Silver Brazing Tips

hey Jody here this video is on silver brazing one method of building bicycles is brazed lug fittings on steel bikes and it's a really cool look and it's usually done with silver brazing and I've got to visit Mike's I cannot oh not too long ago and he showed me kind of some tips on a mock up type joint using a braze fitting and some bicycle tubing so we walked through that but silver brazing is a very universal type very useful skill to have it joins all kinds of metals together and sometimes in the especially in the case of this bike joint with the with the lug fitting if your clearances are right and everything's clean and you do a good job and get braze material to flow 100% it can be as strong or stronger than a will joint so let's get into it this is a Miko oxy-acetylene torch very popular torch amongst experimental aircraft builders who build you know chromoly airframes for kit planes and things like that but it's also popular amongst bike builders for silver brazing nice small torch really easy to handle so the tubes still have to be notched just like if they're if they were to be welded but the lug fittings will make assembly pretty easy this is an anvil bikes fixture and you can see that would be nice for a weld job but we're gonna use lug fittings on it instead for silver brazing after it's not just gonna have some burrs on it so get those off with a belt sander remove all the internal burrs and then clean the inside of this lug fitting with a little drum wheel here get it all down to shiny bright metal that's super important for any kind of soldering or brazing operation and you can see how it just makes it kind of easy to fit a bike together using these fittings fairly fairly close fit too which is also important with silver brazing next thing after all nice and clean like this is to flux them up put them together determined by the silver Braves filler material and it's considered a low temp this is 56% silver alloy and this is low temp white flux you can find this stuff at any bike builder Supply website most welding stores will have that you have white welding flux as well or I should say brazing flux but you slather it on there pretty good and I gotta sleep will do the same thing I am a big believer in over flexing when it comes to something like this you don't want to scale up the surface and then have to deal with removing that scale later it's a lot easier to remove excess flux than it is scaled oxidize film on metal so this is another fixture to hold it up in place for brazing and not done flux and yet gonna flux up the outside of that lug - because again don't want to scale it up and then have to try to polish that off there it's a lot easier to soak in hot water and soap or whatever and remove that flux Oh get the flame going here this is going to be a what's known as a carburizing also called a reducing flame you can see that by the long feather coming out from the inner cone and it's time to start braising now this this this is steel so this gets up to a dull red a pinkish area before it will accept the the silver and the technique here is to that Mike is using is to keep the torch moving and to to use to play that torch on the opposite side of the lug where he's feeding the silver metal the silver braised metal that way he knows that when it's hot enough to melt the brace metal where he's not concentrating the torch that it will draw it all the way through because silver braze metal and solder will flow to the heat got to keep that torch moving though or you'll overheat it once you overheat it it won't accept silver any more and you got to go back and reclaim possibly even cut it loose or pull it loose and redo the whole thing you don't want that so you keeping the torch moving plenty of flux has helps also to keep from scaling it up you keep an eye on those collars when you see that silver come through to the other side you don't need much more than that you can play the torch a little bit just to make sure that it it flows all up through there but over over heating and just packing silver metal in there just means a lot more cleanup afterwards you can see Mike wicking some extra flux up to freshen areas up a little bit that look like they might get too hot and scale almost done alright once it is finished let it cool completely like if this was a chromoly joint you definitely wouldn't want to quench it in a bucket just let it cool off and then with warm water and a wire bristle brush go to town getting all that excess flux off of there that'll be followed by some Emery cloth to get any excess silver is hanging around and that will be followed by a sort of a soft 3m yellow bristle brush it's not too aggressive but it will take off little pieces of oxidation and flux it's left over without taking any actual base metal or lug metal off at this point Mike would go do some touch-ups with a fine small file just to put a nice little chamfer on the edges of that lug and just get those last aesthetics going so that's the best looking product for the customer probably two most important things are cleanliness we want to make sure that surfaces of the materials are free of oil dirt really any kind of hydrocarbon and then the other thing is clearances so to get that nice capillary action to draw the filler material through the joint because that's really what we want to do we want to make sure that we're only