I made quite the goof on Saturday. I'm embarrassed and mad at myself, but I confessed on VAF so that the next guy who screws something up doesn't feel like he's alone in the world. For the slider canopy, you start by laying out and drilling some #40 pilot holes on the aft decks. You then position the "feet" of the roll bar correctly above them, then match drill up from the bottom, then upsize the fwd holes for AN3 bolts and the aft ones for AN4. There's a note on the print that specifies that these bolts are to be as close as possible to the main longerons without actually touching them. If you lay out the holes with 100% precision, you will have 1/32 margin to play with as you bring them up to final size. Due to the difference in bolt size, the starting dimensions are different fwd/aft. Even so, it should be super simple to lay these out. The front layout is even a super easy to read 7/8" So, long story short, since there really isn't anything hard about laying this out, I was obviously not as vigilant as I should have been. I was reading my scale upside down and managed to get off 1 tic mark, so I drilled the left front pilot hole at 6/8", instead of the 7/8" it was supposed to be. I was worried about that 1/32 margin, so I hit that wrong dimension very precisely, which means that I punched a #40 hole exactly through the edge of the main longeron, and took a perfect 1/2 circle out of it about .050" deep (1/2 the diameter of a #40 drill bit). Not even enough to completely eliminate the radius, but certain parts of that longeron are a big load path and there's structure running every which way in that area, so I don't have a good sense of how the stress load paths are running i.e. is this an embarrassing annoyance, or a big deal that will require a doubler in there. Once I realized what I had done, I was able to relocate that hole to the correct location, drill the other 3 in the right spot and continue on with the trial fit of the roll bar and canopy. I emailed pictures to Vans and Sterling emailed me back this morning to let me know that Engineering is taking a look at, and as soon as they have done their engineering voodoo to see if it needs anything other than "use as is" he'll let me know. Regardless, I dusted myself off and continued on with fitting the canopy frame, to be continued in the next entry UPDATE- I got my response back from Vans yesterday (10-21-21). Given the location and the minimal size of the nick, just blend the edges and build on, with the standard caveat about keeping an eye on it for cracks. I blended with a round jewelers file. Here's a cut and paste of the email from Sterling at Vans; Hi Terry Finally heard back from engineering, see their comments below. Sterling Given that he is in between holes and the defect is so small, have him clean up the damage to remove any sharp edges to prevent crack formation and build on. He should add that as an area to inspect during condition inspections though to ensure no cracks start to form there. I understand that may be difficult given the other parts there, but it at least should be remembered. A doubler across that section would be another way to really make it the stiffest part of the whole run, but I don't think that is necessary here given the size of the damage.