I usually do a kirk style tinning pass. Then I let that cool and add some more flux then add the fillet. It makes me FEEL like it is getting good penetration that way. It also acts as a good temp gauge when I am building up the next fillet. Once the tinned pass gets wet I know it’s ready for filler in that spot.
I knock off the really hard flux with a cold chisel. Then a wire brush. I use files to clean up any runaway spots.
I’m no fillet god but Eric has said he doesn’t bother tinning and I couldn’t get the hang of it when I tried. Less heat if you just go for it I guess.
“boiling” the brass is also sign of too much heat.
I do fillets with a small flame, 2-ten with the exact torch/fuel/oxy set up as you and find it better than the 3-ten. I turn it down and heat a very small area to do tacks. I do what someone recommends somewhere on V-salad where I tack at 12 and 6 and then does the fillet in quadrants. Seemed to work okay for me, not sure how necessary it is.
I use 3-ten for lugs and socketed dropouts. 4-ten for lugged BB shells sometimes and for slotted dropouts. 2-ten for brazeons with 45% silver.
I use the same cycle design rods and flux for fillet. I use the hottest water I can get out of the tap and soak for an hour or less depending on how patient I am. I scrub with an old toothbrush while it soaks and that seems to help. Usually there’s still a few little bits left and if it wont scrape off then I hit it with some emory cloth.
OK guys, dumb question time. First, a little backstory. My basket bike (early 2000s Rigid MTB) has garbage wheels on it and v-brakes. I have dick brakes and Motorbacon is building up some dick brake wheels for me next week-ish. I was planning on re-learning how to not burn holes with a tig and weld on some dick brake tabs with that sometime over the spring or summer. I’d also like to re-rake the pokes at the same time to avoid any potential misalignment.
So here’s where I run into trouble, the garbage wheels are dying, the front rim’s seam is coming apart and causing the wheel to loose tension. So, I’d like to push my plans forward to the next few weeks. I do not have time to practice my tig skills nor do I have access to an oxy/acetylene rig. I also do not have the budget to buy any new equipment for this adventure.
In the past I’ve used a mig with gas to stitch stupid stuff like this to heavy wall cromo bikes with great success, just stacking tack welds to keep from burning through but still getting full penetration. My plan is to mig stitch on the dick brake tabs and a seatstay/chainstay brace and then a mapp torch to braze on some of those zip tie hose holder things.
I know this less than ideal method of welding will work, but I’m not quite sure exactly how I should weld the tabs on. My plans are to use this tab for the front to spread the load out across the fork leg and this tab out back with a round steel brace between the stays. Now, for the brace I know I should weld all the way around it. But for the tabs I’ve seen them welded across their whole length and I’ve also seen them stitched on with several ~1/2" welds spaced out across its length. I like the idea of several smaller welds spaced out, is there any benefit to either method? Especially considering the porous nature of mig welding, which should I use?
Now, for brazing on the hose holders, what type of filler should I use? I’ve read that silver is preferred for this. I haven’t seen silver at the hardware store, if I could find some locally is that the right stuff or is there some bike specific stuff I need? I have both mapp and propane with those little adjustable flame torch heads like this:
Which gas should I use? And Flux?
Now for bending the fork legs, they’re tapered from about 1-1/8" to about 1" diameter where the existing bend is down to about 7/8" where it goes straight again. My brain is telling me to continue the bend on the 1" section down to the 7/8" section until I get the rake I want. These are some beefy tubes, unicrown fork. What would be the ideal method for bending these without the proper tools? I was thinking of making a block of wood up in the desired radius with a groove cut down the middle to support as much surface area of the leg as possible. Should I clamp the drop out and apply leverage to the crown, or the opposite? I’ll also have access to one of those park tool frame bender things and dropout alignment trees for some fine adjustment.
Thanks dudes!
Blah.
As far as managing heat with the bronze, Yamaguchi had us spend the better part of a week building ‘bronze towers’.
