contersinking wing spars

A forum in which to discuss topics that are not specific to a particular series of aircraft (ie. how to cut alclad)
Post Reply
wjbruner
Class G
Posts: 11
Joined: Tue Apr 08, 2008 9:45 am

contersinking wing spars

Post by wjbruner »

I understand some builders install the #8 nutplate under the spar flange so that it can be used as a guide to countersink the flange. It appears the CS cutting flutes will engage the flange before the #30 pilot engages the nut plate. Will this cause a problem? Also, should the flange be drilled for the #8 screw prior to countersinking or does it not matter?

User avatar
Mike Balzer
Class E
Posts: 147
Joined: Tue May 20, 2008 11:18 pm
Location: Saugus, CA

Post by Mike Balzer »

You can use a scrap piece of 1/8 aluminum and when opening up the holes to the correct size drill throught the scrap piiece and then it will act as a guid for the pilot on the counter sink.

Remember that you have to go deaper then just flush with an #8 screw so that the dimple in the skin sits flush. Use a scrap piece dimpled with #8 screw to set the depth you want.

Other builders have great pictures of this and you should look at there web for more clarificaation if you need it.

Hope this helps,
Mike
It is better to be on the ground wishing you were in the air, then being in the air and wishing you were on the ground. N78MB

Spike
Chief Rivet Banger
Posts: 4013
Joined: Thu Oct 14, 2004 8:40 pm
Location: Baltimore, MD
Contact:

Post by Spike »

I did just about exactly that, except instead of aluminum I was using a hard plastic fencing type of material. Clamp it to the bottom of the spar flange, open the holes up, then countersink.

I did a whole posting sometime ago on screwing up countersinking and how to stop it.

Spike
http://www.rivetbangers.com - Now integrating web and mail!
Current Build: 2 years into a beautiful little girl

Post Reply