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heat comparisons between brazing fuels

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heat comparisons between brazing fuels

Old 01-19-21, 09:53 AM
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Doug Fattic 
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heat comparisons between brazing fuels

I found this quote on the internet so it must be true. Of particular interest was how much more oxygen propane uses compared to acetylene. This is one reason I like my oxygen concentrators (the other 2 reasons are convenience and safety). Because I have used both acetylene and propane extensively over the years, I can switch back and forth between them without effort. I like using propane when teaching my framebuilding classes because its slightly lower temperature gives students a slightly longer time to react to what's happening at the joint as it is being heated. And of course in some locations, acetylene is not available to amateur users in non-business locations.

"There is a noticeable temperature difference when using propylene (MAP//Pro) versus acetylene and an increase in oxygen consumption. Acetylene burns at 5589 deg F with an oxy/fuel ratio of 1-1 respectively. MAP//Pro burns at 5193 deg F with an oxy/fuel ratio of 3.5 - 1. Propane burns at 4579 deg F with an oxy/fuel ratio of 4 - 1."
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Old 01-19-21, 11:24 AM
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That's a big difference in oxygen use.

I watched Paul Brodie's brazing video and I liked it a lot, even though I really didn't learn much. It was interesting that he said you needed a gas fluxer and then it turned out it didn't make any difference when he turned it off. He must have cleaned that brazing rod really well.

But I wished that someone would make a similar video about using oxy/propane with an oxygen concentrator
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Old 01-19-21, 11:59 AM
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I thought the video was well done for those who are looking at fillet brazing. I am curious about the nickel-silver filler he uses. I'm not familiar with it and it's properties. It sounds similar to Fillet Pro but I don't have the background on reading the technical sheets to compare. I would like to see a follow up to this video on different filler materials and how and when to use them. And maybe add a section on lugs.
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Old 01-19-21, 12:21 PM
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Nickel silver is just like brass (lfb) except it will stick to stainless because of the high nickel content. It has a little higher melting point that lfb, so standard brass flux is a little marginal for it, but it works. He uses it to tack and to tin fillet joints because of the higher melting point. I think it's a little harder to work with than lfb, but probably just because I only use it on stainless and stainless hates to be heated to nickel silvers melting point.

We used it at trek because it has silver in the name, although that's a misnomer because it contains no silver. It got the name because it's silver. Seems like the Chinese call it "white copper" which is probably better name for it.

I'm pretty sure I'm mildly allergic to it, so I don't use it much. I certainly wouldn't use it to build large fillets, but I don't think many people do that. The allergy builds over time, although I guess some people never develop it.
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Old 01-19-21, 12:24 PM
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Originally Posted by Cynikal View Post
I thought the video was well done for those who are looking at fillet brazing. I am curious about the nickel-silver filler he uses. I'm not familiar with it and it's properties. It sounds similar to Fillet Pro but I don't have the background on reading the technical sheets to compare. I would like to see a follow up to this video on different filler materials and how and when to use them. And maybe add a section on lugs.
Yes hopefully he'll do one. He seems to use two kinds of rod: the nickel silver and a brass one. Plus probably silver "solder" for bottle bosses.

That nickel silver is very strong for something that doesn't have much of a fillet and he uses it on its own to do the tops of seatstays. But I think on the fork he used both. Nickel silver first and then a big brass fillet on top. Unless I remembered wrong or misunderstood which is quite possible.
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Old 01-19-21, 12:27 PM
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He tins with nickel silver. I don't think it is significantly stronger than brass. Or at least it's not enough of a strength difference that it really matters. A small brass fillet like what he did on the brazing video would be fine for a bridge. maybe not for a main triangle joint
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Old 01-19-21, 12:42 PM
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Originally Posted by unterhausen View Post
He tins with nickel silver. I don't think it is significantly stronger than brass. Or at least it's not enough of a strength difference that it really matters. A small brass fillet like what he did on the brazing video would be fine for a bridge. maybe not for a main triangle joint
He does use it on seatstays, even on one of his earlier videos which was a pretty heavily built e-bike. I kind of thought he should have tigged those. I can't remember what gauge the tubing was but it was pretty thick like at least 1mm. Although I'm sure the joint won't fail it was hard to believe it was as strong at the tubing which I think a joint ideally always should be.
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Old 01-19-21, 12:43 PM
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Thanks guys that was really helpful.
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Old 01-19-21, 02:04 PM
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Originally Posted by guy153 View Post
He does use it on seatstays, even on one of his earlier videos which was a pretty heavily built e-bike. I kind of thought he should have tigged those.
Even side tacked seatstays are pretty strong, which isn't really that obvious from how many factory bikes have failed there. The issue is that it's easy to screw it up. But a tremendous number of bikes have been built that way. I have fixed broken fastback stays that were joined with silver and tiny fillets right up next to the slot. That is a series of bad decisions. But I have done side tack with fillet pro silver a couple of times. One issue is taking the seat tube out is harder because you might melt the seat stay join. But the most recent bike I made with silver has stainless lugs, and I didn't want to mess with nickel silver.

