Unfamiliar Tool

What is this tool used for?


Here's a description by the aircraft tool seller:

1-2-3 Blocks Matched Set
Hardened Steel
Precision Ground
(2 Sides) - 15 Holes-(5)Tapped 5/16-18
(2 Sides) - 5 Holes
(2 Sides) - 3 Holes

What situation would you be facing to find this tool useful?

Machinist use these

Machinist use these all the time.

They use them for lots of things. Clamping, locating, Indicating, Squaring, Locating Holes, Dowel Pins etc.

Some machinist out there may offer a better description. I have never seen a good machinist that did not have these in their box.

I think it's Bizzaro World Swiss Cheese. No Clue!

Roberta

Don't know but

check this out ... they sell a bunch of whatever they are ...

http://www.wttool.com/category-exec/category_id/12965/nm/Blocks

1-2-3 blocks are precision ground steel blocks that measure 1"x2"x3", ground to tolerances of .0002" for squareness and parellism. They are useful around the shop for various clamping and setup operations, particulary on the mill table or drill press. They come both in solid and perforated, some with tapped holes. They are generally used and sold in pairs. They used to be expensive, but now you can buy imported ones that are reasonably priced. They are very handy to have around when you want to hold something perfectly parallel or square.

strange tools !

Called "parallels". Hardened steel blocks used by machinists as spacers and to keep things level. Not to be drilled into