Matt's RV-7 Project

The rest of this weekend was spent deburring and dimpling the rudder parts. Here's a shot of my solution for how to dimple the aftmost holes in R-903… pop rivet dimple dies with the nail inserted from the outside, and washers to take up the gap:

The lead brick is attached to the counterweight rib with #10 screws. Dimple dies for a screw that big can be expensive, so some builders use their #8 dies and mash the screw in there to expand the dimple. That sounded like an opportunity for a stress riser and an eventual crack to me, so I found some cheap #10 dimple dies on eBay and used them to make the proper dimple. No big deal. The lead then is countersunk to fit the dimple – it's soft enough that I was able to use my deburring tool to do it.

Here are the old and new rudder horn braces. The new one is on the right – notice how much extra edge distance there is if you don't trim along the prepunched guide holes. I used my Dremel tool to make little stress-relieving scallops where the guide holes were.

What's this? It's the R-710 rudder brace I trimmed and installed on Monday. Notice the unacceptably small edge distance on the brace-to-skin rivet holes. I did some web searching and found that it's common to have this problem if you follow the plans and trim along the prepunched guide holes. Would have been nice to have this pointed out in the instructions – "Trim the R-710 rudder brace, but not as shown on the plans!" – but I guess since it's only a nine dollar part it's not the worst thing ever to replace it. Too bad it won't arrive till next week sometime… Van's has good prices and service but sometime it seems like it takes an eternity to receive an order.