Seat tube distortion...

[cicli polito]

I'm wondering if that has anything to do with laying brass in a kind of sweeping motion, from the unmitered tube to the mitered tube, perpendicular to the seam of the miter?

Alistair - I'm not Steve (to whom your question was addressed), but that's sort of how I do it. I hold my filler in my left and my torch in my right, so move from right to left. The "straight" dotted line represents the mitered edge, the tubes are on either side, and the hash marks are where I add my filler and in what direction. So I start on the bottom right, move up and to the left, down and to the left, up and to the left, etc. The X is where I merge it all together (usually in the crotch halfway between the ear and the top miter) and then change directions.

\ \ X / /
------------------------
/ / X \ \


Everybody does what they do for different reasons: I do it this way solely for the reason that I can finish the fillets much faster after the flux has been washed off, as they leave me with a much nicer feathered edge without a tall stack of dimes in the middle.

[Rody]

I hold my filler in my left and my torch in my right, so move from right to left. The "straight" dotted line represents the mitered edge,

See, each of those lines is where the operator has taken the filler from a liquid to to solid state, moved, and the formed another puddle, then freeze, the move, the melt & add - repeat - while also feeding the same length or amount of rod every time for a consistent width

- Garro.

Now simply move closer to the frame by 12 inches, reduce the size of your puddle and materials by 90%, and you are tig welding!

It is astonishing just how quickly a master at either can quickly become functional with some concerted practice in the other discipline.

In the end, it comes down to focused time at the controls, learning how your changing input affects the state of the metal and the resultant joint.

Materials and process may differ, but those that ply this trade daily to put food on the table have learned that seldom can you hurry mastery, it must be earned.

cheers,

rody

[e.Gellie]

There are some gems of info provided in this thread. Thanks to those who contributed!

This is the only issue have. Once this is resolved. I'm happy to sell.

My customers are aware of the 'prototype' nature of my frames. They are being sold at reduced prices because of this. As long as I manage people's expectations, there should be no issues.

I have ridden several versions of my frames hard with no structural issues.

Hey Joe, your latest frame looks awesome. It appears to have some 'novel' detail and framebuilding is if anything, a deceptively refined Craft. Good luck with your endeavours.

You got yourself a whole lot of publicity there http://dirtmountainbike.com/bike-reviews/starling-mk3-prototype-tested.html In my mind, that is a double-edged sword.

[e.Gellie]

There's was Bike Tech article from the 80's written by some dude called Keith Butranger or something that discusses this in more detail. Basically looking at temps of brazing vs Tig and also time spent at temps and how it affects strength. Interesting reading, I'll see if I can dig a copy out. (where's Truls when you need him?!)

Steven

Thanks Steve. It's great to read that again .... and several very interesting and relevant things stood out to me this time ... "What this really shows is that the HAZ strength drop seems to be directly related to heat cycle time."

As an aside, my search for "butt", "gauge" and "wall" in the KB article did not find a use of those terms. KB's gussets are mentioned and so I now read the article as meaning the gussets are intended for plain-gauge TIG-welded tubing. So IMO (as I keep banging on about) the primary reason to use butted tubing is that it is reinforcing the tube near the welded end and so takes the load off the weld/braze. (This makes me more convinced that KB gussets would be unnecessary for butted tubing since the butt takes the role of the gusset and so gussets are an odd thing to use on butted tubing).

So the ends of a butted tube, being reinforced, lessen the impact of the "heat cycle time" somewhat for a fillet-brazed joint. Especially since the drops in Rockwell/strength numbers appear to be only of the order of 5-10%. Have I described that clearly? It's quite a complex thing.

Similarly, a single-butted seat tube has no place at a seat cluster unless it is reinforced with a decent seat lug, (which is what it was developed to be used for ), or a brazed/soldered collar. You might be able to braze or TIG it, or put a silly little seatpost-clamp lug on top of it, but it will break prematurely if it is 0.6mm wall and it aint reinforced. It might break at the hole at the end of the seatpost clamp slot. It'll certainly be more difficult to weld/braze without distortion too.

[Glendmcc]

Now simply move closer to the frame by 12 inches, reduce the size of your puddle and materials by 90%, and you are tig welding!

It is astonishing just how quickly a master at either can quickly become functional with some concerted practice in the other discipline.

In the end, it comes down to focused time at the controls, learning how your changing input affects the state of the metal and the resultant joint.

Materials and process may differ, but those that ply this trade daily to put food on the table have learned that seldom can you hurry mastery, it must be earned.

cheers,

rody

This has been a great thread to read and inspired me to go from lurker to poster here!

To the OP: You will need time, 10,000 hours the old adage says to become an expert. When you do reach those 10,000 hours, the first thing you are going to be enlightened to is that you actually know far less than you think.

