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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 10-25-11, 08:46 AM   #1
jcharles00
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noob seeking welding tips. (pic)

Taking the advice from the "I want to start frame building" thread, I dug out my welding gear and decided to start practicing running beads. As expected, I suck. On this piece I used a neutral flame and pretty thin filler rod. I prepped by grinding a chamfer on the edges to be joined. after tacking the ends of the two steel straps, I tried to preheat the work piece until red/molten, then add filler. on the left hand side I pulled towards the middle. on the right hand side I pushed towards the middle.

obviously the bead is inconsistent and ugly. I also didn't get great penetration. (you could still see the gap between the straps on the back side)

Anyone have advice on how I can improve this?

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Old 10-25-11, 09:41 AM   #2
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Sample looks too cold, use much more heat to actually weld, add the filler rod as small overlapping drops and make sure they are completely bonded into the base material.

Note that brazing is a much cooler bond, no need to get the metals this hot which would ruin the strength of CrMo.
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Old 10-25-11, 11:17 AM   #3
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How can I get more heat? Should I use a larger tip, or do I just need to turn up the gasses?

I figured I'd just start with regular welding since some of the other threads here said it was a good place to start before messing with brazing and any actual bike parts.
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Old 10-25-11, 12:56 PM   #4
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I have just recently tried O/A welding. My mistake at first was to try melting the rod unto the work. You have to create a puddle unto the work, then dip & melt the filler in the puddle and move quickly on the next spot. Getting good penetration in though... right there at the limit before blowing a hole.

A basic exercise is to make a welding bead on a plate without any filler, check for penetration. Then with filler, then with filler and trying to join two halves, then a thicker plate, etc. The tip size depends on the plate thickness.

Welding is similar to fillet brazing, so it's a good way to practice.
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Old 10-25-11, 02:43 PM   #5
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you may need a bigger tip, hard to know from long distance. I would get some bronze and play with that, it's much more useful in building bikes
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Old 10-29-11, 06:40 PM   #6
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What kind of rod are you using? Silver "brazing" alloys are available in a wide range of solidus/liquidus temps. I don't use brass rod for frame work on steel frames anymore...
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Old 10-30-11, 10:24 AM   #7
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jcharles- Don't take offense, but you have a ways to go with the welding skills before atttempting any frame work. And, what you are attempting there is fusion welding of mild steel which has very little use in bike frame construction. However it's as good a place as any to start in learning torch control, so keep after it.

BTW- if you ain't blowing any holes in the material and dripping molten steel on your feet as a beginner, you ain't using enough heat.

Do you have a buddy or an acquaintence who welds? If so get them to show you first hand the procedure required for joining metals. It's not too difficult but a little hands on instruction will go a long ways. Another option wouild be to sign up for a community college class on welding. Not a bad way to start.

Neurocop- I don't know about you, but I couldn't afford to "practice" with silver. And it would be a rare case I'd use much of it for frame construction. The last silver I bought was $48/oz. I told the guy at the welding shop- "I wanted silver, not gold!" Three years ago it was $18- three weeks ago, $48.
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Old 10-30-11, 11:36 AM   #8
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I don't think there is any demonstrated benefit to silver unless you are working with stainless. Bronze is the way to go for practicing framebuilding, you can always switch to silver later.
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Old 10-30-11, 09:08 PM   #9
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Neurocop- I don't know about you, but I couldn't afford to "practice" with silver. And it would be a rare case I'd use much of it for frame construction. The last silver I bought was $48/oz. I told the guy at the welding shop- "I wanted silver, not gold!" Three years ago it was $18- three weeks ago, $48.
I guess that's a silver market issue. I haven't purchased silver rod recently. The last time I bought any was about 5 years ago when a pound of rod cost about $13. I've got about 20lb of rod/wire in various grades in my shop, so I don't really worry about the current cost. It goes a long way, and IMHO works way better than brass rod for welding steel frames. YMMV.

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Old 10-30-11, 09:11 PM   #10
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I don't think there is any demonstrated benefit to silver unless you are working with stainless. Bronze is the way to go for practicing framebuilding, you can always switch to silver later.
Sure, plain bronze will work if you really know what you are doing, but silver "brazing" is much more forgiving.
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Old 10-30-11, 09:35 PM   #11
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I don't think there is any demonstrated benefit to silver unless you are working with stainless. Bronze is the way to go for practicing framebuilding, you can always switch to silver later.
We use brass for nearly everything with an OP setup and it was something I picked up pretty easily... I cannot handle acetylene due to reactions I have to it and it is more than what we need for what we do anyways.

All welding materials have taken a huge jump in price and using silver is nice for many jobs but it is rare that you HAVE to use silver when brass / bronze do a wonderful job and do it at a much better price.
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Old 10-30-11, 09:53 PM   #12
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A basic exercise is to make a welding bead on a plate without any filler, check for penetration. Then with filler, then with filler and trying to join two halves, then a thicker plate, etc. The tip size depends on the plate thickness.
Definitely this.

