One of the most basic and important things when
designing and building a bike frame is having a well drawn plan. I draw out my designs at
a scale of one to ten. Then, as I finalize the shape and details, I do a working drawing
at one to five. I do all my drawings on graph paper because it's easier, and I don't need
a drafting table. CAD programs take too long and for myself, I find them hard to use.
Like Red Green says, the only power tool you
really need is an electric drill. Only about a year ago I bought a Dremel tool to speed up
finishing joints before painting.
When I began building frames, I used to mitre
the tubes with a hacksaw and files. Now I use bi-metal holesaws, which save a lot of time.
Large manufacturers also use hole saws to mitre tubing, except they have 2 ton machines
which allow them to mitre hundreds of tubes per hour.
The essential tools of building bike frames can
be separated into the different stages of building. The first stage is cutting the tubes,
the second is joining the tubes and the third finishing the frame for painting.
For the first stage, a good strong stiff hacksaw
with a top quality blade, with a tooth pitch of 24 to 32 teeth per inch. An electric drill
preferably with a 1/2" chuck. I have hole saws in 1/8" increments from 5/8"
up to 1 3/4". You really don't need all of these sizes, but I like to be prepared.
The hole saws should be designed to cut metal of course; wood holesaws will only scratch
the surface. Files in various shapes and sizes are great for making sure the joints fit as
close as possible.
The second stage is brazing tubes together. For
small projects such as a one off design/frame, I use propylene gas with a high temperature
torch head. The basic setup looks like a conventional propane torch but the temperatures
are much higher. Propane is okay for soldering but brazing requires temperatures of at
least 1982°C or 3600°F. I use flux coated brazing rods that are preferably 1/8" or
less in diameter. Before brazing it's good idea to clean the joint area with emery cloth.
Brush on flux helps to clean the area also but is not always necessary. Propylene is sold
as brazing fuel, or sometimes Mapp (tm) Gas. Under ideal conditions, two 400g tanks can
build a whole frame. This type of torch will easily braze tubes with wall thicknesses of
1/16" or less. I join frame tubes by a combination of fillet brazing and lap joints.
I find brazing to be the best for building frames because you can do so much with it, such
as putting water bottle bosses on, or cable housing guides and stops.
For heavier stuff or areas that need a large
fillet, I'll use a oxy/propane torch. This is a two tank setup which can cost about a
dollar a minute and a single tank of oxygen will last only about 10 minutes. You can go
through up to 10 oxygen cylinders for one propane cylinder. A oxy/acetylene torch setup
would be the best but has a higher startup cost and will impact on your household
insurance policy.
The third stage can take a long time. Mostly
what is required are files (mostly round and half-round), emery cloth, steel wool, and
lots of elbow grease. How well you finish the joints and prep the surface of the frame
will result in a better overall finish. But be careful not to take too much off some
joints, because it may weaken the joint.
