RAIL GUN: linear slide ram shooter

[RRLedford]

Team 3135 has nearly completed our prototype linear ram shooter --- just a trigger cylinder needed, and removing excess length wherever possible. It is structured with slotted framing and uses a unique and largely unknown 80/20 nylon bearing slide element pictured below.

The backbone is a 2" x 1" 80/20 segment, that will end up 24-28" long once we remove the excess length. It is a high force, hybrid pneumatic & surgical tubing system that has two slider blocks on the top. To one block is mounted the ram, and to the other is mounted the retractor/latch/trigger assembly.
Needed force required at least dual surgical tubing elements for ram power, and we needed minimum torque applied onto the slider, so we went with a bilaterally powered scheme of surgical tubing and high tech cord wrapped on pulleys to limit length.

Once we realized that it was primarily just hitting peak ram/ball speed during stroke engagement (not launch force or ram momentum) that gave best shots, we minimized the ram weight (dropping down to 20x20mm frame) and shortened the stroke (10" now and headed for 8" we expect). The ball starts right up against the ram tip too.

Surgical tubing is 1/8" ID by 5/8" OD with ~8* of stretch zone and is prestretched by ~6" at the full stroke extended point, with the retracted & ready to shoot position taking the surgical tubing near to 22" stretched, close to the 3X max. recommended extension. Tubing ends are 1/4" H/W, and tricky to keep from pulling out at near 3X stretch levels.

We were planning to do a variable power gearmotor winder scheme, but opted for initially trying a single power pneumatic ram retractor instead. After shots, the gate latch trigger's slider block reengages the ram end by tension from some thin surgical tubing, that also keeps the cylinder's retractor cord taught during reload cycle.

The 4" omniwheel ram tip seems to give a uniformly good enough force distribution on the face of the ball without adding much weight.

We still need to improve the path of retractor cords to be closer to parallel to the latch slide path.

http://www.fastenal.com/web/products...endingMachine=








-Dick Ledford