It all comes together

As mentioned last time, I wanted to get all the outstanding brazing work completed before I went back to work in the new year. I'm now back at work but I'm pleased to say that I did manage to find half a day to go and hire the oxyacetylene and get the bits stuck together.

I'd accumulated quite a pile of bits ready for brazing and it was good to get them all attached to each other at last. There are 5 sub assemblies to be brazed:

The new bolts into the cantle plate.
The bolts into the spring carrier
The saddle post clamp
The lever pivot castings to the end of the fork legs.
The individual handlebars into the head and attaching the brake lever pivot.

I only made jigs for the handlebars and the lever pivots, the remaining assemblies being too simple to require holding, this proved to be a mistake as I'll explain later.

The handlebars and brake pivot are held in the correct locations with some very special frame building pins - old nails. unfortunately, I drilled the holes very slightly too large and the pins have a tiny amount of movement, this meant that the individual handlebars could move relative to each other and could end up not being aligned. I solved this by zip tying the bars to a thick sheet of MDF to maintain the alignment.

The lever pivot jig needed to be more complex and accurate, the pivots need to be concentric, parallel and correctly spaced relative to each other. They also need to be parallel to the main bearing housings. I recycled the old jig used to braze up the main bearings and with suitably machined spacers I was able to hold everything securely in the correct locations. I had to be careful brazing these castings as I had already had them nitrided and I didn't want to affect the hardness of the bearing surfaces. My idea was to use a large lump of steel as the spacer, this will double as a heat sink and hopefully prevent the inner races from getting too hot. I also tried a new brand of 45% silver solder this time, this has a lower melting point and should flash in quite quickly. I intended to go in quickly with a hot flame and spend as little time as possible heating the castings.

As always the first job is to thoroughly clean and degrease the surfaces to be brazed and then flux and assemble into the relevant jigs. The actual brazing went really well and the lever pivots are firmly attached and still hard after the heating. I've only cleaned up the handlebars and lever pivots so far, the saddle components have yet to be done.

For the first time I can now assemble all of the parts made to date. The sun gear still has a lot of material to be removed and the planet has nothing to attach to yet. The total weight at this point is 33lbs 14oz (~15.4kgs) which is on target as per an original.

It is great to have the basic bike together after all this time. As I mentioned before, I didn't use a jig to hold the saddle post mount and consequently it has come out at the wrong angle. It's only 5 degrees off but it will affect how and where the saddle sits and to my eye it just looks wrong, it not being parallel to the fork legs. You may remember that I wasn't completely happy with it when I machined it up. I'll make another one at some point.

Next week, I'll continue with the saddle.

In other news, we've had a little weather this week. It's been quite varied with snow on the Lindis Pass, very heavy rain on the West Coast that took away a few bridges, a tornado in Ashbuton and very hot Nor'West days like today. It's almost like we've had 4 seasons in one day or something. Hey, somebody should write a song about that.

Alchemy

I am in possession of a secret formula of such value that I hesitate to mention it in a public place such as this. The formula is handwritten and ancient and has been passed down through the generations. The origins of the author are lost in time although I believe that he was a chemist who lived far north of here. The formula would have been lost were it not for the sharp eyes of a friend of a friend of mine as he sorted through the dead chemist's notes.

The formula gives the keeper the ability to turn base metals into nickel plated base metals.

I would love to be able to say that I've been using this secret recipe for years to do all my nickel plating, but the truth is I was only given it a few months ago and I haven't tried it yet. I've been using a commercially available kit for over a decade with excellent results.

This past week I've had an interesting discussion with Tim, an English friend of mine. Tim and I share the view that modern, bright shiny nickel is not an appropriate finish on antique cycles. The nickel plate of old was more mellow yellow than the hard bright finishes available today. This is what originally led me to try my own nickel plating. Old nickel is often quite dull, more of a satin finish. I note with interest that Frosts now sell a dull nickel kit on the above link. If you live in England it may be worth giving this a try. Some of the dullness and colour of old nickel is partly due to the years of oxidisation and environmental pollution. I've experimented over the years with chemically accelerated ageing of fresh nickel. I own a copy of  "The Colouring, Bronzing and Patination of Metals" by Richard Hughes. This huge volume was my own starting point in this adventure. My most recent experiments have involved using the natural geothermal hot springs here in NZ. Some of them will turn any nickel coins in your pockets black. Geothermal hot springs are marked on the topographical maps with a red cross, further experiments will follow...

As an aside, it is an easy matter to 'turn' chrome plate into nickel plate. Chrome plating is always applied on top of nickel plate (which may or may not, in turn, be on top of copper plate). The chrome can be stripped from the nickel with no harm to the nickel by dissolving the chrome in hydrochloric acid (also known as spirit of salts or muriatic acid). I usually dilute my acid (add acid to water, not the other way around) and leave the components for about 30 minutes, then dunk into a strong solution of baking soda (an alkali) to neutralise the acid and prevent rusting of exposed threads etc. Rinse with fresh water and you are done. by the way, HCl is truly horrible stuff, do this at your own risk and use lots of PPE.

