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Adding Thinned Resin To INSIDE Of Cowling...

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Matt Dralle
Site Admin

Joined: 08 Nov 2005
Posts: 25704
Location: Livermore CA USA

Posted: Mon Feb 22, 2010 3:01 pm Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Greetings fellow builders,



In the manual, Van's describes a procedure of mixing some resin 1:1 with acetone to form a thin coating for the OUTSIDE of the cowling to make a filler for the pin holes and other surface imperfections.  Seems straightforward enough.



But what about the INSIDE of the cowling?  That open weave seems like its going to soak up any oil and whatnot that runs out of these leaky 'ol Lycomings. 



Thoughts?



Matt Dralle

RV-8 #82880 N998RV

http://www.mattsrv8.com Matt's RV-8 Building Blog

Finishing up...

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Matt Dralle
Matronics Email List Administrator

n801bh(at)netzero.com
Guest

Posted: Mon Feb 22, 2010 3:30 pm Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Matt. On my experimental I had the same thoughts but went ahead and layed two thick coats of paint on the inside.... You can barely see the weaving of the substrate but it will wick up oil, and any other liquid that drips on it.. if I had to do it over again I would skim coat it with something to make that surface alot smoother.. Now's the time to do it, not after it gets impregnated with oil. 

do not archive



Ben Haas

N801BH

www.haaspowerair.com



--------

rleffler

Joined: 05 Nov 2006
Posts: 680

Posted: Mon Feb 22, 2010 3:48 pm Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Just a coincidence, but I was reading an article from "27 Years of RVator"

this morning that described just that.  It talked about when they transition

to the current honeycomb cowls in which the top skins were thinner than the

original cowls.  The article recommended thinning the epoxy for fuel/oil and

adding a thin piece of insulation material for heat.



bob

--

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Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler

Rick Galati

Joined: 10 Jan 2006
Posts: 91
Location: Lake St. Louis MO.

Posted: Tue Feb 23, 2010 3:42 am Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Many builders including me, coat the inside of the cowls over a period of time using epoxy left over from other jobs.  By using epoxy that might otherwise be wasted, the inside cowl surfaces can be sealed in phases over a period of time. Some guys thin the epoxy, others don't. Occasionally I did thin it, most times I did not.  The result is a smooth sealed surface that is easily wiped clean of inevitable dirt and oils that are certain to accumulate while at the same time providing an excellent bonding surface for the sticky adhesive found on heat resistant foil that you probably will have to install anyway.  

  

 

  

 Rick Galati

 RV-6A  N307R

 RV-8    N308R

 [quote][b]

rv6n(at)optonline.net
Guest

Posted: Tue Feb 23, 2010 4:22 am Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Matt,

  

 I did the thinned epoxy smear and also made an aluminum heat shield with and air pocket under it for where I felt the exhaust was a bit too close for comfort.  I also painted the inside and applied the self adhesive foil for added protection.  I have attached a photo.

  

 Bob Bales

 RV6

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JohnInReno

Joined: 08 Sep 2007
Posts: 150

Posted: Tue Feb 23, 2010 5:53 am Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Is the self adhesive foil insulated or just reflective?

 

 John Morgensen

 RV4 - Purchased flying

 RV9A - wiring

 

 rv6n(at)optonline.net (rv6n(at)optonline.net) wrote: [quote]   Matt,

    

   I did the thinned epoxy smear and also made an aluminum heat shield with and air pocket under it for where I felt the exhaust was a bit too close for comfort.  I also painted the inside and applied the self adhesive foil for added protection.  I have attached a photo.

    

   Bob Bales

   RV6

   

  

   

    [b]

_________________
John Morgensen
RV-9A - Born on July 3, 2013
RV4 - for sale

Paul Valovich

Joined: 11 Jan 2006
Posts: 75

Posted: Tue Feb 23, 2010 6:51 am Post subject: Adding Thinned Resin To INSIDE Of Cowling...

I am just finishing-finishing my -8A cowl and have assembled a list of somewhat obvious and some “life is harder when you’re stupid” lessons learned.  

   

<![if !supportLists]>1.       <![endif]>Fitting – pretty straight forward – but remember the firewall is not straight, it has a horizontal bend in it – a bend that is hidden when the cowl is first taped in place to mark for cutting. One might forget that bend and mark and cut with a straight line. Ask me how I know! Ended up with a gap, but used epoxy/micro on the fus to fill in.  

<![if !supportLists]>2.       <![endif]>Gear leg attach – mine didn’t fit. Had to bend and cut the bracket to get it to work.   

<![if !supportLists]>3.       <![endif]>I hate piano hinges  not so much hate, but really have difficulty getting the pins to slide in and out – so I went came up with the $$ and went with Skybolt fasteners. No regrets.  