I guess Paul has built more than one ebike, the one I was just watching has a rear suspension and looks like it is all tigged.
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Old 01-19-21, 03:01 PM
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Originally Posted by unterhausen View Post
I wished that someone would make a similar video about using oxy/propane with an oxygen concentrator
It is a gentle and easy learning curve switching from oxygen tanks to a generator. I always need to remember to turn it on several minutes before I start to braze so the machine can purge the line and bladder until nearly pure oxygen is flowing through. I've trained myself to turn it on when I start fluxing.

The biggest problem I had when I started was turning the oxygen control knob on the torch handle up too much before lighting the flame. I was fussing with the controls on the concentrator instead of torch handle to try and tame it down. Propane is more sensitive to blowing out than acetylene. Once I got the turn ratios figured out it was easy to light.

I don't think you asked the question about the differences of adjusting the propane flame after it is lit (compared to acetylene) but I will comment on that anyway. With acetylene the cones are so distinct it makes adjustment easy but with propane watching the slight variation of color form greenish (too much propane) to bluish (the goal) to purplish (too much oxygen) can be more challenging. After awhile it becomes 2nd nature. One advantage of a concentrator is not having to turn the oxygen knob off at the torch handle so it is easier to set with just the propane knob the next time it is used.

I've done videos in Ukraine of every aspect of building the frames we need over there so that those that take my class and then go over for 2/3 months can refine their torch skills. Those repetitive brazing steps without long lag time in-between really sharpens their brazing skills. Those videos were deigned to be reminders of what to do and not educational documents to teach the masses. I have no intention of posting them online. My goal is to provide my students with proper framebuilding education here that can be improved with practice over there.
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Old 01-19-21, 03:02 PM
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Originally Posted by unterhausen View Post
Even side tacked seatstays are pretty strong, which isn't really that obvious from how many factory bikes have failed there. The issue is that it's easy to screw it up. But a tremendous number of bikes have been built that way. I have fixed broken fastback stays that were joined with silver and tiny fillets right up next to the slot. That is a series of bad decisions. But I have done side tack with fillet pro silver a couple of times. One issue is taking the seat tube out is harder because you might melt the seat stay join. But the most recent bike I made with silver has stainless lugs, and I didn't want to mess with nickel silver.

I guess Paul has built more than one ebike, the one I was just watching has a rear suspension and looks like it is all tigged.
That's probably the "e-bee" one which looks like it has rear suspension but actually doesn't. He said he changed his mind while designing it.

This was the other one:


He puts the SS (as well as the bridge) on about 18m in. The seat tube is 1.6mm and the SS 0.049", which is super-chunky.

And then it has a really heavy battery box for a DT. I don't think he designed this frame but was finishing it for someone else.
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Old 01-19-21, 05:04 PM
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Originally Posted by unterhausen View Post
Nickel silver is just like brass (lfb) except it will stick to stainless because of the high nickel content. It has a little higher melting point that lfb, so standard brass flux is a little marginal for it, but it works. He uses it to tack and to tin fillet joints because of the higher melting point. I think it's a little harder to work with than lfb, but probably just because I only use it on stainless and stainless hates to be heated to nickel silvers melting point.

