Bike Hardware Spirograph - Bike-o-graph!

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Have you ever messed around with a spirograph set, and wished it was way bigger? Yeah, me too. With a few discarded bike parts and scrap pegboard, it can be.

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Step 1: Materials and Methods

For this project you'll need the following:

Bike chain - should be reasonably straight, but pretty much any crappy, rusty, bent chain will work. You can combine various chains to make one of any size desired. I suggest cleaning off the grease first.

Chainring - any bike gear will work, but chainrings are bigger and have convenient bolt holes to put your pen in. If you use a cog from the rear gears of a bike, you'll need to affix some cardboard or something to make pen holes.

Pegboard - 1/4 inch pegboard with 1inch hole spacing seems to work perfectly. A bike chain is about 1/4inch thick, so this size works well. You can also use plywood, plexi, or probably even cardboard. Those things don't have conveniently pre-drilled holes, however.

Wire - thin, flexible steel wire works well. Nothing too thick and avoid insulation. You'll probably need at least 5 feet. You could use some sort of glue to put the chain on as an alternative. Hot glue would probably work real nice.

Jigsaw and drill to start the cut.

Step 2: Calculations!

For this spirograph machine, you'll be using an old bicycle chainring for the movable circle and a chain for the stationary outer ring.

The graphs you can generate will depend on the number of teeth in your chainring and the number of links in your chain. If you think of the graph as a star, the number of points in the star will be the lowest common multiple of the tooth number and link number divided by the tooth number. The number of times you have to trace around is the lowest common multiple divided by the link number.

Examples? of course

The pictures in this instructable are of two chains: 130 links and 84 links. I also have two chainrings: 52 teeth and 48 teeth. That gives the following
130:52 -> 5 points (5x52 = 260 = 130x2)
130:48 -> 65 points (65x48 = 3120 = 130x24)
84:52 -> 21 points (21x52 = 1092 = 84x12)
84:48 -> 7 points (7x48 = 336 = 84x4)

you get the idea

So once you've decided on a chain length, you'll need to cut a circle out of your plywood or pegboard. Your chain will lay along the inner rim of the circle, and so it needs to be precisely cut. The circle size is calculated as follows:

Radius = Chain length / 2 / pi + chain width / 2

Chain length should be measured from pin center to pin center to be accurate.
Chain width is measured at the widest point, with the chain pins perpendicular to your measurement.

You should be able to just calculate the length based on link number, as bike chains are 1/2 inch per link. (Note: you'll need an even number of links, unless you get a special link to connect an odd number of links). Also, the standard width is 5/16 inch. This gives you:

Circle radius = (Number of links) * (1/2 inch) / 2 / pi + (5/32 inch)

Step 3: Cutting

I put a nail in the center and used a bit of wire as an impromptu but precise compass to draw the circle onto the pegboard.
Now you can cut out the center using a jigsaw.

Remember to use old drawers as support when sawing.

Step 4: Affixing the Chain

The chain needs to lay snugly along the inside of your circle. I used bits of steel wire. Since I used pegboard, there are convenient holes which make using wire simple.
1. Insert wire through hole.
2. Bring around to the chain.
3. Insert through gap in chain where chainring teeth insert. (do NOT loop around whole chain). Chain links alternate between wide and narrow (inner and outer). If you use wire, only attach to the wide ones. The wire in the narrow ones will catch your chainring teeth as you try to draw the spirograph.
4. Twist wire to secure.

If you secure all of your wire to one side of the chain, it will tend to put a twist it, so I alternately secured to the top or bottom of the chain.

You can probably use glue instead of wire. but that is messier.

Step 5: Making Sweet Art

Once your chain is secured to your wood ring, you're ready to rock and roll. Just lay it down over something drawable-on, make sure your chainring spins around the ring smoothly, and lay down some ink.

The procedure is the same as using a normal spirograph. Just put your pen in one of the bolt holes, press out towards the chain, and smoothly trace around until you return to the start.

Combined with a new Sharpie, this should also work to make wall-art, draw on cars, etc.

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22 Discussions

I love creative ideas like this, and this one definitely caught my attention. I will definitely be making one of these.

Try grabbing some of the more modern asymmetrical chainrings like from Rotor which feature many more than the standard 5 chainbolt holes to accomodate different chainring positions.

I tried one of these out this weekend. I have a suggestion. Small nylon furniture pads afixed to the underside of the sprocket(s). Solves several problems. One, you elevate the sprocket slightly to match the centerline of the chain. As it is, the sprocket sits lower and want's to keep falling out of the chain. You really have to concetrate on keeping the teeth engaged which makes it hard for kids to do. Two. the nylon pads could greatly reduce the friction. Three: it's cleaner. Keep the full face of the sprocket from draging on the paper and messing up the image.

2 replies

Well, it's an idea, not an actual implementation. So no pictures. Time for a road trip to the hardware store.

What I was thinking is that it would be neat to attach your central sprocket to a plunge router so that you could cut the rosette out of a piece of wood.

3 replies

lol that was my first thought when I saw this. "Holy crap! I bet I can scale that up to fit my router!" I dont know if you could do it with a chain ring though or a bike chain. The difference in thickness would be a problem. In InkScape you can generate gears that you could print and cut with a jigsaw. That would cover the whirly part but im not sure how to make the track it rides around in. A router that can use bushings may be a good idea or some bearings that will fit on a 1/4 shaft so that your bit isnt interacting with the gear at all.

On second thought, I think that woodcraft.com has a pantograph for plunge routers. That would be the easiest, then you could use a small spirograph and scale it up to the size you want.

yes.  that's actually more what I wanted to do.  Hell you could use a jigsaw to make both the inner and outer rings, though it would be a bit labor intensive.

A problem with the bike-part project is that the chain is a bit flexible (unless you affix to pegboard @ every link) and so there is a bit of distortion in parts of the resulting graph.

This is one of the most randomly cool ideas i've ever seen.  Nice work.

Cut an insert from scrap pegboard to fit snugly inside the chainring and you have pen holes on various radii. Pen holders made from soft wood or structural foam would let you use multiple pens.

Maybe a second chain around the outside edge of the pegboard circle would also make a nice design?