Kogswell

If you've been following the two threads listed just below, you'll know that velonomad has been answering questions and showing examples and has, in short order, done something that is significant: made a lot of us feel like we can really do this stuff.

https://www.bikeforums.net/framebuilders/161263-re-cycle.html

https://www.bikeforums.net/framebuilders/158447-minimalist-framebuilding.html

The wisdom and the willingness to share it and the work that he did to show us examples is worthy of honor and recognition.

I think I speak for many when I say thank you, velonomad, for your helpful, encouraging insight into the process.

In framebuilding circles a gal or guy who does work to preserve (and in this case also teach) the knowledge of how to turn tubes into frames by the use of the hot blue cone is said to be one of the Keepers Of the Flame.

So I hereby propose that velonomad be considered for inclusion into the ranks of the KOF.

What say all of you?

Cyclist0094

If KOF meant Krazy Old F--- I would qualify... Keeper of the Flame? naw... I just love bikes. but thanks for the kind words.

There are a lot of people who build or have built thier own frames and many of them do it better than I.
The act of framebuilding IMO is not art or craft it is just basic metal joinery. Expensive jigs and machinery only make you efficent they don't make you good .
To me the art or craft in frame building is the 1000's of amateur and professional builders around the world that take a similar structure, beat it,grind it,weld it and paint it to fit thier vision or purpose and make it stand out from all the others.
I am impressed by someone who from a few measurements and a 20 minute conversation with a client can produce a bicycle that is the client's dream ride. But I am also impressed by some guy from out in BFE that makes a snowplow from 3 junk bicycles or the bikes I see and read about in Alt Bike Culture here on Bike Forums.
My using a Benzomatic is a bit of a gimmick When I built my first frame around the mid 80's the benzo was the only torch I could afford. I can afford a better torch now but the benzo has not only been my way of building bicycle frames but it is also my way of pointing out that technically framebuilding is pretty low tech and a rideable machine is achieveable by most anyone with the desire,motivation and opposeable thumbs,
I also use the Benzo to piss off tool weenies.

Kogswell

Is anyone surprised by any of this?

I'm not.

This is exactly what I'm talking about. People who are interested in building frames come to forums like this looking for help, guidance, encouragement.

You provide that. And you do it in a way that make us think that we can do it, that makes us ask:

where's my file? where's my MAPP torch? what kind of rods should I ask for at the welding supply

Speaking of which, can you please tell me what rods to ask for at welding supply?

- what silver rods
- what brass rods
- did you mention tacking w/ a bronze rod?
- what fluxes

Thanks, velonomad - sorry about blowing your handle in the title - I'm hoping a moderator will fix my boo-boo.

Abondoned bikes in my neighborhood look different today than they did last week. I was eyeballing a couple this morning...

Cyclist0094

At your welding supply chances are they likely will not have a clue about what you want or are trying to do. If they have silver at all it is probaly going to be Harris 56% because that is what the HVAC and food service maintance guys like to use. Brazing rods are likely going to be bare brass or blue fluxed nickel bronze because many of the tool makers use that.

Best thing to do is stop in at the welding supplier and have a look around to find out what the brands they carry and then google for the manufacturer's website, all of them will have data on and descriptions of their products. Just be aware that many suppliers sell rods in 5lb packages and if they special order for you it may be a 20 lb minimum, Silver is usually a mininum of 3oz troy. Some of the bicycle tubing suppliers may have brazing supplies in smaller quanities. Try googling: "Josh Putnam" he is another amatuer builder and has(or had) a list of suppliers on his website under his framebuilding subtitle.

This is the stuff that works well for me; your experince may be different.
I use Harris Safetysilv56 with Harris white flux for most lugged joints. on bottom bracket and fork crowns I use the higher temp black flux since it takes longer to get these thicker componets hot enough to fill.
For looser joints like dropouts and lugs with more clearance I have good luck with Harris Safetysilv 45.
For fillet brazing I use Gasflux brand rod #C-04 with Allstate 11 flux or Harris Black . The C-04 rod is apparently a popular rod for fillet brazing.
The nickle bronze I like is Harris #40 FC it is precoated with flux and is great for quick and dirty work like punk and junk bikes. I repair most everything ferrous with this rod. if you scrape off 2/3rds of the flux it will make neat strong fillets also but not the big fat ones like the C-04.

Some additional reading about brazing and amateur frame building is found on Mark Stonich's excellent website . https://mnhpva.org/tech/gear_head.html


Some final word of advice to anyone building for the first time: IMO stay away from the thin exotic steel tubsets till you get some skills. All of the failures I have seen by home builders have been with the lighter gauge heat treated tube sets. Overheating weakens heat treated tubing and the thinner the tubing is the easier it is to overheat. IMO heavier gauge non-heat treated Cro'mo Tube sets like 525,RC2, Deddi Zero Uno etc are more forgiving to overheating and mishandling and is a sensible choice for beginners.

have fun!

