Parts Prep (Dimple, Countersink, and Shape) 2/24/23 - 0.4h This step of the build starts by deburring and dimpling the nut plate holes in the inboard wing ribs. Access is a little off for the hole deburring tool, but it is do-able with the extension. The pneumatic squeezer did a good job with the dimples. I started with the larger #19 holes, and then switched to a reduced diameter #40 dimple die that did not interfere with the larger dimples. [Hole Deburring Tools, Edge Forming Tool (Vise Grip Style), Hole and Edge Deburring Tools, 22” C-Frame with #40 Reduced Diameter, #30, and #40 Standard Diameter Dimple Dies, Pneumatic Squeezer with #40 Reduced Diameter and #8 Screw Dimple Dies] Assemble 2/26/23 - 0.3h 10/23/23 - 0.4h 10/26/23 - 0.9h 11/8/23 - 0.9h 11/9/23 - 0.7h 11/10/23 - 3.1h 11/12/23 – 1.4h 11/13/23 – 1.3h 11/15/23 – 1.3h 11/16/23 – 1.6h 11/19/23 – 4.9h 11/20/23 – 1.8h 11/21/23 – 2.3h 11/22/23 – 0.7h 11/24/23 – 1.4h 11/26/23 – 4.2h 12/01/23 – 2.7h 12/02/23 – 1.4h 12/03/23 – 0.9h 12/04/23 – 1.9h 12/08/23 – 1.7h 12/09/23 – 1.2h 12/10/23 – 2.9h 12/13/23 – 1.2h 12/15/23 – 1.2h 12/16/23 – 1.2h 12/22/23 – 0.6h 12/23/23 – 3.1h 12/24/23 – 0.8h 12/27/23 – 1.8h 12/29/23 – 1.1h 12/31/23 – 1.8h 1/6/24 – 2.3h 1/12/24 – 1.5h 1/13/24 – 3.1h 1/14/24 – 1.5h 1/27/24 – 2.5h 1/28/24 – 2.4h 2/2/24 – 2.4h 2/3/24 – 2.1h 2/4/24 – 1.8h 2/09/24 – 0.9h 2/10/24 – 2.1h 2/11/24 – 1.6h 2/15/24 – 0.5h 2/16/24 – 0.9h 2/17/24 – 1.5h ADAHRS Mounting Bracket (0.3h) The main assembly on this page is riveting the bottom skins in place, but before that happens the ADAHRS mounting bracket gets riveted to the left inboard J-Channel. A hand squeezer with a longeron yoke had good access to the rivets, and made quick work of setting them with no issues. I'll set the ADAHRS mounting bracket and J-Channel aside until I'm ready to attach the inboard wing skin. Inboard Bottom Wing Skins (39.6h) Attaching the inboard bottom wing skins is a time-consuming process. There are a lot of rivets, and access to the majority of them can be difficult. The best advice is to give some thought to setting each individual rivet, find the best bucking bar for that rivet, and be patient. I found one of the most difficult aspects of this task was ensuring the bucking bar was positioned correctly. I used the adjacent cleco in most cases to help align the bucking bar on the rivet to be set. The downside of this method is you need to inspect the rivet shop head before removing the cleco in the next hole in case you need to give the rivet a few more taps or drill it out and try again. Fortunately, I didn't have to re-do many rivets. I bought an inexpensive endoscope camera that works with my phone on Amazon to do a lot of the shop head inspection. The attached pictures of rivet shop heads were taken with that camera. I taped the camera to the end of a large paint stirring stick, and fed it through the lightening holes to take a look. The other inspection method was to push my finger against the shop head, and then measure the indentation with the rivet sizer. The area around the flap hinge has four rivets that are very close to the hinge on each side. I used the arbor from my C-Frame dimpler with a flat squeezer set to make a small diameter rivet set I could use with the rivet gun. This technique worked great for these rivets, which all set very nicely. Another tricky area is the rivets just forward of the J-Channel. The right wing was easy – I simply set the row of rivets just forward of the J-Channel before I inserted the J-Channel. That technique does not work on the left wing, though, since the ADAHRS mounting bracket is attached to the J-Channel. The small foot on my footed bucking bar was the best option to get under the J-Channel for the rivets on the left wing. Finishing the inboard bottom skins also had some challenges. Before I riveted forward of the J-Channel, I clecod the forward skin in place to check the clearance between the wing skin and the fuel tank skin along the forward wing spar. There were a couple of areas that were just a bit too long, which prevented the skin from sitting flush with the tanks. I removed the clecos, filed the edge of the inboard skin a bit and deburred, and tried again until I got a clean fit between the two skins. I completed the aileron pushrods prior to installing the bottom skins, and I really wanted to leave the push rods in place rather than trying to install them through the wing access panels after the skin was riveted to the bottom of the wing. Unfortunately, you need that space to set the bottom row of rivets on the forward wing spar flange. I reluctantly removed the pushrod so I could complete the riveting. I was concerned about damaging the rivets that were already set in the wing spar flange just forward of the ones I needed to do here, so I fabricated a “bridge” to help align the bucking bar and protect the rivets that were already set. The bridge worked really well, and I plan to use it for the outboard skins as well. It also protected the wiring that runs along the forward spar flange from the bucking bar. The final step was to set the rivets on the inboard wing rib, install the wing rib nut plates, and install the nut plates for the wing access panel. I used a hand squeezer for the inboard rib and nut plates, which worked really well. I also