Andy(or others), do you limit the flux to the areas you want the fillet to go, and if not how do you limit the brass from flowing outside the target area?

thanks, Brian

I like a lot of flux. More then many feel is needed. I find it's easier to soak off flux then to sand down oxidized/torched surfaces. I will sometimes use flux placement as a way to control where the filler goes but with brass that's not a sure bet. There have been MANY frames built with brass but without flux... Heat control, gravity and filler rod initial placement are the main ways i limit the filler's movement.

An example of this is with the recent practice joints i posted. After a flowing into the tubes' contact surfaces to establish an internal presence of filler (nut always a full fillet but insurance that you got full penetration) I adjusted the flame to be a bit smaller (still neutral) and brought the flame closer to the joint's crotch. By flicking the flame away from the crotch i can control the temp there and not let the tubing away from that spot get too hot. Place the filler rod into the crotch/flame, melt off a blob that wets out to the tubes but does not flow because the temp is not that high, move the flame along the crotch and repeat. After a 1/2" or so of raw fillet has been deposited I will go back and, with the flame running over the raw fillet, sculpt the fillet using the flame's cone to focus the heat just so. dabbing or flicking with the flame gets the raw fillet up to the temp it starts to move (but not flow) and having the place where you want the fillet to expand to hot already will make the filler more there. Too much movement and you flick away the flame, reposition the joint for gravity to aid the filler's movement back and repeat to reestablish the fillet's shape. I am not yet real good at this but starting to get a good feel of the flame placement and temp control.

The big problem I see some doing (including me when I'm not focused) is to get the joint too hot when laying down the fillet of shaping it. It's easy to have the flame heat up an area past where you're looking and disturb the fillet's shape there, not knowing this till you think you're done. You defiantly can't add filler to a fillet with too little heat, the filler will ball up and roll off (watch those feet of yours!). But you can delude yourself in thinking you can make a fillet with too much heat, the filler will willingly be added, just end up gong where you don't want it to be because it flowed to the hot area. So the trick to control where the filler goes it to control where the hot area is, and isn't. Andy.

Thanks a lot Andy, that info helps. I tried some fillets this afternoon, didn't move the tubes around enough to let gravity help(doh!), so I had lots of mtl where I didn't want it. Pretty sure I had the flame a little too big/hot as well. I used an old Purox with a #3, but I'm not sure the torch was working/metering the fuel as it should. I have a victor(larger torch body) that I'm more familiar with, I'll practice with them both and see how it goes.

Brian

Got a tandem in for repaint. Showed up with this...




I got it out, stripped it, and found this...

Why don't they put drain holes in the bottom of boom tubes? I suspect the insides are eaten badly all along the bottom of the boom tube. Pity, but things do wear out.

I use a Victor with a #4 (acetylene) tip with an oxy / propane setup and this works really well and have a smaller generic torch with a smaller #2 tip that I can use for very small fittings and very small work areas.

The Victor #4 tip will heat up pretty much anything, (like all thread and 3/4 inch nuts) and does a wonderful job on more delicate things like frames and racks as it has a very well controlled flame.

I love the Victor, it feels good in the hand and

We use flux coated brass rod with most of the flux knocked off as well as paste flux and silver (when the job requires it) but there is very little you cannot do with brass and as we filet braze most of our work, brass is what we use.

As for the process it is knowing how to read the materials as they heat up and being able to use gravity and that heat to draw the filler where it is supposed to be, and knowing that it does not take much filler to make a strong joint if the penetration is 100%.

I added a bunch of fittings here, all done with brass... rack mount, brake posts, cable guides, and bottle mounts.



Small fittings get a little coating of brass at the contact points before they go on and then when you set them to the frame and heat them up the brass flows and the joint is very clean.

That is a great tip for me, makes the job easier/quicker it would seem. Brian

Attaching guides and bosses is usually pretty easy when you wet them (with brass) first... this is a trick I learned very early on.