531phile 

VeloNomad, how did you start amassing your framebuilding tools? Secondhand? Classiifeds? FleaMarket? Retail? Just curious and what's your line of work during the day?

Kogswell

Thanks, velonomad.

As I think about this stuff it sound like the smart/safe way to start is to start small; avoid bottom brackets and fork crowns that require a lot of heat and focus on head and seat joints for a while.

I have some low-cost mountain bikes that I've pulled out of trash cans and parking lots. I think I'll start with those. The tubing will be a bit thicker which, as you point out, will be less prone to overheating. I'll make some mods and go from there.

531phile 

about 853 reynolds. Since they get stronger when they are heated, why not just heat them till no tommorrow to make the world's strongest bike frame or am I mising something?

Kogswell

It's the old strengh vs. ductility dichotomy.

As strength goes up, ductility goes down.

Stength is what allow the walls of the tubes to be thinner and weigh less while still supporting the rider.

Ductility is what keeps the tube from ripping apart when it gets bumped.

Super light tubes are made from alloys that allow their strength to go way up during heat treating. But those tubes are expensive, delicate, and have to be handled properly. If you impart too much heat into a joint when you're welding it, the strength will go down and you're left with thin tubes that are not strong enough to support a load.

The first popular HT tube set was Reynold 753. Most builders back then had so little experience with thin-wall, HT tubes that Reynold required them to braze a joint and send it back to the factory so that it could be tested to see if you were cooking the tubes or not.

These days TIG welding is so commom that companies like Reynolds make alloys like 853 that are specifically designed for it.

Nessism

Reynold's recommends that 853 tubes should be welded or brass brazed (higher temp than silver brazed). Braze-on parts are suspose to be put on with silver though to keep the air-hardening properties of the metal from kicking in which can create a stress concentration. My understanding is that some of the low cost asian frame shops were welding cable stops onto 853 frames which eventually led to these frames cracking. It pays to heed the advice of the tubing manufactuers.

Cyclist0094

I haven't used 853 and haven't read much about it from a frame building standpoint other than what I read from the 2002 Reynolds spec sheet. so I will defer to Nessim and Kogswell about 853 tubing.Thier analyis sounds logical . The Reynolds catalog I had specs (IIRC) 631 or 525 fork blades which might imply that 853 tubing may have some ductility or long term fatique issues if used outside of certain parameters...

As for staying away from bottom brackets I never had problems with any failures I have used lugged BB shells on every bike except for the one tig welded BB on the red bike. I know of some folks who have run into problems with the seat tube either breaking loose from or cracking around the bottom bracket shell which indicates it is probaly being overheated.

The only joint failures I have had so far was a mono seat stay crack on my third MTB that I spectactularly crashed during practice for the 1988 NORBA mens downhill race at Mount Snow. I repaired it on the tailgate of my pickup and raced it that afternoon. It is still one of my favorite bikes to ride and is now my winter bike

Kogswell

Fork blades are never made of heat treated steel:

• they have to be bent to be used
• they flex a lot while in use
• they just need more ductility to be safe

MnHPVA Guy

I don't recommend my brazing page anymore. I probably should delete it. However the method described there may be appropriate for MAPP gas. I was working on a new version, but now I don't have time to finish it.

I now use a big, hot neutral flame, and get almost as close as if I were welding. I control the heat my turning the flame completely off the joint while things cool. The result is more control and almost no charring of flux. I've also learned not to flux the rod, just a thin coat on the tubes.

I gave a couple of classes last year to MnHPVA members. After a couple of hours of "Chalk Talk" I had them practice on "V" joints. These allowed them to practice without the complexity of working their way around a joint. https://bikesmithdesign.com/brazing/test1.jpg
https://bikesmithdesign.com/brazing/test2.jpg

After a few of the test pieces and watching me do a joint, a fellow who had never held a lit torch before did the joint on the left in https://bikesmithdesign.com/brazing/Samples.jpg My joint is on the right.
Mark Stonich

MnHPVA Guy

I always figured the best reason not to heat treat fork blades was so they would fail before the frame could be destroyed.

MnHPVA Guy

56% Cad free silver should be all you need, though some people prefer 50N for stainless. 3/64" is nicer to use than 1/16" but really hard to find.

In a welding shop, the best rod for fillets is bare low fuming bronze in 3/23" or 1/16"

GasFlux C-04 is IMHO easier to get a nice fillet with. But, a newbie will probably have better luck with 3/32" and Henry James only carries 1/16". If you want enough, GasFlux will sell you C-04 in 3/32". I don't know their minimum, might be 10 lbs. I ordered 30 lbs of 3/32" and 15 lbs of 1/16" for myself and other MnHPVA members.

Flux;
Harris White or Black for silver.

Gasflux Blue for bronze. The best you will find in a local shop is a paste flux for Nickel Silver, such as Welco #17. Not bad, but not "Plan A". Harris Black can be used for bronze in an emergency, but I don't recommend it.