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Techniques
Framebuilding is an art that is filled with little tricks and techniques. Below you will find a few that i have run across over the years, mostly from talking to other more experienced builders. If you have more to add, let me know. In the meantime, have fun!
Internal Cable Routing
This is one that I did once, swore I would never do it again. Then I did it again, couldn't resist. It's a pain, but looks slick when it's all done.
Holding Braze Ons
Getting braze ons to stay in place is aggravating. You can use a clamp like illustrated on the Tools page, or you can use magnets.
Building Lugs
To cut lugs, first you need a blank lugs. Paint the lugs with a black magic marker, then scribe your pattern on it. Then, cut it out using files and a thin saw. You can see my custom lug page and the Labor of Lug article for more info. Also, the lug mandrel used to hold the lug while you work can be seen on the tools page. Adding a nicely shaped point or curve to a lug is easy as well: take a scrap piece of tubing, cut out a small triangle, and then brass braze the triangle onto the lug where you want it. Then , file the transition from lug to point. You braze it on with brass so that when you braze the whole lug into the bike, you can use silver and not melt the point off again.
Seat Cluster
There are many many ways to braze seat stays onto the seat tube. This is one of the more visible parts of a bike, and also one of the places where a bike builder can really show off his work.
Or you can make a side tacked seat cluster. Take the end of a seat stay, and make a several inch long, 45 degree cut, which should end at the corner of the stay. Then, take this piece of scrap tubing out. Now, you can either flip this scrap piece over and place it back onto the stay, or put a half piece of one inch tubing in the spot. IN either case, braze around the edge, clean up the joint, and you have a nicely scalloped seat stay.
Seat Binder Bolts Many great lugs are made of stamped steel, which is formed into the lug and welded down the seam. The seat binder bolt are for these lugs are somewhat ugly. It is easy to change this with a little metal sculpting.
Bridges Making brake bridges and chain stay bridges is also very easy. Just take a scrap piece of seat stay, miter the ends to fit the opposing tubes, and silver braze it in place. It looks nice if you also use little reinforcing plates on either end. These are usually store bought however.
Dropouts
Many fine dropouts are the tab variety: one flat piece of dropout, designed to insert into a slotted stay or forkblade. Often they can be re-worked to look better.
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Take a stainless steel tube,
slightly larger in diameter then the cable housing for your cable. Drill
two holes in your top tube, one at either end. Keep the holes in the
section of the tube that still has the thick butting!!! You will have to
elongate the hole into an oval to get the stainless tube to enter the top tube
at the correct angle, or else your brake cable will bind. Set this all up
BEFORE brazing the top tube into the lugs. Then braze the stainless steel
tube into place.
Once the stainless tube is in
place, braze a reinforcing plate on top of it. The reinforcing plate can
be homemade, or stolen from something else. Here I used a little
reinforcing plate designed for use on a chainstay bridge. 
Here is the other end of the
internal cable routing. I have been told it is easier to run the stainless
steel cable into the top tube if both entry and exit points are kept in the same
plane, i.e. if standing at the handlebars and facing towards the back of the
bike, the stainless tube enters the TT at the 5 o'clock position, and then
it exits again at 5 o'clock by the seat lug. 
Here is a magnet holding a cable stop in
place. Usually it helps to have 2 or 3 magnets holding the braze on in
place. Beware that as the piece heats up, the magnet will crack and
explode, so work fast. 
However, you need something to hold the
lug and the point together while you braze the point on. Here we have a
scrap piece of tubing with a slot cut into it. 
Then, you place the joint between lug
and point over this cutout. The piece of scrap tubing supports the
lug/point combination as you braze. When you braze the point, the seam
will be located over the slot, preventing you from brazing the point to the
scrap piece of tubing behind it. You could also use a piece of stainless
steel pipe, since the brass won't stick to it. In this photo, you
can see a small horizontal line where point meets lug. 
To build a fastback cluster, I start out
with a seat stay and a lug that has ports cast into the back. normally,
you would insert the seat stays into these ports and braze, thus making a seat
cluster. Instead, I will use it as a pattern. So first paint the
seat stay black with a magic marker, and then stick it in to the port in the
back of the lug. 
Here you can see the stay sticking into
the back of the lug. Now scribe a line around the inside of the lug
and file the seat stay to the line. 
Here you have the seat stay with the end
filed to the inside shape of the lug.
Now place the seat stay up against your
lug. It may require slight modification depending on what angle the seat
stay approaches the lug and seat tube. 
Here is the 45 degree cut that ends at
the corner of the stay.
Here is the one inch piece of half tubing
that was laid in the spot after the cut, and it was brazed and filed clean. 
Another view of the above picture. 
Here is a beautiful stamped steel
lug with an ugly seat binder. 
Here is a different lug, but
with the binder tabs ground off. Notice the hole that is left in the back
of the lug once the tabs are gone. 
Here is the lug built into a
frame, with a "patch" of steel brazed into the spot where the hole used to be.
In this case, the patch was cut from 4130 straight guage tubing (i.e. aircraft
tubing) of the same diameter as the lug. A few gaps still remain between
patch and edges of the hole, but this is easily filled with silver brazing rod. 
Side view
Here is what it will look
like, roughly, when all the brazing is done. The seat binder is now a
separate piece (which is cast) and then brazed in place. 
Here is just such a bridge. It
is drilled for a fender. 
Here are two dropouts.
The left is how it comes from the manufacturer, raw. On the right it is
brazed into a stay, but the filing and finish work is not yet completed. I
usually do the final finish work when the pieces are on the completed bike.
I removed one fender eyelet and ground down much of the excess metal on the back
edge of the dropout. Then i rounded it off and tried to make a smooth
transition to the last remaining eyelet. Further thinning and
shaping will be done in the area of the seatstay once it is brazed in place.
Notice the chainstay junction on the non-drive side: it is scalloped. This
is performed by beveling the end of the stay at a 45 degree angle before
inserting the dropout. Once you start brazing, fill in this beveled are,
and a little beyond the stay (toward the dropout slot) with brass. Then
take a sanding drum of the appropriate size, put in your dremel tool, and sand
out a scallop. 
Here is the non-drive side of a
similar dropout. Notice how the stay is flattened to create more room for
the rear wheel. This is more critical on the drive-side dropout to make
room for the cogs. But, you can do it on the non-drive side for symmetry.
To do it, braze the outside surface of the dropout first, the one with the
scallop. Then heat the inside surface of the stay, bring over to a flat
metal workbench, and hammer (gently!) the inside of the stay until it is flat.
Then braze around the edge of this flat part. When everything is cool,
file the flattened part to make it broader, smoother, whatever. You can
also file in a gentle curve to be more ornate. 
Here is the bottom of the stay.
Notice the scallop on the outside surface, and the flattened part on the inside
(wheel-side) of the dropout. Here, i decided to leave the wheel-side not
perfectly flat, but with a little curve, to make things a little nicer.