Monday, 17 December 2012

Saddle Mounts Part 2

Last shedweek I made the saddle mount, the near vertical post that clamps to the backbone. This shedweek, I've made the little doodad that clamps to it and carries the saddle springs. I'm not sure what the correct name is for this part but I'll call it the spring carrier for want of a better term. It's a lovely little thing, very pleasing to look at.

Spring Carrier Doodad.

Calculations on the original facile example and a few others I have handy showed me that I could machine the shape from a 1" bar.

The first step is to mill an identical flat on either side of the bar so that the final thickness is 0.75". This was the first proper use of my new milling machine, the finish is OK but not that great at present, I'll try a new belt to see if I can even out the finish. The finish is not important in this case since so much of it is going to be removed through subsequent operations.

The next step is to drill three holes in one of the flat faces, the two end holes are tapped at 1/4" cycle thread as a temporary means of mounting to a face plate, these end holes are where the springs will be mounted. The middle hole is used to centre the bar on the face plate.

Then bore the central hole to be a nice fit onto the saddle post.

Next machine the side on profile using a profile tool. This type of interrupted cut is very hard on tools, even using small feeds. The finish is unimportant since it will be hand filed later.

Next remount at 90 degrees using an old section of angle iron. Mark and bore the cross hole for the 3/8" bolt to clamp the carrier to the saddle post.

Then machine the profile of the side.

Flip around and machine the back of the carrier in the same way.

Finish with hand files and make the 2 bolts to hold the springs and the larger one to secure the carrier to the post.

In other news, I'm being tossed on the horns of a dilemma. In our house, we try hard not to go mad on Christmas presents. Sure, the kids get a little spoilt and they get things that I would have loved as a child but I'm talking about presents to each other, to my lovely wife. Officially we have a complete spousal gift moratorium. We both agree in advance not to be silly and to treat the festive season as a time to spend together as a family with the necessary reduction in shed based activities. Unfortunately, I happen to know for a fact that my lovely wife has bought me something this year. My daughter told me. What do I do? If I buy her something, I'll have let on that I know that she bought me something and if I don't buy her something I may as well go and live in the shed until next year. I can't win. I think the solution is to buy her a present and wrap it in a generic Christmas/birthday style wrapping paper, then hide it down the back of the sofa rather than under the tree. If I'm right and she has got me a present I can whip it out and still be in favour and if I'm wrong and she hasn't broken the gift embargo, then I can just keep it until her birthday in August. Sorted.

Whatever, happy Christmas to both of my readers.

Thursday, 6 December 2012

Saddle Mount

I am a slacker. There, I've said it in public. I've had so little time in the last three weeks that progress has been slow. Also we've had a few weekends away and consequently my shedweeks have been minimalist to say the least. My focus at present is to get as many parts as possible ready for brazing. I don't own any oxy-acetylene equipment, I just hire it for half a day when I need it. This works out cheaper and safer. About a hundred years ago, I used to be a fire-fighter in the UK and I've seen a few cylinders go pop with fatal results. Acetylene is truly horrible stuff, totally safe when used correctly but lethal when abused. I get nervous just transporting it in my car. But I digress. To get value for money out of a half day hire, I like to get as much ready as possible before hand, hence the work on the saddle mount. In addition, once I've got the handlebars brazed on, I'll be wanting to make and fit the T grips. Before I can do that I need to be able to sit on the machine to position the grips at the best ergonomic angle for my wrists.

The original saddle mount.

As you already know, the backbone is elliptical which means that the seat mount clamp has to be elliptical to match the profile. It is easy to find a suitably sized round thing to use as a form when bending a round shape, elliptical things are not so common. I had a go at free bending a few samples but as I've previously noted, I'm not great at bending things and I wasn't happy with the results. The solution was to make a former so that I can repeat the bend as many times as I like. I have future projects that require elliptical backbones and I'm sure I'll be re using it.

Making the form tool.

First find some strip steel that is the correct gauge and then mill it to the correct width. I found a piece of an old galvanised dustbin that was almost the right size, I don't want the zinc plating but that's easy to resolve later on.

Place the strips into the form tool and using a series of suitable sized round things, squeeze the strip into shape.

The stages of bending the clamp to shape.

Next mark and drill the 5/16" holes for the bolts. Then mark and file the ends to shape. The bolts are 5/16" cycle thread with a slightly domed head, these will be brazed into the upper half of the clamp. Of course these need to be made from scratch, not being an off the shelf item. I used 10 mm coach bolts as the starting point, the dome being machined with my new ball turning attachment. For some reason, I forgot to take any photos of all of this so you'll just have to take my word for it.

At some point I removed the zinc galvanised finish by dunking in some acid for a few minutes. This is a violent reaction that gives off large amounts of hydrogen. I will not say if we collected the hydrogen for purposes of amusing children.

Zinc meets hydrochloric acid - violence + hydrogen.

