Silver Case

Returned to the Rebound Centre this (late) morning to work on Le Chacal. It’s the first time in something like three weekends. I felt rusty. Today’s job was to start installing the S&S couplings into the frame.

The S&S couplers take up 35mm of length in the tube. Step one is to chop out 35mm segments from the existing frame.

Before

I gave myself quite a scare (to the amusement of Michel and Sulaiman). After I made the cuts (which I checked and rechecked) and was dry-fitting the bike back together, I wanted to gag when I realized I had cut way more out of one piece of tubing than the other. How could I be so fucking stupid? I measured and double-checked my measurements repeatedly.

That’s when Michel helpfully pointed out that I had only made three cuts so far, not four. I had simply failed to finish cutting out the segment from the second tube before I left for lunch.

Much relief ensued when I realized I hadn’t shortened the frame. I just needed to make one more cut.

After

Since I was cutting up the frame, all sorts of surprises appeared from inside the tubing. I could see how well my braising penetrated (reasonably well, although later welds were clearly better). I also discovered where all our flux went.

In from Bogota

The rear triangle cuts are finished (yellow) and fitted into the jig. Tomorrow I’ll silver-solder them. The four other joints on the top and down tubes I’ll try to finish tomorrow too. Might be slowed a bit because some of the couplings need to have a decorative scallop carved into them first.

Yellow rear triangle; Blue tomorrow’s tubing

Sulaiman, cheering his victory after guessing the weight of my frame to the tenth of the pound!

I boastfully made a market of 7.5 at 9.0 lbs. I am glad I lost to Sulaiman’s 5.2lbs bet.

Today was the final brazing job — the seatstay. The brazing and setup wasn’t hard, but we had concern about our novel bolt-on seatstay/dropout interface. Especially fear of melting the silver solder (600c) while brass (900c) brazing nearby. Fortunately it was never a problem.

About the only issue was we ran out of Acetylene gas and bronze flux. We ran over to 5 Kallang Place for replacements and lunch.
Oh, that and I managed to burn myself three times being an idiot three times. Here are three brazing tips:

1. Don’t try to hold a hot brazing rod in your teeth while holding a torch with an 8″ lance of 1200C flame in one hand and try to move a 30lb bike jig around it’s Z axis. You tend to have the brazing rod lay across your arm.
2. Don’t touch the bottom of a piece of metal who’s top you’ve been heating to 900+ degrees for the last ten minutes.
3. Don’t try to hold a hot brazing rod in your teeth while holding a torch with an 8″ lance of 1200C flame in one hand and try to move a 30lb bike jig around it’s Z axis. You tend to have the brazing rod lay across your arm. [yes, very similar to tip #1]

Today’s final assembly

the bolt

Foppish Cap

Semi-finished frame

Next session

Pre-gluing for an embroidery project

Puttered around this weekend. Wasn’t especially memorable.

• RC Rockcrawling with Luke. First day I vibrated out a drive shaft set screw. (which I recall having Loc-tited!) Second day I popped a breakaway joint on the driveshaft while scrambling up some rock debris. Need to diagnose why the system spasms. Low voltage onboard power? RC Controller? or the radio is broken?
• Finished mitering the seatstay Saturday. It’ll be the final braze. I planned to go in on Sunday, but woke up late, and Luke wanted to play.
• Watched James Bond ‘Quantum of Solace’ last night. OK movie. Enjoyed the violence and the scenic shots of Italy and an Andean desert.
• Bought a large, square chopping board at IKEA to make a table top workbench for my ‘clean’ lab in the attic. I don’t want to ruin my antique marble coffee table by soldering over it. Also bought some IKEA plexiglass trays that are meant for kitchen storage but will be great for disassembling things with lots of miniature bits to fall off.
• Started working on a small bag project. Inspired by a bit of red felt I found.
• No great meals, although had a nice spinach salad Saturday night and some decent chicken burritos. The reason Matilda can cook pretty well is that she is not afraid of adding enough spice and, as I do, totally ignores volume instructions for spices and seasonings in cook books. It’s easy to double or treble the seasonings and the result is often substantially better.

seat stay custom connectors machined by Sulaiman

The process for brazing in the threaded inserts was interesting.

The insert was a short 1.5cm plug. So I pushed a plug of silver flux paste into each seatstay blade. Then clamped the stays vertically (with the openings I needed to braze pointing down to the ground). Then we made short coils of 48% silver flux rod and pushed them into the blade openings, followed by the inserts. Then we used some spokes to hold the inserts up in the stay blades. Silver melts faster than brass. The trick here was to get everything hot, and then get the walls of the seat stay hottest, so that when the silver melts (which happens suddenly), it follows the hot walls of the stay and runs down to the bottom.

