braze-on technique, jigging, pinning, distortion

Subject: [Frame] RE: Braze on Jigs
From: "d.chambers"
Date: Thu, 01 Mar 2001 22:00:44 +0000

Personally, I've tried g-clamps, but have never had much success with them.
I found that they either took too much heat, crushed tubular braze-ons,
slipped as the tube and braze-on expanded with the heat or loosened as the
flux melted.

Apart from built jigs for gear lever bosses (thankfully becoming obsolete)
and front mech fitting, I've used a combination of a weighted hooked wire
custom bent for each job (as basic as a bent heavy gauge spoke with a wrench
hanging on the end) to hold the fluxed part in place on the tube (watching
the alignment as the water boils off the flux), and orientating the frame so
that the correct location is uppermost. This works well enough for larger
cable guides and seat clamps etc.

For smaller fiddly parts such as single cable guides, stops, number tabs,
pump pegs and chain pips, I dab a patch of silver onto the tube, pick up the
cleaned fluxed braze-on with old needle-nosed pliers and hold in place while
reheating and cooling. This is fast, doesn't need three hands, uses a
minimum of the expensive stuff and generally leaves a good clean fillet,
especially with a wide melting range cadmium free silver such as SIF 39.

Happy brazing,

Dan Chambers


From: "Diane Feldman"
Subject: Re: [Frame] RE: Braze on Jigs
Date: Thu, 1 Mar 2001 17:40:11 -0800

Okay, I have the Enco catalog in front of me. The item that I use to help
fix brazeons in place (especially helpful with shift lever bosses and
canti/v brake posts) is the "Enco 1 5/16" V block and clamp" part #
One of these years I'll take pictures of this thing holding a part in place
and send them out to the group. It's the most help of any fixturing tool I

David Feldman


From: ThomasT41(AT)
Date: Sun, 23 Jan 2000 01:28:34 EST
Subject: [Frame] Tubing blocks and body material

I use hardwood blocks as quick and dirt holders for odd diameter stuff and
shapes when mitring (proud own of a Gary Hale tube mitring machine circa
1980.....honk if you've heard of it). They will not last forever but will
work well for awhile. I also use split square blocks of wood drilled in all
the various tubing diameters. Indispensible holding tubing, forks, frames in
the vice. In vice work wood clamps are far superior to metal ones most of
the time.
The wood is far, far more forgiving to tubing than metal blocks.

A hint in jigging single frame and tandems. .....hold the head tube and the
seat. the top and down tube are not as important. If you have the seat tube
and head tube held correctly the other tubes are almost self jigging,
presuming everything is cut right. Down tube is the cheat tube.
thaks tom


From: "Edward Ness"
Date: Mon, 26 Jan 2004 13:31:07 -0500
Subject: Re: [Frame] Brazing to minimize distortion?

Wanted to drop a little note of thanks to Freddy and others for their
advice on how to minimize brazing distortion. By making sure to pre-heat
the joint throughly before brazing, my need for coldset correction has
been greatly reduced. I feel a little stupid for not discovering this before.

Also, I used pins per the recent discussion with great results. For those
using a wood Talbot style jig like I am, pins are a godsend!!

Thanks for taking the time to help those like myself who know just enough
to be dangerous!



From: Freddy Parr
Date: Sat, 10 Jan 2004 21:59:08 -0800 (PST)
To: Edward Ness
Subject: Re: [Frame] Brazing to minimize distortion?

Dear Edward,
That is an over simplification. First lets discuss the tip size.
I'I've seen guys use AW202 tips to all the way to AW207 tips, depends on
how you adjust the flame, how fast you attempt to work and feed when
building lugged bikes.
The one thing you need to avoid is super heating one side of the joint
without the other side of the joint becoming hot. That will cause distortion.
Learn to spend more time preheating the entire joint and don't get anxious
to start feeding rod until the joint is capable of slurping it up.
Richard has a cute little phrase that he uses to help new framebuilders
understand the distortion process. "As a sunflower grows towards the sun, the bike tubing moves towards the flame"
If you heat only one side, the tubing will stay that way and go out of
alignment. You need to be as consistent in heating 360 degrees as
possible. Don't preheat from one side. Preheat all the way around the
joint. Keep moving around the joint or use an additional torch to preheat
the joints -- that you can hang up on an automatic shut off valve(Gas
Saver).(We sell them if you can't get one from your local shop.)
I started using t he 2 torch method over 35 years ago. It saves gas, it
saves time, it saves the hassle of doing so much cold setting after joining.
A simple Y joint and a cheap Turbo Torch will do wonders in addition to
your regular acetylene torch rig or what I do is just run a big propane
Turbo Torch off of cheap LP (Propane) to do the preheat work. A 5 gallon
patio BBQ cylinder will last forever and you will not waste your expensive

If you are going to work with a single acetylene torch, your best bet is to go with
a torch tip a size or 2 bigger than what you think you will need and
preheat with a soft flame and increase the heat of the flame when you
begin to flow your rod. It takes a little practice.


