Thursday, August 2, 2012

Anti-Servo Tabs On Hold - Moving On

The anti-servo tabs are on hold waiting for rivets. As mentioned in an earlier post, my plan is to use a solid rivet wherever possible because solid rivets are stronger and lighter. Took a close look at the anti-servo tabs and decided I could squeeze rivets where the hinges attach to the anti-servo tab’s spar as long as I hold off on riveting the bottom skin to the ribs.

Using a rivet gauge, determined a 470AD4-4 rivet was just a little short and a 470AD4-5 is just a little to long. Checked the Aircraft Spruce’s WEB site and they stock some half sizes … fortunately they carry 470AD4-4.5 rivets. The anti-servo tabs will be put on hold for a few days until the 4.5 rivets arrive.

Mean while I decided to move on and get better acquainted with the stabilator's parts. Because I’m dimpling the stabilator skins for flush rivets and also trying to use solid rivets to attach ribs wherever possible, I had some home work to do. I put the spar box loosely together to get a better picture of what is going on plus reading and rereading the instructions then reading again before dimpling any parts.

After getting a better picture of the spar box assembly, I realized I would need to put dimples in four layers of material at a couple of locations so I brought out the 120 degree dimple dies and dimpled away. Because the ribs used in the spar box do not have a flat web where the lightning hole is, I discovered I could not use the pneumatic squeezer to make the dimples…the small taper near the hole prevented the squeezer from sitting square on the hole to be dimpled.  Fortunately, I had the dimple die set that can be used with a hand rivet squeezer to dimple the two outer ribs of the spar box.
Setup for dimpling the two outer spar box ribs using the hand riveter to make the necessary dimples. If you look at the photo closely one can see the taper on the lightening hole that prevented the pneumatic squeezer from getting a square fit.
                                 The finished dimple with a countersunk rivet sitting nice and flush. Amazingly,
                                 the dimple dies designed for use with a hand squeezer make nice dimples.