It worked pretty much exactly like that. After some heating, suddenly silver appears a bit out of the edges, and that’s it. The braze looks pretty clean from the outside. One side bled a bit of silver on the wrong side and got solder on the threaded section of the insert, but we easily cleaned that out with an M8 tap.

Hunter: Was that you shooting?

Leary: Yes.

Hunter: That’s a cool gun you got there. Could I see it?

[Leary gives him the gun]

Hunter: Shit, that’s light! What’s it made of?

Leary: Composite. Like plastic.

Hunter: Mind if I give it a little dance?

[Leary shrugs. The hunter shoots a duck]

Hunter: That is great! That is really really great! You wouldn’t want to sell it would you?

Leary: No, I need it.

Hunter: For what?

Leary: To assassinate the president.

[Hunters laugh]

Hunter: Now what do you want to do that for, mister?

Leary: Why’d you kill that bird, asshole?

[proceeds to nonchalantly kill both of the hunters with his gun]

Today was my last day of Gardening Leave. I came into the workshop in time for lunch. Sulaiman and I discussed how to mount the seatstay to the rear dropouts. We settled on some kind of hinge. It was a sufficient idea, but not compelling.
Lunch wasn’t over, so we brainstormed alternatives for sport. The idea we liked best was to somehow plug the seatstay to the dropout and then tighten it down with a bolt.
We came back to the shop and made some drawings.

first rough sketch of the idea

working out the finer details

doing the arithmetic to mill the base plate

Both Sulaiman and I were excited by this design. It seemed cooler and less of a kludge than a hinge. In our excitement, we worked out the dimensions for the base plate, which Sulaiman milled and I fitted to the dropouts. This week Sulaiman with lathe-turn the flanges. On Saturday I’ll miter the seatstay blades onto the wishbone neck. Then we can start to silver solder the threading into the tubes and the flange onto the plate. There is a really clever way to silver solder this. We stick a ring of silver up on top of the thread block. Then we heat up the whole mass, the silver melts, flows and solders up the lot. That’s instead of trying to jam a rod of silver braze up there.
The dimensions should work. We chose M8 bolt because it is most likely to be field-replaceable if I lose it. It should be a fun finish to the design… some machine work, some interesting brazing, and some picky mitering. The end product could look pretty cool and definitely customized.

Today I efficiently mitered and brazed the chainstay to the bottom bracket. I only had three hours to spend today. I wrapped up and turned off the OxyAcetylene tanks rights at my 1pm curfew.

Today’s job

Sulaiman was very busy painting a litany of bicycles but when he saw my results said that my brazing had improved considerably. That was quite a high note to end on.

underneath the bottom bracket

Now the next step is to figure out how to attach hinged seatstays to the dropouts. After that’s finished, the frame is complete. Then I’ll proceed to cut it into seven pieces a reconnect with S&S couplings.

Sulaiman lent me the dated, but interesting, http://www.amazon.com/Designing-Building-Your-Own-Frameset/dp/0960241833.

Just starting to read it now. Seems to emphasize lugged frames. Hopefully it can help me improve my brazing chops and give me some accuracy tips.

One chainstay to rule them all, one chainstay to find them, one chainstay to bring them all, and in the darkness bind them.

Today in a crash Saturday session Sulaiman and I rebuilt the chainstay. Now it’s back to normal and only cost me four hours for my idiocy.

There is a good chance that I will be able to complete the basic frame during two energetic sessions on Sunday and Tuesday. S&S couplers will have to happen subsequently.

Don’t worry, this won’t hurt a bit…..

Sulaiman applies some Tender Loving Care

You stay on the right side from now on!

I was very pleased with yesterday’s progress. I mitered and fabricated the chainstays of Le Chacal “quickly” (for a hand-made miter) and accurately (<.3mm gap between mitered pieces). I gave them enough brazing to keep everything together. Today I was to miter and mount the chainstay to the bottom bracket.

Except, today I realized that yesterday I made a terrible blunder: I welded the left dropout to the right chainstay and the right dropout to the left chainstay. They aren’t symmetric…. the right dropout (on the drive side) should have the derailleur hanger. Now that’s on the wrong side. As well, the tabs for the seat stays are angled at the wrong direction.

Such a stupid fucking mistake.

Anyway, Sulaiman recommends the best solution to surgically remove and transplant the derailleur hanger from the left to the correct, right, drive side. That’s apparently far easier than to try to remelt the big plugs of brass and pull out, clean, switch, and re-braze the dropouts onto their correct side.

