Wednesday, 28 March 2012

Speaking of Spokes

This week I have been repeating myself. I try hard not to do it but as I get older I find that it's an undeniable truth. I think I'll start paying the kids to poke me when they catch me doing it in public.

But I digress and that's not what I mean anyway. This week I have been making the spokes which involves a huge amount of repetition, none of it is hard or arduous but it's easy for the mind to wander when doing something for the 100th time. A wandering mind and a large hammer is not necessarily a good combination I find.

The 13 gauge spokes are made from 2.4mm (0.094") wire. The threads are rolled on which raises the crest of the thread and increases the final diameter to 0.099" (#3 x 56 UNF).
The donor wire I have used is 308 stainless steel TIG welding rods. I'm somewhat reluctant to use stainless as it isn't an original material in use in the 1880's, However in my defence, I have scoured NZ for high tensile wire in the correct size and failed miserably. It is very easy to get 2.5mm wire but this is too large for the thread roller and the threads produced are then too big. That 0.1mm does make a big difference! If I do find a source in the future, I may revisit this. for reference, most modern stainless spokes are made from 304 stainless.

The first step is to put a head onto all the blank pieces of wire. I haven't done this for a few years and it took a bit of practise to get good at producing a decent shaped mushroom. The wire is clamped between the two halves of a die with a few mm extending. This is struck with the hammer to form a head into a slight countersink in the top surface of the die.

Now having previous experience of this I was able to make a suitable die to overcome some of the issues. The first one is that the wire has to gripped very tightly. I made my die from a length of angle iron I found in my magic cupboard. By clamping a sheet of paper between the two sides of the die before drilling the hole at size, the final hole will be a very tight fit when the paper is removed. The hole should be as long as you can drill it to increase the friction of the clamp. The second problem is that as you are hammering away, the die will get deformed. I've found I can get about 20 spokes headed in a mild steel die before it needs cleaning up. It is possible to make a die from tool steel and get it hardened to prevent this deformation, these do last considerably longer but can also shatter.

With no tool steel in the cupboard, I've solved this problem 
by making a throwaway die with a series of holes, 
when one gets too munted, start to use the next one along.

A few mm extend out of the die...

...which is then clouted with a big hammer.

I found I was unable to cold head the stainless steel, I needed to heat up the wire extending out of the die with a torch before hitting it with the hammer. This is not ideal as the resulting heads will be weaker. Time will tell.

The raw spoke heads out of the first die.

The heads at this point are all over the place, functional but very irregular and just a bit crap. Mr Middleton would have been fine with them but my OCD (according to my lovely wife) made me improve them.

I made another die from some tougher 4140 steel, this die is not split but has a slightly larger hole and a countersink (actually both sides were used since it still got munted from the hammering).

The second die.

I then poked the spoke through the hole and held the head up to the 
side of the bench grinder. By twiddling the spoke around in the hole 
I was able to make the heads round (rounder anyway)

Then resting the die on top of the larger vice the heads are hammered down 
into the countersink, producing a far more even, consistent head. 

Next step is to calculate the length of the spokes using a bit of trig. I did this twice on separate evenings to check that I'd got it right before I did any cutting.

Finally roll the 13 Gauge threads onto the other end and we're all done.

I didn't think I had a 13G thread roller but my magic cupboard produced the goods once again.

The finished spokes.

The rims have finally been painted, but with the colder weather, the paint is not drying as well as I'd like. I'm itching to build the wheels up but I need to be patient.

In other news, my lovely wife is to have some fairly major surgery next week. Obviously, I am incapable of looking after her and the children unassisted so my Mother-in-Law is coming for a month to help out. We are all very excited about this as you can imagine. I have been given a very long list of "stuff which must be done". I suspect that if I haven't got the wheels built by then the paint will be fully cured by the time I do get around to it. We will see.

Le race is on Saturday. I realised last night that drinking beer and watching the TV does not constitute "training". I'll do 20km tomorrow night after work, that'll do.

