Tuesday, August 30, 2011

Tech Force TF79 / AR2078A Upgrade--Part 8 Adjustable Cheek Piece

With the adjustable butt plate ready for installation, I went back to the stock for an additional change. Wanted to make a relatively simple adjustable cheek piece. Didn't have a bandsaw available and didn't want to bother anyone for a single cut. What's the worst that can happen? Taped up the stock and just made the cut with a scroll saw. Had to do only a minor amount of truing up the cut surfaces. Just to make things even easier, the rear of the piece was cut at an angle. With the thickness of the saw blade as well as the clean up on each piece, there was a gap. Found a piece of maple and the Gorilla Glue... and clamped it up. Trimmed the maple back a bit. Glued up a second piece of maple to the angled rear cut. In a huge fit of stupidity, I elected to use blind holes for the adjustment rods in the stock and cheek piece. Had I any sense, I'd have drilled from the bottom of the stock upward into the cheek piece before cutting it off. That would have aligned all the holes--but left two visible holes in the bottom of the butt stock. Blind holes require drilling four holes in two pieces and get all of them correctly aligned. As I'm working on this in my free time, it took a couple days to work out how to make this happen. After marking the butt stock, I center-punched the marks. Set a 1/8" ball bearing into each marked hole. Aligned the cheek piece and seated it firmly into the stock. The two ball bearings transferred small dimples to the cheek piece to mark the hole locations. Used a bubble level to align the bottom edge of the cheek piece. Drilled the holes with a 1/2" forstner bit. These are the holes in the cheek piece that the adjustment rods will be glued into. I didn't get any pics while drilling the butt stock. My fixture was too horrific for pictures. Essentially, I leveled the flat section in a similar manner to the above pic and drilled the holes. Uh, essentially. Cut off a couple pieces of 0.500" aluminum rod. Faced then beveled the butt stock ends The cheek piece ends were test fitted, marked for seating depth, then grooved for the eventual glue that will hold them in place. It took an evening, but a test fitting proves the cheek piece holes all line up and it slides up and down. Need to make a couple fittings to hold the cheek piece in place, then refinish the stock. Astonishing sidebar: This is the 550th posting for the blog. Congrats, Nick. As always, more soon.