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.