From: Orin Eman <orin(AT)nwlink.com>
Subject: [Frame] First frame (long)
Date: Thu, 5 Jul 2001 01:00:48 -0700 (PDT)
I've been slacking too long about writing up the adventures of
making my first frame.
Towards the end of last year, I decided to go take a welding
class at a local college, for reasons more than just bicycles.
So, at the beginning of January, I started the class. We started
with safety and personal safety equipment - for this course,
the passing depended mainly on turning up to class and being safe,
actually welding something being of secondary importance.
We started off with oxy-acetylene welding. How to check the torch,
set the regulators, light the torch, turn it off etc.. I get some
sheet metal welded fairly well by the end of the first night.
I learn that filler rods stay hot a long time after I lean on
one that I'd put on the bench and it burns through my shirt
and makes a mini-dent in my arm - fortunately only a 3/32" rod.
A few classes later, some want to move on to TIG, so I follow,
to see what the fuss is about - what's the big deal with TIG?
The instructor demos it and mostly, I can't see a darn thing
with others and helmets in the way. We are loaned the removable
parts for the TIG torch and two of us share a booth. We can
hardly get an arc between us. It turns out the high frequency
start feature of the machine is broken... setting it to
continuous (usually only used with aluminium and AC) works
and we are off... to the grinder mostly to regrind the tungsten
electrode after dunking it in the weld pool. My first attempts
at a bead wander at funny angles due to poor visibility, but
I get better. You get up real close to the arc - only a few
inches between the arc and your helmet to see well. Gloves
are essential to stop burns from the UV light from the arc.
It will sneak up you shirt sleeves if you aren't careful then
you wonder where the sunburn on the inside of the forearm
After I while with the TIG, I decided to try some bicycle type
joints. I got some .065" tubes from a local steel supplier
some hole saws and cheap ($30 Harbor Freight) tubing notcher.
I did a 1" tube at 73 degrees to a 1 1/4" tube. After a night
of this, I ended up with a piece of 1/14" tube with 1" tubes
sticking out at strange angles. Only one hole that I blew
in the tubes is still in evidence. I also had a 1 1/4" tube
at 90 degrees to a plate that the 'tubing monster' could
slip into. I took this home... the next evening, when I
got home, the 'tubing monster' is sitting in the tube/plate
with coffee mugs hanging off its arms!
065 tube being rather, thick, I ordered some 049 and 035 chromoly
and start working down to the 035. Eventually I succeed with
some 3/4" 035 tube to the 1 1/4" 065 tube. The instructor
suggests we destructively test it. The big tube is clamped
in the bench vice and we put a pipe over the small tube and pull.
I hang on the pipe and nothing happens. The instructor gives
up... The big tube is slipping in the vice, so the pipe
goes on the vice handle and the 1 1/4" tube is now squished
down to more like 7/8". Finally, with the pipe back on the
small tube, something breaks and the 065 tube tears. I'm happy
with the amount of abuse required to break the joint.
It's now near the end of the quarter and the instructor thinks
I should make a frame, so I sign up for another quarter and place
a call to Henry James... I chose True Temper RC2 tubing
for all but the seat tube where I decided the RC2 tube was
too thin for my skills and chose the AVR externally butted
tube instead. (Now both are called 'Verus' by True Temper
and my frame sports a pretty gold Verus sticker.)
A box of tubes, dropouts, brazeons etc. arrives as the second
quarter begins. I have fork blades to rake, dropout plugs
to file, tubes to miter and so on. Another trip to the local
steelyard gets some angle iron to make a fork/rear triangle jig.
I make the jig to rake the fork blades out of 3/4" ply from
plans that Henry James supplied.
Optimistically expecting that the frame will turn out OK, I
place an order to Total Cycling for a Campy Daytona groupset.
When it arrives I find I'll have the pleasure of doing a
front derailleur brazeon. Good thing I found out this early!
In class, I start brazing practice for the forks and brazeons.
(I had ordered practice kits from Henry James.) I made messes
for a while, but things come together... and stay together eventually.
I made a paper drawing of the forks. I got the rake of the
blades right by laying the blades on the drawing after bending
them and bending more if necessary. With two pieces of angle
iron, some bar stock, threaded rod and lots of 1/4" bolts,
I made a jig for the forks. I used u-bolts to hold the
steerer down to two pieces of bar that went perpendicular to it.
the bars were bolted to the angle iron that ran parallel to the
steerer. Two more pieces of bar provided uprights to hold
the threaded rod that simulated the axle. Rake was set by the
height of the threaded rod above the angle iron, adding for
the thickness of the bar and half the thickness of the steerer.
