SMR
Entropy Demonstrator
- Joined
- May 15, 2009
- Messages
- 2,134
- Reaction score
- 171
Before I can proceed with the chassis frame, I need to confirm the distance between the upper "axle" and the lower "uplock" of the truss. I am using a TR-4081 (3 meter) segment of F33 Global triangular truss, which has 2" vertical tubing with 3/4" individually welded diagonal bracing. Since the truss tower has to come off the base for transport (design spec - fitting inside my 10' vee-nosed trailer), I am using Global Pro Clamps to securely attach the truss to the hinge bracket. These clamps wrap around the vertical tube which limits their position in the areas of diagonal bracing. Here is progress on the axle bracket... a 4" x 12" x 1/4" steel plate with the Pro Clamps on one side and a pair of mounted sleeve bearings on the other. The sleeve bearings allow the whole truss to rotate around a 5/8" shaft mounted on uprights of the base.
Fortunately, my dad taught me how to drill steel when I was a kid. The drill bit is a much harder steel than the steel you are drilling into, and will have no problem shaving off metal as long as it keeps its edge. Keeping the edge is where the bit needs help. Drill a pilot hole first, and keep the bit cool, using a medium oil and keeping the drill turning slow. Torque is your friend, not speed. By switching belts around on the pulleys of my drill press, I got the speed down to a leisurely 240 RPM. After holes drilled, deburred edges with a larger bit.
Fortunately, my dad taught me how to drill steel when I was a kid. The drill bit is a much harder steel than the steel you are drilling into, and will have no problem shaving off metal as long as it keeps its edge. Keeping the edge is where the bit needs help. Drill a pilot hole first, and keep the bit cool, using a medium oil and keeping the drill turning slow. Torque is your friend, not speed. By switching belts around on the pulleys of my drill press, I got the speed down to a leisurely 240 RPM. After holes drilled, deburred edges with a larger bit.