoxy primer and then a polyurethane top coat. I can give
you
specific information if you want it.

We eventually chose a material from Dupont called Corlar 810R. This is an
etching wash primer containing chromate and is availible
from automotive body repair supply dealers. On the data sheet it
specifically
says treatment with chromic conversion coatings prior to priming
is not required. The float maker I spoke to and a light aircraft paint shop
I
spoke to both use 810R. Dupont recommend covering this material with a high
solids primer called 1020R or 1044R. The difference between these is only
color. We plan to use another compatible Dupont top coat called Imron. It
is
said to be important to choose one manufacturer of paint products and stick
with
a compatible "system" within that manufacturer to ensure the paint will stay
where it is put!

Dupont also have a version (820R) which requires chromic conversion coating
prior to priming.

A side comment. In this forum you will get many opinions
including that you should use the green epoxy which comes with the kit and
use
it to "glue" pieces when you rivet them together. We chose to
not do this for a number of reasons. First, while the material is an epoxy
primer it does not state on the package that it is a chromate and if I
recall
corectly I spoke to the factory and they confirmed this but I am not 100%
certain. It also does not etch the base material for adhesion like the
Corlar.
Finally, it is not readily availible like the Dupont products.

We made our decisions based on this information including consultation with
the
Dupont Tech. center and local aircraft refinishing resources, if you find
better
information, we would like to hear about it also.

By the way, I spoke to someone at Cessna, he told me that they do chromic
conversion coating and priming of all piece parts prior to assembly
for their light aircraft (172 etc.). I did not ask what they do to keep
water
from entering through the seams, that would seem to be an important
concern that we have not addressed yet. Our local EAA chapter "guru"
suggests
applying Proseal/PRC after assembly as he did on his RV-4.
I suspect somthing like the more liquid pro-seal or other type of material
would
be useful if "painted" on the seams just prior to assembly. Perhaps
automotive
seam sealer applied during or after assembly would be good. It could be
wiped
off until just a small amount was left to seal the joint.

SHOP PRACTICE:

When we apply these primers we do it using a spray gun in our garage and
remove
the vapors with a powerful fan. The fan actually lowers the
pressure inside the garage so that fresh air is forced in. We also use a
fresh
air system (a hose from the output of a shop vacuum cleaner located in an
area
of fresh air) to provide clean air to breathe (inside a hood) for the person
painting. This is MOST important because the normal "painting gas masks" do
NOT
filter the isocyanates from the fumes of the paint. Isocyanates are part of
most epoxy or two part paints and are very serious! This is the same basic
material you find in Crazy glue etc.

The vendor of each of these materials, when requested, MUST provide you with
a
Material Safety Data Sheet (MSDS) describing toxicicity
and handling information. These will permit you to understand safety of
these
materials.

Back to the rivet question, we dip each (and every !!) rivet in Corlar (not
quite up to the bottom of the head) prior to installation and install wet.
theory being that the wet paint will go into all the gaps of the joint.
Don't
forget though that you still have the end of the steel mandrel exposed to
the
atmosphere (although down in the hole in the rivet), it will need to be
treated
in some way such as your external primer/top coat.

On painting the inside of everything, we are doing that (and assembling dry
like
Cessna) but don't do the insides of the fuel tanks or anywhere the sealer
(proseal) will be applied. We haven't gotten that far but those that have
will
be clear to tell you that you don't want to chance the proseal not sticking.

On your elevator/stabilizer question I will let the Rebel builders comment
on
this since our Rebel is an Elite and is built differently.

Well, that is about it for now, hope this is helpful in getting you ahead on
your decision making!

Dave R.

Ryan Amendala wrote:
All,

Just picked up our kit (Rebel #669) this weekend (can you see the huge
smile
on my face) and have been reading ahead in the manual with some questions:

1: Chromate. Apparently an overlooked item by us. We were surprised not
to see it in our kit. Can you buy this form local auto paint shops or do
you have to order it?

2. Salt Water application. I have read some archives on this. Seems as
though some people dip every rivet and spray the inside of panels with
chromate for heavy salt water use. My question is then, Do you spray the
inside of EVERY panel before assembly including the entire inside of the
wing (excluding tanks), ailerons, elevators...? If so do you spray say
the
top skin before you put in on and then let it dry or do you apply chromate
and immediately install top skin? We do not plan on painting the outside
at
this time we are trying to save on weight.

