Beer-view Mirror




This is a small rear-view mirror, meant to mount on your bike helmet (or glasses, or baseball hat...) so you can see behind you with just a little turn of the head. It's made from a bottle cap, a bike spoke and nipple, acrylic mirror, and glue.

Materials for one mirror:
Bottle cap (pick a good one!)
Acrylic mirror (TAP plastics has scraps for real cheap)
Bicycle spoke (free from local bike shop, ask when they cut up a wheel)
Spoke nipple (should come with the spoke)
Glue (I like "E 6000" from TAP plastics)

1 1/8" Hole saw (sans arbor)
Access to a Drill press
Dremel tool (not needed, but nice)

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Step 1: Cutting the Mirror

I'm making a bunch, but if you're just making one that's cool.

Take the arbor out of the hole saw. (That's the drill bit in the middle of it, that helps center your hole. Since that would put a hole in the middle of the mirror, we don't want it there.)

Mount the hole saw and mirror on your drill press. Have a punch-out tool (I use a blunt stick) ready. If your mirror piece has the protective film on it, leave it on! It will help keep the mirror surface good throughout the process.

Cut the mirror out, and then swiftly punch it out of the hole saw before the acrylic gets too solidified. If you're doing lots, do one at a time! Filling up the hole saw with stuck-together mirror bits is bad.

Step 2: Drilling Out the Bottle Caps

In this step we'll drill out the bottle caps to accept the spoke.

Clamp the cap down securely.

Use a sharp nail or the like to punch a small hole to start the hole.

Drill out the hole with a drill bit.

Match the size to your spoke diameter! It's nice if the spoke's threads engage with the hole, it makes it more secure with the nipple. This could be over-engineering, but whatever.

Step 3: Cutting the Spoke Nipple

This step is not necessary, but it is nice.

Clamp the spoke nipple in a vice or something.

Use a dremel with a cutoff wheel to cut the nipple just where the square part of the shaft ends. (Wear safety glasses!)

Save the cut-off ends, they will go inside the bottle cap uder the mirror, and act as a backing for the nipple on the outside to tighten against.

Step 4: Assemble the Bottle Cap and Spoke

Thread the spoke into the cap.

If the bottle cap isn't rotationally symmetrical and you care what side is up. make sure you go through the right way. The nipple will be on the outside of the cap when it's mounted, so if you're looking at the cap from the front, the spoke should go in the left side and out the right. Clear as mud, right? Look at the pictures for help, I guess.

Once it's in one side, thread the cut-off part of the spoke nipple onto the spoke.

Then thread the spoke though the other side of the cap, and thread the nipple on.

Step 5: Glue in the Mirror

Put a bunch of glue in the bottle cap and set the mirror down into it.

Not so much glue that it gooshes all over the place, but enough to securely stick the mirror in there. It also adds some resistance to the spoke rotating inside the cap, so the mirror stays where you aim it.

Step 6: Wait 24 Hours for the Glue to Dry

Ok, boring step. But necessary. The glue I like does really take about that long to fully cure.

Step 7: Bend Up the Spoke for Attachment

This is hard for me, and I sometimes wish for a jig. But, we're almost done!

First, bend the cap and mirror about *that* much. It's a little past 90 degrees.

Then measure about 7cm from the initial bend for the first little loop. You want the mirror to not interfere with your helmet visor, if you have one.

Bend the spoke 90 degrees, in the opposite direction from your initial bend.
Then grab it with a needle-nose pliers and bend it backthrough 180 degrees, making a tight little loop. Pinch that loop together with your pliers. Bend the rest of the spoke back out, following its original line.

Move down the spoke about 1cm, and repeat the bending process to make another loop. Do it one more time.

Finally, cut off the remaining piece of spoke (if you started with a long one). I usually use a dremel to make it smooth there, but that's not necessary.

Step 8: Attach the Mirror!

In this step we'll probably void the warranty on your helmet, so you may want to use another mounting technique (glasses, visor, etc.).

First figure out about where it should go on the helmet. You can put the helmet on and hold the mirror in about the right place as a guide, then push it against the styrofoam to make an impression.

Use a sharp object to poke into the styrofoam and make some holes where the impressions from the loops are.

Then, shove the mirror's loops into the holes. Secure!

I like to glue it in place also, using some more E-6000.


How to aim it? You should see just the tip of your ear in it, and have to turn your head just a little to the lft to be able to see behind you.

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    27 Discussions


    1 year ago

    I've made a number of these. After making a few by cutting out the mirror discs as described (sort of a hassle), I found bags of 1" diameter glass mirrors at Michael's. Cheap! Much easier, and they fit perfectly.


    5 years ago on Introduction

    BTW, if you don't have access to a drill press, try drilling through a 3/4" board with the hole saw before removing the arbor. Then clamp together a sandwich of wood, acrylic, and the piece with the 1" hole on top. Use the 1" hole as the guide for the hole saw. Not as precise, but close enough for beer-cap work.


    7 years ago on Step 8

    I like it. I might make some for my friends


    9 years ago on Introduction

    Just finished my first one, used a Bell's Oberon cap (great beer, great cap!). Thanks for the instructable!


    9 years ago on Introduction

    What is the final diameter of the mirror? I measured a bottle cap and it seems to be barely 1" inside diameter, so I'm wondering if the mirror you're drilling out is just under, maybe 15/16" or 7/8"?


    9 years ago on Introduction

    Drilling holes into the inside of your helmet weakens it ability to cushion impact . I suggest not useing this method .


    10 years ago on Introduction

    Nice rendition on the Chuck Harris helmet mirror. I like cap idea because it is already shaped and all you need is a 1" hole saw. The only thing I would add is bending it in a way so it clips on the helmet.


    11 years ago on Introduction

    i like this. i had bought some mirrors to make one, but wasn't able to find good cheap wire. i had a busted tire, and didn't even think of using the spokes. the bottlecaps are nice, too. i'm waiting for the glue to dry one one now. i'll be making it so it can be mounted onto glasses rather than a helmet. i also put some rubber tubing over the folded over parts (the parts that you stuck into the helmet) as to not scratch the glasses.


    12 years ago on Step 4

    Have you tried making an S-bend to the spoke and let the glue fasten it to the bottle cap instead of hacking the nipple? Do you leave the plastic seal to the cap on purpose?

    2 replies

    Reply 12 years ago on Step 4

    I thinkk an s-bend would work fine. I've never tried it, but I can't imagine it being a bad idea. I never used to cut the nipple and assemble it this way, and they worked fine---you just had to be a little more careful tightening from the outside. Peeling the plastic seals out is really hard! So it's not on purpose, it's more laziness. I don't think it makes much difference though---why do you ask?


    Reply 11 years ago on Step 4

    Ooh, I just thought of why an s-bend is bad: then you have to twist the spoke to change the mirror angle! Not so good. The nipple-nut system means you can position the mirror and then lock it in place.


    There's a guy in San Diego who makes these too. My wife bought one of these at our bike club. No nipple on this one though, works well. Great idea Benstar.


    12 years ago on Step 2

    that blue paw wheat ale is good stuff

    book worm

    12 years ago

    great idea will have a go i have a miniature pipe bender set i bought for modelling that should do the job.just have to go out to buy some beer now.

    1 reply
    mw3book worm

    Reply 12 years ago on Introduction

    I made something similar with a plastic dental mirror. I heated it up where it bends, twisted it back to a 90 degree angle and attached it to my glasses with a couple of small zip ties.