I started welding and fabricating 17 years ago for the sole purpose to build frames. I grew up in New England admiring the IF, Merlin, Rygin, Ted, Hot Tubes and Richard Sachs frames showing up to the XC races and realized, "Those, I want to make those!" Fast forward 17 years. I am finally building my first frame. I weld every day for work, have been for 9 years but have never made a frame. Finally I feel as if my skills as a welder and fabricator are up to par to make the quality bike I have always dreamed of. Still, I have questions, the concepts are all the same, measurement, machining, heat management, distortion, etc. but the specific wisdom, I have no way of knowing unless I humbly ask those who do, such as: how many vents? What size vents? Which locations? Fully weld this and tack that? Miter after tacking or not for these?

What I am seeing is a group of wise, experienced frame builders that take their craft very seriously. Someone said "it's just sticking tubes together" Maybe it is, but that's what Huffy does, and even then, there is knowledge in those factories that you may not ever have with the wrong attitude. It's going to take frames and frames to get it right. I won't sell any for more than the cost of tubes plus 20% or so to cover meals and consumables for a long time. I want my bikes ridden, broken (hopefully not), and critiqued before they go to the general public.

In terms of brazing, I have done very little, but spent thousands of hours in glass hot shops and foundries. Learn about heat, watch it manipulate everything, pluck a hair and put it over a candle and watch it move, stare at a campfire. Knowing heat is knowing metal. To know any of it, the only thing you need is time and experience.

Be humble and work hard, with time and attitude you can find yourself on this forum as one of the crotchety elders. For me, that's a long time from now.

Cheers,
Glen
gm-fab.com

[duanedr]

Along with ways to do it correctly.

- The time to start brazing (for reals) is just before your tacks pop
- Garro.

As always, greatly appreciate the sharing of hard won experience.

Can you elaborate on the 'pop'? This would seem to suggest that there is tension in the joint which I suppose makes sense but it also seems that we would pre-heat to avoid the tension as much as possible. Are you saying the pre-heat of the whole joint should be to the point where the tack nearly melts (the 'pop' being a sort of exaggeration)?

thanks again

[phutphutend]

OP here. I can now braze my seat tube with no distortion.

I'm afraid I've come up with an enginerring rather than master of crafts approach. I turned some thick walled steel tube to the OD of the seat tube ID. It extends about 3" past the toptube junction. I then tack and fillet with the tube in place. The insert is thin enough that it doesn't pull too much heat and not allow you to get up to brazing temperature. But it stops the distortion happening. I do still give the whole area a good heat before brazing to get it up to an even temperature. But in this case the insert helps spread the heat around a bit. I also fillet from the horizontal sides to the top/bottom to minimise built in stresses.

I did try a few test pieces attempting control the heat to stop the distortion, but then I though why am I making it hard for myslef. Why not put a bit of though into the problem and increase the sweetspot I am aiming at. Perhaps with 10,000 hours practise I could braze upside down, left handed and always true. Or I could reduce the impact of human error with another more rapid solution.

I'm afraid I striggle with the whole idea that you need to have put in the time and felt the pain to be a framebuilder. There's plenty of other trades out there that have textbooks telling you how to do it. If I wanted to make a table or a chest of drawers, with the right tools and a bit of patience I could follow a book and get the job done. Why is framebuilding different? Admitedly the 10th table would be better than the first, but they would all still work.

Engineering NOT master of crafts!! What are other people views on this?

[Andrew R Stewart]

OP here. I can now braze my seat tube with no distortion.

I'm afraid I've come up with an enginerring rather than master of crafts approach. I turned some thick walled steel tube to the OD of the seat tube ID. It extends about 3" past the toptube junction. I then tack and fillet with the tube in place. The insert is thin enough that it doesn't pull too much heat and not allow you to get up to brazing temperature. But it stops the distortion happening. I do still give the whole area a good heat before brazing to get it up to an even temperature. But in this case the insert helps spread the heat around a bit. I also fillet from the horizontal sides to the top/bottom to minimise built in stresses.

I did try a few test pieces attempting control the heat to stop the distortion, but then I though why am I making it hard for myslef. Why not put a bit of though into the problem and increase the sweetspot I am aiming at. Perhaps with 10,000 hours practise I could braze upside down, left handed and always true. Or I could reduce the impact of human error with another more rapid solution.

I'm afraid I striggle with the whole idea that you need to have put in the time and felt the pain to be a framebuilder. There's plenty of other trades out there that have textbooks telling you how to do it. If I wanted to make a table or a chest of drawers, with the right tools and a bit of patience I could follow a book and get the job done. Why is framebuilding different? Admitedly the 10th table would be better than the first, but they would all still work.

Engineering NOT master of crafts!! What are other people views on this?

I don't think framebuilding is any different. Just more complex to the newbie then many other crafts they might have done before. There are books (and a lot of digital books called videos) about framebuilding and many do use them to end up with a finished and rideable frame. And just like the example of making a table and that the 10th table would be nicer then the first, your 10th frame will be nicer then your 1st.

The struggle to get skilled at this craft is just the learning curve. No more no less. Some of us find it easier and some harder to go up that curve. Like many crafts the more you know the more you understand that there is a lot more to know to fully master the craft.

