Quick Tip: Using Calipers to Set Up Marking Gauges and Squares

February 21, 2023 2 min read

setting up a marking gauge or square with calipers

Everyone knows calipers have jaws for outside and inside measurements. Most people know the little bar at the bottom is a depth gauge.

But a lot of people don’t know there’s a fourth way to measure with calipers — and it’s the best way to set up your marking gauge or square.

Say you’re cutting a half lap and need to mark exactly halfway through the thickness of a board.

First, use the calipers to measure the thickness of the board. Make sure to measure where the half lap will actually be.

Divide that measurement by half and set the calipers to that number. Lock it down tight.

Now to transfer that measurement to your marking gauge or square…

Place the fence of your marking gauge or square on the TOP of the calipers. Then adjust it so the edge of the blade rests on the little shelf below, on the back of the calipers.

This setting will exactly match the reading on your calipers.

It’s a whole lot easier to balance your tool’s fence on the bigger surface at the top of the calipers than the spindly depth rod at the bottom — and the measurement is exactly the same.

Marking gauges with a micro-adjust feature make precision even easier. That’s what I always use — and also what we carry in our store.

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Any other caliper tips? Let us know in the comments below!

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Jonathan Katz-Moses

6 Responses

Ken Roth

February 22, 2023

I’ve been using calipers for years and never knew about the (secret) 4th use of calipers—it really took me by surprise! Thank you Jonathan!

Don Tardiff

February 22, 2023

Using that feature of your calipers is often a better way to check height measurements rather than using the depth gauge (thin rod or extension on the right end of your calipers) for example checking the height of your router bit or table saw blade. The depth rod by its size is better used as a way to measure the depth of a drilled hole or counterbore.

Steve LeLaurin

February 22, 2023

At the risk of sounding picky, the math geek in me is compelled to point out a common mistake. You say “Divide that measurement by half and set the calipers to that number.” What you really mean is “Divide that measurement by TWO …” If you “divide by half” you are actually multiplying by 2!

KG

February 22, 2023

For a specific/arbitrary measure, that’s an excellent method. Thank you for sharing.

For scribing 1/2 a given thickness, I find it’s way faster and less error prone to set the gauge to a best eyeball guess, lightly press it/mark from one edge, then repeat the light mark with the gauge referencing the opposite edge. Micro adjust the gauge to split your 2 feint marks and 9/10 times you’re done and another mark+compare from the opposite side confirms it when the cutter drops into the previous mark.

Takes about 100 times longer to write it than do it.