Thursday, November 17, 2016

The Art of the Jig

Every manufacturing process requires jig to hold parts in place.  In a sense a mill vise is a jig--it holds a part firmly in place while the mill cuts the part.  To hold round tubing in position while cutting in the chop saw (because holding tubes by hand is both risky and not great clamping force), I cut some square aluminum tubes slightly larger than the OD of the tubing, drilled and tapped 3/8"-16 holes near he cutting end, and clamped the tubes down with hex head bolts.  Use a clamp on the flat surface of the tube, use a socket wrench on the hex head bolts and cut.  Works great.

Crude in its materials, but effective, was something I saw on a tour of the GM assembly plant in Van Nuys.  They needed to close each Camaro/Firebird door at one point which a human could have done, but instead they had a big stick covered in rubber to protect the paint and a series of springs that allowed it to go almost to ground level before exerting enough force to slam the door, and come up to contact the next door coming down the line.  (Great moments in, "Where have you been?"  An elderly couple asked, when they saw the Firebirds, and this was 1978, "How long has Pontiac been making small cars?"  Even worse, Firebirds weighed about 3800 pounds.)

1 comment:

  1. Jigs and fixtures. I can not remember the differences now. Sigh... I used to design them... And the parts that used them.