So, as part of my quest to tool up in a proper manner, I decided to liberate a 4ft x 3ft cast iron surface plate from Glasgow University.
With the help of two Tirfor winches, a pallet truck and an engine hoist, my good wife and I brought the plate across the bridge to the island, down the steps and onto its base in the workshop.
50 years old but in fine fettle due in no small part to being kept with a protective wooden cover, I had one more task to do before it was ready for use.
I had to drill a hole through the plate to mount my bottom bracket post. Like some noisy hardened steel harpoon though the skin of a great silent whale, I broke through the 40mm hide of this grey leviathan and ran paper under thumb to smooth the burr. The fine hardened stainless steel post was made in the new world by Mr Alex Meade. The post is designed to be used with Park facing tool threaded inserts.
I measured and drew out the shape of the casting ribs on the underside of the plate so that I could choose the optimum position for the post.
I used a thick piece of hardwood clamped to the table as a drilling guide. I pre-drilled the wood on the pillar drill.
I used a spring washer, a flat washer and a nylon lock nut on the stud underneath the table.
Made in 1964, grade B (toolroom grade). More than adequate for bicycle frames.
Ready to go. Most bike frames will fit without overhanging the surface at all. The post can be removed in 30 seconds and the wooden top replaced to use as a general work surface.
I’m really looking forward to checking and aligning frames on this table.
So after about a year in production brazing at the Brompton factory I’d say may brazing quality was starting to ramp up considerably. I’m still nowhere near the quality of the top dogs in the factory but I’m confident that I’ll be doing clearcoat quality fairly consistently before too long.
I did some practice brazes the other week in the workshop with flux paste. As I’ve previously built my own frames with lugged BB shells, this is my first ever fillet brazed bottom bracket shell:
Didn’t go too badly, but I’ll be doing more practice.
The brazing that I do in my day job at Brompton has been really useful.
Last month a bunch of us from the factory took part in the British Heart Foundation London to Brighton ride with 29,000 other cyclists. And yes, I did get over Ditchling Beacon on my 2-speed Brompton without stopping. Just.
Also, my friend John, a lifetime engineer and machinist has offered to work with me as I start up as a frame builder, giving me use of the facilities at his factory to make jigs, etc. What a guy. Watch this space..
The approach to the island workshop, a 1920s boatyard built for repairing Thames lighter vessels. The boat moorings here are tidal.
I decided to set myself up in a workshop nearer to my brazing job at the Brompton bicycle factory. The building is an old boatyard on a small island on the tidal Thames in west London.
Original heavy machinery still features on the island.
My unit – compact, but everything I need in an inspiring setting.
Still some organising to do, but it’s taking shape.
The cockpit – I really like the atmosphere here – skilled yet modest craftsmen come and go in the building and the light and changing tides alter the feeling of the place daily.
Finding a place for everything took time but it’ll pay off.
I thought it was about time that I bought myself a decent torch.
I bought this old Harris 19-2 torch set on ebay the moment I saw it.
Decades old, but never been lit. Even has a cutting head. I am based at a working boatyard, so you never know, I may find a use for it.
I found some reverse flow check valves for it too. Obviously I’m already using flashback arrestors.
Harris is a US company, but my torch is made in Italy under licence as “Harris Europa”. It’s really nice to use and very quiet.
In my day job as a production brazer at Brompton, we use injector-type torches which are great for use with gas fluxers as they really help to push the braze forward and shape the beads with their added thrust. I believe that my Harris torch here is what is known as an “equal pressure” torch, which gives a slightly gentler flame that’s easy to control and should be good for making smooth concave fillets.
I’ve also decided to restore an old Honda CD200 motorbike as a project so that my commute to the bike factory and errands to and from the workshop might be more practical. Sorry if this appears off-topic, but I was without a workshop and a torch for a good few months..
The countershaft was worn where the front sprocket mounts, so I thought I’d rebuild the engine and replace any other worn parts, seals, piston rings, etc.
