cudak888 

I've never worked on any of the old W-series, but judging from your description, that sounds like the UCA pivot bolt installation, am I right? Sounds like fun...not

It reminds me that I'm completely over-engineering the modified, mad-scientist Twenty that I've been rapidly over-complicating, and I'm just now starting to come up with integrated front rack ideas. Avoiding hard-to-service bits has been part of the design gestalt, but that went out the window when I decided that the Sturmey hub had to be supplemented with a 52/36 up front...and nothing in back. Chain tensioner + IGH time. If that isn't a German approach to engineering, I don't know what is.

-Kurt

unterhausen

I'm pretty sure that BITD, many companies considered the lug to be the joint, and just got enough tube into the lug so that it would hold together. There are plenty of pictures people have taken of frames that were taken apart that show very rudimentary mitering. Still, good mitering and full penetration are really the minimum anyone should expect of someone calling themselves a framebuilder.

xiaoman1 

Sesquilaminate construction with Rustoleum finish!

Nice color match..if you want to splater paint, You can use a toothbrush to splatter the frame...wet the brush and then put one hand near where you want the splatter and tap the brush against your hand and splatter away! You could also flick the bristles with your thumb.
Ben

scarlson 

Thank you for the pointers on splatter technique! I had no idea how to do it, actually. I may try later, if the bike seems like it's not going to break again. The Rustoleum does seem to match ok, which was really a happy accident

scarlson 

At the risk of going off-topic, yes, it's the UCA pivot bolt. And worse yet, the ball joint is part of that arm so you have to change the entire assembly whenever the ball joint gets loose. Maybe I'll tell myself that is why I (infrequently) drive a SAAB! Only things that ever break are German-made Bosch or TRW or AtE. German engineering indeed! Unfortunately that's half the car. Other half's reliable though, I swear.

scarlson 

AND it broke again. I don't remember if I mentioned this, but in prehistory (2017) the BB threads were no good on the adjustable cup (left) side, so I filled them with silver and re-tapped them. This time, the other side of the BB went bad. I noticed it the same way I always notice it on this bike: the cranks start rocking as I'm pedaling.

Not wanting to melt the silver I'd already laid in there, I decided I'd build up the inside of the BB with mig weld, file it down, and cut threads with my BB taps. This would be more local heat but less total heat, so it might not even get toasty on the other side of the BB shell. I also figure it's stronger than silver!

Tooling up, I love my taps and I think they were like $35 on Ebay. I have paid shops more than that to chase threads.


And here goes. I only welded on the top and front, because that's where I did the silver on the other side. This should improve alignment in there, since I don't use piloted taps. A bit pigeon-poo, but it doesn't need to be pretty, it needs to be strong. Also note how little paint was burned off! Didn't even soften the braze. Phew.


File to knock it down to a decent depth.


Tapping the threads. I did not have a tap handle big enough for my BB taps so a breaka bar with 12-point socket had to do.


Finished product!


Bear in mind, it may look crummy but a lot of the thread engagement is coming from the back and bottom of the shell, which I did not weld on at all, but which got skimmed a little by the tap. The cup went in nice and tight and I was back on the road in 2 hours.

And to be clear, I wouldn't do this on anybody's bike except my own, and only on a locally-used commuter, not on something I'd take on tour. This is a hail-Mary sorta thing. Next step would be to weld the fixed cup directly to the shell.

Drillium Dude 

Good job! I like how you keep bringing this frame back from the edge of the pit

DD

scarlson 

It is my old war horse. Rocinante to my Quixote, at least here in the city and in foul weather. I guess I'm somewhat sentimentally attached to it. After I got the crack, I went through some of the stages of grief, and poured a lot of energy into my Trek, but I couldn't get the feels to go away. You know how it is. Better not to fight it.

bulgie 

Nice kluge!

Another quick'n'dirty method I have used a few times is the Cut'n'Weld. Do you know it? Read on for details if interested.

You hacksaw through the shell underneath, parallel to the spindle axis. Not all the way across, just in from one end, farther than the extent of the threads but less than halfway to the other side.

Then hammer on it until the slit closes up. I like a hard plastic-faced mallet for the hammering, but most any hammer will do. Not all in one place, we're try to maintain roundness, though of course it won't be fully round anymore. You're just reducing the radius in the lower maybe 1/3 of the circle, good enough for jazz.

Then you quickly weld or braze the slit. I always brass brazed it, which I think may be best because you can flow a little brass into the existing threads inside in the vicinity of the slit. Large flame, do it fast. If you do it quickly enough, very little paint is burnt, and it's all on the underside. Soak the brass flux off, dry it, hit it with a little rattle-can and retap the thread. I guess welding rather than brazing would have the advantage of no brass flux, saving the soak and dry steps.

I did maybe a half dozen of these and never had one come back. Though I suppose it's possible that someone had it fail later and just threw it away without telling me -- but I doubt it. I think this is a reliable repair, and really quick (thus cheap).

On a few of the frames that got this repair, the thread damage was severe enough that I decided closing up the kerf of a single hacksaw blade would not reduce the hole size enough to get all new threads, so I ganged up two blades on my hacksaw frame to get double the kerf. Not all hacksaws allow this, so make sure a hacksaw frame does allow it before buying one -- this has proven a useful feature pretty often. If you gang up two or more blades, try to find ones where the "wave-set" is in phase, so the blades "spoon" with each other when mounted on the saw frame. Hard to describe but easy to see. It seems the wave-set phasing is somewhat random even within one pack of blades, so it's useful to have a bunch of blades to try and find the ones that match. I can probably take a picture to illustrate this if anyone needs it. If the wave-sets are out of phase, it's possible for the blade on the right to skew to the right, and the left blade to the left, leaving a piece of uncut metal in between.

I was taught this by a master framebuilder, so if you're learning it over the internet, you might want to practice on a junk frame first.

Mark Bulgier
Irony Cycles
Seattle

79pmooney

My Carleton Competition was one. I saw a void under the DT shift lever stop, didn't trust the bike and wanted other work done on it anyway if it was a keeper. I already knew it was da bomb on gravel so I took it to TiCycles to have stripped, inspected and work done if needed. Well, after the fact, Dave Levy reported it came back with nothing under the lugs, that he flowed braze in like it was a new frame. Also that several tubes had cracks at the lugs, presumably from none of the expected lug support. Dave used your exact words to describe what I'd been riding. I've had my frame failure crash of a lifetime already. I'll take safe over sorry any day since I know all too well what sorry is.

And yeah - I know you wrote this last summer. Some of us are slow.

Ben