feeding from one direction and we're drawing that filler material across the entirety of the joint until we see it on the other side that can really only be done if you have the correct clearances between the parts and that depends on your the actual phrase alleyway that you're using for instance if you're using a 56 percent silver maybe you're going for a seven to ten thousandth gap if you're using low fuming bronze that might be opened up considerably to get a good to get a good capillary action to draw that raised material across so I think those are the two most important things is your surface prep and then also your tolerances they've been plenty of looks plenty of flux I like a lot of folks it's yes cheap insurance also I noticed a couple of things I noticed I noticed things that's they I've noticed you keeping the torch moving yeah you lit it with a you know somewhat carburizing fluid so a little bit of excess of acetylene you know a nice feather coming out that the cone again keeping the torch moving feeding the feeding the filler metal on the opposite side of the look where you're heating so that when it did draw in and would pull it all the way yep that's a good that's a good practice if you think about what you're when you're sweat to copper pipes which I'm not very good at but I do know that I try to heat it up and heat it up down in the bottom of the joint and then if I got that hot and in the top is hot enough to feed in I know it's gonna pull through pretty well yeah you can't see the other side I always won all right on a joint like that fortunately with the loads you can see the other side and see when that collar of you can brace material comes through that's what you're looking for right absolutely yeah you want to see that nice ring of silver or bronze coming through the other side I know some guys that actually braise with the light stuff believe it or not because especially with bronze you can actually see the shadow of the material when it's cherry red you can actually see the shadow of the filler material working its way through really yeah yeah this it's pretty cool I never would've thought about that yeah yeah I have an x-ray vision pretty much yeah that's cool so you know I remember I remember about when I first started doing some silver braising in a fab shop I was in it was on some kind of heat exchanger but also made a belt buckle mm-hmm so it hasn't had some brass plate like eighth inch thick brass plant cut an arrowhead out I've been up some stainless wire solder braised it on the backside for a hook that was my favorite belt buckles nice so anyway that the point of that story is and I think all stories should have a point the point of that story is that it's very versatile silver braces there's all kinds of different alloys for different applications but there's a lot of overlap too so if you get a nice versatile silver braze material you can stick copper to brass to stainless steel to steel to all kinds of things yeah absolutely for instance we use the 56% silver when we're doing mugs but then if we're gonna join steel the stainless will use fit the end which is two percent nickel and that does a nice job wedding out on the surface of the stainless another thing just as I'm thinking of it one important point is in our mock-up we didn't have a breather hole but it is important to when you're soaking to get that flux I think anyway from the inside so a real frame I would have had breather holes and all the tubes primarily to elect gases escape but also yeah that we can when I so get it it does a good job getting rid of yeah that flux do you have the same issue with silver brazing lugs that you have any well without breather holes and sometimes where the seals up it absolutely yeah you'll get a fountain of silver fuse it's you don't want that I don't even want that okay so get cleanliness again clearances good fits plenty of flux keep the torch moving and use a technique where you feed from the opposite side where you heat so you can draw it from draw that through the capillary action draw it through yeah and I can't stress the cleanliness enough with any material really icy post sometimes about especially you guys who are trying to learn whether it's a take or any other process and they'll say here's what I'm do it and then they get kind of cut down by some of the more senior people and saying no you're doing too much you know to me cleanliness is godliness when it comes to this type of work so yeah you might as well give it your best shot yeah but when it comes to the titanium and aluminum and silver brazing that we've done I'm gonna guess that you've never stopped and said you know what that didn't go very well it must have cleaned it too much okay yeah you know that were as square as if you don't clean it enough man why didn't I spend the extra minute cleaning that because it would have gone better yeah that's a great point it if things go wrong at least there's one less thing that you need to troubleshoot yeah and thanks to Mike for having me and let me film this video see you next time you

Channel: weldingtipsandtricks

Views: 170,002

Rating: 4.9404802 out of 5

Keywords: silver brazing, silver braze, silver solder, silver brazing tips, silver soldering, brazing, bike buiilding, bicycle building, braze bicycle, bike brazing

Id: no-OWfC5-RY

Length: 11min 59sec (719 seconds)

Published: Thu Sep 06 2018