screw or rivet

SvingenB · #1 06-15-2011, 12:55 PM

At the trailing edge of the elevator and other hard to reach places I use cherrymax (got a ton of those from military surplus). But now it is so tight that I can't fit one on each side (CR3212-4-2) I can fit one, but not the other. I should have staggered the holes, but didn't think of it at the moment.

I guess I can use a screw/bolt, in that case what kind? or a small block of aluminium and a slug through both holes and the block?

Thanks.

terrye · #2 06-15-2011, 01:44 PM

On my RV-9A I was still able to get an AN426 flush rivet in at the trailing edges of the control surfaces, but it was really tight. I "presqueezed" the rivets in my pneumatic squeezer so that they would just go through the dimpled holes (which are bigger than the #40 drilled holes before dimpling). Then used a special "L" shaped bucking bar to set them.

Screws/bolts are going to be heavier than a rivet and will be made of steel which will corrode before an aluminum rivet will.

My recollection of Cherrymax rivets is that the installed length is longer than an AN426 rivet, so this may be limiting your ability to install either another Cherrymax or an AN426 rivet on the opposite skin.

If the rivets are really close to the trailing edge, and aligned, you might consider the way the later RV's trailing edges are made, that is with an aluminum extrusion between the skins and a single AN426 rivet installed flush on both sides.

SvingenB · #3 06-15-2011, 01:57 PM

A bucking bar problem it is - initially, any recommendations for "ultra-thin" bucking bars?

terrye · #4 06-15-2011, 04:28 PM

Make your own bucking bar. I have made several. The one I made for the trailing edge area was a 1" x 1" piece of cold rolled steel. I cut a slot at one end leaving an "L" shaped end that was about 1/8" thick that I tapered so it fit in the RH and LH ends of the control surface. Still, it was hard to use.

Do a search on this forum for close quarter bucking bars, custom bucking bars, trailing edge bucking bars.

Some people have used a bar of steel tapered on the end bolted to the bench instead of the "L" shape I describe.