Framebuilders - Brazing stainless

I have a guy who wants Paragon sliding dropouts (stainless) on his CX frame. I know that the only 2 options are tig welding the stays or silver brazing. I don't tig weld, only fillet-braze. I have brazed stainless dropouts before but not slotted. What advice can anyone give me on silver brazing a track style dropout? I know the tolerances have to be next to nothing but is this a safe avenue or is it better just to get it tig welded. I spoke with Paragon and they said you can use silver but I couldn't get a feel of if he would recommend it.

Heat control is critical, as overheated stainless will make a mess and the silver won't adhere well if at all. Silver is also more difficult to get "suspended" in the gap between the dropouts and tubing. Hank Folsom suggests filling the space, as much as possible, with nails or pins prior to brazing. I have not tried this and instead opted for (expensive) practice with junk tubing and dropouts. I probably used about $100 worth of silver in learning, but can now do a passable job.

What sort of mess are you speaking of? I have only brazed stainless dropouts a couple times but it didn't seem that bad. I just filled in the gap between the tubing and dropout, not a real difficult task. At what point do you consider overheating? Does it give you a sign when it is reaching that point? Also, since brazing slotted dropouts seems to be very technical would you prefer to use tig welding? Thanks for your time. I was beginning to wonder if anyone was gonna reply to this thread.

Given the cost and importance of the parts it would seem to make seense to get them TIG welded if you have someone who does that, but handing off to a non- bike experienced welder would be a poor choice usually. There are very tallented welding god types, that can do anything. Just so long as they are really up to it.

The main thing with the Harris silver/flux I use is that you put it on, heat it until it crusts up, then heat it further until it melts, then further still till bubbles form and you are good to go. Filling a large gap is relatively easy with the 45% I use, but I guess a lot/most people use 56%? In one of the Paternek tapes he fills the standard CS open end with silver. Not sure which one it is since I have both tapes.

The idea that you can't silver solder a tight gap isn't true, there are all kinds of joints in stuff like express sights on rifles that are done very tight, it is all a mater of how one goes about it.

There are a number of ways of closing the gap to make the tolerances tighter, machining little space filling metal bullets, or forming the tubing ends so they close against the drops. I haven't done the latter, but I saw online instructions somewhere, maybe Sach's site.

What sort of mess are you speaking of? I have only brazed stainless dropouts a couple times but it didn't seem that bad. I just filled in the gap between the tubing and dropout, not a real difficult task. At what point do you consider overheating? Does it give you a sign when it is reaching that point?

In my experience, getting stainless red hot results in some type of oxidate contaminating the flux, and the silver then doesn't want to stick to anything.


Also, since brazing slotted dropouts seems to be very technical would you prefer to use tig welding?

I personally wouldn't, since I think tig welded joints are unattractive. It's your world, though, and if it doesn't bother you, then have at it!

Mark at Paragon told me to plug each end of each stay with a solid plug, then cut the slot, is this the way you did yours. I was wondering, if the slots were cut and fit really tight to the dropouts, would the plug be necessary? would the silver have a lasting hold? Tig welding becomes more attractive if you consider the joint failing and having to redo this process.

The main thing with the Harris silver/flux I use is that you put it on, heat it until it crusts up, then heat it further until it melts, then further still till bubbles form and you are good to go. Filling a large gap is relatively easy with the 45% I use, but I guess a lot/most people use 56%? In one of the Paternek tapes he fills the standard CS open end with silver. Not sure which one it is since I have both tapes.

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There are a number of ways of closing the gap to make the tolerances tighter, machining little space filling metal bullets, or forming the tubing ends so they close against the drops. I haven't done the latter, but I saw online instructions somewhere, maybe Sach's site.
I've found that you can saw 3/8" steel rod lengthwise to create a couple half-round pieces you can slide in to fill the gap. I'm not sure if it's any stronger, but it sure uses a lot less $ilver.

In my experience, getting stainless red hot results in some type of oxidate contaminating the flux, and the silver then doesn't want to stick to anything.

I have brazed hundreds of joints using the Harris white flux and 55% Silver alloy process. If you clean the joint reasonably well and apply the flux and heat the joint till the flux melts and flows there is absolutely no problem with getting the stainless "red" hot. The silver alloy will jump into the joint and stick like stink on poo. All this assumes you know how to braze of course. You just get the feel of this after you have done it enough and it is just simple after that. I think the key is not so much in how much heat, but where and how fast you apply it. I guess you just have to do it to know what I am talking about.

I would add that I use oxygen/propane instead of oxygen/acetalyne. It gives me much better results and is cleaner.

Obviously I don't know how to braze, nor does Paterek, Hank Folsom, or any of the other experienced frame builders I have talked with who have told me the same thing about silver and stainless.

But thanks for taking a moment to let me know I'm not as good as you! :thumb:

I don't have much experience brazing stainless, actually I have only been building frames for about a year and a half so I definitely need the practice but I believe that heat control is an important factor regardless of what your brazing, also I am not familiar brazing with propane. Its good to get different opinions though because it gives me clues as to what to watch for. Thanks.

See posts #3 and #4 in THIS THREAD (http://www.bikeforums.net/showthread.php?t=536284), same subject.

I use propane, and it seems a lot of silver guys prefer it. In one of the Paternek tapes he is shown filling a CS end with silver, and comenting that it was possible contrary to popular verdict. So you can take him off the list. I don't think it was SS, but I don't think that maters so long as it is silver being used, it doesn't seem any different in use to me.

Looking at this thread and some others, it would seem like there is just about every method imaginable used. That is normally an indication it comes down to practice, if everything works in someone's hands then just press on through till you get it.