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Repurposing bicycle components

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Started 7 years ago by kaputnik
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kaputnik
Moderator

I'm currently working on a top secret* contraption involving some bits of wood and some bike wheels.

The contraption involves the bike wheels rotating. This could be done by handspinning the wheel but ideally I'd like it to be done by a hand crank. One is an old rear wheel freehub which my intention would be to put a chain on linked to a sprocket and then turn that by means of a driveshaft with a crank and handle at the end.

So my question is, does anyone have any suggestions as to how to interface a bicycle sprocket with a piece of steel rod which could act as my driveshaft? Or any suggestions as to something light and readily available which might work as a driveshaft/crank/handle.

Ideally it's something that is low cost, I can do from readily available (or even better free/recycled/repurposed bicycle components) and which doesn't involve welding.

It's all fairly low speed/low load so I'm not too concerned about it being structurally impressive or even that true, I can get away with a certain amount of wobble and misalignment..
* - for now, until I can actually make the thing work at which point I will post details and photos here for all to admire.

Posted 7 years ago #
I were right about that saddle
Member

I'd start with the axle out of an old-school bottom bracket with a left hand crank and the spindle of a pedal as the handle...

Are you spinning wool?

Posted 7 years ago #
Greenroofer
Member

Can I just say that I think this is the most infuriating and tantalising post from @kaputnik.

Knowing his creativity and flair I'm sure it's going to be a wonderful thing, but I hate being teased like this.

:-)

Posted 7 years ago #
chdot
Admin

Some variation on this no doubt

Posted 7 years ago #
gembo
Member

Bogey

Posted 7 years ago #
kaputnik
Moderator

Guider round my way (or at least, my dad's 1950s childhood in Gorgie way).

I am liking your suggestion IWRATS. The only thing to overcome is what to do if I want to extend the driveshaft so that the crank is mounted about a foot away from the sprocket that is driving the chain. perhaps a circular piece of pipe that could be jammed in to a square taper bracket at one end?

I am not spinning wool, although you're not a million miles away.

Posted 7 years ago #
I were right about that saddle
Member

perhaps a circular piece of pipe that could be jammed in to a square taper bracket at one end?

Bit of 15mm copper pipe? Soft enough to take the square shape with a bit of hammering and then a bit of epoxy resin?

Posted 7 years ago #
kaputnik
Moderator

Most of the useful articles I've found online are about folk custom-building go carts / carties / guiders / bogeys.

I came across something called "J-B Weld Steelstik" which is an epoxy putty adhesive that's meant for attaching steel to steel in lieu of welding; http://www.jb-weld.co.uk/j-b-weld-epoxy-putty-sticks/j-b-weld-steelstik-epoxy-putty

Posted 7 years ago #
I were right about that saddle
Member

Cartie in my youth.

The last time I had to get something welded (Allen key onto a great long steel rod) I took it to the blacksmith on corner of Willowbrae Road and Duddingston Road. £5 cash in hand, cheaper than that glue...

Posted 7 years ago #
kaputnik
Moderator

The bottom bracket solution is perfect actually, as it means that future parts of the contraption can be added in series, driven by another shaft from the other side of the BB, all turned by the original crank handle.

A trip to the Bike Station ensues this afternoon.

Posted 7 years ago #
dessert rat
Member

I am very much looking forward to the next not-PY

Posted 7 years ago #
I were right about that saddle
Member

Me too.

Posted 7 years ago #
kaputnik
Moderator

Quick question if anyone knows (or has one and some Vernier calipers handy), what is the "diameter" of the end of a square taper BB spindle?

P.S., nice suggestions above, but you're all wrong;

Posted 7 years ago #
wingpig
Member

JIS: 12.65mm
ISO: 12.33mm
...according to https://bicycles.stackexchange.com/questions/10186/how-can-i-tell-the-difference-between-a-j-i-s-and-iso-square-taper-bottom-brack

I'm going with

Posted 7 years ago #
kaputnik
Moderator

Then according to my calculations the diagonal section will be between 17.3 and 17.8mm (probably a bit less when accounting for the curved corners of the spline), and the circumference would be about 49.2mm, meaning a piece of 15mm pipe with a 38.7mm diameter is unlikely to stretch around it, I ideally need a piece of at least 15.6mm pipe! You can get Stainless Steel or Aloominum pipes with a 17mm internal diameter, that might do the trick.

Posted 7 years ago #
I were right about that saddle
Member

@kaputnik

Copper is both malleable and ductile. Like most problems, this one can be solved with a hammer.

