Printable and reversible calipers (for wood working, speaker repair, etc)

Do you do wood turning, wood carving, are into hi-fi/car audio and/or speaker repairs?

Do you need to know how thick or how wide something is?

Do you balk at paying hundreds of dollars for Vernier calipers that still don't have the jaw length to work around curved shapes or reach into deep recesses?

Are you working on a one-off project where a "to the millimetre" (1/25th inch) accuracy is good enough?

Can't find a Vernier Caliper over 300mm (1 foot) long..... anywhere, and need a solution fast?

Then you're not alone, and you might be interested in this.

WHY USE THIS MODEL?

Basically, is a printable (albeit somewhat simple) caliper, the kind often used in wood turning, but I needed a big one it for discerning the dimensions of a speaker surround/suspension so I could replace an old failing one on my 12" speaker. It can also be reversed so it measures the inside dimensions of many objects. Combining this with a steel ruler or tape measure got me close enough to order a new after-market speaker surround.

Each limb of the caliper can successfully be printed (barely) on a build volume of 235mm x 235mm as is, which when joined in pairs, can easily span distances of 320mm (13" ish) If you need to shrink it down you can do that too.

NOTE: Make sure your limbs are stuck down well, or are printed carefully so there's no warping. The thin end of each limb is prone to this, and alignment can suffer. I also recommend increasing walls/perimeter thickness to increase strength and reduce breakage.

HOW TO USE THIS MODEL:

This model needs two identical limbs to be printed. It's designed so that you can flip one over, and join them with an M3 machine screw. I recommend 12-15mm screw length, and a washer at each end, but you can get away with 10mm long screw and a nut if you wish.

I do not recommend a washer between the limbs, I like the friction to minimise any unwanted drift during use. Also, I recommend making the screw tight so that the spacing is firm, but not stuck.

Then simply hold the calipers in place, and expand/contract the limbs around whatever you're trying to measure, then carefully remove the calipers without changing the limb angles, and then measure the distance between the two points with a ruler, and simply note it down!

I printed my own (see photo of it sitting on A4 spiral bound pad for size reference) . I'm happy to report that it worked well.

I hope it helps you in your DIY endeavours!
harmo_hammer