Tyres, Teeth & Tuhoe

I've haven't had much time to actually do much this week although I have spent time working out how to make the backbone, more on this later.

The tyres are red, they are not pink darling.

I've had the tyres fitted to my wheels, or more accurately, the tires since I've used the American system rather than the English one. The English system uses a spiral of wire moulded within the rubber. The tyre is cut too short for the rim and and inch or so of the spiral exposed on either end of the length. Then by twisting the rubber the wrong way for the same number of revolutions as coils are exposed on the spiral, the tyre can be joined and the spiral screws into itself and the gap is closed. The loop is then stretched over the rim and is held in place by tension only. This is usually OK for normal use but recent batches from the UK have been a bit crap. This is what can happen when crap rubber is used, the Rider is Jack Castor from California, he was quite seriously injured but is now fully recovered. This happened on an NZ tour a few years ago, Jack was descending from the Otematata saddle between Omarama and Kurow, notice the 'loop' forming in front of the wheel before it all goes pear shaped.

In contrast the American system uses a rubber extrusion with an empty hole through the middle, the rubber is cut too long for the rim and wire fed through the hole. The wire is tensioned on a special machine in such a way that the excess rubber gets bunched up evenly around the wheel whilst leaving a short section of each end exposed. The two ends are trimmed and silver soldered together. When the jig is removed the gap closes up tightly. The rubber used has been sourced directly from the states and is of very high quality, it wears well on our rough roads but is still grippy enough to be safe in the wet.

I painted a couple of pinstripes on the rims before the rubber was mounted. I've been collecting images of original Victorian pinstripes for years now. Every time an original machine gets restored another unique reference point gets lost. But don't get me started on that. It is surprising how gaudy some of the Victorian machines were. We tend to think of the Victorians as very straight laced with stiff upper lips and little skirts around table legs lest the men think unseemly thoughts etc.. Actually, I'm not sure that the table legs thing is true but it's a good story. The point remains though, that to our modern eyes, some of the pinstriping and painted decoration seems way over the top. The double pinstripe on each rim is common, I've seen it on many original machines.

Tax free teeth?

Also this week, I've got the gears back from the gear cutter, he has done a fantastic job and I'm very pleased with the result. I will not say if he waived the GST when I waved cash, that would be rude. They need to be lapped to polish the faces but there is also a lot of machining to be done on both gears anyway. I'll oil these and set them aside for the time being as I focus on the rest of the frame so I can get the bike sitting on it's wheels.

This week I'm going to make some more rollers for my elliptical tube rolling mill, I need to make two sets. One for the elliptical backbone and one for the rear forks. The facile I am copying is a later model and has fully tubular fork blades either side rather than the half open style of earlier machines.

In other news, the family was at a loose end on Saturday so we took a trip on the MV Tuhoe moored at Kaiapoi.

MV Tuhoe.

It was fantastic in that old fashioned, slightly naff way. Sunday's trip coincided with the 'Super Moon' so the tidal river was very high.

Oh, that's super.

I particularly liked the way we were allowed free access to the engine room. If you find yourself at a loose end, I can highly recommend it, just wrap up well if an Easterly is blowing.

The engine room complete with engineer complete with engineer's cap.

Gear Blanks

After all that geary theory, it's time to get our hands dirty again. This week I've been making the gear blanks. I had previously started the sun gear blank because I needed to machine the main bore before I built the wheel up, All that remains is to machine the special key way that locks the gear to the front hub.

These pictures illustrates the key way, 

a tapered key fits into the shaped key way and is 

drawn up the matching taper on the hub by a locking screw. 

The original that I measured came apart very easily and has obviously been apart before as the tapered key and screw have both suffered at the hands of an enthusiastic hammer owner. The key (pardon the pun) to getting this kind of interface to work successfully is to have very close tolerances and as it turns out I had two attempts at the tapered key before I was happy. I may need to make another after everything has been hardened and plated, the tolerances are that tight.

The first job is to drill a hole that just grazes the edge of the bore 

and then countersink the outer end for the locking screw to locate in. 

I actually used two end mills for this job rather than a drill.

The next job is to flip the sun gear over and mill the back of the gear 

from the hole into the bore to create the key way. 

Note that the plug to bolt the gear to the vertical slide already 

had a recess machined out. This cut has to be at exactly the right depth.

Then we can machine the key itself, first job is to drill and tap

 a 1BA hole up the centre of a length of barstock. 

The original really was 1BA, I measured it very carefully.

Then without removing the work from the chuck, remount the chuck 

on the dividing head and mill away the excess to form the correct shape.

Finally, mill the 4 degree taper, this is where the size become super critical. 

With such a short taper, if the key is too tall you can't assemble it 

and if it is too short the key bottoms out as it is tightened.

Next make the locking screw, this is just simple turning and threading with two slots milled at opposite edges to adjust it. Of course, I also needed to make the special tool to do the adjusting...

Finally we can test the assembly of the lock.

Then I just need to make the blank for the planet gear, which is also just straightforward turning at this stage. All the fiddly stuff comes later.

Gear blanks ready for the teeth to be cut.

In other news, last weekend we had a local steam extravaganza at Steam Scene. I took the kids and we had an excellent time. A particular favourite being the miniature train rides which seemed to go almost to Christchurch and back. I was examining the gearing (for topical reasons, you understand) on a traction engine when the owner appeared and asked if I was "Claudia's Dad". It transpired that our respective daughter's were friends. During the course of our conversation, the geared facile came up. I enquired where she got her casting done locally and was referred to a small, local Christchurch foundry that should be able to help. I took my patterns and a photo of a geared facile around on Monday lunchtime. Well, again, it turns out we have mutual friends and had attended many of the same events together, we just hadn't met yet. The upshot is that my parts will be cast in steel and will be ready next Friday. I'll be sure to let you know how they turn out.

In more other news, On Sunday afternoon I helped an excitable, young Tinkerbell build her faux pathracer in my workshop. She arrived laden with Jaffa Cakes (I don't do this for free you know) and we proceeded to prep the frame before using vast quantities of my spare parts. Two of her chums from the local tweed riding scene, Dylan and Pete, also arrived and helped out. We finished it off, sans brakes, and she was able to ride it up and down the street before heading home very happy. She has since added some brakes. Tweed Pete also gave me a recommendation for a local gear cutter. I'll give him a ring tomorrow.