jaredanderson

I am trying to build a lugged frame bicycle with Columbus SL steel. I am new to brazing. I read in "Designing and Building Your Own Frameset" by Richard Talbot that it is possible to braze a lugged frame with propane. After trying to braze the head tube/down tube I cleaned off the flux with hot water and checked my work. It was clear to me that I didn't use enough heat and there are gaps where the silver didn't flow through. Am I screwed now or is it possible to reflux and reheat it with a hotter torch to fill in the gaps? Maybe this is a dumb question, Im just not finding a lot of info on what to do if you mess up..

Six jours

IMO you should heat it back up, pull it apart, clean it thoroughly, and start over. Otherwise you'll never really be sure what you've got.

Also, in my experience, propane just doesn't get hot enough to do a good job. Assuming you're using something like the Bernz-o-matic torch, you'll get much better results with MAPP gas.

HTH!

Andrew R Stewart 

While it is in theory possible to reflux, heat and braze a silvered joint I wouldn't suggest it. Silver is more sensitive to joint cleanliness. Also steel's degradation is not just heat dependent but also time spent at temp. So a reheat will double that aspect. Third is that many fliers need to be heated to a higher temp to get them to reflow.

While Talbot's book is a better then some others attempt to teach frame building many find fault with some aspects of it. The torch used is but one. Propane/air is not very hot. If you combine it wit O2 then you get far more heat/energy. Of course this means compressed O tank with reg or a O concentrator that has the right out flow. Of course the propane needs it's reg too. Don't forget that the OP torch tips are a bit different then the far more common OA ones.

Really I would use the, now scrap, as practice stock and get a proper torch set up. Then practice your brazing before cutting the replacement tubes. Read more previous posts here and soak up what you can and/or find someone who can instruct you. Andy.

busdriver1959

To follow up on what Andrew said, get a proper torch, but don't begin to think that the MAPP/oxy torches at the big box hardware stores are proper. I made that mistake. Their oxygen tanks are just the right size to run out on you in the middle of a preheat. It'll take at least three to do a bottom bracket shell. That's if you rush and you will rush, because you don't want to run out. Rushing doesn't work well either. The flame is too small. That caused me to overheat small areas because I'd get in too close and stop moving the torch for a moment. A bigger "softer" flame worked much better as an inexperienced brazer.
The overall cost will quickly exceed a real torch setup. The tiny oxygen bottles add up very fast.

unterhausen

SL probably wasn't your best choice anyway. I'd cut it up

Six jours

Christ, this place can be tough on a newb. I never would have started building frames if I'd heeded the typical advice here.

hueyhoolihan

Six jours

New guy: "Hey guys! I just got a book and a torch and a tubeset and I'm real excited! Thanks for all the help!"

Bike Forums: "You've got the wrong book, the wrong torch, and the wrong tubeset. And you're probably ugly too."

himespau 

What's wrong with SL? Too thin for a first build? Too old of a technology?

unterhausen

modern SL is very good tubing. Problem is, it's better left for experienced builders. Old school SL would have been better. I would suggest starting with a cro-mo, like the typical Nova house tubing or low-end deda or true temper.

I'm not trying to be hard on him at all. It has to be frustrating. But if I screwed up a frame like that for some reason, I would cut it up. I think that is really good advice, and it's good for the soul. Taking a frame apart is harder than putting it together unless there is no penetration at all. And the torch is a problem. He's not going to get it back apart with a propane torch.

jaredanderson

Thanks for the advice, everyone. I am going to get a new tube set and try again with a better torch.

unterhausen

If you have never done this before, my suggestion is to get some 4130 tubing and practice. My suggestion is to get some 1" x .035" wall tubing, and some 1 1/8" by .058" wall tubing. Cut the bigger tubing into rings. Make a couple that are 1/2" and some that are 1" long. You can go longer if you want, but start with the 1/2". Braze the rings onto the 1" tubing, pulling the filler from one edge to the other -- don't fill from both sides of the ring. The more you learn to pull filler around with heat, the better. I did this when I decided I wanted to braze lugs with bronze, and it made all the difference. And I've been brazing lugs for 40 years now. One thing that heat control will help with is cleanup. If you can move filler with heat, it's much better than using a file.

