Brazing cleanup photo montage

Mini-update

I brazed the brake and chainstay bridges on Monday.  I wanted to keep the height consistent between the front and back brake.  I also wanted the fender mounts to be the same distance from the dropout.  

I measured things out with a pair of Anvil axles and a bent brazing rod.  Once I had the approximate position of the bridge, I found the widths of the deepest cuts with a caliper, added some breathing room, marked them, and went to work with a file.  It took some trial and error, but I got things nice and even for the brake bridge.  Doing the last tiny bit with some emery cloth and a scrap seat stay really helped.

The brazing went pretty smoothly. I think I'm starting to get the hang of 50N silver.

Here's one of the fender eyelets in inaction.  I just drilled a hole in each bridge, cut the eyelet short enough not to get in the way of brake mounting, etc, and brazed it in place.

Next week: sealing the seat stays, touch up with solder, grinding out the tubes in the BB area, thinking about cargo racks.

Right Stay

I started on the rear triangle on Sunday!.  My strategy is to get the right side just where I want it, then I can put a wheel/rear triangle t-square in it to properly align the left chainstay.  I'm mostly going at it this way because my homemade jig doesn't keep the dropouts lined up perfectly, and the extra steps let me tweak it on the fly.

The dropout went on easily.  I used some more of the 50N silver; I think I'm starting to get a better feel for it.  It certainly seemed to jump when I wanted it to.

I pinned the bottom bracket in the jig using the square profile nails that Cycle Design sells, then brazed it freehand.

The one issue I noticed was that the pins wanted to draw the stay up just a little bit from how it fit in the Jig, so I used the sophisticated method pictured above the add a little weight to the end.

Here it is, brazed and soaked.  On this bike, I've left all of the bottom bracket miters a bit long., with the intention of grinding the inside smooth when I finish.  

As a bonus, here's a picture of my cable routing:

Crossing the cable from the right shifter to the left side of the down-tube (and the left to the right) keeps the housing from having sharp bends, but looks a little odd since the cables must cross back under the down tube.  I spent a little time with some stainless tubing to solve that.  It's silly, it's overkill, but I like it.  This way the correct cable goes to the correct shifter, but the cross happens out of sight so the cables will stay roughly parallel to the down tube.  As it turns out, this stainless steel ball of spaghetti creates very little friction.

For the curious, here's the great Sheldon Brown's take on crossing the cables.  To keep things balanced, here is an opposing viewpoint.

Also worth noting, I've drilled the bottom bracket for drainage.  Almost all water related damage that I've seen or heard of on a bike was the result of standing water, not just exposure.  Hell, I've been riding my first build, sans-paint, in the rain on and off, for years and the rust hasn't made any real progress.  Since I can't totally seal this area (there's always the potential for a little water to sneak in through the seat tube), I wanted there to be a good way for it to drain.

Fork, Part 2

Had some time to work on the fork this week.  The fit up on the crown was a bit on the gappy side, so I went with 50N silver instead of my customary 56%.    

56% flows faster, melts at a slightly lower temperature, and I just generally love working with it.  

50N is a bit thicker, and a bit more sluggish.  It has a few advantages: it will fill larger gaps, it will form small fillets for strong joints on brake bridges/other high stress braze-ons, and I'm told that it wets out more easily on stainless steel than some other silver alloys.

The downside is that I just haven't gotten the hours in with it to feel totally confident when it's necessary.  I ended up doing a second pass to make sure I had good penetration, and definitely crisped some flux near the end (should have let it cool down and re-fluxed it instead of heating it right back up).

That said, I think I'm going to stick with this one.  I was able to draw the silver through to the pins, and I think it's unlikely that I have a bad fill.

Here's the crown all cleaned up.  I love Henry James' crowns, they have this beautiful elegance to them.  I can't wait to see it with some paint on it.

I also love hourglass spindles.  I set these up to work with Nitto/Rivendell's Hub Area Rack.  It's a gorgeous piece of gear.  I can't imagine actually needing four bags for the kind of riding that I do... but WHAT IF? 