Buddy of mine and I have decided to teach ourselves to [weld and] make frames. I'd like to think I have a baseline aptitude with from the years I spent brazing artsy fartsy stuff for a traveling sculptor- I was his apprentice/production worker for a couple summers over the years. Yes, I worked at renaissance faires. Loved the work, hated the cosplay dorks.

Annnnyway:
My friend has already picked up a frame jig, so that's something, but prior to today, neither of us had really fit two tubes together. Plates, sure, but tubes? notsomuch

Today we hand mitered 3/4" galvanized EMT (hopefully, the sanding we did took the zinc off. otherwise, it was an open garage, not too worried about it). Before today, I'd laid maybe of foot of bead with an arc welder, but had spent years brazing copper and bronze with an O/A torch so I felt like I might have a touch.

On the left is the second joint I attempted, the right is the third. Think I burnt through mostly because the fitment was poor and the end of the tube just melted, beaded up and rolled away.






Just this little exercise with oversized and small tubes was a wake up call about what framebuilding really involves. Excuse my enthusiasm, but I think I'm starting to see the magic here. I do, however, see that I have LOT to learn- the miter was supposed to be a right angle and came out nowhere really near 90 degrees.

Tomorrow I'll be firing up the O/A torch and seeing just how hard a fillet really is. Should be fun.

Anyone care to chime in on the welds? Frank? I'm feeling pretty good about them to be honest for this being one of the first efforts ever with electrical welding and cylindrical objects.



More pics:

if you did that with a stick welder, I have to say I'm impressed. Now don't do it again. I think you'll find that fillet brazing is a lot easier if you have the right filler/flux.

A stick welder (MIG) is not suitable for bicycle tubes because they are far too thin and burn through is almost certain to happen.

stick isn't MIG, it's a stick of filler on the end of a big alligator clip. Both stick and MIG have been used to build bike frames, as has oxy/acetylene welding. Not the worst idea, but also not a general practice.
Of course, the phrase "arc welder" is pretty imprecise because it could mean stick, MIG or TIG

It was a TIG.

From what I understand a stick welder could be improvised with a pair of jumper cables.

Just edited to add, thanks for posting pics. It's hard for most of us to put our rough first attempts out there for comment. I always like it when I see someone's first attempts and then a couple of years later look at the same person's current work and see the progression from beginner to a high level of skill. You obviously have a clue, it's a matter of practice and getting the details right.

I'm no TIG welder, so take this with that in mind. You didn't get any penetration. Of course, your tubes are thick, so that makes penetration harder. I have no idea if an experienced welder would tell you to go back and practice on sheet metal, but that sort of thing never hurts.

I urge you not to take risks with your health, 4130 is not that expensive. Get some from McMaster-Carr. If you order now, there is some chance it will be there tomorrow, definitely Monday.

Yeah, I spent last night a little woozy- This galvanized thing is NOT the way to go. I'm going to head out today, grease some palms and see what kind of scrap I can land at some of the fabricators here in town. If that doesn't work, an order is in the works.

As far as penetration: even with the thick tubing (that's 3/4" OD, so really thick) the inside of the hollow is deformed. Isn't that, by definition, penetration? I have a feeling I have a lot of reading and watching (thank goodness for youtube) yet to do. I know for a fact my technique is off- I come from a background of O/A brazing on copper and steel (see picture album of sculpture in the first post of mine in this thread) where I taught myself to just lay the rod down and kind of swirl the torch to get a stacked bead. I need to get to dipping the rod. Electric welding is so counter to what little skill I've cultivated over the years- I'm really having a tough time fighting the urge to back the torch head off to achieve less heat.

Maybe this is a better picture vis a vis penetration:

Now that I go back and look at your pics, you get penetration but it's not complete. I was looking at the inner wall of the butted tube. The inner edge of that has areas that aren't consumed. That's the penetration you are really looking for. Otherwise you have just laid a weld down over a crack.

