Seat tube distortion...

[false_aesthetic]

<SNIP> "GETS IT




- Garro. </SNIP>


ARGH!!!! There is so much info in what's Garro has posted above. This probably cuts 100-150 hours out of any newbie's 10,000.

No, I'm not being snarky.

[Dallas Tex]

One unique & quirky thing about the custom industry in general and this forum specifically is access. Access by nearly anyone, to the best most experienced folks doing this anywhere.

Some of these guys are, quite literally, among the top 8 or 10 folks doing this on the entire planet. I honestly don't know why they participate & try to help so much. And I also don't know why it gets watered down by folks adding in their two cents when they should be listening.

[David Tollefson]

- Don't "rob" your puddles, as you start the next puddle, don't let your previous puddle slop into you new one, creating a void

- Watch your "ears" as they will drink excess filler, creating an internal bulge

- Garro.

This is speaking directly to me, thanks!

- Flux inside & out

Just want some clarification on this -- I've never fluxed the inside of the uncut tube, only the inside of the cut tube. Are you saying to flux the inside of the uncut tube as well?

[steve garro]

Just want some clarification on this -- I've never fluxed the inside of the uncut tube, only the inside of the cut tube. Are you saying to flux the inside of the uncut tube as well?

Yes!

The metal follows the flux - you don't have to fill the tube, but picture it.......the metal follow the flux to such an extent that you can use this to your advantage, the metal will stop if you clean the flux off, making a barrier of sorts.

Edit: uncut = no - I am saying inside the actual joint, inside the cope/fishmouth - Capish?

<SNIP> "GETS IT




- Garro. </SNIP>


ARGH!!!! There is so much info in what's Garro has posted above. This probably cuts 100-150 hours out of any newbie's 10,000.

No, I'm not being snarky.

I really am trying to help - I've tried almost every way to do this to exhaustion - I have brazed most days for the last 13 years


- Garro.

[David Tollefson]

Thanks for the clarification! I owe you another round.

[Eric Estlund]

Flux the inner and outer faces of the joint. Additional flux is a handy/ easy temp guide, but not strictly necessary (if no filler is going there).

I'm of the tack/ preheat/ one shot pass school. I'm also of the slow down to go faster school. A little time with an EVEN preheat helps wet out and helps prevent spot overheating (a major cause of internal distortion). A major cause of seat tube distortion is hot seat tube/ top tube interface, but a relatively cold seat tube "inside" the radius of the top tube cope. They expand and contract at different rates and buckle. Internal push/pull of wedged top or down tubes can exaserbate.

It might be science from a best practice stand point, but there is a lot of muscle memory and learned intuition in the timing that can only be experienced through repetition.

[cicli polito]

I also use a small amount of flux inside the coped section. One pass after tacking. Everyone's quiver has different arrows, but mine for fillets is a smith 205 tip and 1/16 rod for everything but the BB cluster, where it's 3/32. While I do the fillet in one pass, I personally don't stitch in a complete circle, more like an "S" shape. I also do a small amount of post heat, it helps feather out any edges which i may have left.

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[ulrich vogel]

a few years ago Dave Kirk wrote the following:

Hello All,

This is an extension of the “fillet BB” thread in the Eye candy section. I’ve been asked for some fillet tips from a number of folks so thought I’d make a general post. There are a number of things that can make or break the whole fillet thing. I’ll break this into three sections – prep, laying fillets, and finish work. FWIW this is just the way I’m comfortable doing this and by no mean the “only” way or the “right” way to do this. I’ve seen plenty of very nice fillets that didn’t go by this recipe.

Prep –

1) Clean the tubes. I dip the tubes into my can of acetone and then wipe clean with a clean rag. I then use new, fresh, 80 grit emery and sand each end. I then dip the tube into the acetone again to get any dust off and wipe with rag again.
2) Clean the rod. This is very important. The brass rod lies around for months getting tarnished and dirty and it will work much, much better if you clean it. I wipe it down with a rag wet with acetone. You’ll be amazed how dirty the rod was.
3) I use a Gasflux machine and I like it. I know many do not and that is cool. But I use one and I always check the flux level before starting. It’s a bummer to run out mid-fillet.
4) I use a Victor torch with a #2 tip. In fact I use it for everything not just fillets.
5) So everything is clean and ready to go – I flux everything up before putting it in the jig to tack. I flux a good two inches up into the tube. Might sound silly but it does a very good job of preventing heated up oils inside the tube from running into the joint. It provides a barrier if you will.
6) I tack each tube in four places.

Laying fillets –

1) Preheat the entire joint. Take your time and don’t be in a hurry to lay down the fillet. By heating the entire joint you minimize the amount of distortion of the tubes. This is very important on head tubes and BB’s where ovalizing can cause real issues in machining. I heat the bottom of the BB and the front of the head tube just as much as the part I’m laying the fillet on. This will make your life much easier down the road.
2) “Tin” the joint. This is in effect tacking the entire joint. This is the real structure of the fillet and will make sure that the bike is still together after your death. Tin it well and flow brass into the joint evenly all round.
3) Once the joint is tinned I start laying the fillets. Turn the torch way, way down. I use a flame that is about the same size as I use doing bottle bosses. Small. When laying the fillet ALWAYS work away from the torch. I’m right handed and hold the torch in my right hand……….so I work from right to left. This will assure that you are preheating the spot you want to lay down the next bead of fillet and also make sure you aren’t melting the stuff you just put down. This is super important to me. Lay the fillet in beads like a TIG welder does. Overlapping beads. If the fillet starts to get away from you and is getting sloppy back off and let it cool some. Do not rush. Back off and take a few long breaths before going back in. It will still be there. The few seconds of time this cost you here will save you hours later in finish work. Go slow.
4) Do everything you can to NOT go back over the work to reheat and smooth things out. This can get away from you in a hurry and you’ll end up with the fillet on your foot.
5) I have the frame in a Park stand so I can rotate it and get the angle I want for each bead. Take the time to get the frame is a good position. Do not try to work around a corner. Take you time and move the frame so you can get at it properly. See the trend?……..take your time.

