Brief Description: My Formblock System - A how to (part 5)
Rib blanks are cut using a Air Nibbler from Harbor Freight (http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46061) that works great. Just place your Rib Form on your sheet metal, trace with a black sharpie and cut. I left just enough space in between my ribs to allow for the tool head plus a touch. You can easily get all 46 nose ribs out of one 4’x12’ piece of 0.025” with loads left over for many rib stiffener angles. My kitlog shows just how much metal I needed to get all 170 ribs plus spars plus angles.
1. Transfer jig pin holes to each Rib Blank a. Suggest you clamp form to rib blank (on top of another backing board to drill into) b. Drill one hole c. Insert bolt (AN3 or equivalent) into hole to stop any misalignment (ask me how I know about this) d. Drill other hole e. Repeat 45 more times (for nose ribs) i. NOTE: exact jig pin hole placement is important to my system as the router blocks and the lightening hole jigs all use these holes 2. Clamp three rib blanks in between upper and lower layers of router blocks using 2” long bolts and nuts. Ensure that bolt head is below lower layer surface. 3. Using a Unibit, drill a large router bit entry hole at the EDGE of the lightening hole area. See kitlog for details. 4. I used a 1/2” diameter, 1/2” shank, 1” long router bit to rout my ribs 3 at a time a. Plan on some sort of chip retention as this will create “the Mother Of All Messes” 5. Rout away. Be warned though: the chips are sharp and hot all at once. I had to break one of my cardinal rules about shop safety and used gloves while using a spinning tool. Extra caution and attention is required throughout this whole process!
As I was writing this I got laughing. I explained to my wife that when I put all the steps that I take down, I sound like a nut! “If the shoe fits…” was her response. Thanks a lot, Hon. LOL
So, I hope I haven’t overwhelmed you with my method. Feel free to contact me anytime to share Bearhawk ideas!