went ahead and installed the nut plates around the outboard wing skin access panels. Outboard Bottom Wing Skins (39.9h) The outboard bottom wing skin installation starts at the rear spar and moves forward, just like the inboard skins. The rear spar rivets are a long reach, even with the forward part of the skins pulled forward for additional access. There are also a lot of set rivets along the rear spar from previous steps (e.g. gap seals) that complicate accurate placement of the bucking bar. Fortunately, the lessons and techniques learned from the inboard skins apply to the outboard skins, which seemed to speed things up a bit. Riveting the outboard bottom skins starts with the rivets on the rear spar adjacent to the outboard flap hinge bracket. Rivet gun access is tight in this area, so I went with the small diameter flat set on the end of my C-Frame arbor. I made some rivet gun guides from several layers of duct tape to help hold the very long and narrow rivet set straight, and I drew lines parallel to the rivet set on tape affixed to both sides of the flap hinge to help line things up. That setup provided plenty of clearance for the rivet gun, and the rivets went in nicely. I continued inboard from there, but ran into a problem on the last rivet before the two skin over-lap rivets. I set my rivet gun and bucking bar just a smidgen too far inboard, and ended up with a nice ding where the outboard skin overlaps the inboard skin. After looking at the dent for about two days, I drilled out the rivet next to the dent to attempt to at least minimize the damage. I worked a lot of the dent out, but it is still visible. I decided to stop rather than risking additional damage, set a new rivet, and continued with the two skin overlap rivets on the rear spar. All three rivets went fine this time. Riveting continued along the rear spar all the way to the outboard end. I learned that I could improve my access and riveting position by standing in front of the hole rather than to the side, and using my shoulder to hold the wing skin out of the way. I also used that technique on the aft half of the wing ribs. Riveting the wing ribs stops just past where the J-Stiffener is riveted into place This makes it easy to set the rivet that will eventually fall just under the J-Stiffener, and there is still plenty of room in the wing rib channels to install the J-Stiffener even though the rivets just forward and aft of the J-Stiffener are already set. The way the plans are written implies that the overlap joint between the bottom outboard and inboard wing skins should be done last. However, I think the intent is actually to do the overlap joint at the same time as the rest of the ribs since the instruction is in the same step as the other rivets. I did the aft over-lap rivets after I installed the J-Channel on the left wing, but I set the overlap rivets on the right wing without delay and without any issues. Setting the skin overlap rivets at the same time as the rest of the rib rivets is definitely the best approach. One of the unique aspects of the left wing is the pitot mast. I saved that for the very end to avoid blocking access to other rivets along the main spar. The main spar rivets, toward the middle of the outboard section are some of the most difficult to reach on the entire skin, and any obstruction significantly complicates setting those rivets. I calculated the lengths of the rivets needed to install the pitot mast as shown below, and then riveted it in place according to the manufacturer's directions. One thing I planned to do was to put a small bead of tank sealant around the hole where the pitot mast comes through the skin to prevent water from getting in the wing at that point. I pulled out my remaining tank sealant only to find that it had turned into solid rubber about the consistency of an eraser. The old sealant went into the trash, and I proceeded without it. I'll put some silicon sealant around that area before the wing is exposed to the weather. Overall, the pitot mast installation seems solid. Rivet Length Calculation: Rivet Length (RL) = Total Material Thickness + (1.5*Rivet Diameter) Thicknesses - Spar Flange = 0.0625” = 1/16” - Pitot Mount = 0.0625” = 1/16” - Bottom Outboard Skin = 0.025” = 1/40” - Rivet Diameter (AN426AD3-?) = 0.09375” = 3/32” Pitot Mount and Skin: - RL = 0.0625” + 0.025” + (1.5 * 0.09375”) = 0.228125” = 3.65/16” - Result: AN426AD3-4 Rivet Spar, Pitot Mount, and Skin: - RL = 0.0625” + 0.0625” + 0.025” + (1.5 * 0.09375”) = 0.290625” = 4.65/16” - Result: AN426AD3-5 Rivet This page of the plans took nearly 2 years to complete start to finish. There were some significant breaks in there when I worked on other things, but this step is significant and takes time and patience. I got a lot of practice with both left-handed and right-handed riveting, and lots of callouses on my finger tips from measuring the diameter of set rivets to ensure they were set adequately. A lot of people put this step off for later in the build, which is understandable. Just don't underestimate the time and effort it will take to complete! [Hand Rivet Squeezer, 3" Squeezer Yoke, 4" Squeezer Yoke, 3x Rivet Gun, Flat Swivel Rivet Set, Small Diameter Flat Rivet Set, Rivet Set Arbors (Short and Long), Assorted Bucking Bars, Endoscope, Inspection Mirror]