Improvised deep throat calipers

[mklotz]

The typical six or eight inch calipers don't have jaws deep enough to measure large objects. Fortunately, it's easy to improvise a deep jaw caliper using things commonly found in many shops.

Almost everyone has a combination square. If you're lucky enough to have two, you can remove the head from one, attach it to the other, and voila, deep jaw calipers.

If you don't have two squares, but have the protractor head for your square, you can use that to form the second jaw. Just be sure to square it against the combination head before making your measurement.

Even if you have two heads and the protractor head, I highly recommend the Hi-Gage Square Attachment. In addition to being useful as a caliper jaw...

it has many other uses, some of which are pictured here...

Lee Valley Tools - Hi-Gage Square Attachment

You can buy it here (standard disclaimer applies)...

Hi-Gage Square Attachment - Garrett Wade

but shop around - that may not be the best price.

[j.bickley]

Marv, just wow! Thanks for this nugget!

[mklotz]

Marv, just wow! Thanks for this nugget!

You're very welcome.

If you have a metalworking shop with a surface plate and a height gauge, you can often use those to imitate a large capacity, though not necessarily deep throat, calipers. The problem arises if the part to be measured can't be brought to the surface plate. That's where these improvised calipers come into their own.

Not the accuracy of a micrometer but most parts that big don't need to be measured with micrometric accuracy. A pi tape will give good accuracy for smooth round parts but is no help on other shapes.

[gatz]

that's great idea
always been a problem with 6 or 8" calipers