After finally brazing the blades in, and setting the spacing
at the dropouts, a freshly built wheel centered perfectly.
Better than I had expected!
On to the main triangle... well, some of it was done inbetween
operations on the forks. I started with the seat tube.
This merely has to be square and centered on the BB shell.
I accomplished this with a simple bar clamp... clamp,
square it up, tack weld it, check for squareness then
complete the weld, alternating sides to minimize distortion.
Then the down tube. This needs the angle between the seat tube
and down tube to be correct as well as being square to and
centered on the BB. Also, it needs some hand filing to clear
the existing welds on the seat tube. After plenty of hand filing,
it was ready and again, the bar clamp was enough to hole it square
for tack welding.
The head tube to top tube was next and was the joint I'd practiced
before. With a decent miter, it was just a matter of positioning
it the right length along the head tube (actually not a critical
position since I'd planned for a 20mm head tube extension and some
extension at the seat tube - a couple of mm wouldn't matter here).
Now, the hard part came - tacking the two halves of the main
triangle together. At this point, I finished filing the
miter on the down tube where it meets the head tube. The
top tube was ready to go. Again, the trusty bar clamp comes
into use to hold the two halves together. This was the hardest
to clamp as the tubes are at an angle rather than square like
the BB joints. I believe something slipped before tacking
since I had to some twisting prior to the final welding...
and required some cold setting afterwards.
Now for the rear triangle... "the chain stays look like you
clamped them in a vice..." Exactly. I wasn't going for beauty,
but tire clearance. I rearranged the angle iron I'd used for
the forks to make a jig for the rear triangle. Two uprights
and a threaded rod to hold the dropouts, two uprights and
threaded rod to clamp the BB. The bottom of the BB sat on top
of the angle iron and could slide back and forth a little,
making chainstay length non-critical. The BB drop was set
by the uprights that held the threaded rod/dropouts and was
the critical dimension on this jig (other than everything
being square of course). I spent so much time at the drill
press making this jig that the instructor was joking that it
was welding class, not machining class...
With the stays brazed to the dropouts, I hand filed the chainstays
to fit the BB then moved on to fitting the seatstays to the
seat tube. Getting these to behave was frustrating and
eventually I TIG tacked them together at the top so I could
fit them as one piece. Now I made the mistake of using a
different TIG machine for the chainstays and seatstays.
The results weren't pretty, but they were functional. The
top of the seatstays are somewhat ugly. A little cold setting
(stand on one side and pull up on the other and a rear wheel
centers perfectly). One issue I had thought of and didn't
solve was getting the dropout slots parallel. They lined up
without help for me, but I'd like to know what I should have done.
Before going on, it was time for some machining. The local
Performance bike shop helped with machining the fork crown
race seat, chasing the BB threads, facing the BB and facing/reaming
the head tube for an amount I may not disclose ;)
Now I was ready for brazeons. Yes, I hadn't drilled the tubes
for water bottle brazeons, so I had to find a right-angled
drill attachment. With the help of spring loaded clamps from
Home Depot (they have plastic covers that I removed), this
went easy enough for all but the cable stops. A BB and cranks
were installed long enough to get the position of the front
derailleur brazon marked on the tube. The clamp held the
brazeon perfectly and the silver flowed nicely, though I
used a little too much (actually, a common problem with my
brazing, I had to do quite a bit of filing/sanding to remove it).
The only real mistake with the brazeons was the rear cable
stop on the top tube. It digs in my shoulder when I carry the
bike up the stairs to my apartment.
Of course, the bike got built up and test ridden now. It required
a trip to the Bikesmith in Seattle to ream out the seat tube,
the only 'machining' step that hadn't been done. (Val was very
observent in noticing that the bike had no paint ;)
Finally, paint. Matt Houle responded to my request here on the
list and arranged for it to be powder coated - thanks Matt!
I've been doing longer and longer rides on it - so far I've trusted
it to 27 miles from home and it seems to be holding together.
In fact, my money is on the seat binder bolt being the first
thing to break.
PS, the dimensions:
ST 57.5 C-T
BB drop 7.5
CS length 43.5 (wheel all the way back)
Fork rake 4.3
Head tube extension 2cm
Clearances for 700C wheels with long reach brakes.
1st frame account from bikelist.org