Dodecahedron from Bike Rims

 

1. Progress to date - 3 rims drilled, and 3 edge joiners made.

2. Detail of rims joined and drilled. Joiner is ......

3. this which is a piece of 25mm round dowel timber. Surrounding it in black is a drilling jig which ensures holes through are correctly positioned.

4. Dowel cutting. There are 30 connectors to be cut so this setup was worth it to cut quickly and accurately. Plastic pipe is another option but I wasn't sure about cutting it with this setup.

5. Typical source of rims. This is a discarded De Carlo bike with the 27" steel rims used in this project. Its resto is documented here. The now-installed 700c aluminium-rimmed wheels are lighter, easier to get parts for, and brake better the the old 27's.

6. Layout diagram for wheel drilling and drilling jig shown in 2.

Hi Good progress on this project in the last few days. I have been thinking about it for ages and finally got working on it a few days ago, after gathering enough wheels and buying some dowel to make the edge joiners from. Principles to make this sort of thing are outlined in my article for the Australian Mathematics Education Journal which is here (official site) and here (full version through researchgate). Also, this post describes building the same thing in beer cans!

Basically, any old circle can be made into a polygon (pentagons shown here) , and from there into a platonic solid outline (dodecahedron started here). 

The rims I am using are mostly 36 spoked / holed, which is not divisible by 5. This means some extra drilling has to be done, and I worked out a diagram for the drilling, which is not too hard.

Another donor vehicle. This Apollo bike has frame damage at the head tube and so is being ripped apart. I will take its frame to the recycle depot soon.

All the wooden dowel pieces have been drilled and varnished now, and this was the drilling setup. The jig stays in the vice, then the dowel is inserted and drilled. Quite quick.

Rims have all been despoked, and I've numbered the spoke holes so I know where to drill.

The top rim in this shot has been drilled, the rest are marked up.

Update 2/1/2023: Happy New Year!  And hi ho, its back to work we go.  Quite close to finishing now, I've extracted all the 27" rims I need, and just need to drill 9 of them with 5 equispaced holes before assembly can start. Quiet time in Melbourne, I went for a 7am swim in the yarra which was nice. 28 degrees C already, quite warm.

Assembly while watching "Rivers" on the TV. If it was all put together, it would be too big to get outside.

All the bits

Centrepunch done, drilling follows next.

22mm spacing markup

11mm spacing markup. A spoke nipple is used to make a centre point for one leg of the dividers.

 11pm update!

Close to finishing now. I smashed through some rim marking up, rim centre punching and rim drilling this evening so I could start assembly. About 1/2 of that is done but I came across a drilling mistake, and will fix that and keep assembling tomorrow.

 

Update 3/1/2023 Finished now!  It was just as well I stopped last night as there were 2 drilling mistakes that needed correcting. Today I've drilled holes in the correct spots in 2 of the rims, assembled half-sections inside, then assembled the 2 halves of the dodecahedron outside. 

I kept a lot of the screws loose until the last screw was in, which was just as well, as there was a bit of a fight to get the last screw in. Properly marking out the first 3 rims might have helped.

The selfie photo was a bit of a challenge, as there is a 12s time gap from pressing the button on the camera to the photo being taken. During that time I needed to slither my 62 year old body into the thing. I tried this twice and banged my head on it on the 2nd attempt!

As you can see the back garden is a bit crowded with moderately sized bike rim sculptures, and the tetrahedrons will have to go!  The big tetrahedron folds flat at least! It is described in previous posts here and here. Very glad my late wife Chistine got a laugh out of it!

 Update Jan 4

Overnight I did some calcs on how big the dowels have to be on platonic solid structures like the one I've made, and the results are shown above. The size depends on the shape concerned (due to its dihedral angle ) and  the rim width and geometry. My dowels seem to be undersize, but I think because of the rim rounding I got away with it.

The last pic shows a modest sketch of what's next, or what could be next. I've already established that 3 rims can be bolted together to make a larger side, and by putting 15 sides together, a part icosahedron could be made. this could be a good greenhouse or cubby house or chillout tent. Even larger would be a 6-rim-per side part icosahedron.

Regards  Steve Nurse

Final Version of research published

 

Hi

The final version of my article "Circles for Maths, Art, Play and the Circular Economy" has appeared on the Australian Mathematics Education Journal website, and I have added the article to my Researchgate profile, so it can be downloaded here.  

The article talks about using items that may otherwise be scrap for sculpture and maths education.  I am now working on a project to make a dodecahedron from bike rims, wooden dowel, screws, and washers. It uses techniques described in the article, and I will be writing about progress in the next few days. With me luck!

The Art of Dating

 Hi

A short while ago I posted "Sorry Bettina Klussman" about my very trepid, very tepid  steps back into the dating game, after my wife's recent death and 30+ years of marriage. That was then, and this is now, a whole 3 weeks down the track.  

I haven't slept very well lately, so I thought I'd put some of these ideas down to get some of them out there, so I can process them I guess.  

The whole thing is like I am an atom, and have been locked up in a molecule for a while, and then the molecule gets busted, and I am an individual atom again. Because my chemistry is now different, I now react differently to others, have license to be in different places and situations, and so things have changed.

Firstly I don't seem to have too much trouble meeting eligible partners (mature women in my case) and starting chatting to them is a strange sort of dating game. I'm only just learning the rules, and coming to the conclusion that I'm doing ok by old fashioned methods and not relying on dating apps and other such things. It probably helps that its Christmas and there have been quite a few events on in the last few weeks. I'm optimistic.

Anyway, euphemisms abound in the dating game, and I said to one lady "I wouldn't mind hanging out with you at the bike shed and could teach you some bike mechanics" which actually meant from my point of view "I quite like you, do you want to go out sometime?"

And similarly, a lady I got talking to at a caf had said, "Oh, I might drop in here for brunch over the next few days, I might see you then". Which I think meant the same thing.

Caf's are quite a good thing. Once you start talking, you can skip all the hullabaloo about asking for a first date and pretend you are already on one!

Lastly there is the mobile phone, an essential tool for the aspiring dater. You have to accept whatever form of communication your potential partner wants to use, and sometimes that's a volley of text messages where a simple, shorter phone call (ie actually talking) might do. So recently I was out training on my bike and had to duck under a tree to reduce the light to read and send text messages. (Yes my phone competency is about as good as that of a 6 year old child, maybe worse) But messages got through and we met up and had a good time. So still on trainer wheels with this sort of thing but the training wheels have been oiled.

Best Wishes Steve Nurse

Prepint Released

 

Hi

Just now, I have posted a preprint of an article on building sculptures from everyday objects and 3d printed joiners. It has been approved, edited and will shortly appear in the Australian Maths Education Journal, issue 3 of 2022. Anyway, I wanted to move on and get it published, so here it is on Researchgate.  I will replace this with the properly formatted and citeable version as soon as the journal itself is released.  The article gives an overview of my work joining cds, drink cans, bike rims and other miscellaneous items together to form regular and other polyhedra.

 

Regards

 

Steve Nurse