Ring Tape Measure

We are only in February, but how much time did you lose thus far looking for the elusive tape measure you were sure the location of? In this very short Instructable, I am introducing a very simple concept, the “ring tape measure” so you always effortlessly have one on you.

3D printer + (small) donor tape measure

3D models are availables here: https://makerworld.com/en/models/2641143-ring-tape-measure

The idea behind this project is to make some modification on a tape coming from one of those gadget tape measure and then repackage it into a ring shaped case so that you can effortlessly have it on you at all times without even having to think about it. The main drawback of this project is that in this new case, the tape measure loses it self winding capability but this drawback is mitigated by the fact that, because the tape is quite short, hand-winding it is not so much of an effort.

The case is quite small, but its simple shape makes it easy to print (almost) flawlessly. It is composed of the main tape housing (this part has a small amount of 3D printed support that you will have to remove) and the winding cylinder.

This cylinder is the “rotor” of the case, the tape will be glued on to it (see step “ASSEMBLY”) and rotating it will wind the tape back into the case.

It is interesting to note that for practicality reasons the interior of the ring has to be part of the “stator” to make this tape measure usable even worn on a finger.

The tolerances built-in these 2 parts make them unlikely to disassemble after the tape is wound. (more on this in the “ASSEMBLY” step below)

In this step, we are removing the tape from the tape measure donor and preparing it for the assembly. Opening the case of the tape measure donor was simply a case of squeezing it with some pliers. In these very affordable tiny tape measures, the only part inside the case is the tape itself. The tape is composed of a long section that is graduated (in my case with both metric and the wrong units) and a shorter section that is completely blank and serves as the winding spring. We do not need this 2^nd blank part of the tape (and we are also very much space constrained inside the ring case) as such; you can simply cut it still leaving 2-3 cm of blank tape. Now take a file or sand paper and remove the paint of the tape on those 2-3 blank centimeters this is to make sure that the glue will hold onto the metal of the tape not just the paint of the tape. The side of tape that we will glue on the rotor is the marked side (the one with all the graduations), you do not need to remove the paint on the other side of the tape (took we a few second before realizing that)

Pass the tape 10-20cm through the hole of the stator part of the case making sure that the marked side (the one with all the graduations) is facing the interior of the ring. Carefully apply superglue on the bare metal of the tape (the 2-3cm were you have removed the paint) and press it around the winding cylinder.

Coil a few turns of the tape around the winding cylinder and push the winding cylinder into its final place inside the stator, you should feel a little bit of resistance coming from the tape twisting a bit, try to twist the tape as little as possible.

And you are done !

You can use this tape either on your finger or you can remove it and use it as a standard tape measure. To make sure that the tape measure is correctly assembled, you should be able to use the tape measure whilst on your finger and still be able to wind it with one finger from the same hand. The winding cylinder should be able to rotate easily but it should not dislodge itself from the stator even if you shake the tape around.