So this week I've been polishing and plating all the bits made so far.

Polished, ready for degreasing.

Polishing on a high speed rotary buffer is hot, dirty and dangerous. The potential to loose fingers is high as is the potential to have your exquisitely made components flung randomly around the workshop at high speed. You need to be careful, very careful. And alone with no distractions.

Cleanliness and preparation is everything when plating, the actual process is just chemistry.

Note the dull finish, I've spent ages trying to perfect this.

Plating adds a very thin layer to the base metal, usually not enough to effect clearance except where tight clearances are already designed in. Threads usually need a quick clean out after plating.

Soft soldering the flanges onto both hubs, 

note the three threaded wires installed to ensure 

that the flanges are timed correctly relative to each other. 

The temperatures used for soldering with lead are much lower than will effect the temper of the hard hub centres so this is safe to do.

The completed hubs.

The rear hub is familiar as being similar to a modern front hub. The front fork legs need to be sprung apart to install the front wheel when it is built, being 4130 this is possible without fear of bending or breaking. Assembly is then as described before. 

This is the first time that the front hub bearings have been assembled 

with the flanges in place and you can now just see the labyrinth seal 

formed by the recess in the flange and the inner bearing race.

In this photo I've installed a pair of threaded wires 

of the same length as the spokes to check that 

I have the spoke angle in the hubs correctly calculated.

Next week, I'll start work on the hollow rims.

Brazing the Front Forks

As promised last time, I've been directing my efforts at getting the front forks brazed up. There seemed to be an endless list of things to do before I could light up the oxy-acetylene though. I needed to hollow out the stubs that extend into each of the tubes. As mentioned before this is for several reason, firstly it helps to prevent cracks forming at the junction of the stub and the tube. Secondly it makes the brazing process easier as a large mass of material that is hard to heat is removed, this helps to prevent overcooking the tubes. And last is the obvious weigh loss from removing metal. In this case, hollowing out the 6 stubs (2 per 'knee' and 2 on the head) removed a pound of weight (0.45kg). Not insignificant.

However before I hollow out the stubs, I need to stamp the top of the Abingdon Ball Head with the appropriate patent information. I need the stubs to be solid to support the hammer blows required to do this. I admit to putting this task off for ages, the potential to completely screw it up is high. Every now and again I'd have a little practise on some scrap until I had developed a method of working that reduced the chance of errors. I was still shaking when I struck every letter and number though. The hard bit is to get the individual letters to be correctly aligned vertically with respect to each other and correctly spaced. My method is simple, I use 4 layers of masking tape to define the lower edge of each letter or number, placing each stamp onto the surface of the workpiece and then sliding until it contacts the ridge of masking tape. With practise, it becomes easier to apply the same pressure against the tape and the letters then line up with each other. To get the spacing correct, I mark the tape ridge at the correct intervals and then line up each stamp with the next mark.

It is worth noting that letters or numbers with less area, such as I and 1, require a lighter blow

 other wise they appear over struck compared to larger letters.

The results aren't too bad although the I is too far to the right,

I'm not too bothered as the original is also clearly hand stamped.

With this onerous chore out of the way I can now hollow out the stubs. I very roughly drilled and milled out as much material as possible before getting stuck in with a carbide burr mounted in an air die grinder. I bought a cheap Chinese die grinder that will run at 25,000 rpm without over running my compressor too much. Think of a dentist's drill on steroids. You really do need those high rpms when removing steel. It is a truly horrible job and results in thousands and thousands of razor sharp needles of steel *everywhere*, regardless of how carefully everything else is covered up. I've been digging steel splinters out of my fingers (and feet!) ever since despite wearing a ridiculous amount of PPE.

Roughly removing as much material as possible...

...before getting the carbide burr out

A pound of steel was removed from these 6 stubs.

Now I need to make a jig to hold everything in the correct location whilst the heat is applied.

I happened to have some angle iron in my magic cupboard, so this got chopped up... 

...and with some 10mm threaded rod, I can locate all the bits in a frame that doesn't move.

I used 40% silver solder to keep the heat on the 4130 chromoly tubing down. Silver solder has suddenly got really expensive, still I only need the one kidney. It all appears to have been successful with good penetration into the joints and very little distortion from the heat, although one of the blanks in the bearing house was *very* hard to get out afterwards. Fortunately I had previously made a 1.75" x 26tpi tap and had it hardened for exactly this eventuality and I was able to clean out the threads nicely.

This week I'll clean up the joints and mill the slots for the locking tabs. Then I can continue with the gunmetal flanges. Then I can make the spokes... etc. I've set myself a goal of having the frame sat on it's wheels inside of a year. I'm already 6 months into the project and more or less on track.

In other news, I've finally managed to arrange a small aftershock for my parents, We were having dinner in Christchurch and were rudely interrupted by a vicious little 4.6, I don't think they liked it much. We also had a nasty little swarm last night but fortunately my parents are away on a tiki tour of the West Coast this week. I'll try and save a few for their return.

In more other news, someone seems to have stolen summer this year. We haven't had one yet, does anyone know where it is?