[jmitchell]

Hello everyone,

I am working on a standard build RV-8 kit. (Matched hole).

On page 8-13 (12/02/08 version) of the manual there is a step that calls for "breaking the edge" of F-826-1 center bottom skin so it sits tight with the adjacent bottom skin (F-827-1).

I just can't see this as necessary. You see from the picture the two skins overlap at a very flat angle. Am I missing something here?

Just thought I would put it out there before I check it off.

Thanks kindly for your time.

 

[chaskuss]

Cleaning up skin edges

Jeff,
I might be wrong, but I believe they simply want you to polish the edges of the skin, using either your 6" ScotchBrite wheel or a 2" diameter ScotchBrite disc, mounted on the Roloc mandrel. I always polished the edges of ALL the skins on my 8A. Sometimes, when the skins are sheared, a slight lip is left on the edge. This will prevent the skins from sitting flat against one another.
From your photos, it appears that the edges of the skins are raw (ie, in "as received" condition) It is good practice to deburr or polish all edges using either the above mentioned ScotchBrite methods or a Dove Tail type edge scraper. See

http://www.averytools.com/pc-76-43-6-scotchbrite-cutting-and-polishing-wheel.aspx

http://www.averytools.com/pc-1032-43-scotch--brite-surface-conditioning-disc-kit--2.aspx

http://www.averytools.com/pc-769-43-dove-tail-edge-breakerdeburring-tool.aspx




Charlie Kuss

 

[Mel]

Jeff,
The purpose of "breaking" the edges of skins is to keep the edges from pitching up when you rivet. When you rivet, the edges of the outer skin will tend to pitch up slightly. Breading the edges down will prevent this. It will make a much nicer looking joint.

 

[Rick6a]

You see from the picture the two skins overlap at a very flat angle. Am I missing something here?....

Jim,

Although the skins lie flat now, there is a fair chance some unsightly gap will develop as the rivets are set. The degree of gap can vary from none to severe depending upon material thickness, e.d., builder technique in setting the shop head of the rivets, and length/hardness of the rivets. A slightly longer rivet than is necessary will likely increase the chances of a gap developing along the skin.

By simply using an edge rolling tool as shown below, I personally prefer the small wheel type on the left, you will greatly reduce the chances of a gap developing and is recommended practice by this builder for use on both lap (as your photo shows) and butt joints (where two skins meet edge to edge).

 

[jmitchell]

Thanks so much for the quick replies!

This forum is invaluable.

Of course you are right about bending the edge of a skin that joins another with a lap joint.

I'm not sure why this didn?t occur to me. I have just such a tool, and have used it earlier in the building process! Thanks for reminding me.

P.S. The edges of the two skins in my image I posted with the original question have not been deburred or polished yet. I make sure this is done on every edge of every piece before assembly.

Thanks again, bye for now?

 

[klovning]

the diheadral

The dihedral of the airplane's fuse is part of one of the bulkheads that is attached to the bootom skins.

When clecoed they just overlap, when riveted, without a small bend, there'd probably be a small gap....