Friday, 20 September 2013

Trying to guard your trousers

I've had a disappointingly light shedweek, but I have managed to find a little time to make the trouser guard. Our American friends, who aren't as good at sailing as us, call it a pants guard. When I bought my first original penny farthing about a hundred years ago now, I thought this part was a tyre scraper to help prevent headers from stones getting jammed under the head. I was wrong and discovered the truth when I first rode the bike around a bend on a muddy road. As the wheel is steered to one side, the guard prevents your trousers, or leg, from getting abraided on the mucky tyre.

The guard on the original is a full 12 inches long, much longer than on a penny farthing. This is a reflection of the relative safety of the design, the seat being that much farther back and consequently the guard needing to extend farther back to be useful.

The original guard is bent and mangled, it is probably made from the mildest steel.

Due to the extra length of the guard, the material it is made from is important, it needs to resist bending as your leg contacts it. The obvious choice is spring steel, the same material I used for the saddle rails. Here's a tip if you need a small amount of spring steel rod, you probably already know this but you're cleverer than me and I didn't. Model shops sell it in many diameters as piano wire or music wire. It comes in 36" lengths and is cheap and easy to find. The original guard is 3/16" and this gauge is considerably easier to bend than the saddle rails.

First bend two 90 degree bends at the appropriate places.

Then squish in a handy bending jig to produce the rounded end that wraps the tyre. 
Also bend the guard to follow the tyre.

Next grind the rounded end into a pleasing flat profile.

Then the tricky bit, drilling the holes in the fork legs. 
drilling into a convex surface requires a little care to prevent the drill wandering. 
I mounted the fork legs onto the mill table and milled a flat before drilling the hole. 

A little tweaking to get the guard in the right place and at the correct angle.

I still need to heat treat the guard to remove the residual stresses from bending but I need to wait for my lovely wife to go out so I can bake it in the oven at 200 degrees Celsigrade for an hour. I'll then plate it and soft solder it into the forks before I paint them.

She nipped out tonight but caught me when she got back. 
I think I got away with it. I'll let you know next week.

So that's now the frame completed, there is nothing left to do other than stamp the serial number all over the components. Next week I'll start plating some bits and pieces and begin to prep for painting. The weather is rapidly improving here and I should be able to spray the enamel fairly soon. I do like this time of year, we're on the steep part of the seasonal sine wave and the improvements in daylight hours and temperature are rapid and noticeable.

In other news, today is our wedding anniversary, we have been married for ages now. I had hoped to have completed my lovely wife's deck but it was not to be. I'll post a picture when I've got it done, it has turned into something of an ordeal. My lovely wife visited relatives across the ditch in Sydney last weekend and I worked all the daylight hours possible to try and finish it while she was gone. I failed but I did earn considerable family credits for trying. She says I'm often quite trying, now I think about it.

Thursday, 12 September 2013

On Guard

As promised last time, I've spent my shedweek making the gear guard.

The original guard.

From the literature of the day, the sole purpose of this gear guard is to protect the gears from mud, stones and other debris thrown up from the unsealed roads of the day. By all accounts it was very effective. One reviewer mentioned that he threw a handful of mud at the guard just to see what would happen. It mostly got deflected and what did hit the gears apparently just got squished out. The guard is not designed to protect fingers belonging to inquisitive, small children. The Victorians were unconcerned about such things, at that time common sense was still reasonably common. You lived or died by your wits, unlike today where the government of [insert country of residence] manages your health and safety on your behalf. But I digress.

I did consider making a one off rolling machine to make this guard and also the rear mudguard. I decided against it at present although I may review this later.
So a quick scratch of the head and then get cracking. I approached Autobend again (they did a sterling job bending my handlebars if you recall all of that brouhaha) and enquired about bending some 1.375" thin wall mild steel tubing into the correct radius. "No problem" they said, as long as the correct centre line radius is 101mm (I think they meant 4" but I didn't argue).

By a staggering stroke of good fortune, that is exactly the dimension I require, which was nice. 

So starting with a 180 degree bend, the first thing to do is to make an indent on the bottom of the guard. This is so that the guard sits vertically when bolted to the upper and lower fork legs. The upper legs are angled in towards the head and the difference is taken up by this little indent.

Note the little cut out opposite the hole to allow a screwdriver access.

