[foobarian]

I find binning fascinating when this topic comes up. You start with a pile of 1 cent parts with a 10% tolerance, go through it and measure each and every one, and you magically end up with bins of 1% tolerance parts that now cost a dollar. The parts didn't change at all! And yet merely the fact that they are sorted gives them so much more value.

[sokoloff]

Another interesting story is that in the 50s and 60s, light aircraft shared a lot of accessory parts with cars of the era.

Cessna used the same voltage regulator as Ford. Ford accepted statistical process inspection for their parts. Cessna required 100% parts inspection for the exact same part.

Solution: run the assembly line for the voltage regulators normally, do the greater of the number of inspections required by Ford or the volume required by Cessna. Ink all the inspected parts with an inspection stamp. Now, Ford can use any of the voltage regulators. Cessna can use any of the stamped regulators. Both companies get parts more cheaply than if the lines were separated.

[bserge]

It's still a great way to do it. Instead of 3D printing a custom pulley for your hobby build robot, you could just use a standard VW part that costs much less and will last a lifetime.

[thebruce87m]

Indeed, and when you buy the 10% tolerance part you will get one thats close to 10% out because the ones that were better have all been picked out.