PURPOSE

Is your “Misc.” box/jar/bin overflowing with hardware you meant to sort out “real soon now?” Do you wish you had a certain size nut you know you have, but just have to sort through your random pile? Do you give up, and just go to the hardware store and buy new ones?

Sounds like you need NutMatcher. Get your collection of properly labeled bins ready, and easily verify which nut goes where.

OVERVIEW & SCOPE

This is a set of two small tools for matching nuts to examples of known bolts or machine screws. One is for metric nuts, one for SAE (Society of Automotive Engineers) or “imperial” as used in US and parts of Canada. Print whichever you think you would use, or, if you're like me, print them both.

One note on scope: these tools don't cover every size nut there is. They cover a small, representative range of sizes that seemed reasonable to me. Please feel free to leave a note requesting an additional size; perhaps I've missed some which are really in common, everyday use. I will try to create an additional version(s).

Second note: the tools are intended for use with the common, everyday or “coarse” standard of nuts. In the US, at least, there are “fine” threaded nuts with threads closer together, therefore more threads per given distance. There might even be multiple standards; I don't know, never buy them and can't support them.

PRINTING DETAILS

I printed in VoxelPLA, with 4 perimeters and 15% infill. This is with a 0.2mm nozzle, on a Prusa Mini Plus. A layer height of 0.2mm (Quality) seems good; perhaps 0.15mm (Quality) is better, given the raised numbers on the labels.

ASSEMBLY

Putting this together should be easy. After minimal cleanup, insert the correct size machine screw/bolt up through the bottom. There should be enough room for the screw head to fit in the round opening, whether it is round, bugle, hex head, etc. There should also be enough room for the screw head to fit vertically. That is, when it is all put together, it should lie flat on the table and no metal screw heads should damage the surface.

Next, thread a nut of the correct size onto the screw/bolt and leave it there. This just makes the whole thing tidy and prevents it from rattling.

The two mounting holes fit a #6 wood screw or similar screw. Use these if you have a specific place on your workbench. Otherwise, leave them loose in your tool bag. You're done!

LIMITATIONS

On the metric tool, I believe I left out 6mm. This was intentional; I have some, but have never found a use for them. In my opening for 10mm I used a printed PLA nut and bolt. That was just for fun; I would always recommend putting a real, everyday metal bolt into a tool meant to verify the diameter and threads of a real, everyday metal nut.

On the US side, there are lots of fractional sizes I skipped, haven't seen or purchased these. Again, leave a note in the comments if you think I omitted something important.

These two tools, given their compact spacing, do not support wing nuts, or other large diameter nuts, threaded knobs, etc.

VARIATIONS

As mentioned, if there is interest, I may produce additional versions. 

I did think, briefly, of a version which includes mixed metric and imperial sizes, correctly sorted by diameter. However, I thought better of it. I think it would be a mess.

I have found OnShape fairly easy to learn. If anyone wants to view or (with free account) make your own copy of this design,

use this link.

OTHER RESOURCES:

Rapid Metric Screw Measuring Tool (M2-M5, up to 50mm)

Screw measuring tool, M2-M10, 4-120mm

After I'd just about completed the writeup of my tools, I noticed another, very nice design by @MattG_79511. Metric nut & screw measuring tool

Just for completeness. I enjoy making my own, too!

NUT JOB | Nut, Bolt, Washer and Threaded Rod Factory