A few questions about brazing that aren't asked very often

[pixelnate]

1) When attaching tube to metal plate, what plate are you using? For cages made from brake line? For cages made from brass?

2) Once you have the pieces cut and ready to braze, how to keep them aligned through the brazing process? Welding magnets, a vise, spring clamps?

3) What work surface do you use? Metal table, iron plate, some sort of special stone? Is there a special mat or table that works best?

4) What material is lighter for building cages, brake line or brass tube?

5) How do you cap the ends of the tube? Metal plate, body filler, leave open?

Thanks in advance.

[gyrene]

I'll answer what I can.

2) Once you have the pieces cut and ready to braze, how to keep them aligned through the brazing process? Welding magnets, a vise, spring clamps?

I use all of the above. All have there advantages and disadvantages.
The welding magnets though can be difficult on very small pieces as they have a mind of their own and can be difficult to get the pieces to "sit" together just right before brazing.

3) What work surface do you use? Metal table, iron plate, some sort of special stone? Is there a special mat or table that works best?

I use fire brick. Used in fireplaces. I picked up a package of 4 or 5 at Menards. That was a couple years ago and I am not sure on the price.


4) What material is lighter for building cages, brake line or brass tube?

I am not that familier with brass. From what I remember reading, most people solder it together. I am not sure if it can be brazed, because of the melting point. I would guess that brass is lighter but also not as strong as brake line.

Hope this helps some.

[NGreen]

1) When attaching tube to metal plate, what plate are you using? For cages made from brake line? For cages made from brass?

I've used cold rolled steel, galvanized steel, stainless steel, brass. All are pretty much brazed the same way with small tweeks here and there. Make sure it's all clean by using alcohol or acetone to clean both pieces of metal. You don't really have to clean off the metal but you should if you're looking for the best joint. After that, it's all just practice. You will have to learn to evenly heat both metals at the same time so they're both the same temperatures which can be a challenge sometimes. Different thickness metal obviously heats up at different rates but also, the melting point of metals are also different, so you'll have to be super careful when brazing to thin brass. You WILL melt the thin brass before you melt the steel and that's a pain when you have a nice piece already completed on the brass side. That said, as a general rule, keep the flame on the thicker side of the metal more than the thinner metal. It'll make sense after you try to heat up different thickness metals at the same time with the same amount of flame on both parts. As far as metal goes, it depends on if it's structural or just cosmetic plate as well as if I'm looking for that area to dent easily or not. But anything from 16-22 gauge.

2) Once you have the pieces cut and ready to braze, how to keep them aligned through the brazing process? Welding magnets, a vise, spring clamps?

Yes. I use my vise, magnets, vise grip pliers, and third hand the most. Masking tape also works well if you think you can braze faster than the tape will catch fire. I also have a spool of 0.032" safety wire that I use to hold pieces together in tight spots when I can't use a magnet, pliers, or vice grips. I find that medical tools work great if you can get a set somewhere. Small little medial clamps are just awesome and stand up well to high heat (I'm pretty sure they're stainless steel).

3) What work surface do you use? Metal table, iron plate, some sort of special stone? Is there a special mat or table that works best?

I just work off of a plywood bench. If you can avoid brazing on a sheet of metal, do it. You're trying to heat up a bit of metal and it'll be much, much faster if it's just suspended in the air and doesn't have a sheet of metal to conduct all the heat to. Not to mention, it wont stick as easily if you're not touching something. So, a vise works great, just clamp the metal as far away from the joint as possible and as secure as you can. I will often set the part up on a flat surface, making reference marks around the joint so when it's suspended, I can still tell that it is aligned. Just remember, this is brazing, not welding. You're heating up metal at a relatively slow rate and will take forever if you increase the effective metal size by conducting your heat away from the joint.

4) What material is lighter for building cages, brake line or brass tube?

Brass tube depending on the wall thickness. Obviously, 1/4" wall tube will be heavier than 3/16" brake line. But also, judge your material on strength. I mix my cages between brake line, solid rod, and brass of all different wall thickness depending on if it's a structural part or a cosmetic part.