Worn shaft (top) and replacement.
Now to transfer the gears..
Laying all the bits out – checking against a diagram is important.
Rebuilt gearbox put back together in the crankcase half.
Top view with gasket in place.
The swingarm on the bike was pretty rusty – after shotblasting it looked pretty sketchy so I cut away some steel to reveal the extent of it all. I found a big hole in the tubing inside:
Didn’t fancy riding this too far..
I found it impossible to find a replacement swingarm that was in good condition, and so I bought a used but rust-free US CM200 Twinstar swingarm which is very similar, but I’d have to swap over the driveside fork end (my bike has a bigger spindle to mount a cush drive) and a few other small mounts for the chainguard, etc.
I also decided to remake one of the welded-on plates as the rustworm had made it pretty flimsy:
Marking out the template in new steel.
Then I drilled inside the lines on the drill press.
And cut and filed it to shape.
I brazed it all together with my ace new torch.
I soaked the flux off in a bucket of water.
seemed to go pretty well.
Alignment was good enough.
The finished swingarm. It’ll be powdercoated with the frame and then I’ll push new pivot bushes in.
I promise my next post will be purely pushbike related!
My uncle got in touch with me to ask if I’d build a tricycle for my auntie as a surprise birthday present. It would have to be able to cope with a gravelly farm track in South Wales, be a step-through frame design, and be 2-wheel drive. Er, yeah, no problem..
80mm rake gives this trike around 20mm of trail.
Bolt-on axle housing from an ebay donor trike. It’s one-wheel-drive at this point.
I needed an alignment shaft to keep all bearings within a tolerance of 0.75mm of misalignment. Gulp..
Sandblasted axle housing with alignment shaft fitted. Bearing shells are right-threaded English BB size.
I had some fun aligning this frame, I can tell you. Perhaps a little ambitious for my 4th frame, but I got her made on time, just.
I found a Rogers bolt-on bike-to-trike axle housing, and had a 2 wheel drive cassette & axle made for it by Geoff Booker at Trykit. The Trykit axle and custom cassette body is a lovely bit of kit. I removed the bolt-on tabs from the axle housing, moved the derailleur hanger boss and brazed the housing onto the chainstays with 4 dummy bearings that my friend John Discombe made for me. A cold-drawn 18mm rod was placed through the slip-fit dummy bearings to keep everything aligned during (and after) brazing. The drive-side chainstay had to be bent to clear the cassette housing.
I used a flat surface with marked lines for centrelines, axle lines & BB lines (using another round bar on V blocks & dummy BB cups), and I also used a surface gauge and engineers squares. A digital protractor kept the seat tube at the right angle, and these adjustable V blocks were handy for levelling the rear axle alignment bar and to get the right BB drop:
I’ve got balls. Have you?
I used a ladies’ lugset that couldn’t really give the angles I needed, so I ended up fillet brazing the hockey stick, and I ran into trouble with seatstay heel strike (trikes usually have mega-low BB drops as they can’t lean and the lower C of G is beneficial to handling, and I had unwisely opted for a lugged BB shell that limited my angles), so I built tabs off the rear axle housing to bring the seat stays way back. I drilled the hell out of the tabs to try and save a little weight. For a lot of the build I kept the chainset, a pedal and a shoe cleated-in just to be safe with heel clearance on the drive side.
It was fun to ride.
Trikes always tend to follow the camber of the road, so low trail is preferred to minimise the effort needed for constant steering input. Seat stays are regular bike stays but used upside-down (thin end at the top).
Cross tyres were chosen for the loose gravel surface it would be ridden on in Wales.
I used 700c rims because the rear hubs that I salvaged from the ebay junker donor trike wheels had very small flanges with spokes that were already elbow-to head (they came with 26 x 1 1/4 rims – This is England!)
