bikes

I reached a milestone today on bike manufacturing. My friends were able to help me make a special chuck that can adapt the carbide hole saws I bought from amazon to the spindle of a mill machine. Here is a video of a test miter on some scrap tube.



This is a google drive link so you may need to copy the link into a new browser window to get the video to play.

This is the setup I will likely be using to miter real tube for the bike frame. The tube is held at the correct angle using a 3d printed tube holder, while some steel tube blocks allow the vice jaws on the mil table to grip the tube without crushing it.



My prior miters were done a lathe, a mil has the advantage though that it is easier to align the centers of the tube and hole saw. Compound miters such as seen on the down tube of most bikes are also easier to do on the mill since the four sides nature of the tube holder blocks allows the tube to be rotated exactly 90 degrees without meticulous measurement.

It is taking some time, but I am also making some progress on learning how to ride a unicycle. Today I was able to successfully complete a turn around pillar, which I was very pleased with.



Again this is a google drive link so it will need to be opened in a new tab to play.

If anyone here is still into bamboo/wooden bikes, this is a bike that was recently donated to a bike store near where I live. It turns out that the wooden tubes are affixed to metal lugs, which helps hold the bike together. The bike is not purely wooden.

If anyone here wants to learn more about the mathmatics behind bike handling, this forum discussion here contains a lot of useful information.

https://www.bentrideronline.com/messageboard/forum/main-category/specialty-discussions/technical-discussion/3024052-mathmatical-modelling-of-bikes-and-trikes/page2

I began mitering the tube for my first frame today, this is the miter for the downtube and bottom bracket shell.

I was able to make one more cut on the tube. The down tube now fits well with the head tube of the bike as well as the bottom bracket. If all goes well, I should have some time this weekend to finish mitering the rest of the tubes.

The tubes so far line up near exactly with this 1 to 1 scale printout of my bike. This is a good sign as it indicates my procedure for cutting and mitering tube is accurate.

Just stopping by to make a case for bikes being one of the best modern means of transportation. I believe in subsidizing bikes to improve public health and reduce carbon emissions.

Also, love your work MrPedalMan, keep it up!

what are you doing for the fittings ie the pedal crank, the rear wheel bracket, etc? do you just buy those off the shelf?

also how do you keep them all square in the same plane while you weld them? im super curious

The problem of keeping the tubes in plane is admittedly a problem I am not completely sure how to counter yet. Most of the sources I have consulted though seem to agree that strategic placing of tacks to cancel pulling forces can help, but that the ultimate solution is to use a so called cheater bar to bend any wayward tubes back into their correct position. In the case of brazing a bike together, the braze flux can be removed and tube welded once more, but this does not seem to be the case in tig welding a bike frame.

It is possible to make rear dropouts, but for my first bike I have been recommended to use prefabricated dropouts from framebuilder supply.

https://framebuildersupply.com/collections/rear-dropouts/products/rear-track-dropout-plug-style-for-11mm-id-seatstay-and-chainstay-66-seatstay-chainstay-angle

this guy doesn't even weld - he brazes! 5yo vid. he says a fixie is an easier first bike because there's no gears or derailers to worry about

Yes, cobra framebuilding is indeed a great resource for building bike frames. I have utilized some of his advice on using a mil for tube mitering. I am currently planning for a my first bike to be a single speed bike, not necessarily a fixie in that a coasting mechanism will be part of the design. I agree that having to worry about a derailleur hanger and making room for a cassette on one's first frame is typically not recommended. I have also been recommended to avoid using lugs. Though lugs can be useful for holding tubes in place and reducing the likelihood of the tubes pulling to one side, lugs lock the bike into a fixed geometry. If one seeks to progress towards making an unconventional bike like a recumbent in the future learning with lugs will likely be a liability, because lug sets are near exclusive to upright bicycles.

This is a diagram of the bike I am hoping to make in bikecad. Is is meant to be a single speed with 700c roadbike wheels. This was made in bikecad.

This here are the tube measurements.