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  #11  
Old 03-24-2021, 02:41 PM
jrock836's Avatar
jrock836 jrock836 is offline
 
Join Date: Nov 2020
Location: Burleson, Texas
Posts: 189
Default

Thanks for the input guys.. I can now see there's not a widely used method used by most of you guys.. Guess I will just play around with it and see what I can come up with that does a better job of protecting the paint and hopefully looks decent..

Cheers!
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Joe
Van's RV-12 #120566 - ELSA - N49DD
Hawkins Field (35TT ) Godley, TEXAS!


LSRI-A for N49DD
EAA #1409566 / AOPA Member
Private Pilot since '79!
Retired LEO - Served 28 years
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PADI Master Scuba Instructor / SDI OW Instructor
Scuba Equipment Technician (PT Retirement Job)

If you can walk away from a landing, its a good landing. If you can use the aircraft the next day, its an outstanding landing. Chuck Yeager

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Last edited by jrock836 : 03-24-2021 at 02:49 PM.
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  #12  
Old 03-25-2021, 04:11 AM
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I-TERA I-TERA is offline
 
Join Date: Jan 2014
Location: legnano (milan) italy
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Hi Joe,
I looked for washers that would allow to withstand radial and axial loads without deforming the substrate (fiberglass), but without success. For the axial load the washer must compress the fiberglass and for the radial load the washer must enter the fiberglass with a cylindrical, not conical hole, to avoid deformations and fractures.
Finally I decided to make some special turned washers, and make a tool to prepare the hole in the fairing in correspondence with the fixing hole. The installed washers are glued (epoxy) and painted. So far (4 years) they hold very well and the fairings still adhere without deformation or fractures.
Here the link to the images.
https://www.dropbox.com/sh/49ialxn7q...QGuvddEca?dl=0
Claudio
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  #13  
Old 03-25-2021, 04:36 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 9,947
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Quote:
Originally Posted by jrock836 View Post
My upper cowling has cracks and paint damage, mostly around the Phillips head screws....Has anyone found a better washer/screw combo to use that will protect the paint and distribute the load better than the little plastic washers under the phillips screw head?
Curiouser and curiouser.

I think the question here is why you're getting cracks and paint damage under nylon washers and AN526 screws. It's not the washer and screw choice, which are structurally superior to tinnermans. It more likely goes back to prep and paint choices.

Look at the back side of the panel. Do the cracks extend through the fiberglass? Now look close at the painted side. Are the cracks in the paint only?
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  #14  
Old 03-25-2021, 04:46 AM
thiggins thiggins is offline
 
Join Date: Mar 2020
Location: Saluda,NC
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Quote:
Originally Posted by I-TERA View Post
Hi Joe,
I looked for washers that would allow to withstand radial and axial loads without deforming the substrate (fiberglass), but without success. For the axial load the washer must compress the fiberglass and for the radial load the washer must enter the fiberglass with a cylindrical, not conical hole, to avoid deformations and fractures.
Finally I decided to make some special turned washers, and make a tool to prepare the hole in the fairing in correspondence with the fixing hole. The installed washers are glued (epoxy) and painted. So far (4 years) they hold very well and the fairings still adhere without deformation or fractures.
Here the link to the images.
https://www.dropbox.com/sh/49ialxn7q...QGuvddEca?dl=0
Claudio
I cant believe Im saying this, but those are some beautiful washers. Too bad no one produces them. Really spiffy.
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  #15  
Old 03-25-2021, 07:24 AM
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ronschreck ronschreck is offline
 
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 1,666
Default Another option...

This may be an option for your cowling. I used these the secure my fuel tanks which were painted separately from the wings as I didn't want to be dealing with painted screws when removing the tanks. (Yes, tank removal is not uncommon!) They are called flush or finishing washers and can be purchased for all the screw sizes we typically use.


[url=https://www.flickr.com/photos//[/url]

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  #16  
Old 03-25-2021, 09:24 AM
jrock836's Avatar
jrock836 jrock836 is offline
 
Join Date: Nov 2020
Location: Burleson, Texas
Posts: 189
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Quote:
Originally Posted by I-TERA View Post
Hi Joe,
I looked for washers that would allow to withstand radial and axial loads without deforming the substrate (fiberglass), but without success. For the axial load the washer must compress the fiberglass and for the radial load the washer must enter the fiberglass with a cylindrical, not conical hole, to avoid deformations and fractures.
Finally I decided to make some special turned washers, and make a tool to prepare the hole in the fairing in correspondence with the fixing hole. The installed washers are glued (epoxy) and painted. So far (4 years) they hold very well and the fairings still adhere without deformation or fractures.
Here the link to the images.
https://www.dropbox.com/sh/49ialxn7q...QGuvddEca?dl=0
Claudio
Wow, those are beautiful!
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Joe
Van's RV-12 #120566 - ELSA - N49DD
Hawkins Field (35TT ) Godley, TEXAS!


LSRI-A for N49DD
EAA #1409566 / AOPA Member
Private Pilot since '79!
Retired LEO - Served 28 years
Honorably Discharged USNR - MA2
PADI Master Scuba Instructor / SDI OW Instructor
Scuba Equipment Technician (PT Retirement Job)

If you can walk away from a landing, its a good landing. If you can use the aircraft the next day, its an outstanding landing. Chuck Yeager

DONATED
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  #17  
Old 03-25-2021, 03:06 PM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,377
Default

Nickel Plated Flat Washer - Does that have 100 deg countersink to match aviation flat head screw?

Where to buy / PN?
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
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1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 650

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #18  
Old 03-25-2021, 06:01 PM
skydiverlv skydiverlv is offline
 
Join Date: Jul 2008
Location: kansas
Posts: 346
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Wicks Aircraft Supply.
I use these on my spinner
https://www.wicksaircraft.com/shop/6...hoCGbEQAvD_BwE
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  #19  
Old 03-25-2021, 09:04 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 3,025
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The only countersunk screws on my cowling are for the upper cowling attachment pin retainer plate. Everything else uses #8 round head machine screws with flat washers. No cracks after 9 years and just shy of 1100 hours.
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  #20  
Old 03-26-2021, 05:58 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 5,889
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Quote:
Originally Posted by ronschreck View Post
This may be an option for your cowling. I used these the secure my fuel tanks which were painted separately from the wings as I didn't want to be dealing with painted screws when removing the tanks. (Yes, tank removal is not uncommon!) They are called flush or finishing washers and can be purchased for all the screw sizes we typically use.
Hey, Ron, I have a box of these washers and never discovered the perfect use for them, but- just this week (first 'annual' since paint) got some paint turn-out with my screws (@#$%^&). Will these stick to the paint and prevent that post paint?
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RV-7
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I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.

Last edited by BillL : 03-26-2021 at 06:01 PM.
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