The Abingdon Ball Head - part 2

Spring has sprung, the grass has riz.
I wonder where the birdies is?

etc.

In stark contrast to last week, Spring appears to have been switched on at last. The birdies in the above poem (incidentally not by Spike Milligan as I always thought) being magpies. We are nearly in the attack season again, I know this because I had one shout at me last weekend, next weekend he will be dive bombing me. But I digress.

This week I have made the top lock nut for the ball head, I have chosen to make the flush variant as I won't be using a lamp bracket mounted on the head. The original I am copying does have a lamp bracket as did the Percy Nix machine in the Coventry museum. This machine was used for the 24 hour race and would certainly have required a lamp for the night time part of the event.

This is a photo of the bike taken in or prior to 1931 (when it was in the Sammy Bartleet collection) 

and the lamp bracket is clearly visible. From Bartleet's Bicycle Book, 1931

The bracket has now disappeared as in this photograph I took just a few months ago of the same machine.

But this is what the flush variant looks like, neat eh? 

The Upper example is an early geared facile and the lower is a non geared model, both by Ellis & Co.

Machining the lock nut just involved simple turning and screw cutting 

plus a little indexing to get the holes in the correct place.

Now I can mount the completed neck into the head itself and establish

a) the length of the backbone to provide the correct inclination of the forks, this effects the trail of the machine and consequently how it handles.

b) the correct angle of the backbone to maintain an even gap between the wheel and the backbone. Although saying this, I have seen backbones on originals all over the place, some are very closely fitted with an even gap and some are not. Of the various originals I have now seen and measured, I have yet to see two the same, a remark echoed by other collectors that own these machines.

The angle of the forks likewise seems to vary hugely, the very early machines are more upright, something that is clear in the advertisements and literature. I've measured several from 1887 that have as little as 5 degrees inclination on the forks. This is in contrast with younger bikes that have up to 16 degrees inclination. The anomaly here is the racer from 1888 that has a full 20 degrees, this would produce a high trail value (for the period) that would be more stable at higher speeds with more rider fatigue. This is just my theory at present, I suspect it could probably be able to be ridden hands off.

As an aside I am currently reading the excellent new book on Dan Albone and Ivel cycles by Ray Miller and Lee Irvine (ISBN 978-0-9566337-4-3 available from the VCC UK). In chapter 5 Ray discusses how in 1886, Albone invented the first rear driving safety that could be ridden hands off, the discussion mentions the steering geometry being responsible but no actual mention of the trail. A friend of mine owns an 1887 Ivel safety locally (it is photographed in the book). Next time I see it, I'll measure the trail and report back. Clearly, steering geometry was beginning to be understood a little more by this time and I see no reason why Ellis & Co. wouldn't have adopted the current thinking at the time to slacken the head angle to provide more trail. I have decided to use an inclination of 16 degrees (the same as the original I am copying) which will give a moderate amount of trail.

The next job is to file the stub on the neck casting to be a very accurate fit into the backbone. I have made a little jig from part of the off cut backbone, this jig is coated with engineers blue, an evil substance that will coat everything within a 100 metre radius if children and cats are allowed into the workshop at the same time as the tube is open. The idea is that the backbone is placed into the jig and the high spots are marked by the blue, these high spots are then filed off and the process repeated. Great care being taken not to twist the casting relative to the jig. This took many hours, but the care has paid off and I now have a very well fitting backbone that should braze easily.

The jig to mark the high spots on the casting, 

shortly before engineers blue covered everything.

File off the marked high spots and repeat. Carefully.

Eventually, an accurate fit is obtained.

The backbone can now be cut to length.

A little trigonometry to ensure the forks are inclined at the correct angle before any cutting takes place. 

Ensure that both wheels are on a horizontal surface and the above chart is taped vertically 

to the wall behind the bike, then simply line up the forks with the chosen angle by line of sight.

Measure twice, cut once.

The tube has been left slightly proud of the edge to assist in the brazing process.

It will be filed flush afterwards.

The final job is to hollow out the stubs for all the reasons previously stated.

At last we can now do a dry assembly to see how it all fits together.

Still to do on the backbone is to make the step which is a simple folded piece of steel brazed to the left fork leg. I also need to drill and tap the holes in the rear fork crown to allow a mudguard to be mounted.

In other news, I have promised my lovely wife that I will build her a new deck when spring arrives. I fear that my shed fettling will have to take a back seat for a period if this good weather continues. I did try to bribe my brother to come and build it but he pretended not to hear me.

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.

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.