Basically, literally see how tall you could stack a bead of bronze. The trick was to get it to be taller, thicker, and more stable each time. He’d also wait until they were cool then whack them on the table to see how strong they were, to see if we kept the temperature consistent so it set as one separate piece without any weak transition points.
This was the total Karate Kid ‘wax on wax off’ thing. After building a few dozen of those towers, I had a much better sense of how the bronze would look when it was just right. Too hot, the bronze flowed like water down and the tower fell apart as you tried to add more. Too cool, the new bronze wouldn’t stick and it would break off at that point. I got to where I just ‘felt’ the right temperature, and I could just pile on the bronze in a relatively thick bead straight up that cooled to be rock solid.
If you haven’t done this, you might want to try it. After 20-30 hours my confidence with the bronze increased immensely, and I didn’t stress about the temps so much.
David that’s wonderful
tarckshoop
bronzefinger
Thanks tarck. Time to practice more. I tend to make things too hot trying to get things to flow. Should have ordered more than 1lb of filler. I’m almost out after three days.
Ross, when you point tack, do you: preheat the whole area/ 100% heat only at the point/ somewhere in between?
Flux before tacking? Add more flux after cooling?
When you do a joint in quadrant, does it matter than you go around sequentially? Or is it preferred to do opposite sides to minimize the distortion?
If you try to pull a joint in certain direction, is that done at the tacking stage? Do you consider it mostly set as you begin to fillet the whole thing up?
David, I built two of those towers earlier but didn’t break things apart. Good exercise for sure. I also tried laying thick lines on flat surface.
Also, is this a terrible idea? I want to build something with a sloping top tube. The other nova kits have lugs.
http://www.cycle-frames.com/bicycle-frame-tubing/NOVA-OVERSIZE-GRAVEL-CyCX-Tubeset-Includes-Gravel-CX-Fork-Kit-with-Choice-of-DT/TT-BB-Shell-with-Seat-Lug-Dropouts.html
Pros:
Cons:
That looks like a great deal!
Everything’s pretty nice, known to work together, and you get to skip the fussy micro-optimizing selection process to just build something
The seattube in the kit is oversized, it’s a sign that you should build an 8/5/8 OS yolo frame for the longest dropper post you can get away with. Like make the tube just long enough to fit a waterbottle on it in the frame and successfully route the actuator cable out of it.
[quote=JUGE FREDD]That looks like a great deal!
Everything’s pretty nice, known to work together, and you get to skip the fussy micro-optimizing selection process to just build something
The seattube in the kit is oversized, it’s a sign that you should build an 8/5/8 OS yolo frame for the longest dropper post you can get away with. Like make the tube just long enough to fit a waterbottle on it in the frame and successfully route the actuator cable out of it.[/quote]
I’m concerned that if the curvy stays would be too complicated for a first frame, but if you guys think that it’s not overly ambitious I’m tempted to give it a shot
I mainly want to replace my elephant with more trail/shorter headtube/more nuts clearance/improved bottle placement/cable routing, AKA a worse endpoint for a lot more money and effort
[quote=buffoon]Thanks tarck. Time to practice more. I tend to make things too hot trying to get things to flow. Should have ordered more than 1lb of filler. I’m almost out after three days.
Ross, when you point tack, do you: preheat the whole area/ 100% heat only at the point/ somewhere in between?
Flux before tacking? Add more flux after cooling?
When you do a joint in quadrant, does it matter than you go around sequentially? Or is it preferred to do opposite sides to minimize the distortion?
If you try to pull a joint in certain direction, is that done at the tacking stage? Do you consider it mostly set as you begin to fillet the whole thing up?
David, I built two of those towers earlier but didn’t break things apart. Good exercise for sure. I also tried laying thick lines on flat surface.[/quote]
Somewhere in between for tacking, you don’t need to preheat the whole joint when you’re just tacking since you’re not going to lay a bead. I guess I preheat/go easy just enough to not over cook the spot that I tack.