Worth mentioning: I used 50N for these rack mounts too.  Note the nice little fillet around the base of each of them.  

Here's the whole thing.  It needed a bit of a twist, but I've gotten it pretty straight. 

Bonus image: my co-blogger, Gimble.  She gets her own chair.

Fork, Part 1

It's been a loooooong time.

Over the last couple of years, I finished the bike I was working on, made a sweet single speed, and rode them both a bunch.  I made a lot of progress with my brazing, but still count as a dangerous amateur.  

I've done a few practice forks, and I think this one will turn out well enough to bomb down big hills on.

First, I trimmed the fork down to the right diameter to fit the Llewellyn dropouts that I'm using.  Then I used my home-made blade bender to add a nice smooth bend.  The block was made for me by a coworker out of some scrap wood at his other job repairing boats.

I'm using 1.0/.66 True Temper blades.  As a Dangerous Amateur (tm), I really like these.  They bend easily and are pretty forgiving when I have to mess with them.  The folks at Henry James are always a pleasure to work with, and if I mess up I can get replacements pretty quickly.

48.5 mm rake on both blades, perfect!  The bends are also pretty close to perfectly in-plane.  Next step, fire!

For this bike, I have my own brazing setup.  It's oxy/propane, and the oxygen is drawn from the air by a medical oxygen concentration.  This way I don't have to deal with oxygen tanks or acetylene, and the slightly more diffuse flame that the propane makes actually feels a lot more natural for silver brazing.

I started by attaching the fork crown to the steerer tube.  I've gotten a lot more patient with practice and have stopped burning much flux.  I pulled through some excess silver, but a swipe or two with a stainless steel brush  while it was still hot got rid of most of it.  The rest should come off in a few minutes with emery cloth.

I didn't have time to start brazing the dropouts onto the fork, but I did spend a little time adjusting the jig.  I bought it from someone who'd already adapted it to accept an anvil axle, and with a few extra measurements, it turns out pretty awesome results.

Ok, it's been a while since I've written an entry, so I'm out of practice.  Please accept this blurry picture of a puppy I want to adopt as a show of contrition.

Making Stays

The seat stays connect the dropouts for the rear wheel to the junction of the seat and top tubes.  On the dropout end, I attach a cap that slots into the rest of the dropout.  The inside of the cap has some curves to it, so I started by filing the stay to match.  I used calipers to determine the maximum distance that it could sink in, then measured that on the stay each time I made an adjustment.

Now, since the cap doesn't have a second open end, I had to do things a little differently to see if I'd filled everything properly.  If I were a pro, a blind braze like this wouldn't make me blink, but I'm still a bit paranoid.  On the suggestion of the internet, I curled up a little plug of silver, coated it in flux, and dropped it in the cap.  Then I added the stay and heated the whole end until the silver melted and was sucked up into the joint by capillary action.

For the other end, I wanted to make an abrupt but rounded cap.  I've already done this, so it didn't hold a lot of surprises.  It was a bit harder than last time because I spaced on drilling vent holes before brazing the end up.  That leaves heated air trying to push the filler out.  It worked out alright, but I'll be more careful next time.  I used brass so that the filler wouldn't melt when I braze them to the sides of the seat lug.

Also note that I notched the lug itself to increase the surface area that will hold things together.

The dropout caps go on the chainstays in about the same way as they go on the seat stays, but you have to line them up so that they're in the same plane as the oval in the stay.

Front Quadrilateral

FINALLY

And, at long last, I have a nice big chunk of the bike done. The front triangle (quadrilateral to all of you literal minded geometrists) is a unit now. 

I started by getting the jig set up. I used my little angle gauge to determine that all of the tubes were in plane and clamped stuff in place. Unfortunately, I discovered that the cold set I'd done earlier hadn't actually taken, and was unable to get the down tube/head tube junction at exaclty the right angle. This will make the bike a bit shorter (I trimmed the down tube based on how things fit together before I realized what was going on), and make the seat tube angle a lot slacker. I may have to shove my seat forwards a bit, but it'll still be rideable. Summary: I messed up a fair amount but I think I'll still be able to ride it with pleasure until bike #3 rolls around in a few months to replace it (#2 will be a single speed to take the place of an existing steed).

