Today we are going to learn how to make Drillium! For those that are curious, drillium (and millium) are words developed to describe bike components that have been modified by means of drilling holes in them or machining them to decrease weight and add personality.

I'm not going to give a history of how drillium came about( frankly because I wasn't there to witness it), but it is my understanding that what was originally a way for the elite to save a few grams at the expense of durability became in itself a form of artistic expression. People could take components and customize the to their liking, possibly saving a couple (nearly inconsequential) grams in the process. Today we rarely see drilled/milled components being produced, but some manufacturers do make 'skeletonized' components (*cough* campy *cough*).


Drilling holes in critical bike components can lead to FAILURE OF THE COMPONENTS. I do not suggest doing this to your brake calipers (at first), stem, or handlebars or any other part of your bike for that matter. SERIOUS INJURY OR DEATH CAN RESULT FROM COMPONENTS FAILING.
Seriously, if you're standing mashing the pedals, which is when parts are under the most stress, and the chainring lets go, you very well might faceplant into the handlebars and stem and crotch-plant on the toptube(ouch!). Or worse, lose control and veer into traffic. Please be careful if you choose to ride on drilled components!

That being said, it sure looks pretty when its done right!

and I've been commuting/riding mine for 3 months now with no issues.

Step 1: Gathering Materials

So to make Picture 1 look like the intro picture, we will need:

-A bike crankset (or other parts)    
If you are not pretty familiar with all the processes involved, I would practice on junk components first. Local Bike Shops sometimes keep a box of junk parts for "artistic uses" they sell cheap.

-A drill press (hand drill works but is more difficult)
-LOTS of drill bits. Or a sharpener. Sharp bits are wonderful things
-A countersink, (and some scrap wood if you need a handle like I did)
-some sandpaper
-Wrenches/Allen keys to remove bike parts

-CAD software (I used AutoCAD)
-A printer
-Laser Cutter
-Some stock material for patterns (I used 1/8" acrylic, wood can be used as well but the clearness was very nice.)
-A center punch
-Possibly bolts to fasten pattern to crankset
-A CNC router/drilling machine may also be used here, but alas I did not have access to one.

I'm sure this can also be done entirely by hand, or with a CNC machine, but unfortunately I did neither method and thus have no pictures/wisdom to share.

Step 2: Remove Chainrings

For this project, I'm only going to be drilling the chainrings and chainguard on my bike.

This is usually pretty straightforward, Mine were held on with three bolts, one end socket cap the other hex head. But yours may have anywhere from 3-6 bolts, or more if the Bolt circle on the crank arms is larger than your smallest chainring.

It's nice doing the chainguard as it is not structurally critical, and can have a LOT of holes and not fail in its function, which is to keep me from getting greasy.

Step 3: Measure Twice

Measure everything you possibly can on the chainrings, and write it all down (or put it into the computer if you're a good multitasker).
I measured all the major diameters, and widths of connecting parts. I used things of known diameters (pennies, metal stock, bolts etc.) to approxiately measure the radius of all the rounded corners.

To measure Large inside diameters like these, I hold one end of the (ruler, calipers, whatever) at a fixed spot and move the other end along the other edge, and find the spot where the measurement is the greatest. There may be better ways, but this worked for me.

If it's approximate, always assume there is LESS material when you go to draw it, this way you wont wind up drilling off the edge of your crankset.

Step 4: Draw, Print and Compare

Using your preferred method, draw the outlines of your chainrings as accurately as you can. Include every bolt hole and cutout. Also draw the teeth, these can be approximate as long as their radial location is correct, i.e. one tooth happens to line up perfectly with a certain edge of the webbing.
(This may be important if you are much braver than I and want to drill tiny holes in the teeth)
Once you draw the outer edges, draw a 1" or 1cm box, and print at 1:1 scale.
Measure the box to ensure it is the correct scale, and then com pare the drawing to the actual chainring, and tweak if needed. Once everything looks just about perfect we can move on to the fun part.

P.s. I do still have the file for mine, in case anyone happens to need a drawing of a 70's oddball french Stronglight TS 52-40 chainring set .

Step 5: Designing

This is my favorite step, let your imagination run wild and draw the pattern you want to drill into the chainrings. Have a lot of room? Do some Letters! your initials! or draw a connect the dots picture!

Or be boring like me and stick to traditional radial patterning...

I did however line up some of my holes on the chainguard where I could see the chain behind them, the effect worked out very nicely and when the chain is on the big ring all the pivot points line up with the holes in the chainguard.

I also added holes that were common to all the pieces, so they go through the whole chainring pack.

Sticking to a few consistant hole sizes will make your life easier when you go to get drill bits and drill the holes.

Note: From an engineering standpoint, you don't want to remove too much material, or drill in certain stress carrying areas. Generally, the closer to the inside of the ring you are the safer it is. Also, avoid drilling too much near the mounting holes, or on the areas directly above/around them as this carries the most strain under load.

Step 6: Print It Out and Ogle It.