Posted 7 years ago #
kaputnik
Moderator

Plans by andy a, on Flickr

You get the idea (but not what it actually does, beyond rotates a bike wheel affixed through a piece of wood)

Chain tension will be an issue as it will inevitably sag off the driving sprocket. If I wasn't wanting to do this on the cheap I'd get an eccentric BB for the bottom one. Who knows, I might get lucky at the bike station, or pick up a tensioner that I can incorporate somehow.

Posted 7 years ago #
I were right about that saddle
Member

Shaft to next wheel in series? You're setting up a hand-cranked cotton mill staffed by Victorian children?

Posted 7 years ago #
kaputnik
Moderator

Who needs Victorian children when I have one of my own?

I hadn't yet considered that a belt/friction drive running inside the rim might be an alternative to the chain, but given then way the wheel is cantilevered out from the wood it might not be a great idea to put a drive band around it. Plus I'm pretty keen to use as much bicycle bits in this as possible.

Hmm. Having looked into it, using nitrile rubber O-ring or Urethane belting material, which can be joined into a loop fairly easily would be a less complex drive system. Fortunately, I'll go with the more complex bicycle-shaped option as what I need to attach to the wheels would foul the rim from acting as a pulley.

Posted 7 years ago #
gembo
Member

Wind the bobbin up?

Posted 7 years ago #
wingpig
Member

Stick an old derailleur pulley sideways half-day along the chain run and put the chain through the middle?

Posted 7 years ago #
Arellcat
Moderator

Most chain tensioners in recumbentry are either repurposed dérailleurs or one or two pulley wheel(s) on a sprung arm. Or you could go Triumph slant-four, and have a metal plain bearing that simply runs against the (camshaft timing) chain to provide the requisite tension.

I always loved how W Heath Robinson never seemed to have a piece of string without a knot tied in it.

shaft to next wheel in series

I'm hoping it leads to sector gears, number wheels and carry propagation columns.

And now for something completely difference

Posted 7 years ago #
I were right about that saddle
Member

Page 36 for anyone else wondering what a Triumph slant-four slipper head chain tensioner is.

Posted 7 years ago #
wingpig
Member

Maybe a ?

Posted 7 years ago #
kaputnik
Moderator

I am pleased to report that a test run of the contraption last night (without the chain drive, turning by hand) was successful. I just need to add a cassette to the freehub and sort out the driveshaft for a trial under crank power.

Then it will all be taken apart to sand and varnish the wood and scrub up the bicycle parts so they are free from grime.

Speaking of driveshafts, rather than ram a piece of 15mm pipe on permanently, it struck me that a square taper BB has an M8 (I think) thread cut into it for the crank retaining bolt. I was thinking about putting a long bolt in there from which the head has been cut off and (if the threaded directions cooperate) using that as the driveshaft. It means it can easily be taken apart for fiddling.

Posted 7 years ago #
Arellcat
Moderator

it struck me that a square taper BB has an M8 (I think) thread

Yes but no.

Crank bolts are M8 fine, which is a 1.0mm thread pitch. Ordinary M8 has a 1.25mm pitch.

Posted 7 years ago #
kaputnik
Moderator

Aha. Just as well I went with a hacked off bit of straight handlebar then :)

Thingamatron Mk.1 by andy a, on Flickr

Any guesses? I've tested it out by spinning the wheels by hand and it works as intended, although not yet tried completing its mission under hand cranking.

Will be disassembled and smoothed and cleaned up for varnishing. Some tweaking needed of the fine details like those little eye hooks on the base.

I dissasembled the chain tensioner and replaced the bolt that would normally screw into the derailleur hanger with a long M6 bolt and some handy sized round-bodied bolts that were the same diameter as the original axle. That meant I didn't need to try and mash a hanger in there to mount it on, I could bolt it straight through the timber after cutting a little recess for it to sit in. The end of the tensioning spring catches perfectly on the timber so the whole thing pulls the excess chain slack in the way.

My "blueprint" above suggested mounting them in series using a shaft from one to the next. However that would be very long and rigid. I think mounting them in parallel using a chain to transfer the drive from one of the unused rings of the chainwheel is a better idea. You just make more of these but without the handle assembly and chain them all together.

Posted 7 years ago #
wingpig
Member

Giant kite string winder?

Posted 7 years ago #
gembo
Member

Either a printing press for slow printing of artworks or a giant flywheel for catching dreams?

Posted 7 years ago #
Cyclingmollie
Member

A wool winder? The chain tensioner will also act as a safety feature as the chain will ride over a finger that gets between it and a geared wheel.

Posted 7 years ago #