Thursday, 15 March 2012


Last time I mentioned that I was going to start work on the rims. Now, whilst this statement was true, I may have misled you slightly in that I didn't tell you that I already have the blank rims. A company in Christchurch makes hollow rims for antique machines and they had already made me a set in return for some pin striping that I'd done for them.

Their method is simple and produces very strong, medium weight rims. Two tubes are rolled to hoops, one hoop of a very slightly smaller diameter than the other. The smaller hoop is then cut in half around it's circumference to form the inner part of the rim, this is welded to be a closed loop of a U section. The larger hoop is now nestled into the U section and MIG welded around the circumference on both sides. The excess outer half of this hoop is then cut off and the welds dressed off. The rims end up slightly heavier than they need to be and are a bit functional but getting them made has saved some time. For future projects I'll make myself a proper rim rolling machine, I'll probably replace these rims then.

You can now see the relative sizes of the wheels, 
very different from the contemporary high bicycles.

The first job is to mark the locations of the spoke holes. As I mentioned before, I'm using 50 spokes in the front wheel and 30 in the rear.

I made up a full size template of the rims with the spoke locations
marked and simply transferred the marks across using a square.

With a hollow rim of a fairly thin gauge it is important to ensure that the spoke head or nipple is properly supported so that it doesn't pull though in use. Two methods were used, the first was to drill through both parts of the rim and support the head in a counter sunk part of the outer surface, immediately under the tyre. The second method uses a curved washer or profiled support to prevent the tensioned spokes pulling through. 

The current rims are more like the Roadster profile. 
I'll eventually make some more like the Racer

The curved washers used on Westwood rims are for the same purpose.

I'll be using the first method, a counter sink can be easily achieved by drilling a small hole and using a centre punch to produce the shape required. A little practise in some scrap gave me the size of hole to drill and the weight of the hammer blow to end up with a decent counter sink with a hole of roughly the correct size for the spokes. This approach does have the added complication that the holes have to be drilled at the correct angles rather than just radially through the rim, so I made a simple jig to hold the rims whilst drilling.

I had to move the drill press down to the floor as I 
didn't have enough clearance above it to the ceiling. 

First centre drill every other hole and then flip the rim over to do the other side.

Then drill the small pilot hole through both layers of the rim, 
this has to be done very carefully and at the highest drill speed as the second 
surface is convex to the drill and it will wander and break very easily.

then using a supporting block under the rim, hammer the counter sinks 
into the outer edge using the newly drilled holes as the centres.

Finally put back onto the jig and drill through at the correct size for the spokes.

Then clean up both rims ready for painting. 

I hadn't decided on a colour for the bike and had assumed it would be some sort of deep red (naturally). I asked the advice of my wife (resident soft furnishings and interior decor expert), she immediately vetoed me and said it has to be black. She even got one of my catalogues out to prove the point. She is of course correct, wives always are, it will be black with either red or gold pin striping. My favourite paint has always been Tekaloid coach enamel. The formulation changed from linseed oil to Alkyds at some point but it sprays and brushes on equally well, most people are surprised when presented with a deep, even finish to learn that it has been applied by brush. Tekaloid can be cut and polished back when completely dry to a high lustre. It is an entirely appropriate finish for an antique cycle. Sadly, of course, I cannot obtain Tekaloid in NZ. Resene, however, sell an old fashioned alkyd gloss enamel of a similar type. It has a high VOC value so I suspect it will not be available for too much longer. I've been spraying it with a breathing mask in my spray booth (an old, disused outside loo) with good results. Depending on the weather, I'll try and get a few coats on this week.

In the meantime. I'll start work on the spokes.

In other news, I've just entered Le Race again. I haven't done it for a couple of years now and it will be interesting to see how an old, lardy retro grouch manages. I don't think I'll be troubling the judges this year.

Wednesday, 7 March 2012


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.