What does one call this kind of ID measuring tool?

[Scorpion]

 

[waho6o9]

I think they're called pinch sticks.

 

[Peter_C]

I would call those bar gauges.https://www.rockler.com/rockler-3-i...Atxep5mQeeGdSKheNnjDZFzG5bZO9d_AaAh7BEALw_wcB

Not what you asked, but here is another option, that belongs in every tool box. Come in standard and metric.https://www.amazon.com/Wiha-61620-O...1?ie=UTF8&qid=1538769888&sr=8-1&keywords=Wiha+61620

 

[Cheese]

I'd also refer to it as a bar gauge.
https://www.woodpeck.com/mbg.html

 

[Michael Kellough]

I would call those bar gauges.https://www.rockler.com/rockler-3-i...Atxep5mQeeGdSKheNnjDZFzG5bZO9d_AaAh7BEALw_wcB

Not what you asked, but here is another option, that belongs in every tool box. Come in standard and metric.https://www.amazon.com/Wiha-61620-O...1?ie=UTF8&qid=1538769888&sr=8-1&keywords=Wiha+61620

The folding rule is good (better than the rods imo) but I like the Hultafors Talmeter better. For inside work the tail is used which adds exactly 100mm to the long tape. Both the tail and long end have fine points that can scribe marks on wood.
https://www.ebay.com/itm/Hultafors-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

 

[waho6o9]

Bar gauges got it.

A set of "pinch sticks" here is how - by glideking @ LumberJocks.com ~ woodworking community
View attachment 1

 

[Cheese]

A set of "pinch sticks" here is how - by glideking @ LumberJocks.com ~ woodworking community

Well that’s certainly cool...a bunch of square sticks that yield a bar gauge.  [big grin]

 

[waho6o9]

LOL

 

[Cheese]

LOL

Sorry [sad] couldn’t help it...it was opportunism at its worst.  [big grin]

I’m just envious because we’ve had nothing but rain for the last 5 days. No California sun .

 

[waho6o9]

Understandable rock on.

 

[Michael Kellough]

If you want that type of bar gauge Lee Valley has a very nice set.
http://www.leevalley.com/us/wood/page.aspx?p=69879&cat=1,43513,43553

The hardware for making your own out of flat sticks.
http://www.leevalley.com/us/wood/page.aspx?p=32585&cat=1,43513,43553&ap=1

 

[Scorpion]

Pinch sticks or bar gauges...thanks!

I have a couple folding rules and they work great.

 

[Jesse Cloud]

I like bar gauges and/or pinch sticks because you can lock a measurement in place.  I use them often to compare diagonals, so I don't care what the actual numeric measurement is, just whether they are the same and if not which is larger.

The advantage of 'pinch sticks', using the Lee Valley hardware is that its easy to make the sticks to custom sizes, so you can check diagonals of small drawers or large cabinet carcasses.