When I went to welding school we used sheets of metal and were required to melt a pool of metal across the plate without blowing any holes in the steel. The plate should look the same from both sides if you have good heat penetration. The next step was to add rod to the pool of metal as we traced across the plate. Once again, check both sides of the plate for even penetration.

You may want to try butt welding before lap welding, it's a bit easier to balance the heat between both plates. The lap welding you are attempting requires more heat on the base and less heat on the top, which is just a bit more tricky to do.
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Old 10-30-11, 10:12 PM   #13
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I guess that's a silver market issue. I haven't purchased silver rod recently. The last time I bought any was about 5 years ago when a pound of rod cost about $13. I've got about 20lb of rod/wire in various grades in my shop, so I don't really worry about the current cost. It goes a long way, and IMHO works way better than brass rod for welding steel frames. YMMV.

Nick
20 year low in silver price is $5 per oz so if you bought it for $13 a pound it wasn't retail. I wish the silver speculators would look at the historical price of silver, ignoring the bubble we are suffering through right now, it didn't keep up with inflation over the last 40 years.

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Old 10-30-11, 11:59 PM   #14
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Some of the speculation is probably ocuring at a rate of speed faster than you can post.
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Old 10-31-11, 09:08 AM   #15
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jcharles- Don't take offense, but you have a ways to go with the welding skills before atttempting any frame work. And, what you are attempting there is fusion welding of mild steel which has very little use in bike frame construction. However it's as good a place as any to start in learning torch control, so keep after it.
no offense taken. I thought I was clear in the original post, but I guess not - I'm not attempting to build a frame any time soon. I'm following advice from other posts here and trying to get my torch skills up working with o/a and steel because it's stuff I already have on hand. When I quit sucking at gas welding steel, I'll probably move on to brazing some tubes together for a while before i even think about a bike.

Sadly, no welder friends around here, and I can't do a class because I already work full time and am a 3/4 time student on the side. So I gotta keep wingin it.

The heat definitely seems to be the problem. The most pressure on the acetylene that I'm able to get right now is 5lbs, which I'm guessing is too low. I'm going to swap out the tank soon and see if the old one is just getting empty or if there's a problem with my regulator.
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Old 10-31-11, 09:35 AM   #16
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you don't want to get the pressure in the acetylene tank itself too low. If you have a small tank, you may not be able to safely flow enough gas to gas weld because you'll start to flow the acetone. That's why I suggest getting some bronze and flux. If you look around a typical framebuilder's shop, you will see a lot of tooling that's brazed together. It's a really good way to practice, because nobody is going to risk their teeth using a shop-built tool.

I was trying to gas weld recently, and I didn't have a large enough tip to do it. It was really frustrating, and I really don't have any problem welding when using the proper equipment. I really don't see the crossover between welding and brazing. I think the thing that helped my brazing the most was sweating copper plumbing. You get immediate feedback if you didn't get penetration on plumbing.

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Some of the speculation is probably ocuring at a rate of speed faster than you can post.
if you look at the historical charts, this recent uptick in silver prices is obviously a bubble. I expect that when the economy picks up that it will tank back to $5 an ounce and there will be hundreds of thousands of little Hunt brothers out there wishing they had stayed away from silver. I lived through the bubble in silver prices caused by the Hunt brothers, I expect to see the end of this bubble too.

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Old 10-31-11, 12:42 PM   #17
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I have no skills when it comes to mig and tig and have always used a torch... in the machine shop I used the gas axe enough to learn that I cannot handle acetone but also had to do some small work brazing hard metal like carbide for tooling and have done a lot of plumbing work during renovations.

Have run a sub arc welder on many occasions... if there is a hell this is what I will be forced to do for eternity. That... or be stuck in front of a CNC pushing buttons and watching the machine do all the work.

When I started in the frame shop and was doing test welds the boss was sure I had done a lot of this before as he said the work was excellent and as our shop filet brazes nearly everything this is where most of my experience comes from although I have done internal and external lug work.

Still have lots to learn here and hope to have a new shop space in the new year so I have a little more room for building frames as I already have some people interested in getting me to build them a custom bike that will have my name on it.
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Old 10-31-11, 01:17 PM   #18
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20 year low in silver price is $5 per oz so if you bought it for $13 a pound it wasn't retail. I wish the silver speculators would look at the historical price of silver, ignoring the bubble we are suffering through right now, it didn't keep up with inflation over the last 40 years.
Sorry, my post about the cost of silver was unclear. I was talking about what I paid for 15% silver rod (Silvalloy and Harris Stay-Silv 15) which came in tubes of 28 sticks...I think they were close to 1lb per tube and believe I paid around $13-18 per tube. That was when pure silver was about $5/oz and a pound of pure silver would have cost $80. Obviously the price is way up now. Glad I stocked up when I did.
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