Shit. That has set me back probably 1.5 days (at least). It totally spoiled my mood when I discovered my mistake, so I tidied up, fucked off, and went home. Saturday morning I’ll return and finish the chainstay wishbone miter joint into the bottom bracket. When that’s welded on, it’s going to look dangerously like a big frame… only missing the seatstay which I haven’t fabricated yet.

This is a clever bike hack. The guy wanted a collapsible bike for travel, but he didn’t want to buy expensive S&S Couplings. Instead he bought an old full suspension frame from eBay. Then he removed all the suspension components and converted all the hinges and swinging bits into the connectible/disconnectible parts of the bike.

I’ve been working on the 1:1 technical drawing of my bicycle. I’ve been astounded how lovely the paper has been using and wearing. It seems durable, it’s beautiful to write on, and it takes erasure brilliantly and cleanly.

I decided to figure out what it was, because I’ve never had a paper that can stand up to that abuse. I think it’s vellum.

Drafting Paper – Drafting paper comes in a variety of materials and surfaces. Drawings may be prepared on paper, vellum, or plastic film, one trade name Mylar. Drafting paper, vellum, and film can be purchased in sheets or rolls. Vellums and drafting films (Mylar) are see through material. This is necessary if diazo or blueprints are made. Clearprint vellum is excellent for manual drafting. The vellum is made from 100% new cotton fiber. The vellum is transparentized without solvents to produce the proper translucency as well as the legendary Clearprint archival quality, strength, erasability (with no ghosting) and redraw characteristics. Vellum is good for pencil or ink. Our drafting film is superior long-lasting and chemically matted for pencil and ink drawing applications and will not tear, cut, stain or become brittle or discolored with age. Excellent erasability for both ink and film lead and recommended where dimensional stability, strength and high translucence are desired. Available in single or double matte white finishes.

So I put ‘vellum drafting paper’ in my Evernote “makers wishlist” {to buy} list.

Le Chacal, as my first bike frame construction, has had a fair degree of slop and error in its construction. There isn’t a single pivotal mistake I’ve made, just an accumulated white noise that leaves everything +/- a mm or ° here and there. I admit: I was suprised a millimeter (1) mattered (2) was attainable accuracy.

When Matt and I finalize specifications for his Urban Detective Bike, The French Connection, I want to build it with a much bigger degree of accuracy. I think I can realistically target 0.3mm and 0.25° accuracy. The question is, how do I clean up all the sloppiness in my work?

Measuring
It took the Le Chacal experience to illustrate that sub-millimeter accuracy was possible. When I first started using my ruler to measure things, I wasn’t really pulling full accuracy out of it. And I probably wasn’t using the rulers in ways to give me full accuracy. It’s easy to lazily use the plastic triangle instead of the full ruler, and not really squint and square and true the measure. I suspect having a large toolchest of different measures appropriate for different situations also helps, rather than using the 1m steel ruler on everything from the 2cm bushing to the 300mm tube. What are the best practices for accurate measurement?

Marking
I think this is the other really big issue on this project. I think the most subtle, poisonous mistake I’ve made has been that when I draw a piece on blueprint, my drawn lines really run on the edge of the line I’m trying to represent. The pencil line is 0.5mm wide. Then when I draw the next piece that connects to the first piece, I’m already off by 0.5mm. I am hypothesizing that the right way to do mechanical drawing and machine work is to use the thinnest line possible and try, as hard as possible, to get it right on top of the line you’re trying to represent, not a fence along its edge or anything else.

Also, with metal work, it’s easy to use a dull awl and lazily scratch a few poor lines onto the metal. Instead, I should keep the awl sharp and really try to draw a good, true, single, thin line. Not a chicken-scratch scraping. Those scrapings, often done at slight angles, not straight, can themselves be 2mm of gray area.

Cutting and the rest
I actually don’t even think these are very much an issue if I can get Measuring and Marking done right and well. Are there other things to do ?

Can anyone point me to “best practices” for measuring/marking/transferring between metal and 1:1 blueprints?

I remember as a kid Dad explaining a Vernier Scale to me. I also recall not really listening at all and not really being interested at all. Vernier Scales were filed in the “never pay attention to” drawer of my brain.