Ooooooo pretty!

But make sure it's what you want when you see it full scale. Paper is cheap, chainrings less so!

If you are using Wood as opposed to a clear material for your pattern, you ay want to add indexing holes/slots along the edges to make sure everything is lined up.

Step 7: Prepare for the Laser!

You've most likely drawn what you would like to end up with in the end. In this step, we will make all the holes smaller by roughly 1/32" in diameter.

The reason is that the laser cutter has a kerf just like a saw, it removes a measurable amount of material when it cuts. By making the holes smaller they act like a pilot hole to center a slightly larger drill, and ensure its accurate. Accurate the first time anyway, these are pretty much single use patterns.

You probably don't want to undersize the mounting holes though, or you may have to re-drill them.

Also, go ahead and delete extraneous lines, i.e. things you don't actually want or need cut. This left me with the nifty color drawing shown here.

Step 8: Lasers!

Send the files off to get laser cut. My local community college has a laser cutting service I used, they charge very reasonably and do good work. (I do wish I had my own though)

Step 9: Attach the Patterns

Make sure everything looks right when you lay the pattern over the chainring. This is why I used the clear material for my patterns, I can easily see where everything will fall and make it line up.

I also weighed my chainrings before i started drilling, purely out of curiosity.

Once it's lined up, tighten down the mounting bolts or whatever bolts you are using to fasten the two together.
I suppose super glue could also be sued, but I wouldn't trust it. Perhaps something like spray adhesive that's re-positionable?

Step 10: Bacon Break!

Cook some Bacon and eat it!

Well, it doesn't need to be bacon, thats just a suggestion ;)

Especially if you did all your drilling in one sitting, that's like running a marathon! You need the calories.

Step 11: All the Drill Bits

and now we Drill!

First put on some good music.

Next choose a hole size you want to start with.

Use the laser cut holes as pilot holes to center the drill bit and start making holes!

And Lots.
And Lots.

Change the bit.

and drill more.
and more.
and change again.
and drill.


Make sure the bit you are using is the size you specified in the drawing for whatever hole you're on, and be prepared to spend some quality time with the drill press.

A hand drill will work, but will be much less neat, and take way more time and energy. I did all my holes over three nights, one for each ring/guard.

If you get tired, stop and take a break. have some water, or Gatorade and food.

Step 12: Chamfering

Woohoo! We made it! The holes are done!

Well, almost.

There's probably ugly metal burrs around a lot of them. and it doesn't look finished really...

Now's where that countersink comes in handy!

If you have a working depth stop, you can set up the countersink in a drill press and creep up on how much countersinking you want by slowly advancing the depth stop.

If however, you are like me, and your depth stop is more of a depth suggestor, you could do what i did and drill a 1/4" hole in the end of a piece of wood for the shank, another hole perpendicular to it for a bolt, and use it like a handle!

I like the control using it manually gives me actually, i never worry about taking too much off. The downside is that it takes some time. I just watched movies every night for a week and mindlessly countersunk holes... But it was worth every second of it!

Step 13: Finally Finished!

And now it's time to put the chainrings back on the bike! Hooray! you are done!

If you like, you can use some enamel paint to really make the holes 'pop'.

*Thanks to those who reminded me i forgot to state the weights!
                             Beginning weight          End weight         Net Loss
40 tooth ring-              60.4g                         52.3g                     8.1g
52 tooth ring               116.7g                        95.5g                    21.2g
chainguard                  87.5g                         51.7g                    35.8g
Totals:                           264.6g                      199.5g                   65.1g

*From a pure performance standpoint, I would get much more out of just removing the chainguard and the 6 screws that hold it in place, but that's waaay to easy!

Now carefully... very carefully... go for a bike ride. Maybe wear a cup when you plan on mashing the pedals the first time...

Now responsibly enjoy some age-appropriate libations!

Also, this is my entry into the Epilog Laser contest! As you may have guessed, I tend to view any tool not only as a standalone object, but as something to be used in conjunction with other tools. Whenever I get a new tool, I always thing of new and inventive ways to use it in the context of my other tools, i.e. making super accurate jigs, or even making parts for other tools to make them do things they normally wouldn't.

I was lucky to have access to the Community college's laser cutter for this project. If i did not, I would have had to spend quite a lot of time with a scribe and center punch. Heck I might not have even tried this. I can't imagine what kind of projects I could think of if i had 24 hour access to a laser cutter... I often get my best ideas at odd hours.

