Framebuilders - quick brazing question

I am told to pull the silver through the lug until i see it on the other side so i know it is through the whole joint.
So, Lets say I am doing the lower head lug with the down tube sticking essentially straight up and the head tube sort of perpendicular the the ground. I have been trying to feed the silver from the top (on the down tube above the edge of the lug). I have been trying to pull it all the way through so I can see it on the head tube. I keep feeding and feeding silver, but I cant seem to get it to pull all the way over to the other tube. It seems like it sort of has to go around a corner, as it has to go from one tube to the other, which seems like it would be hard for the silver to do.

Hope this makes sense. Any suggestions?

You need to feed the silver in from multiple locations on the joint and you need to rotate the assembly so the silver is flowing down hill – with gravity. For example on a head tube to down tube junction, heat the entire lug and tube(s) assembly until everything is up to temperature and then position the head tube straight up. Feed silver into the joint on the top edge of the lug where it contacts the head tube – feed from two or three locations around the lug. Use gravity and heat to move the silver into the joint. Once you get some silver flowing into the joint I usually switch to the down tube side of the joint and get some silver into that side to hold everything together – rotate your tubes to put the down tube straight up now. Start feeding the silver in and pull it down hill using heat to get it into the joint. Some will come out the side but just rotate the tube again and use the heat to pull everything inside the joint. You are going to have to play around until you get a feel for this process and find the best positions for the tubes to get the silver down into the joint.

It tend to feed quite a bit of silver into the joint so it some times leaves some on the edges. I’m a lot better at it these days and make sure to pull everything inside the joint to minimize the amount of clean up work. You are better off using too much silver than with not using enough. It’s recommended that you make several practice joints and look inside them to make sure you are getting good penetration – silver inside the joint. It’s not hard but takes practice.

Good luck.

I add silver from multiple locations, but never from multiple sides of the lug. If the silver has not been pulled through from a single side, I have no way of knowing that silver as actually made it all the way through the lug.

Suggestions:

Everything has to be absolutely clean. Some people will use acids; I find that thorough sanding of all surfaces followed by a wipe with fresh rag does the trick.

Tolerances need to be pretty tight. Things should slip together without force, but just barely. Silver doesn't like to fill big gaps.

Flux thoroughly. Every surface to be brazed needs a complete coat.

Make sure that your miters are tight. Big gap, or lots of gaps, make life difficult. Strive for a "water tight" fit.

Heat evenly and completely -- but don't overheat. If the flux is turning brown or black the silver will flow badly or not at all.

And the bottom line is that getting everything to work does take practice.

Thanks guys.

So, if feed with the down tube up and down, and the head tube flat, will the silver flow around the corner and end up at the head tube (I hope that makes sense)? On that joint that is really the only way to feed through so you can see it come out on the other side.

Can anyone estimate how much silver they use on an average frame? All my silver is going into the joint, so I can't be using too much right?

I clamp the tubes in my bike stand and rotate them several times for each joint. I don't recommend just laying the tubes on a bench since you need to heat the entire joint at the same time and you can't do that without a proper holding fixture of some sort.

Not exactly sure how much silver but I think 1 oz. is enough.

Good luck.

I probably use 1.5 to 2 ounces, but that's for a touring bike with every braze-on imaginable.

OK sounds about what I am using. And I am using nickel silver for the dropouts, which is much harder for me to get to work. Have to get it much much hotter, any tips with this?

The first frame I built I used 3 ounces of silver. Sloppy as hell!

I'm paying about 30 bucks an ounce for the silver, is this about right? You guys know of any cheap suppliers?

Thanks for all the help.

OK sounds about what I am using. And I am using nickel silver for the dropouts, which is much harder for me to get to work. Have to get it much much hotter, any tips with this?

The first frame I built I used 3 ounces of silver. Sloppy as hell!

I'm paying about 30 bucks an ounce for the silver, is this about right? You guys know of any cheap suppliers?

Thanks for all the help.

$30 per oz. sounds about right for retail pricing. It's cheaper if you buy 5 oz. at a time I think.

The nickel silver is mostly nickel as I understand it - uses a different flux doesn't it? It takes a lot of heat and is not cheap. Most builders used standard brass for dropouts due to cost, it's still plenty strong.

I use either plug-in style dropouts or domed and slotted, both of which work perfectly with silver. I talked to Hank Folsom (Henry James) about using silver with standard dropouts. He tells me that silver is lousy at filling those big gaps and that even if succesful, will often crack during cooling. He explained that some builders fill the gaps with nails or some such before brazing, so the silver has an easier job.

Overall, I think I will use brass if it ever comes down to it.

I can't find this "standard brass" anywhere. The nickel silver was very cheap, and the people said this was all there was.

I can't find this "standard brass" anywhere. The nickel silver was very cheap, and the people said this was all there was.

The people lied! Regular brass is everywhere, including Home Depot- but the good stuff (the only stuff worth using, imho) is the Gasflux C-04 rod sold by HenryJames.com.

Never trust people, is the moral of that story.

Haha, true. Do they literally have brass at home depot? I know this isn't the best, but will it work?

I just tried to do another dropout with the nickel silver, and no luck (tab dropout). I used flux for regular silver (which i guess isn't meant for this temperature), heated the dropout bright red hot, then melted this stuff on there and in there. I filled up the end of the seat stay with this stuff, all around the dropout insertion. Then, when it cooled i went to cold set the dropout a little bit to get it straight and it just broke right out. Didn't bond at all.

