calstar 

I'm trying to learn fillet brazing, thus my several threads regarding them. My goal(at this time) is to construct fillets that are small, strong, and need little if any filing. With each of my practice sessions/exercises I'm slowing learning how to work the mtl, recognizing the color at which it flows, and how to move it around. Obvioiusly I have a sh#tload to learn so bear with me as I will continue to post pictures and ask questions.

thanks, Brian


these are the two tested


The set up is shown in the pics, a vise and a 1/2" x 3' pipe.




this shows the amount of deformation, perpendicular to the tube axis, until failure, I pulled in several increments until I heard/saw the break and stopped


and this is the failure, as soon as it happened


and pulled open


this is the other fillet pulled parallel to the tube, again pulled until it failed, then stopped


first practice tower, a little over 1"

Andrew R Stewart 

Brian- Nice distruction testing. But your tower, ug. The goal is to have the beads/globs flow into each other. Not just get lumped on top of each other. And you want the base to wet out on the tube to start with. Andy. (Sorry if this sounds harsh).

unterhausen

I like the destructive testing, thanks

calstar 

Doesn't sound harsh at all, actually got a laugh out of me, I didn't know what type of tower to shoot for, thanks for the input. Does anyone have a pic of a good tower? I get the idea but a pic would help. Even though its an ug tower I learned by making it, trying to get a little practice in each day now, every minute with the torch helps.

BTW, I'm always open to input/criticisim especially the constructive type, my goal is to learn(and perhaps have others benefit as well) and I know there is a wealth of knowledge here.

thanks, Brian

unterhausen

I've never done one, I'll see if I can crank up the torch tonight

I think I saw a picture online of Mike Flanigan brazing towers, but couldn't' find it

calstar 

^^ that would be great whenever you have the time, be sure to post a pic, thanks, Brian

tuz

here are some pics (not sure if it's a good example, I've only done it once some time ago). It looks like you didn't get any flow, you probably are melting the rod but not the base. What tip size are you using?

Regarding the destructive testing. One thing to try is to place the cheater bar 3-4 inches from the joint. If you butt it against the bottom of joint it's guaranteed it will fail eventually. You want to test if the tubes bend before failure, although in your case it looks like the horizontal tube deformed a lot before you pulled the joint apart.

BenCooper

The joint I made dozens of when I was learning was to fillet a tube to a flat plate. Then squeeze the tube in the vice to see if it peeled off or bent the plate...

calstar 

great pics. "you probably are melting the rod but not the base", yep I was heating the rod at least as much as the base. Victor #2, I have a 0, 2, and 4.

Do you add flux as you build the tower?

thanks, Brian

tuz

#2 is a big flame, try the #0 for the brass tower exercise. Yes you should dip the rod in powder flux once in a while. #1 or 2 would be better for bike tube fillets. With the bigger tips you can also try a bigger brazing rod.

Andrew R Stewart 

Brian- I just made a couple of 'towers'. Note the well wetted out base. The blob to blob is, while not smooth (and that would be my goal) connected into each other. These have only been water soaked so show true color. There are a few spots that got too hot, indicated by the slight copper tint. But even still the towers held their shape. I fluxed the base surface, used a Purox W-200 torch with a #4 tip (about .036") set at 4lbs of both O and A with a very small flame that is neutral. For a scale the tube base is 1.375"x.065". Andy.

Live Wire 

That tip is a little on the small side, but that's probably a good thing for learning as a smaller flame will help keep things going a bit slower and it gives you a bit more time before its too hot. Speaking of too hot, your joints at the top look like you had too much heat (brass shouldn't sizzle) and the flame was too far away.
what type of flame are you using? Regulator settings? Brass/flux?

calstar 

Seeing the pics that Tuz linked helped a lot. I used my Victor #2 with about 4lbs a/o, next time I'll try the #0 as Tuz suggested. I fluxed the base tube when starting and then dipped the rod into gasflux paste pretty often. I was seated to do this cause of a on again/off again bum knee and I think as a result of working from one side only the "tower" leaned towards me, I rotated it as I went therefore the curve.

In another lifetime(1980s) I had a glassblowing studio(offhand, 100lb crucible furnace, not flameworking where you work borosilicate tubes). Anyway,when working glass itrs critical to control the viscostiy of the glass, keeping it fluid by reheating as necessary, and knowing what its temp is relative to its color. I think that helps out with the fillet brazing I'm learning, viscostiy(flow characteristics), temp, color seem to be the key to making it work, at least from a novice's perspective.

my set up


the brass didn't all stay on the tower!


tube is old raleigh dt for size perspective. According to Live wire ^^ the rust color means it was too hot(yes?) and I did hear it sizzle. You can see the little balls on the column where the base mtl wasn't hot enough so the rod just rolled off down the side.


and it was strong enough for me to wire wheel it for a shine

unterhausen

this is one application where a flux covered rod would really shine. I don't remember if I gave my powdered flux away, but it's hiding if I still have it. I was goofing around to see if I could get the tower I made perfectly smooth and it turns out the answer is no, and I quit before I burned a hole in my foot.

One thing that helped me was going back over my practice fillets to try to get them the way I wanted. Since yours are kinda underfed, there is plenty of room for that. And you can also heat the brass up to the point where it falls off and then start over. Clean off the black stuff and flux it up

Andrew R Stewart 

Brian- The newest towers are MUCH nicer looking. It is mostly time spent to get the ebb and flow of the process and the variables. As you get more comfy with things you should change a parameter and deal with that difference. As an example you mention color. When i had my brazing set up outside I found that color was hard to pick up on. So i relearned to watch my flux. When i switch torches i find the heat control changes. It's said that 10,000 hours is the threshold for mastery, I figure I'm 30% of the way there. Andy.

calstar 

How is the powdered flux better/different than paste like the gasflux?

thanks, Brian

unterhausen

paste flux is superior to powder in every way unless you want to build towers of bronze for some strange reason. But it was really annoying to have to dip the rod in the flux every 3/8" or so. With powdered flux, you can have some flux on the rod.

tuz

here's my brass tower, let me know what you think

link

unterhausen

that's all well and good but you should have made a bicycle

Ubik

These discussions are really great, thank you calstar for starting it and everyone else helping out.

calstar 

If I'm not mistaken thats an Alberto Giacometti (Swiss, 1901-1966, pictured below) sculpture. If its yours you should forget about framebuilding and follow that path

tuz

Haha yes it's a Giacometti (it's in the pic url). The brass towers sorta reminded me of his sculptures... it's my imagination probably

(and that pic you linked is from Henri Cartier-Bresson, the father of street photography. It's a fabulous shot)

unterhausen

that thing freaked me out a little and now that I see the actual scale it freaks me out more. I wonder how he did make them. My experiments with changing the shape of the tower leads me to believe that you could definitely manipulate them in interesting ways with practice.

calstar 

His art is cast bronze(most, although I'm no expert) and the process or a variation of it is described in the link:

https://en.wikipedia.org/wiki/Lost-wax_casting#Process

This is the fun part, at least to watch. Not quite the same as "tower" building!

calstar 

Here is my practice today using the smaller Victor #0 as Tuz suggested, with 4lbs a/o, 1/16"rod(I used 3/32 rod before). The #0 was quite a bit easier for me to control than the larger #2. I was sitting for this session as well, so another leaning tower, built on the same piece of tubing as I used for the other tower.

The phrase "the more you learn the less you know" applies to brazing as it does to every and any endeavor! Or to use another phrase(more accurate for me) "I don't know squat" about brazing but I'm having fun learning.



you can see I still have a heat problem from the rust/burned color and the little balls fallen on the sides