I’ve finished dimpling all of the HS ribs. I started using the 1-inch Scotch-Brite light deburring wheel in a cordless drill to finish off the deburring of the holes in the ribs. Compared to the tools I have been using to debur holes I like this method a lot better. Unless someone tells me this is a terrible idea I think I”ll stick with it.
I also started to countersink the stringers and ran into a couple issues. Some of the holes got countersunk way too far because the countersink cage adjustment came loose without me realizing it. I’ll make sure I tighten it better from now on and will also recheck it regularly while I use it.
The other problem I encountered was the countersink bit cutting it’s way through the part, starting to turn the hole into a line. I think this happened because the part is thin enough that the ends of the cutting parts of the countersink bit extend just far enough down the pilot of the bit to cut into the side of the hole. Here is a picture of the back side of one of the holes I messed up when I was countersinking it.
I decided to spend some time practicing on scrap parts of the same thickness and found that I’m not very good at stopping the bit from moving sideways through the part. Typically I use a 3-flute countersink bit but I do have one single flute bit from the tools I am borrowing from a friend. I decided to give this one a try to see if I had the same trouble with it, and I was happy to find out that it didn’t seem to want to start cutting sideways at all. Even pushing directly on the side of the tool while it was cutting didn’t cause it to cut sideways through the hole so I ordered one of these in the size I need.
I can still use the 3-flute bits that I have but I’ll need to back up the part with a block of wood or something with a hole for the pilot bit to extend into and clamp it in place so that the bit can’t move sideways at all. Or I could just put it in my drill press.