Introduction: How to Make an Emergency Hex Key / Allen Wrench

Picture of How to Make an Emergency Hex Key / Allen Wrench

If you need an allen wrench in a pinch, you can use this trick to tide you over until you find a real one. I used this to tighten down my bike seat and ride it a few miles home to a real hex set.

Step 1: Materials:

Picture of Materials:

1) A Pencil (hexagonal barrel)
2) A Knife
3) No Hex Key

Step 2: Make

Picture of Make

Cut off the end of the pencil. If you press the blade straight down into each face of the pencil (press, turn the pencil, press, etc.), the tip will snap off almost cleanly. If any splinters stick up after the break, flatten them down so the pencil can jam as far as possible into the bolt head.

Shave the sides of the pencil down to size. Keep the peelings parallel to the faces. Make your shavings pretty thin. Test to see if it fits. If it's tight, that's good.

Step 3: Big Emotional Payoff!

Picture of Big Emotional Payoff!

Insert your new allen wrench into the bolt head. Turn slowly.

If the wrench slips, it has been stripped (wood is soft), go back to step 2.

If the bolt is satisfactorily tightened, celebrate! Then do what it takes to find a real allen wrench, and get this baby tightened down for real.

It took me three rounds of cut/shave/tighten to make my bike seat rideable.

You can even make your hex wrench back into a pencil when you're done! So much versatility!


IamTheCreator (author)2008-07-01

Just don't bring this into any airports star......

stasterisk (author)IamTheCreator2008-07-01

a pencil?? seriously??

_soapy_ (author)stasterisk2009-03-19

Not flown recently? "OMFG!!! It's a plastic see-through bottle of water!! Take cover!!!!" "And that will be 10p for the plastic bag. No, you can't use your own. You have to buy ours to put yours in."

mg0930mg (author)_soapy_2010-03-03

I think he was referring to the bomb scare involving star...

robotguy4 (author)2009-05-15

Great idea!

JGB (author)2007-06-26

As a user of power tools, I don't think I'd trust the tork one can get with soft wood versus steel. However, a clever use of thought on your part. This is probably fine for "finger tight" hex screws.

stasterisk (author)JGB2007-06-26

Which is why this is an emergency hex wrench. It's also better than "finger tight" (otherwise, why make the tool?).

_soapy_ (author)stasterisk2009-03-19

It's certainly better than "finger tight" on a socket cap screw like this, where you can't tighten it with your fingers!

frogmeetcog (author)2008-11-21

I actually made an instructable that is more important than I thought when I made it, the "seatpost toolkit". Recently I have considered inconspicious and not-obvious-to-casual-theives places to stash a few allen keys and such, for that time when one's bag falls off on a bump that was just jarring enough that the bag's impact on the road/trail is not noticed. I recently saw, on a rusty beater that looked intentionally neglected for ugliness, a cheap multi-bit screwdriver taped to the toptube. The screwdriver handle was transparent plastic, so the remaining metal bits blended in with the brownish/rust frame. A darn clever idea on a beater, methinks. Also an intersting thing to try: if one can find a small enough set of folding allens, that could be stowed in the seatpost, handlebar, or even barends on flatbars. I suppose even the nose of the saddle could hide a tool or two if it has no plastic strengthener thingy. Imagination is golden...

IamTheCreator (author)2008-05-26


mwwdesign (author)IamTheCreator2008-06-30


johnpr (author)2008-04-11

great idea, i have 3 or 4 hex sets around (1 on my bike) and i still see that this is a great emergency fix, good idea

Rishnai (author)2008-03-30

I love this idea! I always carry a hex set now, but one time when I got a new biycle and the bag wouldn't stay on it, wouldn't ya know, that was the time I needed a hex wrench! If I'd thought of this, it would have saved me a long bus ride home to get my wrenches and tighten the offending bolt.

aeray (author)2007-09-01

A common prison trick that works well, especially for "security" head screws, is to heat up the non-bristle end of a plastic toothbrush until is is soft and then press it into the offending screw. Let it cool, remove, and you have a custom screwdriver.

smokehill (author)aeray2007-11-06

Another trick for hex screws I haven't had a chance to try yet is: stick a small screwdriver or similar tool down inside the hex-shaped hole and pack tinfoil tightly around it, tamping it down as hard as possible with another little screwdriver or similar tool. If I had a bit of 2-part epoxy I'd probably cram some in, also, and let it set up before trying to loosen the screw. I suspect this might work OK if the foil is really tamped down hard, and the screw isn't corroded much. I've kept a scrap of tinfoil in the toolbox but haven't had a chance to try this yet.

smokehill (author)aeray2007-11-06

I used the "toothbrush-and-Bic-lighter" trick once, successfully, and once, unsuccessfully. If the screw isn't really, really tight, or rusted, it stands a good chance. I always keep an old toothbrush or two in toolboxes, and not just to brush off dirt & grease. Another small, handy item that would now help this process is the new (at least to me) WD-40 "pen" -- sort of like a felt-tip but with WD40 instead of ink. Dripping a bit into the screw threads might help the pencil or toothbrush trick work, and it takes up little room in the toolbox ... much less than the WD40 can I used to keep in the bottom of the box. I've also used 2-part epoxy to "cast" hex keys for plastic drain plugs. My drivers kept losing the big metal hex wrenches, which can be very expensive, so I used one of the plugs (female hex) to cast a bunch of epoxy "keys." I sprayed WD40 in the hex socket, stuffed in the epoxy, and stuck a penny in the top, for leverage. Worked great, almost no cost. If I had a working camera, I'd do an instructable on it.

garrettmikesmith (author)2007-06-26

how can that not break? maybe you could somehow incorperate the metal eraser holder. just fuel for thought.

It's easy to cut your fingers shaving the metal eraser crimp, and it's difficult to get it to fit a hex head.

jtobako (author)stasterisk2007-06-26

Don't shave it, pull the eraser (or pencil) and bend the sides into something that looks like a torx bit or star shape.

stasterisk (author)jtobako2007-06-26

You could certainly try that. I don't think it's as easy to get the hex shape. Additionally, since the metal crimp is hollow, the strength will be much less than the solid wood.

jtobako (author)stasterisk2007-06-27

The problem is you are still 'finger' tight instead of 'fist' tight. And you are right, a 6 sided figure is going to be difficult if you aren't willing to spend the time, but three (or two-like a screwdriver) works.

stasterisk (author)jtobako2007-07-04

Have you done this, with a metal eraser crimp?

jtobako (author)stasterisk2007-07-05

A very long time ago (20+ years) when I was a teen.

stasterisk (author)2007-06-26

I didn't make this in advance - I found myself with pencils and a knife and a loose hex bolt. It's a good idea to carry a hex index if you ride bikes a lot.

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