Andrew R Stewart 

I am not sure how to reply to this. But here I go anyway, let's see where this goes. If the Op had asked before starting we'd have given much the same advice. I feel it's best to stop doing the "wrong" thing and get straight early on. If we share our experience and help him build safer bikes I think he'll be happier then if we say "ata boy, you will get the hang of it if only you keep doing the same thing". The Op has a very good tube set for either future bikes (with a couple of replacement tubes) or to do a lot of practice with. His torch will be fine for the home copper plumbing. The book will be a reference (although I wouldn't take it as the best it's a start) which he'll out grow as he gets more exposure/experience (like from this forum). As to his attractiveness- can't say as this is radio and not TV Andy.

Six jours

I know the advice he would have gotten, because I got pretty much the same thing myself and have seen it given to many others. In short, the advice is that without a full oxy-acetylene torch set-up, a professional jig, a granite alignment table, an overhead mill, professional instruction, and at least 200 frames under his belt, he shouldn't bother.

Maybe this place needs another sub-forum, with a name like "Frame-building for amateurs on a budget who just want to build frames for personal use".

busdriver1959

I wish somebody had smacked me before I wasted money on a Mapp/oxy torch from the big box store. The advice in this thread wasn't outlandish. A hacksaw, good files, a good torch and a good eye are all that are needed. If OP only owned a small chainsaw file would you tell him that he would get good miters with that or would you recommend a few half rounds of different sizes?

unterhausen

Propane-air or Mapp-air makes it really, really hard to be successful. I know I couldn't build a frame with those gasses. A good torch, an oxygen concentrator, and a gas grill propane tank is going to set someone back $600, but they actually are going to work. And they can easily be re-sold. But otherwise, a diligent person can do a lot with meticulous prep, a file, a vise and a reasonably flat surface.

I had a copy of Talbot 40 years ago until someone "borrowed" it and never gave it back. I wonder how many frames he ever built (eta: Talbot, I'm sure the book thief never built any). I don't think my copy recommended propane, that's a pretty good sign of a charlatan as far as I'm concerned.

repechage

Pulling things apart always takes big wide heat. I started with trashed frames left by shop customers. Stripping the paint off and observing what is underneath and how the frame was tacked it pinned was enlightening. I would look into the Paterek manual too. Talbot is interesting...

tuz

I think that you should do some test joints before jumping into the actual frame. Get some cheap lugs and tubing. Take that joint as practice and cut it up to see what sort of penetration you got. Maybe the gaps are only on the shoreline, or maybe the filler didn't even go very far. You can get some firebricks to help contain the heat, but as was said the heat from that torch is minimal. Even the Talbot book says it is unlikely to work well for the heavier BB and crown joints.

Andrew R Stewart 

6D- You must be only reading posts from that side of the building community. Some of us have been saying quite the opposite fir years. We do say that the ability to see in 3D, the ability to trouble shoot, the ability to self teach from other's experiences, the ability to step back and take a break (and maybe ask for specific help), the ability to have a more experienced person class you in person, the ability to accept failure and be able to move on and try again, and so on is important to building in the beginning.

While just reading the posts from the most experienced members is great I suggest that looking at the posts of the beginners is better at showing the wrong/more problematic methods. It's like siting in on a advanced level course then complaining about who hard to understanding it is. If you sat in on an entry level class first some foundation would be learned first and that advanced class starts to make more sense. Not the best metaphor but I think it gets the point across.

I also think you're mixing up some of the message from those experienced builders. I have found them to be quite willing to teach and suggest how a beginner gets going but they do tend to be pretty harsh when it comes time for that beginner to go pro. This point is when the claims for experience and tooling are focused. I see the difference in their advice and willingness to be helpful to the beginner and their concerns for their industry's reputation/value and rider's safety.

After doing this stuff for 35+ years I still have questions and am willing to give the best answers first. Andy.

Six jours

I'd tell him that he probably could get fine miters but that would take an incredible amount of time. I'd also tell him that I'd never tried one for the job, so don't know for sure. And yes, I'd suggest more appropriate files - but files are a few dollars. Torches are hundreds.

Six jours

Most of my frames were built with MAPP-air. It worked fine, and in some ways was easier than oxy-acetyline, because of the big, soft flame. You have to be patient, but it's hard to overheat the joint, and it's hard to concentrate too much heat into too small an area. Now, MAPP-air for brass brazing is tough, but the OP wrote that he's using silver.

Six jours

Well, I'm not going to go digging up old posts, but I personally have been told all those things WRT my own building - that I have to have an expensive torch, that I have to have a professional jig, that I have to have an alignment table, take courses, build and cut up 200 frames. And hell, this thread alone tells the story. Within the first four posts he was told that literally everything he'd been doing was wrong, and it just isn't true.

