Centre finder (also known as Center / Centre Sliding Gauge)

It can be quickly attached to ANY steel rule….up to a max. of 28mm wide x 1.2mm Thick.

[21st Oct 2024] Updated  to accommodate larger rulers (now a max. 31mm wide x 2.2mm thick) just be sure to use my print profiles.

This is an extremely simple yet handy marking tool. Its main purpose is to find the centre of round objects (as shown in the images here) but it can also be used to draw 45° lines away from a right angled corner.

Like my recent Combination Square model, I particularly wanted this design to be:

• fully 3D printable
• versatile enough to accommodate existing steel rules, and so avoiding a printed rule component (which could never match in terms of resolution & accuracy).
• Robust! and so able to stand to a workshop environment
• Hold a steel rule securely with easy to operate clamping mechanism.

This model is the result & I am really pleased with how it turned out. Super pleasant feeling in the hand in terms of tactility (but also its weight), accommodates all my steel rules, and its solid as a rock!

Zero support required, and as mentioned, no need for metal fasteners as the wing bolt & captive nuts are printed too. Everything is printed with 3 to 4 walls for strength and so are more than up to the job.

Assembly: Simply insert the captive nut in the slot on the main tool body. This should seat all the way to the back of the slot and align concentrically with the bolt hole. Then just pass the wing bolt into the hole and screw into the nut. See exploded assembly BOM.

Insert Steel Rule of your choice & use: The rule can be set into the tool at any location along its length. Just make sure the inserted edge is seated fully back in the slot to ensure it is held square to the tools inner edge (this can be a bit tricky at first but you will soon get the hang of it, see image 1)……. and then tighten the wing nut to clamp in place. You may need to cinch the wing nut down a little to get a 100% secure fit, but that's fine, this is printed strong!

I hope this increases measuring / marking bliss for you like it has me!