It is seeming impossible to get this stuff hot enough. I get the tubes/dopout red and it still won't get this stuff molten.


Will "regular" brass be easier? Or a better flux?

"Red hot" is way too hot for silver flux. Once the flux starts to burn you can forget all about getting good flow and/or strength.

I have had zero luck with Home Depot brass.

I have heard that brass is very easy to work with. I have also heard that it is much more difficult than silver. I am much more inclined to believe the former, simply based upon sources, but have no personal experience. The only thing that I can say with confidence is that without the appropriate flux for the heat and material, you are wasting time and gas.

definately use the henry james GASFLUX brass rod. he is a true gentleman running a family business and his wife monica is equally enchanting. buy some blue paste flux as well. Hank will hook you up and you'll be rewarded for using quality brass. Mike G.

Haha, true. Do they literally have brass at home depot? I know this isn't the best, but will it work?

I just tried to do another dropout with the nickel silver, and no luck (tab dropout). I used flux for regular silver (which i guess isn't meant for this temperature), heated the dropout bright red hot, then melted this stuff on there and in there. I filled up the end of the seat stay with this stuff, all around the dropout insertion. Then, when it cooled i went to cold set the dropout a little bit to get it straight and it just broke right out. Didn't bond at all.

It is seeming impossible to get this stuff hot enough. I get the tubes/dopout red and it still won't get this stuff molten.


Will "regular" brass be easier? Or a better flux?

They do have it there, good for fixing shovels or wheelbarrows, that's about it. Also, the powdered flux they have is total crap compared to the good stuff. Like Mike said, get the flux from Hank- it will also work with that nickel silver.
If you heat metal to the point where you can see it turning red, you've gone way past the working temp of silver flux and it's cooked. I'm suprised you got the nickel to flow at all, but as you saw, it never bonded.

Haha, true. Do they literally have brass at home depot? I know this isn't the best, but will it work?


They do. I have some that I use for general sheet metal work. Works fine, but get some decent flux. A welding supply store can sell you the rod and flux, too.

I never really found brazing to be that difficult. Back when I learned, the only place to get supplies was the local welding company, which for me was 50 miles away. But we had to braze 10 miles uphill both ways, knee deep in snow. The advantage of that was they pretty much knew what you needed. I guess there are some subtle differences in frame materials now that make mail order better, but I don't think we are talking about that here.

It's always good to go to the local welding supply, they probably have a lot of stuff you need and it's one of the few ways you can put your hands on things.

Local welding supply didnt have the flux for it, they said it was hard to get. Ill just use henry james. Wierd question: what isle would the brass be in at home depot (hard to find stuff if you dont know where to look)?

"The people lied! Regular brass is everywhere, including Home Depot- but the good stuff (the only stuff worth using, imho) is the Gasflux C-04 rod sold by HenryJames.com."

That migh be going a little far. The powdered stuff can be mixed with water to get the results needed. Local suplies of raw brass can sometimes be founds in HD, and any weldign store will have it. Gives you something to work with until the fancy stuff arrives.

Silver will work but you need to tighten the joint a little so the gaps are small.

Local welding supply didnt have the flux for it, they said it was hard to get. Ill just use henry james. Wierd question: what isle would the brass be in at home depot (hard to find stuff if you dont know where to look)?

The person you talked to at the welding store was either an idiot, or lazy. I find it nearly unbelievable they don't have a dry powder borax-based flux on the shelf; certainly they can get any of a dozen brands. HD (and other big box hardware places) hide the brazing rods with the other welding stuff. Some stores have much more than others, though.

The welding stuff is kept in the tool crib at the Home Depot. The brass is in the form of rods sold in hanging plastic bags.

Just so you'll know what it looks like as you try to avoid it. :p

what is so bad about the home depot rod?
on;y asking because i just bought some to do some frame work. If it really does suck i will just head over to the local welding shop, and save my gas.

what is so bad about the home depot rod?
on;y asking because i just bought some to do some frame work. If it really does suck i will just head over to the local welding shop, and save my gas.

Brass is relatively thick compared to silver so flowing into a gap requires more clearance. The Gasfux brass sold by Henry James seems to have more fluidity than run of the mill brass sold by the likes of welding shops or Home Depot. It's not that the regular brass is bad or anything, it's just rather thick so you need to watch your heat and not overheat the tubing when you are joining thin bicycle tubes.

I don't know why some of you are so hung up on wanting to go to HD or a local welding supply store. HJ has every part of what you need, why not just order it through them?

I recently had to buy some brass flux from a local welding supply store while I was waiting for my shipment from HJ to come in and it worked. For some reason a lot of it turned dark almost immediately like it was burnt but then continued to work like the usual stuff.

"HJ has every part of what you need, why not just order it through them?"

Because artfully there was bike building before HJ, and some of us don't live in the US so a small overnight purchase for you, is a nighmare up here. It's OK if you need a large amount, and can minimize all the stupid costs (not HJ's fault). It used to be good dealing with the US but it gets worse every week (doubtless true in reverse also).

I think it has alot to do with the flux. borax sucks.

I used the Home depot stuff last night and it was a bear to get it to flow. Once i got it though no problems and the bond is nice and tight.

When i deside i have the hang of this lug frame building i think i will spend the money and order the stuff from HJ.
Cheers