A shop with a huge fabrication facility I used to work with had a set of large object calipers, somewhat similar to these:
http://www.akcorp.net/aks/Details.cfm?ProdID=179
It's very handy for direct-measuring cutout diameters for subwoofers...
...and has a bunch of other large-scale handy uses in fabrication as well that pop up here and there.
However, the ones I've actually used were made out of plastic, the arms and scale were both a bit thicker, and it was perfectly flat on the backside, so that it could be laid down on a flat table or sheet of wood and you could trace along the inside of the jaws.
Of course I can buy from this place - it's under $50 for a set with 15" deep jaws and a 30" scale on it (that's about the size I want for my personal shop) - and they look to be decent quality - but it's not the same set that I am familiar with.
I've scanned through the online catalogs of all the fabrication supply sources that the shop used - particularly these:
Mobile Solutions
Select Products
We had a close training relationship with Bryan Schmitt of Mobile Solutions, so it's possible he had hooked us up with a non-catalog product...
...and Select Products website is a piece of junk basically, so I have no doubt there are a ton of products they offer that aren't on their website, so that's still a possibility.
Has anyone else owned, or used a large caliper like this, who knows where it came from? :help:
This set I linked might be perfectly good, I don't know.