Next, I tacked the down tube to the bottom bracket and layed it out on the alignment table. The big block you see is a theater weight. It's heavy enough that it pins the plane of the bottom bracket shell to the table. Then I just drag a height gauge around to see if the tubes tip one way or another. 

It took a lot of tweaking, but I got it in plane. At one point a tack popped and nearly made me jump out of my skin, but it didn't damage anything and I just melted it back together. 

I don't have pictures of the actual process because it happened all in one big rush. I basically powered through right before the shop closed. It was pretty uneventful and predictable. I was nervous, so my brazes weren't the best, but they'll do. The only big hiccup was putting a hand down to steady myself while peering into the bottom bracket looking for filler and burning a hole through my shorts with the still hot brazing rod.

Fear not, no genitals were torched in the building of this bike. 

When I checked the alignment, I found that it was fair, but not perfect. I'm pretty happy with it as a first attempt and will make better alignment a big goal on bike #2.

Getting Bikey

Braze-ons

The braze-ons went on pretty quickly this time, except for one brake stop that kept moving around.  Ended up with about a metric ton of silver on there.  I'll have to get some little magnets.  The one I used to hold things still for a couple of other bits worked well, but I managed to ruin it with the flame. 

Head Tube/Down Tube Sub-assembly 

I didn't get a lot of photos of my first joint on this attempt, as my phone ran out of batteries pretty early on.  Luckily, it was pretty simple.  I checked the angles, fluxed it up, and brazed it.  I did burn some flux on the head tube side of the joint, right at the bottom.  Thankfully, after I chipped off the burnt flux and spread around some fresh, I was able to channel enough silver through to feel pretty confident about the joint.

Despite being pretty careful, it seems that the joint pulled back to the original 60 degree angle of the lug, not to the 59.3 that I'd thought I'd filed things to.  It only took a few minutes with a cheater bar through the head tube to make the adjustment, and I managed to finish it out within .1 degrees of correct.  

The above picture was taken after some sanding and filing.

Seat Tube/Bottom Bracket Sub-Assembly

I was worried going into brazing the bottom bracket shell on to the seat tube.  The BB is a big heavy piece of steel, and that makes it a lot harder to get up to temperature without going over.  I did a test joint right before doing the actual work, just to get myself calibrated.  

The test piece came out pretty well, a nice clean ring of silver in each of the cross sections.

When it was time to do the joint itself, I got everything aligned and fluxed, then tacked the front and back of the BB lug to keep it in place, then aligned everything again.  When I started brazing, it worked flawlessly.  I was able to draw the silver exactly where I wanted it.  Best braze I've done to date... until I got half way and  the BB fell right off.  It was comic, and frustrating.  

Basically, I'd had about half the shell up to temperature, so all of the silver was soft at the same time.  On my second try (after soaking and sanding each surface clean), I tacked the piece on four sides.  

This time it worked almost as well, but with less falling.  I used WAY too much silver, in my paranoia about gaps or voids, but that's easily fixed with emery cloth and patience.  I didn't even overheat things much!

I did find that the points were a bit far from the lug, as I'd widened the socket to get the angles right (this tube needed to tilt about 1 degree further in the direction of the down tube than the lug is set up for).  If I'd been thinking more, I'd have clamped the points back into place before proceeding.  As it is, I'll just have to dribble a bit more filler on the point when I do the other joints and sand until it doesn't look dumb.  Internally, it should be fine.

Just for fun, I slotted the two sub-assemblies together and was overjoyed to find out that, if I don't let stuff slip when I braze the last few joints, the vertical tubes should both end up at the required 73 degrees.

Funny story: 

I had to cold set (fancy term for "bend") the BB's angle, after tacking but before brazing.  When I cranked the tube to the side a degree or two, one of the little tacks popped free.  I must have jumped a few feet into the air, and was sure that I'd wrecked the whole thing.