Thanks for reading! I hope your drillium experiments go well, or that you learned something from this.
Guys is orbea better or giant same gear ?
Steampunky, me like:D
And what about the seatpost? cut, drill or something?
If you were really worried about strength, you could run a quick Finite Element analysis on the modeled parts and see where areas of least stress were... &gt;.&lt; <br> <br>Or just wing it. :-D
love the idea of the lasercutting pieces as drill template, inspired me to do some stuff
One other thing about the bacon break, the drippings are usable as cutting oil. (which will also extend the life of your drills).
That's a great idea... the smell would be fantastic as it flashed off!
Actually lard oils (with a pinch of some sulphur compound, and a chlorinating agent, in a closely guarded secret formula) was the old time tool and die maker's trick for working tough steels. For aluminum, things related to kerosene were the ticket, before they developed some aluminum specific formulas. <br> <br>I &quot;grew up&quot; in the age of drillium, but tended to break the over lightened stuff. For your next trick, you can mill groves in your seat post. I assume it was campy, but one popular post back in the day, had what amounted to internal grooving. People would externally grove in the internal bosses, producing a tube that sorta looked like corrugated tin roofing when looked at end on. <br> <br>The age of drillium ended when someone noticed that all those holes increased the aerodynamic drag. Thats when brake cables started getting hidden under the bar tape instead of in big loops, tubing stopped being round, people started road racing on disk wheels (previously reserved for track pursuit bikes) the team pursuit bikes got the small front wheel, etc.. The UCI eventually got grumpy about it, and banned a lot of it.
That's a whole wealth of info! I'll have to remember those cutting fluid bases, could be handy in a pinch! <br> <br>I never knew that about the aerodynamics, but it makes perfect sense now that I think about it, it was very little weight I saved and quite a bit of turbulence I made instead. <br> <br>I actually turned, grooved and drilled my own seatpost not even a month ago! My bike had a chromed steel seatpost that was stupid heavy, and a really weird size (23.something mm) so i got some aluminum tubing and made my own. Wound up being 1/4 of the weight since I cut it to my length. I had no idea about the internal grooving on some posts though, that's really neato! I'll have to keep my eye open at swap meets for one. <br> <br>I don't have any good pictures of the lathe/milling process/setup or Id've posted that as well. Maybe I'll use some fakology and get some after the fact...
Do not weaken the steel doing that? There should be not pleased that the gear breaks when you're pedaling.
It does weaken it, there were a few cases of parts breaking during races and a few people getting hurt in the days when this was more popular. With older lower-end or touring components, i figure they were probably overdesigned to begin with so i can get away with it. There were also a couple things I did on purpose to help lessen the chances of breakage, I actually just went into step 6 and pointed them out in the picture, since I wasn't too clear earlier. <br> <br>But yes, it makes riding a bit more dangerous, but that makes it more fun too! I'm also better at making sure i shift into a lower gear for hills, instead of always standing up and pedaling.
You should say the weight before and after the drills, every individual piece and the total. <br> <br>Good work and keep drilling
Just added it, I meant to when I set out but completely forgot by the end. Thanks for reminding me!
One other tip, instead of a center punch, get yourself a set of transfer punches. They are a set of round rods, the same diameter as your drill set. In one end they have a center punch like tip, centered. pick the one the size of your guide hole, and use it to make your mark. They make the pip dead center in the guide hole, something not guaranteed with just a center punch.. If you have ever found yourself &quot;oval drilling&quot; something to get the last bolt hole to line up, this is how you avoid the problem in the first place. <br> <br> They aren't that expensive (under $20 for a set) but you have to get them from an industrial supply joint. (they used to be a standard early project for metal lathe apprentices - you would turn them to close diameter, heat treat them, then use the toolpost grinder to get them to finish diameter, with a sharp, hard point.. You do the turn, treat, grind sequence because heat treating can warp your part. You have to use the grinder, because your heat treating left it as hard or harder than as your lathe bit)
Those sound very helpful, I'll have to get myself some!
Put that in the laser cutter contest.
Cool! You said you weighed the chainrings before drilling, how much did you remove?
Wound up being about 60g off of a total weight of 250g for just the chainrings. 30g of that was off of the chainguard, and I don't have the numbers in front of me but it was something like 10 off the small ring and 20 off the larger one. I'll recheck and add it in to the 'ible!
Great post. I like your style........especially the drill press on the carpet! Thank god I have tile now
Haha thanks, I just put a rubber mat under it after this project in the hopes of keeping metal bits out of the carpet... Luckily I tend not to walk over there!
Tip, to those that haven't bought their drill press yet. Spring the extra $30-50 and get the floor model, instead of the bench top model. (the only difference between them is the length of the pipe). You will need the space on your bench a couple of weeks after you get it, and will spend the next year, hunched over and squatting down every time you have to drill something as it will never move off the floor and back to the bench,. A year later, and your back will tell you to trade up.
How many teeth are there? That's gotta be a lot of arrays.
The big ring has 52 teeth, and the smaller one has 40. It wasn't too bad actually, i just drew the initial hole and used a polar array to evenly space 52 of em out. Or drew one section and spaced out 6 copies.
That is really cool looking. <br>
Thank you!
Hmm, if you drilled the holes just right, would it make the bike whistle as the wind cuts through it or if you spin fast enough?

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Bio: I'm currently a part-time student part-time employee at Lehigh University, this gives me access to all the wonderful shops and culture a university has ... More »
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