I've mentioned before that I don't like hitting stuff, I prefer squeezing in a controlled fashion so I made a little hard wood insert to go up inside the bend, this has the indent cut into it. All I need to do is then squeeze it in the vice with an external form of a suitable shape.

An indented hardwood plug...

...getting squished in the vice.

Next I need to chop out the inner part of the bend. This is not easy as you can't use a hacksaw, so I bolted a guide to the drill table and drill a series of holes around both sides. A combination of a junior hacksaw and a cut off wheel in the Dremel soon parted the two halves. I was mildly concerned that the radius would change when I removed the inner half of the bend but it stayed exactly the same.

I tried but couldn't get a tune out of this.

At this point the guard is very difficult to hold in the vice without damaging the shape. The answer is to make a suitable clamp from some scrap MDF, this has the curve of the guard cut out with a coping saw and then the inner part radiused slightly so that it sits inside with altering the shape when it is clamped up in the vice.

Cleaning up the edge with an angle grinder back to the marked line.

Then to finish the actual shape of the guard just profile the ends and tidy up with files.

Now to mark out, cut and bend the top mount, this is a reasonable simple affair.

The shape of the top mount.

Bent to shape.

Next job is to establish where the guard is going to sit on the fork legs, it has to be concentric with the sun gear so that the planet is always equidistant when purring round. Once again a little scrap of MDF with the outer radius of the sun and the inner radius of the guard cut out proved jolly useful.

The hole and the cut out are to allow me to scribe positions on the fork legs

The top mount gets riveted to the guard in the correct marked position, I use nails for rivets. My son is 12 and is now taller than me, has much bigger hands and feet and is estimated at current rates to stop at 6'6". I figured it was time he learnt how to rivet, hammering being really bad for my tendonitis at the moment.

The original riveted top mount.

My son's attempt.

I cleaned up this side.

Not bad for a tyro. He already has dibs on this bike, "When you die, can I have this?" Charming isn't it? Just because I've got a gammy hand and fewer teeth than he has, he's already started putting labels on my stuff. Sounds familiar eh Dad?

Then using the MDF jig I can mark out the holes for the screws to bolt the guard to the fork legs. The steel of the fork legs is pretty thin and even with BA screws, the thread count in use would be tiny if I just tapped the threads directly into the tubes. So I didn't, I made some little bosses, just like water bottle bosses, and silver soldered them in.

That's Boss as my kids say when describing something which meets with their approval. 
Honestly, I'm so down with the kids it scares me sometimes.

Make the holes a loose fit and braze them in. I needed to dismantle the bike to do this, it took me an hour and a half and I had quite a pile of bits on the work bench at the end.

I bolted the legs up to prevent movement as the heat is applied.

File flush so that when it's painted only you and I will know.

Finished, and no I'm not going to put it all back together just for a photo. 

I have two more holes to drill for the trouser guard, which I'll do next week.

While I've got it all apart I'm going to harden, plate and paint what I've made so far, studying the photos and my notes of the original, relatively little was plated. Each side of the handlebars, the brake components, the two gears and all the nuts and bolts are plated. Everything else was painted including the crank, con rods and levers. More later.

In other news, we've had a little storm this week. I read on the interweb (so it must be true) that we had 250 kph winds, the strongest on record. Apparently the storm was the worst since 1975 and the second worst ever. I thought our house was going to flat pack itself, we lost power and our trees lost limbs. The morning dawned beautiful, calm and smelled fresh and clean. Commuting in to work took ages due to the many trees down across roads. My lovely wife teaches at a rural school and she's still not able to get to work. They have no electrickery yet anyway.

Monday, 2 September 2013

Purring Gears

You didn't know that gears could purr did you? Neither did I until my daughter came into the shed whilst I was idly playing with the fruits of this weeks labours. She told me that they sounded just like her cat, Flabby Tabby, when she's purring really loudly. "That sounds just like Flabby Tabby when she's purring really loudly" she said. But we're getting ahead of ourselves.

So clearly, this shedweek I've been finishing off all the little bits and pieces needed to complete the gear assembly.

The first job is to drill and ream the holes through the cranks and live axle for the taper pins. I found a local company that had a taper reamer of the right size and upon enquiry sold me a handful of matching taper pins. Hoorah. The taper on these imperial sized pins is 1:48 or 1" in 4'. In practise this means that a hole goes from too small and you can't get the pin started to too big and the pin falling through very quickly. It is very important not to mix and match imperial and metric pins as metric tapers are 1:50 and the two are not compatible.