5) How do you cap the ends of the tube? Metal plate, body filler, leave open?

For brake line, I use 1/8" solid rod brazed in the end. Works great. For larger, just find some scrap solid rod and cap the end.



Also, as a tip, keep all your scrap. Metal is expensive and you never know when you'll need a tiny piece of scrap sheet or rod. I've gone through my scrap box too many times to number and found bits that just work great.

[pixelnate]

Thanks, guys. Great info from both of you. I now have a much better understanding about the process. It's easy find info on the actual brazing, but workflow tricks and tips are hard to find.

Something I didn't quite follow, 53Guy, did you say that in a single cage, you mix brass and brake line?

[NGreen]

Originally Posted by pixelnate

Something I didn't quite follow, 53Guy, did you say that in a single cage, you mix brass and brake line?

For sure. Take a look at my most current project, 53guy - Project Blitzkrieg and you can see for example, the bumper. I mix brass plate of multiple thickness, galvanized steel plate, solid 1/8" rod, brake line, all brazed onto the steel frame rails. The cage will eventually have brass on the dash as well. Brass is much easier to work with and manipulate. Say for instance, you want an artsy looking part with complex curves and bends that will be protected by a cage, ie, a dash board for a scale build; brass is super easy to use and cut with plain old scissors in most cases. It's easy to file, work, shape and braze, so I like to use it when strength is not a concern. It's not overly difficult to mix with steel, you just need to take care and not over heat the brass or it will melt and easily deform on you.

[Nate08]

]1) When attaching tube to metal plate, what plate are you using? For cages made from brake line? For cages made from brass?


Either brass or cold rolled steel.

2) Once you have the pieces cut and ready to braze, how to keep them aligned through the brazing process? Welding magnets, a vise, spring clamps?


Welding magnets work be careful though they melt. I also use spring clamps c clamps and hope and prayer clamps


3) What work surface do you use? Metal table, iron plate, some sort of special stone? Is there a special mat or table that works best?

I have a price of 12"x18" 5/15 steel plate i got from a friends scrap pile

4) What material is lighter for building cages, brake line or brass tube?

Brass is lighter, but harder to bend without kinking i use both depending on the project

5) How do you cap the ends of the tube? Metal plate, body filler, leave open?

1/8" rod fills 3/16 brakeline, insert, braze, cut and grind flush

Hope that helps some

[bob1961]

can't add much to what others have said, but i use a 3/8" thick alum plate as my table so if i get braze over flow onto a steel table or sheet metal my work won't stick to it .........bob

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[panama]

its an art and all folks figure it out along the way you Will get it just because you see it in your mind ,you'll get it .

[C*H*U*D]

I have a large piece of plate steel that I put on two bricks to keep the heat away from my table. I try to make fixtures that will hold the work off of the plate though to keep the heat in the joint. I like the steel plate because I use welding magnets and magnetic third hands.

[Szczerba]

Dumb question of the day.

Any flaws in "tacking" the frame/cage/whatever your going to braze with a small welder to hold it all in place? And then braze it up?
Me and buddy are going to give it ago. I am going to "tack" it together for him and then he will braze it later.

Just curious.

[JohnRobHolmes]

I love tacking first and brazing later. I do it on both RC and bicycle frames. I suggest you have a gas shielded welder for the task.

[Szczerba]

Originally Posted by JohnRobHolmes

I love tacking first and brazing later. I do it on both RC and bicycle frames. I suggest you have a gas shielded welder for the task.

Thanks.
I just have a small 90 AMP Flux Wire Welder. 45% @ 60 amps, 25% @ 80 amps with 0.030 Hobart Flux wire. I am slowing learning how to use it with the small metals I deal with. I bought it at harbor freight to get started.

[JohnRobHolmes]

If you can feed some .025 wire through it, the little tacks will be easier. The little wire fed units with flux core are super tricky to modulate on small stuff, although not impossible. I have welded together exhaust pipes with my miller unit, it is basically just hundreds of tack welds in a row to keep from burning through.

The good thing about brazing is that you can go back and fix places where the weld does burn through a bit.