Match Drilling Of Counter Balance Arm

Between mudding kitchen walls to prep for paint, the Olympics and family obligations, not much was accomplished on the RV-12 during the weekdays this week. However, a lot of thought has gone into how to change the assembly order to best accommodate the riveting of as many components with solid rivets as possible. The spar box has been clecoed together a couple of ways during the week as a sort of dry run for the riveting process. For those builders interested, I’ll post a detailed assembly order when I get things finalized in the coming days.

In the meanwhile, began moving forward and worked on match drilling the upper and lower control horns to the spar box assembly.

                                                     Match drilling the #12 holes that will be used to bolt the
                                                     upper and lower control horns to the spar box assembly.

The counter balance assembly begins by final drilling #30 the counter balance arm sockets prior to attaching them to the spar box assembly with Clecos.

                                                   Final drilling the counter balance sockets on the drill press.

The counter balance sockets are then Clecoed to the spar box assembly 90 degrees off their normal position to facilitate easier match drilling of the counter balance arm. Next the counter balance arm is run into the front counter balance socket through the spar box and into the counter balance socket attached to the rear spar .... then clamped into position so the counter balance arm can be match drilled to the existing holes in the counter balance sockets.

Using a level on the end of the counter balance arm to match the counter balance arm to the same plane as the spar box assembly prior to drilling. Once the proper reading was established, a clamp was used to clamp the rear counter balance socket to the counter balance arm to lock the position for match drilling of the two bolt holes.

Once the counter balance arm holes are completed, the counter balance sockets are rotated 90 decrees and the parts marked for positioning so the correct part orientation can be assured during final assembly.

                                             This is the final position the counter balance assembly. Later lead
                                             weights will be attached to the end of the counter weight arm.

The spar box assembly was disassembled for deburring. Then the front spar received a little match drilling for the four doubler plates.

                                   Match drilling the front spar for the #12 and #40 holes of the four doubler plates.