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Lugs are the first thing
I usually tackle. All lugs need prep work, these got quite
a bit of carving done as well. This bike used Richard
Sach's Newvex lugs. On the left is a picture (borrowed
from Richard's site) of the lugs as cast. On the right are
the lugs after I carve them up. |
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| Once the lugs are all
carved up, sanded and ready to go, I can start mitering
tubes. I use the machine pictured on the right to cut my
miters, I can set the angle of cut on the large rotary
table and then just feed the tube right into the cutter.
This mill set-up is very rigid and the cuts come out
spot-on every time.
The spreadsheet shown above gives me all the miter
sizes and tube lengths that I need to cut the whole
frame right now
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Once the main tubes are
mitered, I file the ends of each tube to de-burr them,
then begin test-fitting them into the jig. I always start
with the BB shell in my jig, then fit the seat-tube. Next
I fit the top-tube to the seat-tube, then the headtube,
and finally the downtube.
Once I confirm that the geometry is correct and the
tubes fit properly, I take it all apart and sand all
ends of the tubes inside and out and then flux them up.
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Here's the front triangle all set up in the jig, ready
to tack. Next I'll braze one small part of each lug to
tack the frame together, then I'll remove it from the
jig and fully braze it in a workstand. Once it cools
from brazing, I soak the whole thing in water to remove
the flux.
At left is what a lug looks like just after soaking.
This picture doesn't show any excess silver since I fed
the lug from the other side, but next I'll clean up any
silver "flash" left from brazing with an abrasive
blaster.
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Now it's time to work on the rear triangle. On this
frame I had to start by bending the chainstays to the
appropriate shape for tire clearance. I don't need to do
this on most frames but 29'ers often need more tire
clearance than I can get with stock parts.
Once the stays have the right shape, I slot the ends
for the dropouts and braze in the dropouts. I do this
with brass as it fills the space between the dropout tab
and the chainstay better. Once this brazing is done,
they cool and the flux is soaked off.
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Next I have to make the scallops and shape the
dropouts. This is one of those small details that really
can make a frame look nice. the scallops must be just
right with no undercutting into the dropout. I do this
with a Dynafile abrasive tool, which cuts very fast, so
extreme care must be taken to remove only what needs to
be removed.
Once I form each scallop, I shape the top and bottom of
the stay-dropout to the desired shape. On this one you
can see I filed in a small scallop on the underside of
the dropout tab.
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Now that the dropout to chainstay joint is all shaped,
I like to clean up the dropouts themselves. Most forged
dropouts have marks on them where the forging dies meet,
so I hand file these to nice square edges. Then I file
the window out so it's nice and clean.
There's a lot of detail work that goes into making a
nice classic looking dropout. This area is probably the
most time-consuming part of my framebuilding process,
but if you want it to look good with paint, it needs to
look good bare.
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The seatstay treatment is next. This frame used
side-tacked, scalloped seatstays, which is my most
common method of doing it. I make my scallops from
scratch and don't use plugs here. It's another nice
touch and makes the frames lighter.
I start off by filing the end of the seat-stay to a
very shallow miter. They're sized to fit the scrap
tubing sections I've cut up to make the scallops. I use
tubing from 19mm to 25mm to make the scallops depending
on the seat-stay diameter.
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| Once the tubing if fitted
to the stay, I braze it in place with brass. No jigs
needed, just flux it up and hold the stay in a vice,
gravity will hold the tube scrap in place.
Once it's brazed, I grind to to a rough shape and
finish file it down to the shape you see on the right.
This one happens to be a 19mm stay with 25mm tubing for
the scallop. On smaller stays I use smaller diameter
tubing to keep things looking proportional.
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Now it's time to join those seat-stays to the rest of
the frame. I cut them to the proper length, then file
slots in the chainstay end of the stay. Then I file a
small groove on each side of the seat-lug where the stay
will contact it. This provides more surface area for the
braze and makes the joint much stronger.
Once all that is done, I mount the stays and braze them
in place. The dropout end is done exactly as described
above with the chainstays. The seat-lug end is just
silver brazed right to the side of the lug as shown
below:
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The main portion of the
frame is done now, all that's left is to clean up the
joints (abrasive blasting) and to install the braze-on's.
I usually install all the braze-on's next : bottle bosses,
cable stops, etc... then soak the whole frame one last
time, then blast it all.
Once that's done, I build the fork, and in this case
the matching stem in the same fashion (shown left).
Once all the fabrication is done, I do an acid etch on
the frame and begin the painting process.
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This frame had a very
unique paint job. The "chrome" on the lugs is actually
paint and the blue main color is a candy that is applied
to the clearcoat.
After primer and sealer, I had to paint the whole frame
silver, then I clearcoated the whole frame with the
candy blue. The frame was then baked overnight to cure
the clear. Next the clear on the lugs had to be polished
out to a perfectly smooth finish and then all the tubing
around the lugs was masked off, leaving just the lugs
exposed. The downtube logo was done in the same manner.
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Once the hours of masking
were complete, I was able to spray the "chrome" finish on
the lugs and bake that paint overnight to allow proper
off-gassing. Once it was baked, I polished it out and
resprayed any areas that did not look perfect and baked
again.
Finally once I was satisfied with the appearance I
removed all the masking and sprayed the final clear.
The final clear is un-tinted and protects the chrome
finish as it would any other paint. It also brings out
the deep luster in the metallic.
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