She’s now in Pembrokeshire, South Wales, and I’m told that everyone wants a go..
Also, I’m getting well stuck-in to production brazing at the Brompton Bicycle factory, and, way off-topic, but I was roped into playing bass in my mate’s “music video” about a fictional darts-playing character. I’m sorry:
So I have to get this bike frame built and to the painters asap to be ready to build up and photographed before Bespoked. There’s no time to lose..
..Better whip out my Herbie Helm lug vice. Stainless, of course.
Checking my hand-filed mitres. Hmm.
New lug and filed lug. Pointy. These can hurt you if you're not careful. Ask Ryan at Oak Cycles.
I wheeled out the Wilkinson "Abominator" jig. I made this in my kitchen a couple of years ago. The swivel vice has a V-groove and I got it from Axminster. I must upgrade soon. Donations welcome.
Silver brazed headtube/downtube. I used Cycle Design's "Stainless Light" flux. It comes off easily with water.
The story so far..
Internal cable routing. How hard can it be?
Some eight hours later, after making sure the internal brass guide didn't touch the tube wall, rattle or kink, I got it all brazed up.
It was rewarding when I got it done.
Lining up everything with the drawing.
Ok, I own up. I made a mistake. When I was planning the cable run I looked at an American bike in the workshop and a German road bike at my house. Brake levers on wrong side. Whoops. What a wally. I had offset the internal cable entry and exit to suit a right hand rear brake lever. Remember that the cables should cross in front of the head tube to give a decent run. So… in keeping with the concept of this bike, and in order to partially conceal the cable entry point, I put it underneath the top tube at the front. This gave me a better cable run and a side-exit to the rear caliper on the correct side. A serendipitous event, no less. Hoorah!
The top head lug needed to be blacksmithed to conform to the tube. I tapped it with a small brass drift made from a bathroom door sliding bolt lock, after squeezing it in a tubing block.
And I also had to file the point shorter on the lug, as it was overlapping the first lug's point. A peril of short head tubes.
Now it fits.
Checking the fit in the lug.
Testing the fit on the tube.
Grinding out the chainstay sockets in the BB shell.
My belt and braces approach to dropout alignment.
Cleaning out a chainstay so the brass will take to it.
Fluxed and brazed with brass. Lots of cleaning up to do here.
Time to silver braze a gear cable stop onto the chainstay too.
After soaking the flux off under the tap.
I decided to put the chainstays in on Ryan's frame jig. The stainless band on the seat tube will stay unpainted for a 31.8mm front band-on mech that won't leave damaged paint to be visible in fixed gear mode.
I ran a cord from the dummy axle to the BB to double-check the seat tube/chainstay angle with a protractor.
Using my angle-finder.
I brazed the tops in the jig, then finished in the Park stand.
Next I drilled holes for the bottle bosses. I had to enlarge them slightly with a round file.
I had to improvise a way to hold the diamond reinforcement while I increased the hole diameter.
I tried to resist the temptation to add that little bit more silver just to "make sure", but it gets me every time.
Let's check the rear spacing..
And the left alignment.
..Matches the right alignment according to the Park FAG-2 tool.
Rear wheel looks fairly centred. I built and dished the wheel myself so I know the rim is centred.
Same goes for the fixed rear wheel.
The H-Tools say yes!
Time to use the piece of extruded aluminium I tapped and put an M5 threaded probe through. Use it like the FAG-2 tool but touch the 3rd contact on the wheel rim, not the dropout. This shows that the dropouts are level, and one is not higher than the other.
After pulling the stays around, the other side matches. A perfectly dished wheel is essential for this. This is used before the seatstays are attached. I checked the resulting angle of the chainstays against my drawing to make sure my geometry would stay as expected.
Getting the brake bridge right. A mudguard has to fit in there too. I have only tacked it in here. I got it in the perfect position eventually, and almost straight.