Two examples of this- My boss is one of the more experienced bike fitters in western NY state. He has taught a number of people in the "art" of fitting. After a dozen or two of fits these people think they have it down (in my boss's description they get cocky). Then the ones who continue fitting riders and get a few hundred fits behind them come around and realize how wet behind the ears they were when the were cocky.

Second is my personal growth (which is still going on) in frame building. When I first started I tracked the number of hours it took to complete a frame. The number of hours initially went down a bit then grew to a point that I stopped counting. Early on I got better at doing the functional skills like mitering or brazing. Then later I began to pay attention to how well I did these processes and how I could best braze, add personalization details, file with less under cutting, hold the dimensions to tighter tolerances and so on. At only a few dozen frames over too many years I'm no longer cocky. Andy.

[bill meyer]

OP here. I can now braze my seat tube with no distortion.


Engineering NOT master of crafts!! What are other people views on this?

Frame building and cabinet making? If a piece of trim comes loose on one of your "early" cabinets, not such a big deal, hone your technique and move on. If a head tube comes loose on a big drop? ..guess that's between you and your customers

For me confidence is the bearer of mistakes. Frame number 3 has had more mistakes than I care to mention.. thought I knew what I was doing with two nice builds under my belt.

[shand]

OP here. I can now braze my seat tube with no distortion.

I'm afraid I've come up with an enginerring rather than master of crafts approach. I turned some thick walled steel tube to the OD of the seat tube ID. It extends about 3" past the toptube junction. I then tack and fillet with the tube in place. The insert is thin enough that it doesn't pull too much heat and not allow you to get up to brazing temperature. But it stops the distortion happening. I do still give the whole area a good heat before brazing to get it up to an even temperature. But in this case the insert helps spread the heat around a bit. I also fillet from the horizontal sides to the top/bottom to minimise built in stresses.

I did try a few test pieces attempting control the heat to stop the distortion, but then I though why am I making it hard for myslef. Why not put a bit of though into the problem and increase the sweetspot I am aiming at. Perhaps with 10,000 hours practise I could braze upside down, left handed and always true. Or I could reduce the impact of human error with another more rapid solution.

I'm afraid I striggle with the whole idea that you need to have put in the time and felt the pain to be a framebuilder. There's plenty of other trades out there that have textbooks telling you how to do it. If I wanted to make a table or a chest of drawers, with the right tools and a bit of patience I could follow a book and get the job done. Why is framebuilding different? Admitedly the 10th table would be better than the first, but they would all still work.

Engineering NOT master of crafts!! What are other people views on this?

I think what you've created here is a crutch. The reason your tube was distorting was because you didn't have the required heat control. You've created a situation that means you can carry on without having to learn these heat control skills. If you keep brazing, you'll learn them anyway and after 100 frames, you'll not need the crutch and you'll wonder why you bothered. The problem with your approach is that could have got to the same end point after building 10 frames instead of 100.

Two other things spring to mind. First one is that one day you'll end up using a seattube that is slightly bowed or slightly out of round or slightly undersized and when you use your heatsink, it's going to get stuck.

Second one is that you're going to have to pump a load more heat into that arrangement to get things done. That's not a good thing.

Steven

[edoz]

Framebuilding isn't any different than any other craft. Sure, you can buy a book and work your way through, but without the practice put in, it still won't be right. It'll just "work". It won't be anything to be proud of, it'll just be the product of the bare minimum effort that was put into it. If that's good enough for you, so be it.

If you're building for other people, then you need to consider that they are putting an amount of trust in you that their face won't hit the pavement when the head tube falls off, and ask yourself if you would accept bare minimum effort and training from your plumber, electrician, doctor or auto mechanic.

In short, it's called pride in your work.

[EricKeller]

it's an interesting solution, even if the editorializing is misplaced. I don't think there are too many woodworkers that sell their first few pieces, and traditionally apprentices sharpened tools and swept the floors for years before they cut any wood. Granted, Trek sold my 4th frame, so maybe I don't have room to talk

[nash]

"Engineers are people who think they know how things work, but they don't"

Proof is in the pudding. Finding a shortcut doesn't amount to knowing how to do it.

[phutphutend]

"Engineers are people who think they know how things work, but they don't"

Proof is in the pudding. Finding a shortcut doesn't amount to knowing how to do it.

Have you come up with that quote yourself? Be interesting to know what all the other engineers thought of it...

Perhaps I'll just do it the old fashioned hard way and hope to never progress to anythink new or different!

[nash]

No, I didn't think of it myself. That's why it's in quotes. Someone else said it. Anyway, I guess to be fair I should keep my mouth shut because I've never built a frame. But I do admire a bunch of people here on this forum who do and I since I admire them I value their opinion and think that if I were to build a frame I would want to listen to their advice and opinions because they have more experience than me. It's baffling to me that so many people post on this forum about problems they have and then don't listen to these very experienced people. But I guess everyone is different and if you admire people who engineer solutions to problems instead of learning to avoid the problem through process and skill, then that is who you are. No skin off my back. One thing that occurs to me is that this is a public forum with lots of potential customers. You're going to sell these frames. I guess if your demographic is people who share your view of making progress, then that's fine. But whatever. Seems like a weird way to relate to people.