3. Elevator/stab construction: Reading this I was wondering if it is a
good idea to build the stab before installing the elevator tip? The
instructions say to make sure that the leading edge of the stab should be
even with elevator tip but if you follow instructions you do not have a
leading edge to reference to.

All parts have been inventoried, building starts as soon as we get our
tools
from ATS.

Thanks in advance

BB&R Amendala
Rebel #669
Long EZ N666BA

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
*----------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*----------------------------------------------------*
--
David A. Ricker P. Eng.
Nova Scotia
Canada

Chromate/Building questions

Posted: Fri Feb 17, 2012 5:26 pm
by mike.davis
Received: from aws1.bp.nrl.navy.mil [132.250.13.17]
(HELO localhost)
by alpha1.tf.bp.nrl.navy.mil (AltaVista Mail V2.0J/2.0J BL25J listener)
id 0000_0055_37f3_4118_29f2;
Thu, 30 Sep 1999 06:53:12 -0400
Received: from NTW1 (192.168.0.179)
by axp1.tf.bp.nrl.navy.mil (V5.0A-1, OpenVMS V7.2 Alpha);
Thu, 30 Sep 1999 10:53:47 +0000
Message-ID: <00aa01bf0b32$65fbbbd0$b300a8c0@tf.bp.nrl.navy.mil>
From: "Mike Davis" <mike.davis@dcsol.com>
To: "Murphy Rebel Builders List" <murphy-rebel@dcsol.com>
References: <19990927153116.16621.qmail@hotmail.com>
<37EFE4CB.37D1148F@dbis.ns.ca>

<005201bf0a6f$40041440$b300a8c0@tf.bp.nrl.navy.mil>
<37F1FAE2.1D9CB651@dbis.ns.ca>
Subject: Re: Chromate/Building questions
Date: Thu, 30 Sep 1999 06:56:06 -0400
MIME-Version: 1.0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 5.00.2014.211
X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211

I'm not sure what it is they're using now... I'm an avionics type, and only
went to the paint school because I had the opportunity, and I knew way back
then that I wanted to build my own plane someday! I've never actually
worked in the paint shop, so I'm not sure what they're using. I'm still in
the reserves, and I drill this weekend, so I'll try and remember to ask.
I'm pretty sure that they still use chromate to prime all metal surfaces,
but I'll check on that too.

Mike

----- Original Message -----
From: David Ricker <ricker@dbis.ns.ca>
To: (Murphy Rebel Builders List) <murphy-rebel@dcsol.com>
Sent: Wednesday, September 29, 1999 7:41 AM
Subject: Re: Chromate/Building questions

Mike

Since the military phased out isocyanates in '92, what have they moved
over to?
Dave R.

Mike Davis wrote:
I just wanted to comment on the Isocyanates mentioned in this message.
When
I went to aircraft paint school in the military we were still using
paints
with Isocyanates, so we covered the hazards in detail... the bottom line
is
the molecules are shaped like an S, and this causes them to embed into
your
lung tissues, and not come out... ever! It's like a double headed fish
hook. The military stopped all use of Isocyanates in about 1992 because
of
the health hazards. As mentioned below, if you use Isocyanates, it is
imperative that you use a "Fresh Air" ventilation system. A "Filter"
type
mask just isn't good enough.

Mike

----- Original Message -----
From: David Ricker <ricker@dbis.ns.ca>
To: (Murphy Rebel Builders List) <murphy-rebel@dcsol.com>
Sent: Monday, September 27, 1999 5:42 PM
Subject: Re: Chromate/Building questions
When we apply these primers we do it using a spray gun in our garage
and
remove
the vapors with a powerful fan. The fan actually lowers the
pressure inside the garage so that fresh air is forced in. We also
use a
fresh
air system (a hose from the output of a shop vacuum cleaner located in
an
area
of fresh air) to provide clean air to breathe (inside a hood) for the
person
painting. This is MOST important because the normal "painting gas
masks"
do NOT
filter the isocyanates from the fumes of the paint. Isocyanates are
part
of
most epoxy or two part paints and are very serious! This is the same
basic
material you find in Crazy glue etc.
*----------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*----------------------------------------------------*
*----------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*----------------------------------------------------*