DIY Nut And Bolt Sizer

Picture of DIY Nut And Bolt Sizer
Ever wish that you could have one of those nifty nut and bolt thread check/sizer gauges they have at Home Depot, Ace, etc? Well with a little time, you can have your very own in your home shop. There are commercial options available, but this one cost me a whole 15 bucks in materials. So follow along and I'll show you how to make your own. As usual, the second image was my inspiration for this project.

Materials Used:
1/4" Plexi Glass sheet (had on hand from another project)
Dymo Label Maker
Super Glue
Nuts and bolts in the following sizes (bolts as short as you can get for the size it comes in)

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Step 1: The Layout

Picture of The Layout
The first thing I did was cut my plexi down to size. I've had mixed results doing this in the past but this time I managed to get a nice clean break. I could have used wood for the base or metal, but I had the plexi on hand so I used it.

Once I had it cut down to size my next issue was how to mark my layout without marking the plexi itself. The benefit of using the plexi came in nicely here. I just took a piece of paper and laid out a 1" x1" grid pattern on the paper and set it under the plexi on my workbench.

Step 2: Prepping The Hardware

Picture of Prepping The Hardware
The issue with glueing the bolts directly to the surface of the plexi is that most bolts are not flat on the heads. They come with grade or manufacturers marks cast into the heads. Obviously to ensure a secure bond, these needed to be eliminated. I just used a hand file and filed the heads down nice and flat. This has the added benefit of scuffing the surface to ensure a good strong bond, so I filed the nuts a little bit as well.

static1 year ago
When I use do work with this stuff daily, unless a metric fastener was thrown in the lot, I never need a tool to determine the size other than my eyes. 18 years out of the loop I can't trust my eyes to be correct anymore. Your version of the tool is as good as any others out there
luvasu1 year ago
Add in METRIC size M3, often used in electronic apliances
stopngoman1 year ago
Great Idea for a project ! One thing that would have made the project easier to make is not using glue for the hardware. My solution would have been to drill the plexi and use a long enough bolt to be able to have at least 2 nuts on it. Install the bolt thru the drilled hole and secure with the first nut. Loosely put the other nut on. When checking another bolt remove the loosely installed nut; when checking a nut, thread on the stud.
criggie1 year ago
Just a thought - it'd be hard to use this on something like an engine. Why not leave a nut on the bolt and a bolt in the nut, so you can take it away to try?

Label the loose one well to save issues.
MFXPYRO1 year ago
These will also do the same job :-]

Note also that certain combinations of metric/imperial threads will screw onto each other (they may be a little tight or a little lose depending on the combination) so while the gauge shown here is a good quick and dirty check it's no substitute for proper measurement. BTW interestingly while Australian Propane regulator will screw onto UK propane cylinders, UK regulators won't screw onto Australian cylinders, this is because although the pitch and diameter are near enough the same the profile of the thread is different.

clgonsal1 year ago

If using clear plexiglass an alternative to using a label printer might be to just print all of the labeling on a single sheet of paper, and place it behind the plexi. (How to attach this to the plexi is left as an exercise for the reader -- there are numerous possibilities.) It should be pretty easy to make a nice label sheet in anything that supports text and a grid (vector drawing programs, word processors with table support and even spreadsheets are all possibilites here.)

If going this route it'd probably be best to mount the label sheet before mounting the hardware, and use the label sheet as your layout guide.

One disadvantage to this approach is that having the labels behing the plexi means there'll be parallax, but that shouldn't be a big issue as long as you don't place things too close together.
adunster1 year ago
Don't forget there are different thread pitches for metric sized bolts, and possibly the SAE ones too (I didn't look super close).. For example M12x1.25, M12x1.5, I think I have seen M12x1.75 around... so JUST an m12 peg is not necessarily going to allow you to get the right bolts or nuts!

I don't remember exactly which ones are generally standard, I know some thread pitches are more common on Asian cars and others are more common on US cars now that they use metric, etc, but I couldn't give you a list offhand. But for most usefulness in the application it's something to definitely look into!!
KaptainKen1 year ago

I'm going to do the same except add course and fine thread samples. I often have trouble figuring out whether a particular bolt or nut is "inch" but with different threads or metric. And vise-versa.
92greenyj (author)  KaptainKen1 year ago
I had planned to do that initially, but Ace didn't have much for fine thread in SAE. I still have plenty of plexiglas left so I may make another one for fine thread hardware
jackew1 year ago
Now, if we could only convince this country to "give in" to the inevitable and switch to metric, half the problem would be eliminated. Nice idea.
mot13021 year ago
one quick way to see if a bolt or screw is metric is to measure the length metric is in millimeters standard is decimals
simple and perfect …
Good Job! You may have saved my partner from trouble. Every time he sees one of these used at Orchard Supply Hardware, he threatens to reach over and take it home. :-)
I made a similar one in the past, but kept the nuts screwed onto the bolts and removable. It meant you could possibly lose them but you could also remove them and take them to the car/whatever you were working on and check the nut on the bolt.

Must find it again!
92greenyj (author) 1 year ago
Thanks for the Kudos guys. This is only my second instructable so far. Obviously I like to make useful items. While this isn't really a need to have item it sure is a nice to have item. I can't tell you how many times I have needed to figure out the size of a bolt and forgotten to take it with me to the hardware store! Not anymore!
profpat1 year ago
nice project!
GarageGuru1 year ago
Great idea! I've often said while doing projects or repairs I could use one of these things. Simple, clean, effective, and priced right.
I agree! Definitely I must do something like this. Maybe you can include washers in a new version.
Cabe rimar20001 year ago
Surely you just check washers on the bolts? Or am I missing something terribly obvious?
rimar2000 Cabe1 year ago
Yes, but there are some differences between washers whit equal hole. The outer diameter, the thickness, etc.

Plater washers have a big diameter and a little hole, squeeze washers (arandelas de presión) have big hole and small outer diameter, etc.

I don't know if there are another types.

Yes, I have wished I had one of those bolt sizer things! Thanks!
pfred21 year ago
I have my nuts and bolts and screws etc. all sorted into separate labeled containers. So I grab a possible match out of one and test the unknown hardware against it, if I can't tell by just looking. I usually check though if I am tapping work or something, just you know, to make sure.

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