The Abingdon Ball Head - Part1

We've had some weather these past few weeks. Sadly it's not been of the kind that makes cycling enjoyable. This means that my shedweeks have been slightly more inflated than usual and consequently I've been busy. There are lots of photos for those that are hard of reading.

Do you recall the patterns that I took to the foundry some time ago? I received the castings back quite a long time ago, I just didn't get around to doing anything about them. Or telling you.

Freshly cast and very hard.

I've had them cast in p20 which has a similar composition to 4140 chromoly. p20 is classified as a tool steel (it's used for mouldings) and since the castings are small they have cooled quickly and become chilled. the castings were hard, too hard to machine so I took them to the heat treatment place around the corner and had them annealed. They were Rc52, they are now Rc31, still too hard for high speed steel tooling but OK with cobalt or carbide. I know this through experience after burning several HSS drills.

The first job is to make the Abingdon ball head so I can get the neck properly located in the head. This will then enable me to file the backbone stub to the correct angle so that the backbone will sit at the correct angle to the wheel.

I've been doing a little more research on the Abingdon ball head and it turns out that it was patented by Isaac Watts Boothroyd (of Ellis & Co. and later Crypto) and Philip Louis Renouf. I need to to do some more research on Renouf, his name pops up repeatedly in the 1880's. So it seems that Ellis & Co. the makers of the facile, invented the ball head and the Abingdon Cycle company then made it under license and also supplied it to other manufacturers. I have recently got hold of a copy of the American version of the patent (as stamped on the head) and when I figure out how to do it it, I'll make it available for download.

The American patent for the ball head, the text references 

the English one by number, 3294, as stamped into the head.

The original facile had all the correct pieces including the lamp bracket which mounts on the head by a lock nut on a lock nut (this will become clear). There were two options for the first lock nut, you could either have one flush as in the patent drawing or have one proud so that the lamp bracket could be mounted around it.

The original components.

As usual here is a series of photos describing the steps taken to machine all the bits.

mark the centres on either end and drill through, 

even using cobalt drills this wasn't easy, I ended up using carbide drills.

Then create the 60 degree inside cone on either end. I bought a special cobalt cutter for this, it was very expensive and I haven't told my lovely wife yet.

Next make the bearing cups that fit into either end. These each contain 10 x 5/32" balls and I needed to do some calculations on these to ensure the wall didn't become too thin.

Rough out the inner bearing surface.

Then machine and polish.

Finally, create the 60 degree cone. Part of by drilling through.

Then make the axle and the top cone, washer and lock nut.

Turn the axle between centres since it was frequently removed to check clearances.

Rough cut the thread and clean up with a die.

Mill the flats for the lock washer.

Turn and thread the cone.

Then knurl the outer edge and part off.

I hate knurling, it's a brutal, unsophisticated process.

Machining the grooves in the lock nut with a slitting saw.

Actually two slitting saws mounted side by side.

The component pieces.

The complete assembly then fits together in the same way as a pedal axle.

It takes standard ammunition...

Next week I'll make the top lock nut and file the stub to fit the backbone.

In other news, my lovely wife celebrated a significant birthday (-1) this week. In the usual manner I had asked for a concise list of potential presents well in advance. She wanted one of these, specifically the simple, non digital version that the Queen has. This is just as well since New Zealand is a simple, non digital country that the Queen has. It is possible to buy them in Australia but not here. I contacted the parent company, who have an office in Auckland, and asked if it was possible to buy the analogue version anywhere in NZ, they promptly replied that no you can't buy the analogue version in NZ because we don't have digital radio yet. I didn't reply.

I have ordered one from England and it will be arriving real soon now.

Spoke Flanges part 2

This week I've been drilling and tapping some holes, quite a lot of holes actually. Which in itself is an interesting question, how many spokes does a geared facile have? There doesn't seem to be an easy answer. I've conducted a survey on my own original sources which includes original photos, catalogues, adverts and machines that I know have original equipment. I've disregarded restored bicycles where I either don't know or suspect that the equipment is reproduction. Front wheels can have 50, 56 or 60 spokes with 50 being the most common, rear wheels can have 24, 28 or 30 with 30 being the most common. Also bear in mind that wheel sizes varied, with the front wheel offered in 36", 38" and 40" throughout the 5 years of manufacture, The rear wheel size varied with age, earlier bikes having a smaller rear wheel of 22", later bikes 24". I don't yet know if the rear wheel size varied with front wheel size. The machine I am copying has 40" front and 24" rear wheels with 60 spokes front and 30 spokes rear, this is a pneumatic bike though and Ellis & Co. may have felt that the new fangled tyres required a  stronger wheel. I have decided on 50 front and 30 rear, which is a common combination, it also has the advantage that both wheels have the same spoke spacing at the rim. Aesthetic reasons and all that....

So the next question is what gauge are the spokes? Fortunately this is handily stamped on the flanges.

60 x 13 gauge spokes. 

The remains of the original spokes measured 0.093" x 56tpi they are also (fortunately) straight gauge with no butting. I have made butted spokes before but it adds a considerable amount of time to a project. So all I need to do is get some 13 gauge wire of a decent tensile strength and roll some 13 gauge threads on one end and head the other end. But what thread do I use for the tapped holes? 13 gauge spokes are a very good fit in #3x56 UNF threaded holes. For the record 14 gauge spokes are #2x56 UNC.

The first job is to make a mandrel with a keyway to securely hold the flanges whilst I drill and tap them.

I used a chunk of aluminium just because I happened to have it lying around. 

The important bit is to not take the mandrel out of the chuck after it has been turned, this ensures that the flanges will be true to the register and the holes will all be centred on the flange with no wandering. The dividing head is invaluable for the drilling and tapping operations.

First centre drill the flanges, then drill the through holes and finally tap the threads.

The second flange requires a little thought since the spokes holes must be timed correctly relative to the first flange, spoke holes falling between opposite spoke holes and all that. I've been indexing at 1/25 of a circle for the holes, so If I advance 1/50 and then continue at 1/25 this will all work out.

The rear wheel flanges were easier when I realised that I didn't need to make a mandrel at all since these flanges are not keyed and the holes are aligned at the time of assembly.

First bore through for the cones and then cut the mounting recess 

and the inner profile. I've tried to catch the shower of chips 

that comes off when machining gunmetal, it really is spectacular.

At this point I can remove the chuck with the work still 

mounted and remount on the Myford dividing head and drill...

 ...and tap the holes as for the rear wheel.

Then remount in the lathe and cut the outer profile and part off.

Next week I'll polish and nickel plate all of the hub components made so far at which point I can then think about rims.

In other news, today is the last day of summer. We haven't had much of a summer at all really and the mornings are decidedly cooler and definately darker. The commute this morning was quite chilly.

My daughter celebrated her birthday on Sunday, she invited a gaggle of school friends to come around and practice make up and do some shouting and other such stuff. My son and I decided to go out for the evening and watch one of the star wars films in 3D which was wasome. He wants me to make a podracer in my shed next. I bet they don't use 13 gauge spokes.