A record of my efforts to construct a python recumbent bicycle, also known as a moving bottom bracket (MBB) or pivot steer bicycle.
Monday, 26 November 2018
So that's why there's a guard on an angle grinder....
Flap disc abrasive on an angle grinder that I had been too lazy to replace the guard on. Silly chicken.
Friday, 23 November 2018
New wheels from Germany
The wheels arrived. I had them built by Ginkgo in Germany, as the single sided hub and suitable 406 rims are impossible to source in the UK. I've added 50mm Schwalbe Big Apple tyres - these are heavy, but will be the python's only suspension.
https://www.ginkgo-veloteile.de/ginkgoshop/en/home/
https://www.ginkgo-veloteile.de/ginkgoshop/en/home/
Wednesday, 21 November 2018
Tuesday, 20 November 2018
Monday, 19 November 2018
Dropouts with tapped hole for mech
Small parts manufacture continues, today the dropouts. Information about dimensions were a little hard to find - Shimano publish standards that they recommend if you want their gears to index, but it wasn't clear if they were universal (I like SRAM kit). So I made them to the Shimano standards and here's hoping for the best.
I bought the cheapest bench drill I could find. It is remarkably accurate - as long as the quill is not extended too far a 10mm hole is +/- 0.01mm, almost lathe / mill accuracy.
I bought the cheapest bench drill I could find. It is remarkably accurate - as long as the quill is not extended too far a 10mm hole is +/- 0.01mm, almost lathe / mill accuracy.
Sunday, 11 November 2018
More welding practice and pivot assembly
More welding practice - still not consistent enough.
I made a holder for my TIG torch.
I decided to do some engineering while my welding skills are developing, so I made the pivot.
The pivot cosists of 2 12mm rod end (Heim) joint bearings. These are relatively cheap, so that when they wear out (as they will, because they will get wet and dirty), they can be easily replaced. They are also arranged so that the pivot angle can be adjusted ∓ 5 degrees.
The steel comes from a local industrial supplier that will cut and sell small quantities and offcuts to visitors - very handy. It is 5mm mild steel. The channel section is cut from a square section.
I have a week of leave in 2 weeks time - I hope to weld the front frame then.
I made a holder for my TIG torch.
I decided to do some engineering while my welding skills are developing, so I made the pivot.
The pivot cosists of 2 12mm rod end (Heim) joint bearings. These are relatively cheap, so that when they wear out (as they will, because they will get wet and dirty), they can be easily replaced. They are also arranged so that the pivot angle can be adjusted ∓ 5 degrees.
The steel comes from a local industrial supplier that will cut and sell small quantities and offcuts to visitors - very handy. It is 5mm mild steel. The channel section is cut from a square section.
I have a week of leave in 2 weeks time - I hope to weld the front frame then.
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