Once you’ve tacked shit can still move, so you manage the movement with technique.
This is where I got that tip: http://www.velocipedesalon.com/forum/f10/more-experienced-brazing-techniques-18650.html
I don’t do the tinning though. This video is also good: https://www.facebook.com/eric.estlund/videos/10206246568503260/
At the tacking stage your miters should be nice and tight if not when you braze it will pull at the gaps. So if you got nice tight miters you tack to get the geometry of the joint fixed-ish so you can braze it freehand.
Tack on the centerline of the bike so the tacks don’t influence the alignment. Also tack on the side of the tube that will pull the opposite end of the tubing into the joint instead of away from it. So for example at the ST/TT, tack the top side first and it will pull the top tube tighter against the head tube as it cools (for a level-ish top tube).
You don’t need to preheat to do the tack. I usually flux up the inside of the joint and the tack area and flux the rest later when I do fillets. I don’t tin the joint either.
People usually work in quadrants to minimize distortion and balance out the heat. Some people go 12-9, 6-3, 9-6, 3-12 or some other variation of alternating sides. It also lets you reposition the frame so you can work uphill.
I’ve never seen anyone try to influence a joint to get it to pull in a direction. With two small tacks you should be able to do some cold setting assuming your miters aren’t totally wack. Once the fillets are done you can modify the alignment by witch-wanding the tubes.
[quote=buffoon]Also, is this a terrible idea? I want to build something with a sloping top tube. The other nova kits have lugs.
http://www.cycle-frames.com/bicycle-frame-tubing/NOVA-OVERSIZE-GRAVEL-CyCX-Tubeset-Includes-Gravel-CX-Fork-Kit-with-Choice-of-DT/TT-BB-Shell-with-Seat-Lug-Dropouts.html[/quote]
Seat tube will need an external sleeve of 1 3/8 x .058 if you don’t want to hate yourself. That means the included collar won’t work, though you could cut off the back of it to use for a binder.
S-bends save you from having to do any bending. They shouldn’t add any real complication.
Thanks Ross/Marc, that cleared up a lot of things for me.
I think this is enough right now for me to practice/experiment and find my method.
I need to make a better fixture to hold my work and some better abrasives.
Current plan is building the frame ala Marc’s instructable. Probably going to use MDF as a surface plate.
[quote=drwelby][quote=buffoon]Also, is this a terrible idea? I want to build something with a sloping top tube. The other nova kits have lugs.
http://www.cycle-frames.com/bicycle-frame-tubing/NOVA-OVERSIZE-GRAVEL-CyCX-Tubeset-Includes-Gravel-CX-Fork-Kit-with-Choice-of-DT/TT-BB-Shell-with-Seat-Lug-Dropouts.html[/quote]
Seat tube will need an external sleeve of 1 3/8 x .058 if you don’t want to hate yourself. That means the included collar won’t work, though you could cut off the back of it to use for a binder.
S-bends save you from having to do any bending. They shouldn’t add any real complication.[/quote]
Awesome. I guess I’ll get the kit.
I would add an external sleeve and use an aluminum binder. I was wondering how the included collar is supposed to be used. The included alloy shim is only to allow the use of 27.2 seatpost, and provide no structural support to that joint, correct?
Yeah, it’s a shim.
If you’re planning to run it with a 30.6 dropper post, you’ll probably have to do a bunch of reaming.
to build yourself a sweet Soma or All-City, of course
anyway you really don’t want that crudely clamping the hydro dropper post you’re totally gonna use 
I ended up with a granite surface plate I lucked into on craigslist for cheap but one of many options I considered that is low weight/not space intensive is cast aluminum tooling plate (MIC-6 or other brand name). 3/4" or thicker has just as good flatness as a B grade granite plate. 12"x36" would work well for something like a c-channel bringheli table.
If you need centering cones for making a jig I have some I don’t think I need anymore.