Wednesday, 28 September 2011

Bicycle Love

Is it wrong to fondle another man's bicycles? Absolutely, if uninvited. However once proper introductions have been made and an understanding of the shared passion is made, it becomes perfectly normal behaviour.

And so it came to pass that last week I hopped across the ditch to Melbourne to visit a World Renowned Pair of Cycling Enthusiasts (WRPCEs). Their shared love of all things cycling is manifested in a breathtaking collection of antique cycles, an astonishing lifetime's work. I had heard the stories. It was time to make the pilgrimage.

Upon arrival at the WRPCE household, I was issued with a bicycle to use for the next five days. The success of the trip was already assured by this point as far as I was concerned. I'd never been to Melbourne before and was hugely impressed by the place, it is an easy city to cycle around. I firmly believe that the best way to breathe a new city is to explore it by bicycle, you get to hear snatches of conversation, smell things, good and bad, and stop whenever you feel like it. If you get lost but know roughly where you need to be, you can always get off and walk. My hosts took me on some wonderful rides to local areas of interest and at the weekend organised a ride on a borrowed penny farthing to Williamstown with members of the local antique cycling group. Good company, good riding and good food. The real treat was yet to come though. The borrowed bicycle was returned to its correct place in the collection, tea was drunk and farewells said to new friends. Mr. WRPCE then suggested that I might like to try one of the more exotic bicycles in the collection.

I already knew that the collection featured an early example of a geared facile and I had already taken the few measurements I needed and many photographs. I didn't want to ask for a ride but jumped at the chance when offered. Some years ago I had previously ridden a slightly older, non geared facile and enjoyed the experience enormously. I was keen to compare the characteristics.

video
A non geared facile some time ago

The most striking difference is that a geared facile is (obviously) geared higher, this particular example has a 40" wheel with a 36T sun gear and a 12T planet gear. This makes it equivalent to a gear of ((36 + 12)/36) * 40 which is 53.3". The lever action is not intuitive at first and takes a little getting used to. After pedalling in circles for a lifetime, pedalling in arcs does not come naturally. The bike itself is in fine mechanical order and other than the usual jingly tune from the brake lever, was very quiet. I was acutely aware that this was not my machine and was extremely cautious but I felt that it would have the capacity for a fair turn of speed in practised hands. I rode up and down the street wearing a huge grin. I did however make one mistake which I regret. I rode the bike back to the collection and pedal dismounted as I usually do. Mr. WRPCE promptly chastised me and pointed out that it places huge stress on the mechanism. Clearly mortified, I apologised profusely but no harm was done to the bike. I will need to remember that tip.

Later, we rode a pair of authentic, replica hobby horses around the block. This was a new experience and it was really good fun. Although slightly too small for me, it was easy to learn to ride and I now have a new respect for these machines. I can best describe the action as akin to the easy, fluid motion of ice skating, you alternate thrusts with each leg but not furiously as I had previously imagined. You briefly pause between each stroke and can easily cover 10 metres with each leg. Not as slow as you imagine either. I'm not sure I'd want to tackle a long down hill though.

In other news, Mr Middleton had commanded that I visit the Ian Potter art centre to view a particular painting by Arthur Streeton, "The purple noon's transparent might". I had strict instructions on how to view it which I mostly managed to follow. The idea being that close up it is just a bunch of brush strokes but observed at a distance it becomes a very good painting. We all agreed (5 of us) that close by it was a collection of daubings and that at a modest distance it was OK. I felt a little foolish for dragging all these people in here just to view this. It was only when viewed from right across the room that it began to look really good, the water in the lower left of the picture took on real depth. We all agreed that actually it was quite good. But what do I know? I fettle chunks of steel for fun.

"The purple noon's transparent might"
I may possibly have improved the painting when nobody was looking

Wednesday, 21 September 2011

Filing

I have sore fingers. Since I spend many hours at a keyboard this has made the working day even more fun than usual. Most of my shed time this week has been spent making powdered steel. I don't actually want the stuff, it's just an inevitable by product of shaping metal. I also made a lot of swarf, I don't want that either.

The first job was to make the upper and lower legs fit nicely onto the knees. With the tangs milled to width and depth it simply meant carefully filing the stubs to the correct elliptical profile. As the correct size and shape is approached it is important to go carefully as it is quite difficult to file metal back on again. The fit needs to be reasonably snug so that the braze will get sucked up into the gap by capillary action. The upper legs were easier than the lower legs since the lower legs are tapered. One of the upper legs has a very slight twist from the rolling process described earlier, this is only a few degrees and by filing the tang to compensate, I've been able to remove the error at the top end of the tube. The result is not noticeable and will mean the head will be easier to make when I get to that part.