Bearing All

Last week I mentioned that I would take my pretty patterns to the local steel foundry. Unfortunately my foolhardy foundry foray floundered. The foundry wasn't at all interested in a small run of one offs. I still have a couple of less local options before I try even farther afield, this will all have to wait until the new year though as New Zealand stops for a month at Christmas for the summer holidays. If this fails then I'll just have to fabricate the bits from scratch rather than cast them. Sigh.

Also, I went to pick up the tubing for the backbone from my local supplier. A piece of 1 3/8" 0.049" chromoly that I ordered two months ago. It seems that my supplier isn't. I'll have to look further afield for this as well. Trying to use local companies can be too trying.

So, in the meantime I'm going to start work on the wheels as a complete break from the recent disappointments. The front hub has a most complicated arrangement of bearings, featuring a double row of balls per side and then a live axle running concentrically through the hub on a pair of bearings. The hub has 6 bearing surfaces that all have to be concentric, I'll need to plan how to machine this carefully.

However before I can start on the axle, I need to make the bearing races that screw into the bearing housings, the knees, previously made.

Starting with a lump of 4140 steel that happens to be ground at 1.75" already

Centre it carefully and cut a 26tpi thread along enough of a length so that I can make all four races without removing the work from the chuck so that the threads and the bearing surfaces are all concentric.

Checking the fit.

Bore a big hole using my fabulous new boring bar.

Rough out the bearing surface as a plain bore with a 45 degree bevel at the inner end. 

The idea is to minimise the amount of material to be removed by the form tool as much as possible. This photo is from the second bearing off the bar as I forgot to take a picture of the first one I made.

Then use a form tool to profile the bevel to a radius of the correct size.

 The picture makes this look easy but in practise I had a nightmare on this job. Using a form tool on an external surface is hard enough what with all that chattering going on distracting you, but internally it all gets harder still, literally. I initially used a ground piece of HSS as my form but found that if it rubbed even a little, then the 4140 work hardened and I got extra grumpy. I had to use carbide to prevent this and slow the lathe right down. Carbide plus slow is not a normal combination, but it works really well in this application. Note that I also had to relieve the tool holder to prevent fouling on the work piece.

With the form cut I can then polish the bearing surface.

I'll need to do this again after I've had them hardened.

Then part off each bearing with enough meat left to clean up the inner, parted off, edge.

The inner races have an extra flange extending inwards, 

this forms part of a labyrinth seal with the hub flanges, more later.

I still need to machine the castellations on the outer races that allow the adjustment to be locked. I'll need to figure out a set up for that on the ever versatile Myford.

In other news, I've set up a small work bench with a vice in another part of the shed for the kids to play with. I'll get them a selection of tools for Christmas and let them cut off digits at their leisure. They don't read this blog, so I won't be spoiling any surprises.

Note that the vice is on the left, both my kids are sinister despite my wife and I being dexter. 

Weird eh?

Patterns

This week I've been making pretty patterns in my shed.

I use patterns most days in my job, but I don't mean that kind of pattern, I mean casting patterns. Although of course it amounts to the same, something easily repeated.

You may recall that some weeks ago I requisitioned Mr. Middleton's wood lathe to turn up the blanks from some 'donated' apple wood.

Part payment for my appalling injuries sustained whilst at Mr. Middleton's house.

I've spent a little time removing some bits and adding some more to make the final shapes. Isn't it quick to make stuff out of wood? I don't do it very often but I quite like woodworking. I often think that working with metal is digital or binary in that what you make is either right or wrong, it fits or it doesn't. Whilst wood is analogue and you need to allow for inconveniences like grain, knots and movement. Wood is a far more emotional medium. But what do I know?

I do know that I now need to clean up my workshop again as it has a pile of wood shaving instead of swarf. I think I'll bribe my children to do it for me.

Some slots to allow other bits to be firmly stuck on.

Some more bits to be stuck on. The filler to radius the corners is a two part epoxy resin.

The elliptical profile has been left oversize to allow for shrinkage and to make adjustments
 when filing to fit the  backbone. The sealer is also a two part epoxy compatible with the filler.

The paint is just an automotive primer.

I'll take these to the local foundry next week and see what they say.

In other news, last weekend was the Santa Parade here in Christchurch. The route was different this year as the traditional route has been somewhat munted by the earthquakes. We were invited to take part as usual on the antique bikes and we had a good turn out this year with quite a few younger riders which is good to see. The weather was as hot as it always seems to be for this event and the crowd was as big as usual despite the route change. An estimated 100,000 people lined the route.

This bit is actually part of my commute, Usually more cars, less people, different bike