But whatever. At first I was trying to keep it light but I'm actually getting a little irritated by it now. So good luck to the OP, don't take the advice here so seriously that you decide to give up, and have fun.

Andrew R Stewart 

So to be even more helpful to the Op and try to explain where some of the advice is coming from here.

OA torch sets are often available used on Craig's list. The Op lives in or near a major city, I'd be surprised if there wasn't a used set listed every month or two. They tend to hold their value well, once the initial depreciation has happened. So if the budding builder decides to give the building thing up they can recoup most of this investment. Having a bit extra ability, heating wise, will be learned to be nice sometimes. Being able to have a number of frames (and practice) before one needs to replace/refill the tanks is also nice. Having the ability to have different tips and therefore flame size is nice.

Miters can and are done by simple files, tube blocks (self made often) and a bench vise. You'll need all these to do the after finishing work any way. Angle control can be dealt with by a scale drawing and cutting out a template to hold against the tubes/joints. One of the most regarded builders uses only files to miter with. I've tried many other methods (Joint Jigger, lathe and milling machines) and currently use a bench grinder to rough cut and a file to finish my miters. Takes about 15 to 30 minutes each because I'm slow and like beer. Only when I'd be getting paid for my building would a faster mitering method make investment sense.

Alignment can be done by a drafting comparison, careful point to point measuring for the geometry aspects and builder's wheels and good eyes for the flat to plane aspects. I've posted a number of times about using non precision tools to get forks and frames straight. Some builders use counter tops, milling machine beds and doors for their flat surfaces (if that is what you feel the need to use). I only got a used steel flat surface plate after making a dozen+ frames first and learned that I wanted to do this for the rest of my life and wanted a faster path to alignment. Note I don't say a better riding alignment.

Building one joint at a time, tacking as you go with alignment checking is a valid process and doesn't need any formal jigs. Some sort of tube/angle holding method will be needed but this is part of the discovery/experiment process all budding builders go through. Hose clamps, Vee blocks. Wood struts all are simple low cost "jigs' to deal with tube to tube holding. Again my first, about, dozen frames were built w/o any formal jigs.

Taking a course will quicken up the learning curve A LOT and minimize the pot holes along the way. There is something to be said for learning good technique (like how to hold and move the torch/flame or how to draw a file across a fillet) that will make these steps go easier. But many hundreds of nice frames have been made without any formal or paid for instruction. I've taken two paid for classes, the first after about 8 frames and the second almost 30 years later. Both were worth it for my world.

There can be a lot said for getting proficient at what ever you are doing. But when one's building for their selves how efficient they are is pretty moot. How fancy is their workshop is only a personal choice. Only when going pro do these really shift. Then one's efficiency, repeatability, quality control, integrity, insurance, range of fitting and design experience, ability to manage the business and money side, the reputation and perceived value to your customer make the difference to both you and your customer. This is when having done the practice and testing (destruction, cutting up to check penetration, alignment documentation) start to be needed, expected and dangerous if not present. The claim of needing to build 200 frames first is more of saying that it takes a lot of practice before many of these aspects of being a skilled and profitable builder who makes well fitting and durable frames is accomplished. We all (customers and one's peers) hope/expect that a pro is all this.

So back to the Op. Don't give up. Listen to all and try to pick what advice you can work with. Don't be afraid to fail and understand that learning can be frustrating and gratifying. Please feel free to ask for more help/advice. Some of us will work with budding builders off line, I'm open to this.

To 6D- Sorry that your early experiences with the on line advice forums was so frustrating and off putting. But you did manage to keep going and now you are giving advice. That's the way things can work. Put in your time and offer back where you can. Andy.

unterhausen

most people report that MAPP actually results in overheating, because the heat content is too low and beginners tend to over-concentrate the flame in one place anyway. My suggested practice exercises would allow the OP to either perfect his technique with MAPP or decide to move on to something with better heat content. What I found with LFB was that I needed a hotter flame to be fully successful, but I only found that out by trying it on practice pieces that didn't involve significant investment. I certainly wouldn't have been as comfortable experimenting on a full frame.

busdriver1959

To the OP. Search google for "acetylene vs propane velocipede salon". Ithe thread is up to 10 pages now but all good info. Post #47 has a partial list of some of the supplies for a propane torch setup. It includes sources and prices. It looks like you could get most of what you need at about $300 dollars using that list.