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View Full Version : A Little Bit of Varnish Might have been Nice


rwanttaja
05-15-2018, 05:07 PM
This is one of about ~16 #8 machine screws that go through the wooden top longerons to attach the metal that forms the top of the forward fuselage (in front of the cockpit). It was removed about ~30 years after the initial installation.

Due to the moisture content of wood, it is recommended that all bolt holes be coated with varnish to minimize corrosion. Like this.

Looks bad, but it wasn't much effort to remove, and I don't think the strength was greatly affected.

http://www.bowersflybaby.com/tech/screw.jpg

Ron "Rusty" Wanttaja
conodeuce
05-15-2018, 10:54 PM
Are the screws dipped in varnish before inserting?
rwanttaja
05-16-2018, 01:13 AM
That, or a small brush is used to coat the hole through the wood. Wood has a ~12% moisture content, so if it's in solid contact with metal, corrosion can occur.

Mind you, I didn't add varnish to the holes when I replaced the bolts. I figure in another 30 years, someone can cuss ME out....

Ron Wanttaja
Frank Giger
05-16-2018, 01:55 PM
After 30 years, that may in fact be an example of minimized corrosion!
Tralika
05-21-2018, 09:51 AM
What about using stainless hardware that contacts the wood?
rwanttaja
05-21-2018, 10:38 AM
What about using stainless hardware that contacts the wood?
Certainly. But varnish is cheaper. :-)

Ron "Squeezing a nickel so hard that Jefferson's head is coming out the buffalo's ***" Wanttaja
Sam Buchanan
05-21-2018, 01:07 PM
What about using stainless hardware that contacts the wood?

Most stainless hardware isn't as strong as AN cad-plated steel fasteners.