Compression tube construction

[PoconoJohn]

Just to verify I understand correctly; I'll find a machine shop to take a round bar 4130 (sized to fit in the tubes), cut it into 3/4" sections (14 pieces), trim a 3/8" section from one end of each to .060, drill/tap a hole in it's center and taper/chamfer... stick it in the tube and do a weld in the 1/4" holes I'll drill in the tubes about 1/4" from the ends...no need for PEM's. Then I weld the bracket to it. Is that basically it?

Sheet 5 calls for 8 of part 5 (PEM), but looks like I would need 10 (if I were using PEM's), so either I can't add or that's a typo. I'll be using part 6 instead of part 5 PEM's. BTW, found those PEM's at McMaster http://www.mcmaster.com/#pem-style-nuts/=lvq5xp the part number is S-0524-2 (zinc plated).

What does that symbol mean that has an arrow going to where the tube attaches to the bracket? And a couple have a note to tack to place, if I'm reading it correctly.

Thanks again,

John

[dougm]

The compression tubes that utilize the threaded plugs call for the plugs to have a shoulder that matches the O.D. of the tube and is then reduced to fit the I.D. of the tube. Welding is accomplished by both plug welds and an edge weld where the shoulder on the threaded plug is welded to the end of the tube.

The PEMs are carried by McMaster Carr as you found. I made my own, but either will work. The PEMs are tacked to the bracket.

Regarding the rosette (plug) welds, AC43.13 Section 4 discusses welding and covers this. It explains how to determine the size and spacing of the plug weld based on the diameter of the tube.
( http://www.faa.gov/regulations_policies ... ntid/99861 )

Welding (like electrical) has it's own set of symbols, some of which are on the plans. Here's one link that explains some symbols. Scroll down for some diagrams.
http://www.therangerstation.com/Magazin ... ymbols.htm

[dougm]

You will also have threaded plugs of two different diameters. The ones that fit in the cabane & N struts are different than those in the compression tubes.

Here a pic of mine before they were finished...

[PoconoJohn]

Got it..thank you Doug.

[dougm]

Don't forget, you'll also have left & right hand threaded plugs.

[Nick]

Great looking jig.
On NX1279, we took a different approach. We made up the ends with just under half required tubing length. As the wings were being assembled, the tubes were Bolted to the spars then joined in the middle with a simple fishmouthed outer sleeve.
Really simplified the alignment/length issues.
Mark

Gee, I wish I'd thoughta that!

Nick