The first hole is the easy one as it is in left hand crank which is tightened up to a shoulder on the axle so there is no adjustment needed. Drill through with the appropriate size drill and then hand ream the taper, checking periodically that the hole isn't getting too big. I need enough of the small end poking through that I can cut a thread on to secure the pin.

Another shockingly bad photo, this time of hand reaming a tapered hole.

The hole through the right hand crank required a little more thought as the cranks need to be exactly at 180 degrees to each other. By fiddling around with shims and scrap plate steel I was able to come up with a combination that sat flat in both orientations thus guaranteeing that the cranks were aligned correctly.

The right hand crank was locked with a lock nut and the hole drilled and reamed.

Fitting the taper pins.

Next mark the taper pins to cut the thread and shorten to length. Which raises an interesting problem. How do you grip a taper in the chuck? My solution was to make a little doo hickey to assist me. I drilled and reamed another tapered hole in some scrap bar and then split it with a hacksaw. Each taper pin can then be inserted, lightly tapped in and when the chuck is tighten up, it grips the taper very well but still makes it easy to get out again.

A split doo hickey with a tapered hole, yesterday.

Trim the big end and cut the thread on the little end.

Next make the locking tab for the live axle bearing adjuster. As before I only briefly considered machining it before I came to my senses and hand filed it. The recess is milled, it turned out that this was the last time I used my Myford machine vice...

Hand filed locking tab.

Myford machine vice shortly before it died.

Next drill and tap the hole for the oiler in the left hand crank arm. The placement of this is critical, too far inboard and it will foul the planet gear and too far outboard and the thread will break through to the bearing surface.

A little care with the edge finder and then using the mill as a drill.

Before tapping the hole at 2BA for one of my oilers I made previously.

Note I had to use a different machine vice as my lovely Myford had an unfortunate accident. When tightening it up the screw just kept turning until the end popped off.

You can see from the oil ingress that it has been cracked for a long time. 

I will mourn this, it was in almost new condition when I got it, I even still have the box for it. Now that the original Myford company is no more, my chances of replacing it are slim and none. Anybody have an unmolested one they'd like to sell me. Seriously, I'll pay a fair price for one. And btw, I didn't make those holes in it either, that was a previous owner.

Finally, I just need to stamp the patent info into the left hand crank arm as per the original.

I used my same techniques as before and it went well...

...although the N on the second line is double struck for some reason. 
I'm unconcerned as it shows the hand made nature of these things.

Then I can reassemble everything again for a photo shoot.

Right hand side compared to the original.  
Use your skill and judgement to spot which is which.

Left hand side not compared to the original as I don't have a photo of this assembly. 
I've jammed a wedge into the gears to stop the crank hanging down, just so the text is visible.

A gratuitous photo of the complete progress so far. 

Total weight at this point is 37.7lbs which is possibly very slightly heavier than an original as per the catalogue. Although I read an interesting comment from 1879 today. Henry Sturmey was complaining that manufacturers weren't truthful with their quoted weights and from now on he was going to weigh each machine he reviewed himself. Nothing changes I guess.

Next week, I'll start work on the gear guard. I need the gear assembly to be complete for this, then I can dismantle it all again and get all the components hardened. I seem to be rapidly running out of bits to make. I'm still unsure how to do the levers though.

In other news, I've caught tendonitis in the back of my right hand. It is most painful and I'm unable do anything with it, even the simple action of using a screw driver is out of the question. Fortunately the pain from my removed wisdom teeth is mostly masking this. My hand does mean that I can't even ride a bike at the moment, I'm going insane. And getting fat.

In more other news, this last week my father acknowledged a rather unusual anniversary. It was 50 years ago that he was knocked off his Matchless G3LS by a less than attentive driver. His injuries have caused him much trouble over the intervening years. This is clearly where I get my excessive grumpiness from.

Exactly 50 years previously, to the minute apparently, this spot was a less than happy scene. 
Hey, I pinstriped that tank.

Last weekend I took the family down to Lake Tekapo for an end of winter break. the kids loved the snow tubing which is a little like an icy Brooklands negotiated on large inner tubes.

Apparently it was just as bumpy too. 

We did some excellent local walks which the kids were less keen on. However a quick game of rabbit poo snow balls soon encouraged them along. This is an unfortunate side effect of making snow balls at the end of winter when the snow cover is very thin.