Fun with Fixtures

[TomG]

Just to show that it's not all fun and games, I thought I'd share a little fixture that I threw together to modify some parts at work.

We are two weeks out from shipping a brand new product and there was a slight issue with the molded front covers on the instrument. It seems the mechanical design guys didn't leave enough room for paint buildup on the front panel of the instrument and a removable access panel doesn't fit quite right.

The solution is to remove the offending paint on two mating surfaces of this first batch of parts (Luckily the plastic is almost exactly the same color as the paint), then have the mold changed. Since there are fifty pieces to modify and clamping them is kind of like trying to clamp a potato chip, I decided that a fixture would be worthwhile. I milled a key on the bottom of a block of aluminum and added a couple of holes so it could be clamped to the mill table, then milled a bunch of relief cuts to clear all of the features on the underside of the cover and then added a couple of reference edges to locate the part. A few toggle clamps made switching the parts out a cinch.

It ain't pretty but it sure saves a lot of time. I just wanted to bring this up because any time I have to make more than a couple of parts, I always consider investing some time and making a jig or a fixture. It can save a lot of time in the long run and prevent a lot of grief when machining multiple or complex parts.

Tom