Spinning and skiving

Herewith, two metalworking procedures that look like magic.

One: Metal spinning.

Many people are familiar with "spun metal" - you might have a salad bowl or arty lampshade made of "spun aluminium", for instance. But the actual procedure, done by hand on a normal lathe or by automatic machinery, is quite mesmerising:

There's no real upper limit to the size of the objects you can make by spinning. If your lathe can accomodate the initial piece, you can spin larger...

...or much, much larger...


Two: Skiving.

Skiving is shaving a thin layer off something. I think an ordinary woodworking plane actually more or less qualifies as a skiving tool. It's a standard procedure in leatherworking, but you can do it to metal, too, and that's where it shades over into the miraculous, if you ask me.

A metal-skiving machine doesn't just carve thin layers off a block of metal, like a plane would. In one stroke, it can cut each slice to a uniform length and leave it connected to the base, standing up parallel to all of the other slices.

And so, hey presto, you've suddenly got CPU-heat-sink fins like these!

Skived heat sink

Skived heat sink

In more detail:

Skived heat sink detail

Unfortunately, I can't find a video clip of metal skiving in progress. There's a little picture accompanying the Wikipedia article on skiving machines, but that's all. Do please tell me in the comments if you know of a clip.

Break the laws o' physics, win a prize

Another Metafilter-inspired post, but at least this time I've got some comments in the thread.

Here in Australia, we've got a TV show called The New Inventors, which does not always do as much due diligence on the inventions they feature as they ought.

So, every now and then, something turns up on the show that sounds absolutely fantastic, and is therefore picked as the best invention of the three featured in that episode, and gets significant publicity as a result - but which is actually a scam.

I mention a couple of previous examples in this comment; any readers who watch the show more often than I do (those two examples turned me off it...) may be able to suggest others.

The Exhausted Air Recycling System has done very well for itself. It was named Invention of the Year for 2006.

The trouble is, it just doesn't make sense.

It's meant to be able to make air tools (which are notoriously inefficient) consume up to 80% less power, by routing exhaust air back to the compressor. But I, and others, can't see how this is possible without reducing tool power by exactly the amount you're apparently increasing efficiency.

My bullshit detector didn't trip the first time I saw the EARS - or the second, third or fourth, for that matter - because on the face of it, you'd think that it would be possible to take the above-atmospheric-pressure air coming out of an air tool and do something useful with it.

But now that I've thought about it some more, it seems quite clear that whatever you put on the outlet of the tool will restrict outgoing air flow, which will inescapably reduce the tool's power.

Other commenters on the Metafilter thread and elsewhere have gone on to express severe reservations about other aspects of the system, like for instance the fact that the return hose is the same narrow diameter tubing as the feed hose, despite the fact that the return has to handle a much larger volume of air, now that the pressure is lower.

[blinks innocently] Comments, anyone?

I doubt this'll end up being as much fun as the Firepower saga, but there still ought to be some entertainment to be had.

(The latest update on the Firepower story, by the way, is a good summary of the whole sordid story.)

Is it a snow cone maker?

This comment prompted me to point you all to another site which, just in case you haven't already discovered it, I must warn you will probably eat your whole day. And then some.

I give you: What is it?

Therein, you will find pictures of odd devices - so very, very, many odd devices - which you are asked to identify. Or you can just skip to the answers. Though they're not always complete, damn them. And I still think it's cheating when the picture is of only part of some larger contraption.

The current items are a bit dud, but they're the hundred and fiftieth set. There are plenty of gems in the older sets.

If you're like me, you'll get just enough of them right to keep you going.

(Occasional rewards, and all that.)