Step 12: Drill the metal angle brackets
Summary: In each angle bracket, drill or widen one hole for an axle and enlarge two holes for screws or bolts.
- one Simpson GA2 and two Simpson A34 angle brackets, or equivalent.
- cutting oil.
The angle brackets need holes for wheel axles. On the wide face of each A34 bracket, drill a 13/32" hole, more or less centered.
The GA2's center hole is perfectly located for widening. If your propeller wheel has a hollow axle and a quick-release skewer, drill out the GA2 center hole only to fit the skewer, 13/64". Otherwise, widen it to 13/32", to fit the axle.
The A34s already have holes suitable for screws. On the GA2, on the other face from the axle hole, widen the top and bottom holes to 3/16".
If you're not experienced in drilling through sheet metal:
- Make a dimple where the hole is to be, using a hammer and a centerpunch or large nail.
- Drill a small-diameter hole first, then enlarge it with larger bits.
- Keep the bit tip wet with cutting oil (or 3-in-1 or WD-40 as a second choice) to ease the work and save drill bits.
The best tool for enlarging is a step drill bit, and this project is a good excuse for buying one. If you're undertaking this job with just twist drill bits, use a sequence of larger and larger bits, drilling from both sides of the metal alternately. Keep your vise jaws tight and maintain a good grip on your drill.