Today I was inking in some finalized parts of my blueprint (the brazing is done — there is no more slop). I traced out the top edge of a tube, and then measured the diameter of the tube with calipers. I used a ruler to draw in the bottom edge according to that measurement. The result was terrible — I was way off. Then I inspected what I’d done and realized I’d misread the weird calipers I’d used (used an edge, rather than the -zero- mark). That pissed me off. (I have a 370mm of whiteout on my blueprint now)

Then later on I needed to precisely measure the length of some tube segments. The digital calipers’ jaws wouldn’t open wide enough, only the old school Verniers that had bit me earlier in the day. But now I was facing a vernier scale. But this time it made much more sense and I was fascinated with how horrifyingly precise such a simple thing could be (0.02mm or 0.000787 inches). Then I challenged myself to measure all sorts of things with it. It was great fun. Now I want a vernier caliper set, it’s so elegant and powerful. Even the math of why it works is terribly clever.

Of course then Sulaiman startled me by mentioning the Japanese calipers I was using cost around $300SGD. oops.

Now I want to learn to use a Micrometer

crowned fork replaces the original plans for a unicrown

The front fork was planned as a custom unicrown affair. Very tough to miter and get right. As we studied the diagram for it, we realized fitting in room for a fender would be very, very tight indeed. As we thought about alternatives, it occured to simply use a crown fork lug. It would give us plenty more space, be far far simpler to construct, and probably come out much closer to spec.

When I considered that there were no meaningful advantages to the unicrown design, I tossed it out, and replaced it with the simpler crowned affair.

The only weird part will be actually bending the fork rake into it. That’s just done with physical brutality. Sulaiman assures me it’s not too terrible a job, and next to impossible to overbend the rake. Last time they had to recruit a 200lb man to lean into ti. Anyway, the fork goes in the bottom drawer until after I finish the rear triangle.

Now the rear triangle is the tricky part. I’m building monostay unicrown stays. Essentially they’re also unicron bicycle forks in service as chain- and seat-stays. The monostays will be split into two using S&S Couplers. This is what makes the bike massively deconstructible. The better part of the day was measuring, squaring, and rechecking the design to ensure everything fits.

unicrown monostay system with S&S couplers

I included two special considerations, this being a touring bike: 1) enough wheel clearance that I can install a fender onto the monostay 2) worst case scenario, I destroy my tires entirely and need to replace them with the crudest, chunkiest shitty BMX tired I can buy off someone. This bike is meant to be a survivor, a JACKAL, not a highly-strung, finicky athlete that needs a precise diet and care. This lengthens the wheelbase of the bike beyond original plans, but that only makes for a more comfortable ride. My headtube angle came in too sharp (69° instead of 70°, so I would like to prevent this to becoming an itchy, irritable criterium racer bike anyway)

It took me the better part of an entire afternoon to clean up the drawing and then map out the stay system. Tomorrow I will commence building the chain-stay. Should be fun: unique bespoke engineering.

Yubari melon and a random (?) apple

I love the classic Japanese understatement:

The Coal Mining Museum was established with considerable contributions from public funds and is a conversion of an old coal complex. At first the Museum seemed to be successful in attracting tourists including family groups. It now seems that this was at some cost and the budget deficits of Yubari city has meant that the city is officially in financial reconstruction.

But it’s not all a joke. Outside a desert highway in Nevada, when is the last time you could travel a 100km and see no stores or gas stations?

And of course it’s all documented in thorough, accurate Japanese style. I’m ready for my bike to be done!!

Today was a potentially dicey day. I had to miter the top tube, which connects the headtube and the seattube. It has to be done with good precision, otherwise the steering geometry of the bike becomes goofy. To put 1° in perspective… the range of almost all bikes’ head tube angle (from country cruisers to velodrome bikes) is 70° to 74°. So a one degree screw up is meaningful.

Uploaded with plasq‘s Skitch!

We did a lot of double-check measuring, scoring lines, and calibrating the jig. Then I spent an hour mitering the joint. I had mark lines I was working against, plus I was fitting for a good miter. Thankfully I had the presence of mind to slow down for a moment and think, “is there any way to doublecheck what I’m doing, rather than blindly filing for the perfectly flush miter?”

Of course there was, to measure the actual distance on the tube. Whew. 569mm on the top side of the tube, just like it should be. Any more mitering, and it would have been too short. Glad I did that cross check. Sulaiman and I went through some more checks and confirmed it should come in OK. When I am back from Vietnam on Tuesday, I’ll finish up some fine touch on the miter, and everything should fold together flushly and accurately.

When I started the mitering job today, I had a good bit of surplus meat to chew off the end of the pipe. Grinding it would be slow and wasteful. My thought was to cut off some bits with a hacksaw. Sulaiman’s ideas was to use his set of tin snips. Yes, set of tin snips. There is a left handed set and a right handed set. The difference? Depending which set you use determines which side of the cut stays unmolested and which side gets the fury of a pair of metal-cutting scissors cutting the steel. I was (1) amazed by the force these things could lever (2) amazed how clean it leaves the blessed side. I remember Dad’s set of tin snips as being ambidextrous, taking frustratingly tiny bites, and (to me) being mostly useless.

