ID an old device

December 22, 2007 9:03 PM

What is this device (180KB jpg)? My dad has had it for years but doesn't know what it's purpose is. It has a jaw that opens (103KB) and a scale (67KB) that reads up to 72, labeled every six divisions, and closes with an odd spring. I don't think that's in degrees since the jaw does not open that wide. It's obviously for measuring something but what that something is we can't figure out. My brother's idea was something involving maps. It is made of steel except for the brass scale.
posted by 6550 to grab bag (13 comments total)

Definitely not maps. It measures the thickness of something, like a mircometer does. Sorry can't be more specific.
posted by artdrectr at 9:07 PM on December 22, 2007

If you expand the caliper to its highest (72) does the space equal roughly one inch? This is a shot in the dark but perhaps it could be a typesetter tool to measure the size of a block in points? 72points = 1 inch and 12 points = 1 pica. The fact that its labeled every six divisions and that 72/6=12 that seemed to suggest this.
posted by postergeist at 9:17 PM on December 22, 2007

It's a thickness gauge. Very similar to these products. Designed to quick and dirty readings of something's width in circumstances where using a micrometer would be overkill.
posted by tim_in_oz at 9:22 PM on December 22, 2007

At 72 it measures just over half an inch (17/32) but interesting idea nonetheless.
posted by 6550 at 9:22 PM on December 22, 2007

For checking thickness I'm not sure what the units would be.
posted by 6550 at 9:24 PM on December 22, 2007

Yeah looks like a woodworking gauge caliper. Here's a slightly more modern one.
posted by JaredSeth at 9:29 PM on December 22, 2007

Is the 72 .72 inches? If so, it could be for measuring bullet caliber.
posted by Jahaza at 9:32 PM on December 22, 2007

The 72 is about .53 inches or 14 mm. I could believe it's for measuring thickness but the fact that the units don't seem to correspond to anything standard is what throws me.
posted by 6550 at 9:40 PM on December 22, 2007

An interesting little puzzle...using this site I ascertained that the only unit that is particularly close is the unit "douzieme" for watchmaking. So I guess this is a douzieme gauge, and in fact there's a near identical device on that page.
posted by advil at 9:46 PM on December 22, 2007 [5 favorites]

And, according to that page, they're usually divided in groups of six, so I guess that's another indicator.
posted by advil at 9:47 PM on December 22, 2007

Thanks a lot, advil. That's got to be the device!
posted by 6550 at 9:52 PM on December 22, 2007

nice find advil!
posted by postergeist at 10:27 PM on December 22, 2007

Hive mind to the rescue again. Good one advil!
posted by i_am_a_Jedi at 7:14 AM on December 23, 2007