So, I mucked it up

[veryredbike]

Did a terrible braze on a head tube/down tube lug. I'm pretty sure there are some big gaps in the fill... got silver everywhere. It's pinned, so I'm not sure exactly how to get it all back apart. New lugset costs 50 bucks. It's OS with a 36 head tube, and I'm not finding those lugs sold outside of a set. Frustrating!

Any thoughts?

[veryredbike]

I took some deep breaths and I think I'm going to build and ride the damn bike. It's for my 10 minute mostly flat commute anyway... it's oversized, lugged, done with 48%, and I have trouble seeing it failing catastrophically, even if there's a bit of a void at the bottom.

I think a bad week colored my judgement on how bad things were. From now on, no brazing angry ;-)

[veryredbike]

A thought... I always seem to have trouble with that one spot... How do folks feel about tinning it ahead of time? Is that kosher?

[Chauncey Matthews]

A thought... I always seem to have trouble with that one spot... How do folks feel about tinning it ahead of time? Is that kosher?

Where was the "one spot" ? I'm guessing it was in the tight spot on the acute side of the dt/ht connection.
My thoughts:
-Your first reaction was probably right, seems like you had to talk yourself into believing it will be ok.
-you needed a more even preheat. It helps the spend a little time inside the ht.
-56 flows the best.
-I don't know how you would tin a lugged joint, but there's no reason you should ever need to.

[Craig Ryan]

If you think it's bad, I'd start over. A tubeset and lugs aren't that expensive when you take into account the time period covered in building the whole unit. Why put time into something you can't look at with confidence.

[EricKeller]

Always best to trash things that don't go right.

Silver everywhere means your preheat wasn't even enough. Sounds like you tried to force things. Everyone has the occasional bad moment, you always have time to take a deep breath and relax. The flux stays active for a very long time if you don't overheat it.

There is no shame in practice. Actually, there should be more shame in not practicing, but I understand why it doesn't work that way

[Eric Estlund]

When possible I try to never start a project without a "back up" part. If I muck something up (it happens) I want to be able to discard it without a second thought and start right away. Having a back up on hand removes the temptation to call it "good enough" when it really isn't, and helps save the only commodity I can't replace (time).

Cut it apart to learn about what really happened. Cutting it apart will also save you from trying to make it work.

PS- You can drill out the pins and remove the tube. Pins do add a layer of complication (on both ends). Some people swear by them- I don't use them.

[veryredbike]

Where was the "one spot" ? I'm guessing it was in the tight spot on the acute side of the dt/ht connection.
My thoughts:
-Your first reaction was probably right, seems like you had to talk yourself into believing it will be ok.
-you needed a more even preheat. It helps the spend a little time inside the ht.
-56 flows the best.
-I don't know how you would tin a lugged joint, but there's no reason you should ever need to.

I think you're right all the way around on this one. It was that spot in the acute angle. I had a lot of problems with heat because the tip I was using kept causing problems (I had to stop a couple of times and clean it, but it didn't really take), and I'm talking myself into it being ok. I was using 48 because it'd be stronger and there was a bit of a gap at the top of the lug... but I have less practice with it, and it made it hard to draw through.

I'll dice it and report back.

Thanks all! Good advice all around.

[Craig Ryan]

The bottom of the HT/DT is a bad place to not be sure about. I always start my feed there. Others may do it differently, or enjoy using 48, but I've never cottoned up to it. I think the 48 was your problem. I only have 56 and brass in my shop.

[dbohemian]

or enjoy using 48, but I've never cottoned up to it. I think the 48 was your problem. I only have 56 and brass in my shop.

48% was not the issue. It does melt at a slightly higher temperature than 56% but with proper technique it should work just fine. Once I grabbed 48% instead of 56% and brazed a joint and during I was like, this is a little odd. Things went well and only noticed I had taken it out of the wrong box after it was done.

48% BTW is not stronger than 56% when we are considering the same gap clearance. Under greater gap clearances lower content silvers can provide a greater shear strength but then we should use this material mindfully and ask why we have gaps like that. Sometimes it is unavoidable but it is not a replacement for poor fit-up.

My guess as has been said before is that your pre-heat is too short or inconsistent. I like Eric do not pin as a general rule either but this has much to do about your fixturing and procedure. Like many things if you have had no coaching as to what you are actually doing you could be doing something way off base and not really know it. To make you feel better I trashed at least five frames when I started out. I just cut the front's off and made chairs or cut them up. It hurt financially but it was worth it in the long run. (should have done more of it actually)

[steve garro]

So did you end up going with the 7/4/7 or the 9/6/9?
- Garro.

[Human Epic Jolt]

Those airbus jokes never get old.

[Erik B]

Did a terrible braze on a head tube/down tube lug. I'm pretty sure there are some big gaps in the fill... got silver everywhere. It's pinned, so I'm not sure exactly how to get it all back apart. New lugset costs 50 bucks. It's OS with a 36 head tube, and I'm not finding those lugs sold outside of a set. Frustrating!

Any thoughts?

Strawberry Andy sells individual 36HT lugs.

