If you make ducts by milling you're doing something terribly wrong or you are in the aerospace business.

Leno has this thing about bashing 'machinists', I've heard him rant about that before.

At the end of the day a machinist can only make what you spec, if you spec it wrong you end up paying and you'll have to do it again. Measure twice, cut once.

> If you make ducts by milling you're doing something terribly wrong or you are in the aerospace business.

To be fair, the car he made the duct for did have a jet engine :).

hehe, good point :)

Aerospace CNC work is amazing stuff, it's not rare to see a block of aluminum be reduced to less than 5% of its starting weight as a finished part, the rest is scrap.

They don't recycle?

Yes, absolutely they do. But it's not as straightforward as it should be because the aluminum swarf is contaminated with cutting oils and other nasty materials.

All the scrap gets recycled, a typical price for a pound of 'dirty' scrap is $0.09. Contrast that with $.70 for a pound for stock (and more expensive if it is a special grade or shape).

I'm curious where you got that scrap price. The last time I sold aluminum scrap (about a decade ago) they were paying $0.24 a pound for dirty scrap.

According to the article, the 3D prints are his way of carefully speccing.