The most complicated thing I've had to cobble together so far, though, is shown in the photo below. Our team's first battlebot had a welded frame of fairly thin wall square steel tubing. Armor and other things had to be attached to this frame and the best way to do that quickly (we only had 2 months to build the monster) was with rivnuts, also known as nutserts; basically pop-rivet type fasteners with an internal thread.
Since a great deal of gripping power needs to be applied to the hand tool, putting in several hundred of them would have been rough on hands and wrists and it would have taken forever, too. I found a power tool for the task, but the retail price was nearly a thousand bucks! Harbor Freight has since come out with a cheaper unit, but it still cost several hundred bucks and it was only designed to do pop rivets. Being the cheap bastard I am, I dreamed up this widget, ordered the parts (one Bimba air cylinder: 1-1/4" bore, 5" stroke) and had it operating all within the space of 2 days. I already had a pneumatic foot pedal switch from another old project so I didn't have to buy one of them. Total cost: less than $40.-
|Photo #1: It's a pneumatic power-assist for an ordinary "rivnut" or "nut-sert" inserting tool. Aside from the cylinder itself, all parts were made from aluminum bits I found in my scrap bin. The handles of the nutsert tool are just mashed into holes on the aluminum bits and it's ready to go. The 3/4-round bit of aluminum, located between the cylinder and the top handle gripping piece, is a free-floating rocker which maintains contact with a saddle-shaped cutout in the top handle gripping piece. This prevents the cylinder from slipping out of position. The bottom handle gripping piece has a free-floating bit of rod running thru it. This rod is tapped to accept the air cylinder's rod end.
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