Note to self: procure something more fireproof to shield the drawing whilst tacking. Although we have a cast iron surface plate in the workshop, I tacked the frame tubes on shimmed V-blocks on top of my drawing, which was on top of a sheet of 12mm toughened glass.
I’ve now taken the frame and fork to the painter. Tamsin my customer has chosen a very vibrant green. You have been warned..
I’ve made some progress with my 3rd frame build. Here are the pictures:
These are my fork ends. I'm going to cut the rack mounts off them but keep the mudguard mounts. One is done already in this picture.
Filing them smooth after cutting.
Bending my fork blades in the bender I made. Not 100% happy with the curve I get, but it's not too bad.
Checking the fork rake against my home-made gauge. I want 43mm of rake. There are lines to centre the blade so it's straight.
Cutting the blades to length.
Finding the straightest side of the seat tube. The worst side will be used in the fore and aft plane of the frame to minimise lateral misalignment.
My seat tube is brazed into the bottom bracket shell after tacking and checking alignment.
Oh yeah, and they let me try out brazing a bottom bracket assembly at work a few weeks back - here it is (it was rejected)... Come off it, it was my first one!
Here's my fork held in the Wilk-O-Matic SPX-3000 De-luxe laminate construction steel-reinforced fork jig that I made in my kitchen 3 years ago. My workshop mate Ryan's just bought a proper fork jig so perhaps if I ask nicely next time I can use that..
The bits 'n' bobs so far.. The top tube will have internal cable routing.
After brazing in the fork legs. The flux got a little tired and began to darken after I chased around the shorlelines with the flame, but I'm confident that I didn't overheat the joints as the steel didn't go red. It cleaned up nicely.
I’ve done quite a bit more on the frame at the time I upload this, so there are more pictures to come when I take my camera to the workshop.
Ok, So I need a jig to tack my seat tube into the bottom bracket shell.
I had all these bits..
I found all this stuff down the back of the sofa..
Then I said the magic words, “jiggy-wiggy-wamma-jamma”.
And the Wilk-O-Matic ST1 jig was born.
Complete with Park stand clampability.
Nearly got this one in focus..
An adjustable parallel is used to shim up to the height of the seat tube just as it exits the BB shell. The base is a precision straight edge. I had this side of it clocked at work at less than 0.1mm error over 1 metre.
The screws lock the adjustable parallel at this height. I had to make sure the tube was sitting flat on the top of it.
Then I moved the parallel to the other end of the tube and insert it into the slot I cut to allow it to sit on the flat surface. I close the toggle clamp after adjusting its set screw and locknut to give the correct downward force and travel.
Detail of angle bracket with brazed reinforcements. I stuck some cushioning clear rubber, the type you use to protect bike frames from cable friction or chain rub, underneath the bracket to protect the flat surface. It's self-adhesive and stuck to the bracket.
I had just enough room to double-check along the top with my surface gauge.
Both ends matched for height.
I made these rectangular washers out of some 3mm stainless bar so they would sit in the gap and raise the nut above the flat surface, thus protecting it. I filed the edges off to leave them slightly rounded.
At the other end I made a double washer with 2 holes for the bracket bolts.
All in all, I’m happy with the jig, but I have to be careful not to drop the adjustable parallel on the concrete floor. Perhaps I can improve the design in this respect.
I brazed my fork crown to the steerer today.
I took this shot while filing away the excess steerer tube and silver.
I cleaned up the crown and filed the points to be crisp and sharp.
Next I mitred the seat tube with a half-round second cut file.
My tubing blocks came in handy.
Checking the mitre against the BB shell. The "ears" need to come down a bit.
View through the down tube socket. I've filed the points and the edges of the socket walls to sit at 90 degrees to the tube.
Good old John milled my dropout faces down by 1mm and gave them a near-mirror finish. Then it snowed.
Now the track faces are nice and shiny. I've cleaned up the brass and started to shape the edges to more rounded chamfers since these pictures were taken.