Or you can hand-spin a narrow countersink bit. It's pretty easy to cut a short wooden dowel and drill it to accept the bit. The shank will pretty much tap itself into the dowel and, if you want to be fancy, you can dip the other end in plastic. Keep it short because it not only needs to fit into the spar but some flanges are also angled inward so a longer handle/bit combo can find itself interfering with the spar web. Don't worry about sturdiness; deburring aluminum is not an industrial strength operation. Most people over-do it.
__________________
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
EAA Technical Counselor #5357
|