We used it at trek because it has silver in the name, although that's a misnomer because it contains no silver. It got the name because it's silver. Seems like the Chinese call it "white copper" which is probably better name for it.
When I was with Trek (1980-86), we only used nickel-silver for dropouts, because it was easier to fill the stay ends with nickel-silver than with low-fuming bronze.
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Old 01-19-21, 05:46 PM
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When I was there earlier than that, there was no LFB in the building. Anything that you would use LFB for we used nickel silver.

And we also used cadmium bearing silver for most of the time.
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Old 01-20-21, 08:09 PM
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I used Nickle Silver rod when I took the Eisentraut class in 1979. This was the first time I had used it, didn't find it too much different then brass under the torch but back then I was so wet behind my ears any brazing was "easy" (said with tongue in cheek). What I do remember was that it is harder then brass and thus more painful to file. Not the issue for an experienced brazer but for us newbies then... I don't think more then a couple of us 8 students left the class with a fully file/finished frame. (And mine was stolen a few weeks later with only a couple of rides on it. This is one of the few things I might risk personal harm getting back, and I will recognize it if it ever went by my sight.)

Some time I should hang with Doug again and try P/O flames. I do like the easier living with the stuff that P/O allows. Andy
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Old 01-21-21, 07:41 AM
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Originally Posted by Andrew R Stewart View Post
Sometime I should hang with Doug again and try P/O flames. I do like the easier living with the stuff that P/O allows. Andy
Road trip! Maybe meet up with unterhausen in Clevland so you both can come together the rest of the way on I-80 to spend a day or three at my shop. I'm signed up to get vaccinated by the Berrien County Health Department but don't know how long it will take for my number to come up. Playing with all the different tips I have can give you a better idea of what you might want to get for yourself.
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Old 01-21-21, 04:17 PM
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Is what's in the Paige tools tip set sufficient? Maybe add a rosebud?
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Old 01-22-21, 09:46 AM
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Originally Posted by unterhausen View Post
Is what's in the Paige tools tip set sufficient? Maybe add a rosebud?
I would definitely want a rosebud to take apart a brazed joint. In a perfect world I would have 2 torches going at the same time brazing a joint. I'd do the general warming up with a rosebud and then quickly switch to a smaller tip to finish it off. A rosebud can work pretty well brazing a steerer to a fork crown.

The Paige tips were originally designed for the jewelry trade making delicate stuff so the smallest ones I don't use very often. However unlike some others, I like a really small tip for both fillet brazing and doing forged rear dropouts to stays. For example while I usually use the Paige M3 for brazing those joints, I sometimes use the M2 (and the M2 works well for students because its less heat output slows down the process so they have more time to react). Having said that I have no trouble using the M5 anytime I am brazing with brass.

Sometimes I prefer using a big flame and the propane specific Victor 3-TEN and 4-TEN are on my pegboard for immediate access. Paige Tools has come out with a new more powerful tip I haven't tried - the MX. They realized they needed to add a bigger tip to their line designed for jewelry trade. Their new adaptors (that they were motivated to have made because a number of us frame builders called to request them) now take their market in new directions because they can be used with bigger torch handles.

If I was placing my 1st order with Paige, I would definitely want the M5 for general brazing like doing lugs. I like their tip organizer too.
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Old 01-22-21, 11:17 AM
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Doug, do you have any experience with a Victor 5-TEMFN rosebud tip? If I am going to want to set up two torches, I would probably have the Paige tips on a A1WA and rosebud on a J28 and using a Victor rosebud would save me $60. Of course, if it's not that great I would just get the Paige rosebuds.
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Old 01-25-21, 08:51 AM
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Originally Posted by unterhausen View Post
Doug, do you have any experience with a Victor 5-TEMFN rosebud tip? If I am going to want to set up two torches, I would probably have the Paige tips on a A1WA and rosebud on a J28 and using a Victor rosebud would save me $60. Of course, if it's not that great I would just get the Paige rosebuds.
No I don't have any experience with the Victor rosebud. I've used a Smith one and have both a Meco and Paige rosebuds. The rosebuds are all kind of similar in that they put out a lot of general heat - even though some put out more than others.
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Old 01-25-21, 10:56 AM
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Thanks Doug, I guess I'll try it because the knockoffs are $15.

ETA: can anyone recommend a fuel regulator?

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