I treated myself to two new files this week.
Fitting the tubes
The next job is to smooth the transition between the tubes and the bearing. This is the fun part as time spent here will pay dividends in the overall appearance of the finished machine. I'm aiming for an authentic reproduction and I don't want anything to look out of place.

Rough cuts, note the tube off cuts protecting the tangs
Smoothing cuts
A lovely pair of knees. The channel in the side of the
lower tang is to allow the inner weld bead to remain intact.
Still to do is to hollow out the ends of the tangs for about half of their depth. This has several advantages other than the obvious weight loss. Firstly it will make the braze up easier as the braze will be able to flow to the extreme end of the joint more easily without having to over heat the tube. Secondly and more importantly, it removes a stress riser at the end of the tang. This was well understood back in the day, early bikes tend to have a solid stub brazed into tubes, whereas later bikes have a hole bored into it and the latest examples have feathered edges. The most obvious joint where this is a problem is where the neck casting is brazed into the backbone. Paul N. Hasluck describes the problem and the cure in 1897. This evolution can also be clearly seen in contemporary drawings.

Cycle Building and Repairing - Paul N Hasluck 1st Ed. 1897
Click for a readable view
I have experienced this issue myself when I cracked one of the fork blades on my racing penny half way around the 'Cambridge 50' some years ago. The crack was right at the end of the tang on the sharp V edge of the fork blade. Interestingly, It also demonstrated to me how squirrely that particular bike is (22bwg tubing) since I only noticed when the crack had propagated fully half way through the width of the blade. Fun to ride though.

I had to walk 15 miles because I failed to spot this early enough
With all the filing complete, I can do a trial fit up. I've made another of the male threaded blanks with the same recess and also machined off square a tube that is a snug fit into these recesses. By installing a blank in each knee and bolting up with the tube in the recesses I can ensure that both knees are spaced at the correct distance, parallel and concentric to each other.

Holes for the oilers and inner bearing locking grub screws will be drilled after brazing
The top ends of the upper legs are spaced at the correct distance for the head. The lower legs are correctly spaced but are slightly out of line with each other, probably only by 1 degree, but I'm a pedant and I'll need to correct that with some more careful filing. I won't braze anything up until I have the head machined since I'll probably need the jiggle factor of all the joints to get everything in the right places.

In other news, I managed a short ride at the weekend. Sunday was a fantastic day, so I borrowed my wife's recently completed Royal Enfield (with permission) and took the kids on a gentle 22km potter around the Canterbury Plains, we had plenty of breaks and snack stops to keep the kids and my backside happy. The Enfield was the perfect machine for the experiment and I'm pleased to report it went very well. I'll try and ease back into regular cycling over the next couple of weeks or so. You have no idea how good it felt to be back in the saddle.

I've had a request for a photo of my wife's shoes.

Red ones, naturally
She bought some more at the weekend too, she doesn't know that I've found them yet but that's OK because I've hidden a new bench grinder behind the door in the workshop.

Wednesday, 14 September 2011

Weight Watching

Apparently I have fat knees. The very kind Mr. Middleton informed me of this fact after last week's post. Now, whilst I do have a baker's cyst behind my left knee that periodically causes mild swelling, I wouldn't exactly call them fat. It appears that Mr. Middleton is referring to the junctions between the upper and lower fork legs, the bearing housings, as the 'knees'. I like this description and will use it henceforth and also pretend that I invented it. There will be no royalties.

The knees have been put on a crash diet this week. Just out of interest I weighed one of the blanks before machining, it was a hefty 1lb 14 3/4oz. (~ 872g) according to my wife's kitchen scales. Which I obviously didn't just use to weigh a dirty lump of steel, darling.

The first item to make is a male 1.75" X 26 tpi blank to act as a thread checker for the female thread of the knees. It's easier to machine an accurate male thread and then machine the female thread to match it rather than vice versa. I used a 60 degree thread form rather than a 55 degree as I don't have 55 degree tooling and BSC threads are 60 degrees. I like BSC threads anyway. During this period, the early 1890's, bicycle thread standards were beginning to settle down a little. Prior to this, each cycle company would have it's own proprietary threads that, generally, were not interchangeable with any other. This usually means that when restoring old bikes to running condition, most parts have to be hand made to suit. I use the three wire method to check when I have the thread to the right depth rather than just relying on tool feed as this doesn't take into account any radius on the tool tip.
Here's one I made earlier.