<![if !supportLists]>4.       <![endif]>If using Skybolts, pay attention and understand the fitting of the attachment strips to avoid visible gaps.  

<![if !supportLists]>5.       <![endif]>Skyboltss – really understand how to adjust the receptacle depth. Another one of those things where the RV gremlins seem to appear overnight to change what you thought was a perfect adjustment.  

<![if !supportLists]>6.       <![endif]>I installed the Skybolts, hung the cowl(s) then had to depart for  couple months on business travel. During that time some preservative oil from the engine leaked and was absorbed by the lower cowl. Painting with epoxy/acetone is a good idea.  

<![if !supportLists]>7.       <![endif]>Pinholes – friggin’ randomly appearing pinholes. Tried Vans recommended 50/50 acetone/epoxy on the outside. Looked ok with some pinholes – but when I covered with primer, it was obvious that many pinholes were still here. Ended up with multi-coats of smoothprime, second coat of epoxy, more smoothprime, hours of sanding and finally a couple coats of dark grey primer. No pinholes – but a high minutes/pinhole ratio.  

   

<![if !supportLists]>8.       <![endif]>Now on to the oil door – anyone know why Wicks charges around $11 for a Hartwell hinge, but ACS charges $80+? Obviously a difference in quality / durability – but does it matter? Anyone know of other good sources?  

   

Paul Valovich  

N192NM Reserved  

      [quote][b]

Doug Gray

Joined: 10 Jan 2006
Posts: 112
Location: Sydney, Australia

Posted: Tue Feb 23, 2010 10:48 am Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Mat,

 

 Do not thin West Systems Epoxy with acetone!  I found it turns the epoxy into a chewing gum like mass that never sets up.

 

 Use it as mixed with slow hardener and brush it on thin. Thinning was unnecessary but it can be warmed slightly to help it to flow. It is more akin to squeegee-ing  with the side of the brush.  This works very well in my opinion.

 

 I'm sure I added less than 1:1 in acetone - or perhaps the West systems product is different in this country, I don't understand why this happened with mine.  Fortunately I experimented before using it on the cowling.  	  Quote: 	
		  



Doug

	
 

 

 On Mon, 2010-02-22 at 14:57 -0800, Matt Dralle wrote:

 [quote]     --> RV-List message posted by: Matt Dralle <dralle(at)matronics.com (dralle(at)matronics.com)>

     

     

     Greetings fellow builders,

     

     In the manual, Van's describes a procedure of mixing some resin 1:1 with acetone to form a thin coating for the OUTSIDE of the cowling to make a filler for the pin holes and other surface imperfections.  Seems straightforward enough.

     

     But what about the INSIDE of the cowling?  That open weave seems like its going to soak up any oil and whatnot that runs out of these leaky 'ol Lycomings. 

     

     Thoughts?  [b]

HCRV6(at)comcast.net
Guest

Posted: Tue Feb 23, 2010 11:13 am Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Same thing happened for me when I tried to thin Tap brand epoxy with acetone.  Took me days to scrape the mess out. I wound up doing it the same way Doug describes below.



Harry Crosby

RV-6 N16CX, 662 hours



---

chuck(at)chuckdirect.com
Guest

Posted: Tue Feb 23, 2010 1:05 pm Post subject: Adding Thinned Resin To INSIDE Of Cowling...

Mix plain epoxy resin/hardner.  Lightly sand inside of cowling.  Wipe with

clean cloth soaked in alcohol. Paint on epoxy resin mix.  



Worked beautifully on both my Ten and Nine.  Move on to next step in the

building process.  

Chuck



Hi Matt,



In practical terms the fibreglass is pretty impervious to oil leaks. I just

use a bit of degreaser to wash the inside of the cowls at 100hr inspection

times and everything stays pretty clean. The extra weight of all that

additional fibreglass just isn't worth it in the long run.



If it really worries you buy an English Wheel and a TIG welder and make a

set of new cowls out of aluminium. 



Good luck



John Morrissey

Greetings fellow builders,



In the manual, Van's describes a procedure of mixing some resin 1:1 with

acetone to form a thin coating for the OUTSIDE of the cowling to make a

filler for the pin holes and other surface imperfections.  Seems

straightforward enough.



But what about the INSIDE of the cowling?  That open weave seems like its

going to soak up any oil and whatnot that runs out of these leaky 'ol

Lycomings. 



Thoughts?



Matt Dralle

RV-8 #82880 N998RV

http://www.mattsrv8.com Matt's RV-8 Building Blog

Finishing up...

rv6n(at)optonline.net
Guest

Posted: Tue Feb 23, 2010 2:05 pm Post subject: Adding Thinned Resin To INSIDE Of Cowling...

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