Finish work –

1) Soak the frame in very hot water to get the flux off. Don’t waste your time with warm water. If the water cools down replace it with really hot water. It will go much faster this way. Soak ALL the flux off before trying to do anything else. Finishing with glass hard flux is a waste of time.
2) This is a bit of a diversion – I check the alignment before doing any finish work. On the 1 in a 1000 chance that the alignment is crap you won’t waste you time doing the finish work.
3) All finish work should be done from the middle of the fillet out toward the tubes. This will assure that the fillet is a quarter circle shape and not have a flat in it. So work from the middle.
4) I start with a 10” round file and take off the high spots. Don’t touch the file to the steel……..ever.
5) I then wrap the same file with 80 grit emery and sand the joint.
6) I then rip the emery into narrow strips about 8mm wide and sand with those……..working from the center and blending into the tubes.
7) Lastly I use an abrasive brush wheel to buff the joint. This makes it shiny which is fun but the real purpose is that it will highlight defects. File marks and low spots will stick out in a big way once you use the wheel. When you first to it you will be bummed but you’ll learn a lot about where you leave poorly finished stuff. Once you use the brush you’ll have to go back in and refinish some stuff that wasn’t right.

My aim is to make a straight bulletproof bike with pretty joints that will need no putty. Anyone can lay down joints that will hold the tubes together but look like ass and then putty them into shape. Take the extra step and you’ll be proud of your putty free work. This takes lots of practice and you won't master it quickly. Be patient and methodical and it will come around. Over the years I've done many thousands of fillet bikes and they go like clockwork now but it wasn't always that way. Practice makes perfect.

I hope that helps and answers your questions. Thanks for reading.

Dave

and
Kirk - Fillet Brazing at Framebuilder´s Collective

[Too Tall]

Awesome. This is exactly why I and others give a #*^% and keep this place going.

[steve garro]

a few years ago Dave Kirk wrote the following:

[I]Hello All,

Fuckin' bible right there.

- Garro.

[shirk]

- Tack big, tack small, just make sure your tacks have "root"

What you mean by "root"? Is this just that it has wet out and you can see that it's not a cold tack

[shand]

Three passes?

NO

You are off base if you think tinning & then two filler passes isn't pre or post heating!

And if you want to do damage to steel, it's not just how hot you get it, but how long it stays that hot.

And think about the effect of a tiny fillet cooling rapidly vs a big one cooling slowly.

I could spell it all out, but there is nothing to learn that way.


One pass, 3/32nd or bigger - get in, get out - put some F'ing metal on there

- Garro.

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

[ulrich vogel]

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

have a look at: Bob Brown / Engineering Analysis / Section II Fillet Radius vs. Joint Strength

[shand]

have a look at: Bob Brown / Engineering Analysis / Section II Fillet Radius vs. Joint Strength

Hey Ulrich,

yes, that comes directly from the article I mentioned. I have a copy and for those interested you can download it from here for a while :

bicycling_bike_tech_vol_4_2.pdf

I'm really not sure what the implication are for posting this online. If someone knows who owns the rights to this let me know. I'll make it available for a while before I remove it.

Steven

[phutphutend]

Op here. The thread seems to have gone off in a tangent.

I've been given some sound advice to solve my problem, but would still like some more detail on how to preheat the tube/joint?

[Will Neide]

Op here. The thread seems to have gone off in a tangent.

I've been given some sound advice to solve my problem, but would still like some more detail on how to preheat the tube/joint?

With your torch. :)

[phutphutend]

I was thinking if lighting my farts...

How big a region do I need to heat? How hot does it need to be? Do I need to top-up the heating as I fillet?

I known can findd out all of these things by by doing multiple test pieces. But some guidance would be appreciated.

[shirk]

Pre-heat = bring the whole joint up to the flux's active temp. Go back and re-read Steve's process description.

Apply flux several inches past the joint and get it all nice and glassy, then dive into the joint and get the metal up to brazing temp any lay your fillets.

[shand]

Op here. The thread seems to have gone off in a tangent.

I've been given some sound advice to solve my problem, but would still like some more detail on how to preheat the tube/joint?

I flux the whole area, well away from the joint and round the backside too. I use a bigger flame and get the whole area (both sides of the tube you're joining to) up to an even temp (use the flux to gauge this). I like to get the whole area hot enough that when I turn the torch down a little and get in close, I'm not having to add very much additional heat, the rod is already starting to flow. Like the Garrmeister says, get in get it done fast and get out. Biggest rod you feel comfortable with (that way you're not dicking around shoving skinny rod in when you could be half way round).

However, and it's a big however, I'd suggest doing your stays at the same time as the top tube on that join you're working on. I know some like to add seatstays at the end as it helps with staged alignment but why put that are through multiple heat cycles if you don't have to?

Finally, if you're on a forum asking how to pre-heat, you probably shouldn't be taking anyone's money.

And I sense a reluctance to practice from your previous posts but you really do need to do the work. Sure, you can 'work smart' but you still need to put the hours in.

[ulrich vogel]

Hey Ulrich,

yes, that comes directly from the article I mentioned. I have a copy and for those interested you can download it from here for a while :

bicycling_bike_tech_vol_4_2.pdf

I'm really not sure what the implication are for posting this online. If someone knows who owns the rights to this let me know. I'll make it available for a while before I remove it.

Steven

Hi Steven,
Thanks for sharing!

Ulrich