From: Freddy Parr
Date: Sat, 10 Jan 2004 13:02:32 -0800 (PST)
To: Edward Ness ,framebuilders
Subject: Re: [Frame] Brazing to minimize distortion?

The primary issue of distortion can be broken into two parts and broken into many causes.
The simple and most misunderstood one is not using a broad flame and
working 360 degrees and not just one side.
Either work with a lot of motion with a small tip or do as I do, which is
to make tight joints and work with a big soft flame.

The second is and can really mess things up.. pressure which will cause a
ripple inside the adjoining tube... Clock wise tacking in fillet joining
will minimize that.

Flame adjustment should be 50/50 the littl e blue flame should extend to
the middle of the darker blue flame and they should be an inch or more
long total... forget the whiskers.
A fine flux that has micro metal such as the All-State 1113 will lower
joining temp and speed wetting and flow, and My Pickle juice makes that
even faster.
If the prep and pre-heat and flux activity doesn't allow you to just go
right around the joint.. you are doing something wrong.

For lugs forget the clockwise tacks
Use broad heat and add filler quickly, don't dab it.. flow the joint.
Flame photo attached

Freddy Parr
3557 Jasmine Ave. #4
California 90034


From: "henox"
Subject: Re: [Frame] Should tubes touch?
Date: Sat, 17 Jul 2004 16:41:35 -0700

[re: a long post from a newbie on whether the ends of mitered tubes should come in contact with the sides of unmitered tubes]

My approach is to have the tubes touch but I also coarse file the ends so
that there are lots of tiny gaps thru which the brazing alloy can penetrate
to the inside of the joint.

For TIG joints I want no gaps at all.

Hugh Enox


Date: Thu, 16 Mar 2006 08:21:56 -0500
From: "John Clay"
Subject: [Frame] Re: Jigless Building

Here is a photo of a particleboard jig I made (first one), similar to the
one in the Talbot book. I brazed in this one but that's not the hot setup.

If you backspace the URL into the main body of my photos you'll see much
of the jig evoloution I went through - though in no particdular order and
with many holes. What's missing is a complete photo of my best version of
the particleboard jig. It was very capable for preparing all the joints
except the right chainstay and seatstay. Basically a good, flat piece of
particleboard large enough for the entire frame. Like the one in the
attached link:

* paste full size drawing to board
* use short pieces of aluminum angle (or whatever you have handy) to
locate the tubes correctly over the drawing - screw them down so the tubes
index against them.
* drill holes and install two bolts under each tube a couple inches from
the ends - these so you can level and support the tubes without lugs -
just regular bolts and run them through - adjust for level tubes as you go
* make some hold down things - I used flat steel screwed to the board -
bent/slide the steel over the tubes - that held them gently down on the
bolt heads
* bolt a bb cup to the board to hold the bb
* this was the best part - make a standoff out of a block of 2x2 wood (or
whatever), drill clear through for all thread. square the ends and bolt
this to the board on the rear axle center point. the wood standoff is
maybe 3/4" short of the inside face of the drop - then use a pair of nuts
to locate the drop (for me it was the left drop) to correct half space.

This rig was dirt cheap and way good enough to miter all the joints except
the right side stays (actually you can do that too - just on the left
size). Drill and pin too.

Then I used a tablesaw wing as a flat plate to braze one joint at a time
until the main triangle was done. I used clamps and a straight bar to
level the plane of the bb face to the ST and DT, each in turn. I made a
beam jig to do the rear end but the key with that crude device was to
braze the stays on one side then ditche the jig and use a wheel or other
device to get the otherside aligned/pinned and brazed up. I brazed the
drops to the CS before doing the rear end.

That's it in a nutshell. Look at these sites and you'll get good ideas:
Richard Sach's photo site, Robin Mather, M Steel, Drew Devereaux
(spelling?), Suzy Jackson

John Clay


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