Actually that's a lie because I got my kids to help me cut the thread and bore the recess. I had one watching the dial thread indicator and the other engaging the lead screw at the correct moment. They argued over whose turn it was to do each job. Watching the dial was boring but engaging the half nuts was "awesome". Apparently. In this manner I hope to instill a working knowledge of engineering stuff that they can possibly use one day. I have fond memories of being similarly instructed in my own father's shed from a young age, but mostly I just wanted to squeak the rubber rabbit that lived in the middle of the drill bit holder.

The next job is to mount the blank onto a face plate and bore the undersized hole through it. I can't remember where I read it, but a great tip is to use old bearings as parallel spacers behind the workpiece so that you can machine right through without fear of damaging the face plate. 
A boring photo
Now without changing the setup, I can thread the bore. Due to clearance issues, I had to feed in at right angles rather than the preferred 29.5 degrees.
Note the upside down tool to cut on the backside (no topical jokes please)
of the bore so I can  see what's going on



With the thread complete, the next job is to convert the lathe to a milling setup.
This is adequate for small jobs like this but I wouldn't want to remove
a lot of material like this, it isn't rigid enough.
The male blank machined earlier becomes very useful as a means to securely bolt the blank to the vertical slide. Pivoting the blank around this central bolt into the appropriate position allows the tangs that insert into the elliptical tubes to be milled to width and thickness. The upper fork leg is also angled in from the bearing to the narrower head joint. This can be accomplished by swivelling the vertical slide (thanks Dad) to the correct angle. The elliptical shape will be filed by hand afterwards. 
Progress this week has lopped 12 1/4 oz (~ 347g) from each knee
with plenty more to remove yet
In other news, now that I'm temporarily unable to ride, I'm also having to watch my weight. I usually come in from a ride and eat everything. Clearly that has had to stop whilst I'm incapacitated. I seem to be using my lathe as a surrogate bicycle and spending more time with it than is probably healthy. Last night for example, I just popped out to the man cave for a quick spot of milling and when I next became conscious of such things it was bedtime. My wife swears that the shed has Tardis like qualities, she was not impressed.

Wednesday, 7 September 2011

Christmas comes early

Yesterday was a bit like Christmas in my shed. Except that I had to buy all my own presents and I already knew what they were. And they weren't wrapped up. The companies I used to weld the lower fork legs and laser cut the bearing housings both phoned to say the parts were ready for collection.

Q. How did Darth Vader know what Luke Skywalker was getting for Christmas?
A. He felt his presents...groan
I used Pete's Customs & Performance Ltd. to TIG the chromoly tubing. Pete has a lot of experience welding 4130 for roll cages and he was happy to take the job on when I described what I wanted, he did a first class job with a very quick turnaround for reasonable money. After explaining to Pete that I wanted to dress the welds off to almost flush and he was careful to get complete penetration. Dressing off welds like this is generally a bad idea as it significantly weakens the weld. I've taken them as far back as I need to though and the parts aren't too stressed anyway.

Lovely shaped pair of legs
After the fun and games re learning some CAD skills, I was impressed what Prometal were able to do with the resulting files. It wasn't possible to laser cut the central bore of the bearing housing as the heat build up would have been too severe for the thin section remaining. This isn't necessarily a problem though as it makes marking out somewhat easier and boring a hole won't take long. Prometal were easy to work with and happy to deal with a small order like mine. I've deliberately stayed away from the Eastern suburbs since February as I don't want to be an earthquake voyeur. It's hard not to be shocked by the destruction to the general infrastructure in Bromley, one of the hardest hit areas. We have plenty of damage where I live but it's nothing compared to this part of town.

So now I need to get busy machining the bearing housings so that both the upper and lower forks legs are a nice sliding fit ready for brazing on. Also a 1.75" threaded hole needs to be machined through the centre. The threads are used to adjust the double row front wheel main bearings. More on this later.

This week, I'll mostly be bothering this chunk of steel.
During my enforced idleness, I've taken the opportunity to collate all the diameters and lengths of steel I need for most of the rest of the bike. I nipped around the corner to the local branch of Atlas Steel and presented my list, again they were very happy to help out with a small order which should be ready in a few days.

In other news, my wife later phoned to say that she'd seen some nice things in a furniture shop. I imagine we'll go shopping at the weekend to even things out again. I have a simple rule, "keep the women in your life sweet and the rest is easy".