Left Elevator Dimpling

Tonight’s goal was to get through most of the remaining scuffing, deburring, and dimpling so I can hopefully prime parts tomorrow.  Scuffing prior to dimpling is definitely a lot easier than doing it after dimpling. For large parts, I found that using my random orbit sander with a scotch brite pad made the work even quicker and a whole lot less tiresome.  This method takes the shine off of the aluminum in just a few seconds vs minutes of manual scuffing.

Once all of the parts were scuffed, I moved on to dimpling.  I got everything done except for the skin, which I’ll have to tackle tomorrow.

I ended up needing to modify my #30 dimpling die. I’d always heard that at some point you will need to grind off metal of various tools. The problem was that the #30 female die was so large that it hit the radiused edge in the flange of the rib I was working on. Not only would it leave a little divot in the flange angle, but it would also bend the flange out beyond the 90 degrees it needs to be at. I ground down one edge and rounded it off so it would clear the rib flange/web radius.  I hate doing this to such a high quality tool, but there was just no way around it, and it still does the job it’s designed to do.

The last thing I did tonight was countersink the top edge of the trim tab spar.  I’m a little torn on how this turned out and will probably contact Van’s on Monday to see if it’s ok or if I need to replace the part and try again.  The reason this part gets countersunk vs dimpled is because it needs to be flat on the bottom side for the interface with the trim tab hinge. A dimple wouldn’t allow the hinge to sit flat.  The problem is this spar is made of very thin aluminum, so by the time the countersink is big enough to accept the skin dimple, the hole is far larger than what it should be for the specified rivet.  That’s okay to a certain extent, but I think the holes might have gotten bigger than is acceptable. That’s because I didn’t back up the material with a piece of wood to allow the pilot of the countersink bit to stay centered. I got a lot of chatter and some oblong holes. The ones in the picture are actually the better ones. There are some that are really ugly.  So we’ll see what Van’s says. It may be okay simply because this piece is getting sandwiched between two other pieces during riveting. I’ll let them weigh in.  It’s a cheap part if I need to replace it and try again.