April 2020 Posts

Handlebars

Handlebars

I copied this handlebar from Jon Thompson, who made some in this fashion for fixies (http://tomobikes.co.uk). As such he made them quite narrow, ideal for London traffic, but maybe not ideal for hillier northern roads. His idea was that the design of most handlebars is not really anatomical and setting the handgrips at a more natural angle may be more comfortable. It also struck me that apart from being a simple design to make I may be able to accommodate some integrated lights so I decided to make my own version for my upcoming fixed wheel frame. This is in fact a project I have had on the go for some time. Realising the angle of the bars may not be exactly the same for everyone, or indeed exactly the same on both sides, I decided to start with a variable handlebar to establish the best position for me.

Oxy-Propane Brazing Update 3

Oxy-Propane Brazing Update 3

I use oxygen and propane for my brazing. I did not want the expense and extra safety concerns of storing and using acetylene, and in particular did not want to get involved in contracts given the small number of frames I am likely to build as a hobbyist. Though contract free acetylene cylinders have become available, personally I see no advantage in using acetylene for building lugged frames, but it does have advantages for fillet brazing. Propane is relatively cheap and long lasting and widely available for a small cylinder deposit. I use a 11kg cylinder. Smaller ones are OK but I have found the larger cylinder more stable, especially when using a gas fluxer, I don’t know why. Storing the smallest size cylinders of practical use of any flammable gas is common sense.
IMG_0925

Tube Mitering on a Lathe – Update 2

Tube Mitering on a Lathe – Update 2

Tube mitering is a fundamental part of custom frame building and I am sure there is always a need to be able to produce good results by hand and eye. Paper templates are a boon for speeding up the process and increasing accuracy but some time ago I decided to see how I would get on with some form of automation for the process. A milling machine, lathe or tube notcher can all be used but as I already had a lathe this seemed the way forward. Although I have since acquired a milling machine I feel the lathe is easier to set up for the process. I have described elsewhere making the tube blocks to enable this. My lathe is small with 500mm between centres.
I initially obtained several Coba-Tech hole saws from Stakesy’s metalwork machinery suppliers (https://www.stakesys.co.uk/hole-punches-hole-saws/hole-saws-arbors/coba-tech-10-tpi-fine-tooth-holesaws). These are fine tooth saws as opposed to the more usual coarse tooth saws I have used in the past. For cutting good mitres in fine tubes I would say these are essential and Stakesy’s were the only supplier I could find. Tube notchers are available, such as these: https://www.stakesys.co.uk/tube-notchers/tube-notchers. They are designed to be powered by a hand drill and are considerably cheaper than a lathe, though obviously are a one trick pony. The speed of the saws is set by the drill trigger speed and will be determined by feel rather than dials, but I am given to understand can be used quite successfully.

Coarse and fine tooth saws (fine on the right)

Coarse and fine tooth saws (fine on the right)