Today’s work was supremely important to Le Chacal. It was time to braze the downtube to the bottom bracket. It needs to be right so that the head tube angle (targeted at 70°) comes out exactly 70°. This will severely affect the handling of the bike. Yesterday I was annoyed because some cross-checks indicated the angle was going to be messed up. Today we double-checked measurements on the 1:1 scale drawing and thought out the geometry. On further reflection, Sulaiman and I worked it out that things were still fine.

Seat and downtubes jigged an brazed to the bottom bracket

Closeup of the bottom bracket

The first half of my day was a difficult mitering job — mitering a tube onto the bottom bracket, but adjusting for the existing brazing of the seat tube. Finished that, it was time to do a careful mounting on the jig and braze it up. I did a respectable job brazing it (maybe left it a bit more gnarly than I will enjoy sanding out).

Checking the accuracy of the build.

We checked the results. The resulting top tube space should be 573mm. My brazing job left the gap 571mm. So I was two millimeters off. Sulaiman said that the high-end tig-welded racing bike he’s working on had an error in the same dimension of 1mm, so we considered my job a good one.

Checking that all the tubes are in the same plane

We also tried to make sure the tubes are all in the same exact plane. But since we haven’t faced (planed) the bottom bracket, the results aren’t exact. One we brze on the rear chainstays, then we can plane the BB, and confirm it’s all in the same, true plane.

Tomorrow will be tricky because I have to miter out the top tube and make sure it is exact-a-fucking-lutely 573mm. That will be tedious and a bit wracking.

Went to Bishan park with Luke and Ling this morning. Rode bikes and had breakfast at Canopy. Afterwards, went to Rebound Center to work on Le Chacal. Made slow, halting progress. Wasn’t very satisfying.

Today’s goal was to miter the connection between the downtube and the bottom bracket. The seattube/bottom bracket is already done.

I had an awful lot of fussing to do with the jig. And the jig itself kept slipping out of adjustment, so there was a lot of readjustment and remeasuring during the procedure. Somewhere some arithmetic has slipped, too, because I was astonished to find my 5mm safety margin had evaporated to almost no safety margin left on my filing. I need to reconfirm my blueprint and figure out if there are any poisoned measurements.

So tomorrow I should be able to finish the miter joint and then look to cut the top tube for the final fit of the front triangle. Not sure whether I’ll have enough time to braze the lot. Hopefully I will.

I think the most difficult thing about this job is measurement. Wielding the tools is comparably trivial. Definitely you want sub-millimeter measurement accuracy, and you want it repeatable, and you want the marks to be consistent. But the problem is the pencil is sloppy, it’s not clear if that’s a “cut on” “cut behind” “cut in front of” line, or light is low and the mark isn’t clear enough, etc. etc. etc. And the problem on things like a bike frame is a bad measurement early on can really poison downstream. I would like to find some folk wisdom on doing good measurements on metal work.

The industrial estate I work at in Geylang

Victim One

Dialing in the flame

Fluxed, jigged, and ready to roast

Smoothing out the filleted mounds of bronze

After brazing the joint

Fortunately, this process is only tedious, not hard. I didn’t finish up, but made good progress on one piece. I’ll finish these up next week.

Checking the piece versus our blueprint

Looks like the braze pulled the piece a bit. By our measurement, the angle came out almost 0.5 degrees off expected. Not massive problem. We can deal with it, and it won’t be a meaningful affect on the geometry. This is also why we work in a carefully proscribed order of pieces.

Tuesday (no work Monday — it’s swimming lessons with Luke), I’ll finish those two pieces from today and start work on cutting the cut side of some new pieces we’ll braise on soon.

Spent the morning here, drafting the bike design

Elements of Bike Geometry Design

Sulaiman has nice files and a nice vice

Downtube

Seat tube mitered into the head tube

The tubes are from Nova Cycles. They’re cro-moly double-butted tubes. Meaning the outer diameter is constant, but the walls are thicker near the ends and thinner in the middle. There is a “miter” end and a “cut” end. The cut end has a longer thick section before it tapers to the thinner middle zone. The wall thickness can be seemingly-insane… 0.3mm in one case I saw. My tubes are a bit beefier (intentionally) 0.9/0.6/0.9 (though some measurements show them to be more like .7 thick sides.

I got home, filthy (it’s been a long time since I had metal and shop grit covering my face and hands), and zen-fully happy. Then once I was home I realized I also felt bone tired.