So today was a good day.
First I decided that galvanized was all kinds of scary so I found some bike tubes (not bike tubes, but they were formerly something bike shaped.):







Then I practiced the dip and slide method of TIG welding instead of the OMGI'DBETTERHURRYORELSEI'MBLOWINGTHROUGHTHISMOFO method I attempted yesterday:





Still a long way to go, but a lot more solid looking.

Then last but not least, laid my first fillet EVER.





I need a gasflux- you can't see anything under all that black bubbly crap.

After a spitshine:





For those keeping score at home, here's the Jig we picked up (custom made by Mr. Swan back when). Bonus shot of the door of the 10' x 20' shed this is all happening in.



Album with more pictures and detail and stuff: https://imgur.com/a/YQTUL

Please advise with the filleting: I was totally flying on instruments.

Apparently every day is friday- I've been posting in this like it's the "Today I" thread in SSFG.

Hey Dan, looking good with both. What did you use to strip the frame tubes? I'm using old bikes for my practice and the paint remover I used is crappy.

thanks, Brian

An angle grinder with a cupped [knotted] wire brush. It would get about 1/4" of paint at a time, so I had to do it in strips- picture eating corn off the cob (typewriter method). Took the fittings off with an O/A torch and some pliers. The pliers were too short and I'm now missing knuckle hair, but that's a different conversation for a different day.

I touched it up the areas that saw actual heat with some waterproof 160 grit sandpaper (the stuff that comes in a rolled strip about 1.5" wide- the stuff plumbers use to prep pipes before they sweat them). Worked well- no paint fumes to speak of.

paint comes off really easily after you burn it with a torch. Did I just say that?

Fillets look good in that you aren't overheating anything. With practice you should be able to get closer to your final profile. I don't know how you went from lumpy to so smooth without hating life though. Cut the joint apart and see if you got any penetration

Here's what I did recently. I have some Singer lugs and metric tubes (531 Extra-Léger i.e. SL), but no BB shell. I was able to find a shell for metric tubes & BSC threads (or Swiss, not 100% sure yet) so I modified the sockets in the French pattern.

I was just gonna post to ask how that fillet joint looks from the inside...

I have to cut it down to get a better look, she's too long right now to get a good shot of it.

More than anything, I really need to get my mitering together. At the moment I'm just winging it with a hand file. I'm flirting with the idea of using a tubing miter calculator (link) and a sharpie, but ideally, I'll just skip over that and get a mill.

Actually, THERE'S a question- I have a drill press, is it at all feasible to use something like a hole saw and some creative tooling to miter these puppies?

Dan- Many believe that the common drill presses are too flexible for thin wall tube mitering. I've used a Joint Jigger and that was both flexible and not made straight. There are better notchers but they are more often seen as rough mitering tools for thicker wall stuff. Even my Atlas 6" lathe was too flexible for decent mitering. I do have a collet vice that would make a really solid tube clamp if you ever get a mill. Andy.

Since last Friday I had three fillet practice sessions using some old frames for tube mtl, first times I attempted fillets.

My first session I used a purox torch I've had forever but not touched for 30yrs, it didn't seem to be metering the a/o correctly(hard to control flame size and heat, it was safe just couldn't dial it in) but I went ahead and continued to use it anyway. Gasflux CO rod and Gasflux type B flux from HJ. I mitered on a grinding wheel and eyeballed the fit, not too worried about how tight the miters were which in retrospect made it more difficult(filling the larger gaps without mtl runs). I also held the tube in a vise so I wasn't able to readily position it so gravity would help me rather than fighting me. The first batch of pics are from that session, lots of mtl running where I didn't want/need it.

In each of the sessions I took pics of the brazing in progress, as rinsed after the brazing, and then as soaked and cleaned with a wire wheel, no file work. After the second session I took a few minutes and gave a quick filing to one fillet, quickly realized how long it would take(without a dyna file) to clean up all the fillets on a frame if there was much excess brass.

first session, didn't have much heat control, think I burned flux, etc., close up pics of them warts and all












soaked and wire wheel clean up




continued below