[veryredbike]

So did you end up going with the 7/4/7 or the 9/6/9?
- Garro.

This was an 8/5/8 chromo set. Mr. Sachs talked me into pegorichie for the next one. The shipment isn't in for a bit, so I'll practice up a lot and if I'm not ready, save them for #4 or #5.

Strawberry Andy sells individual 36HT lugs.

Doh! Too late, already ordered. If I mess it up again I'll know where to go. Thanks!

[prolix21]

If I had doubts I'd start over and cut that tube/lug assembly in pieces to see where the gaps are

[Doug Fattic]

First of all my sympathy for messing up. Big mistakes can be really frustrating. I think many wanting to learn how to build frames underestimate how difficult it is to braze – especially a lug. My interpretation of your description is that you are not yet ready to braze a frame for real. Your minimum goal before you move beyond practice should be silver everywhere on the inside and none on the outside.

My observation after years of teaching brazing is that beginners don't get it quickly. Even with lots of explanation and demonstrations, its tough to make hands work like the head is telling them to do. And that assumes one knows exactly what to do. It takes practice to get your hand/eye coordination to be in sync with your recognition of the heat indicators. My recommendation is to work on mastering the fundamentals first with simple exercises. This can begin with short pieces of .058" thick sleeves over .035" tubes. Practice until every time your hands hold the silver in the best position and move the torch with the right motion. Lots of brazing mistakes begin because the silver is positioned wrong requiring more attention to keep it where it should be (resulting in the flame going awry). Keeping the flame at just the right distance, moving the right speed, following the correct pattern is difficult. Then we add the others factors in heat control like aim (not everyone hits the target of where they want the flame to go), using the right angle (it can be straight on, coming at an angle or using the side of the flame) and flicking it on and off the joint. All of these factors are adjusted at the same time when reading the heat indicators to bring the joint up evenly to brazing temperature and then modified to keep it within its melting window. The mistake I most commonly see is the inability to heat the selected area evenly. Often beginners have too hot/too cold spots within their zone and color outside of their lines. It makes no sense to me that anyone would think these skills can be learned without real effort that takes significant time (and I would add coached by someone experienced) because some aspects have to be in muscle memory or there is too much to keep track of at the same time.

What throws a lot of beginners off is the difficultly of working the flame pattern with their dominant hand while independently moving the silver when it is melting with their other hand. All of this requires lots of practice to do it well even if one is given expert instruction. If you are on your own learning by trial and error, that greatly extends the learning curve. Of course it is in my self interest to say this (and it may be annoying to the DIY types) but learning from a master gives assurance the frame won't fail later. I've been forever thankful I was taught by one.

[ScottB]

Newbie question: why can't this joint be reheated, allowing the silver to draw in and completely fill the joint? If veryredbike knows or strongly suspects that the joint did not get completely full, can't he/she reheat it and try again?

[veryredbike]

First of all my sympathy for messing up. Big mistakes can be really frustrating. I think many wanting to learn how to build frames underestimate how difficult it is to braze – especially a lug. My interpretation of your description is that you are not yet ready to braze a frame for real. Your minimum goal before you move beyond practice should be silver everywhere on the inside and none on the outside.

I definitely know where you're coming from... that being said, I've been able to get a fair number of joints like that. My pattern seems to be "bunch of successful practice pieces, flow the lug on a frame, get paranoid and put way more additional silver than necessary in 'just in case'" with the exception of that one little nook. I've got a bit more practice material to work with now, so we'll see how it goes. This case seems to have been extra bad primarily because the tip kept getting gunked up... I had to stop a few times and got dumb and impatient. I could use some professional guidance, but it's hard to schedule and I have limited funds... admittedly more limited after my ceeway order.

[prolix21]

I definitely know where you're coming from... that being said, I've been able to get a fair number of joints like that. My pattern seems to be "bunch of successful practice pieces, flow the lug on a frame, get paranoid and put way more additional silver than necessary in 'just in case'" with the exception of that one little nook. I've got a bit more practice material to work with now, so we'll see how it goes. This case seems to have been extra bad primarily because the tip kept getting gunked up... I had to stop a few times and got dumb and impatient. I could use some professional guidance, but it's hard to schedule and I have limited funds... admittedly more limited after my ceeway order.

if you're flowing the silver correctly your shorelines will be your indicator when you've got enough, or too much. also, if your torch is getting gunked up, you're way too close to your work. you should be using a reducing flame and keeping that entire lug heated up and using your flame to pull that silver throughout the joint. your flux should be nice and glassy. just keep moving that torch around so you don't burn it and pull that silver through. if you're feeding from one point and build nice even shorelines around the lug, chance are you've got a solid joint.

this isn't soldering (based on your tinning comment) - at no point should you be dragging your rod along the edges of the lug.

[Andrew R Stewart]

"this isn't soldering (based on your tinning comment) - at no point should you be dragging your rod along the edges of the lug." (prolix21)

I will drag my filler rod along the lug line after the filler has hardened but before the flux has. This helps me "feel' the fill along the shoreline without adding more filler. I have had one builder tell me this is wrong technique, but I learned it from another who predates us all. Andy.