Wednesday, 9 November 2011

The Neck Hole - head part 4

For various reasons I've not had much shed time this week although I have managed to nip in every now and again. Enough to make the hole in the back of the head for the neck to insert. Compared to the earlier Stanley type head with plain cones, the cutout appears to be much wider. This is because it is. The extra width is to allow the bearings to be inserted. On an Abingdon ball head the bearings are attached to the neck and the whole assembly inserted and locked into the head. This assembly is 1" wide so the width of the cutout has to be a corresponding width plus clearance.

This illustration is from 1887, a year after the patent
I had originally intended to drill out the bulk of the material and then mill the edges clean. In the end I just milled the whole hole, this proved to be the easy part.

It's hard not to mill away part of the threaded rod securing the head to the  vertical slide
Since the mill couldn't remove all the material in the lower corners, I needed to file these to shape. This proved quite time consuming since I had less than half an inch travel on the file tip only. These lower corners are also slightly flared to provide a smooth edge for the neck on full lock (the head is tapered and the neck only contacts at the bottom edge).

The original

My copy. I was pleased that the counter bore has come out really well,
this is the first time that I've been able to see it.
The observant reader will notice a difference between the head of the original machine I am copying and the head I have made. The original is a rare pneumatic model, that was made for 1 3/4" Boothroyd or Dunlop tyres. (I need to do some more research on this). Clearly these new fangled pneumatic tyres are significantly wider than the older solid tyres they usurped. This meant that a new head casting was needed. No need to produce a new neck casting though if a relief is made at the back of the new head to mimic the dimensions of the original size. This is what the curious shaped cutout is for, it allows the original shaped neck to be retained with no modification. Notice in the illustration above how closely the neck follows the head casting at this area. I have only personally seen one such pneumatic geared facile although I know of one other. My geared facile will have 3/4" solid tyres so I am using the dimensions of the solid tyre head rather than the pneumatic head. I suppose I could make some 40" pneumatic tyres but with my shed time as limited as it is, I'll go with solids.

In late 1891, Ellis & Co. and the Crypto Cycle Co. merged under I.W.Boothroyd as Managing Director. Boothroyd was a firm proponent of front drivers and continued to manufacture various models of crypto cycles right up to the late 1890's. Interestingly, the Boothroyd patent tyre was the design that became universal in the USA (single tube) after being promoted by Col. Albert Pope whilst the English preferred the infinitely superior separable inner tube designs (of which there were many). By this time the company was only offering cushion tyres (1" or 1 1/4") or pneumatics, solid tyres were all but gone. This table illustrates the rapid rise in popularity of the pneumatic tyre at this time.

Cycling by H H Griffin, revised second edition 1893.
As with all pictures, click for a larger image
In other news, we have much sadness in the house now that the grandparents have gone home. We all went mountain biking at McLeans Island  to cheer us up. My daughter flying off and leaving us in her dust. I was on a tandem with my son and and we couldn't keep up. Obviously due to the lack of manoeuvrability and extra inertia, obviously. Just last week she won every event in her school sports day except for the discus. She is built like a racing snake though. One day she'll be faster than me on a road bike. I'll think I'll probably take up golf at that point. My in-laws have left their golf bats in the garage for me to look after, have they recognised this already?

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