The upright post that the saddle itself clamps to isn't vertical as you would ordinarily find on an ordinary Ordinary. Instead, it is inclined at the same angle as the front forks. You can see this on this woodcut from 1891, this is right at the end of production and the bike has more inclined forks than the earlier more upright examples.

Note that the saddle clamp is parallel with the front forks.

I've carefully measured the original I am copying and also measured directly from the assembled frame of my copy. The angle was the same in both cases which was pleasing. The saddle post has this angle milled onto one end to locate it at the correct angle on the clamp, to add extra support an additional piece is fitted around it, this piece has been filed to accurately fit onto the curved clamp at the correct angle. To hold this all in place a small bolt is screwed from underneath, the head will be filed off after it is all brazed up.

The saddle post has a flat milled on the front facing surface, I'll mill this after brazing. This is in contrast to the usual rear facing clamp found on most Brooks B70 saddles from the period.

Rear facing clamp, note the flat milled on the rear of the upright member.

Initially I thought that the clamp I measured was a 'Friday afternoon special' until I started looking at contemporary images and sure enough, the clamp is forward facing on the facile. It does makes sense when you think about it though, The geometry of the facile means that there is ample space to get in with a spanner, unlike a penny farthing, and it's out of the way when mounting the bike.

Front facing clamp, lots of room for a spanner.

I'm not completely happy with the clamp, but I'll braze it up and see how it performs when bolted onto the bike. If I need to, I'll simply make another one.

The clamp seems to be very flexible, I may need to use slightly thicker gauge strip.

In other news, I've been press ganged into being part of a works team for a mountain bike race next February. This means I have three months to get lean and fit. Over recent months I've been developing an excellent abdominal 'one pack'. Clearly things will have to change. We visited friends in Ash Vegas at the weekend and I rode the last 50 km from just the other side of Methven. The route is across the Canterbury plains and is slightly downhill all the way, I calculated the gradient at 0.6% which is nothing but boy does that 0.6% make a difference! Admittedly, I had a strong Nor'Wester blowing straight up my bottom bracket in the early part of the ride but this had died to nothing by the end. I've even ridden to work twice this week, once in 30 degrees Celsigrade no less. Last year I rode 15,000 km, this year will be much much less mainly due to injury, museum leave and badly inflamed wimp glands.

Wednesday, 14 November 2012

Handlebars - take 2

I have recently been introduced to an excellent young fellow known as Tweed Pete. Tweed Pete likes to tinker with old bicycles, indeed he is making one of these...

This is taken from Andrew Ritchie's Blog.

...and making a fine job of it too. 
This is his MkI, an improved MkII is already in the planning stages. 

In his own words, "old bicycles have bitten me pretty hard". Saying that Pete has a big shed would be a little like saying that Christchurch has had a few earthquakes. It is a most impressive shed, containing large amounts of spares parts and materials that will be useful for future projects. Or 'some old crap' as my lovely wife would call it. Like any normal man, I thoroughly enjoy poking around in other people's sheds. I'm trying hard to reduce my list of 'future projects' and I suspect that Pete is doing the same. He appears to be better at it than me as the last time I visited, he managed to get a couple of spare 1/4hp Crompton Parkinson electric motors in the boot of my car without too many complaints from me. I'll get my own back next time he comes round.

Tweed Pete recently put me onto a new source of chromoly tubing in NZ, the USP being that they sell the stuff by the foot, rather than only a complete 18' length. I found them easy to deal with and in just a few days I came home to a shiny length of plain gauge 0.75" x 0.049" chromoly tubing sitting on the doormat.

I've going to try a change of approach with making the handlebars. I have experimented and racked my brain (didn't take long) for a solution to my problem. Indeed, I've even had real engineers racking their brains to solve my problem. Engineer Dylan is another excellent young fellow that has contacts in the real engineering world. He has suggested that I get the tubing spun to produce the taper. Btw, it's worth watching that video, if only for the bloke's accent. Spinning is a bit like magic, I still don't understand it. I took my tubing to see a local spinner in his shed and he believes he will be able to do the job, The downside being that I will have to make a mandrel and I still have the problem of bending the finished tapered tubing. So before I go any further down that route I'm going to try something else.

Of the various original machines that I have seen or have seen photographs of, the handlebars fall into two distinct types, deep or shallow drop, with either pear or T grips. My dodgy back tends to prefer a more aggressive position on a bike so I'm going to be making my handlebars with a deep drop and T grips. The same as the Welsh and Austrian[1] bikes.

I've taken the plain tubing to a recommended tube bending company along with an accurate sketch of what I require.

The first attempt didn't go well as the chromoly didn't like the sharp bend.

We changed to a larger radius and all was well. 

It is interesting to note at this point what a high quality mandrel 
bend looks like like compared to a poor quality bend.

Actually that's a little unfair since to see a really bad bend you'd need to go and see Mr. Middleton.

Next I cut a sliver from the underside of the handlebar.

 I drew the shape on masking tape on a flat surface...

 ...and then transferred it to the tube.

Everybody should own a Dremel tool.

Cutting this sliver proved slightly tricky because I couldn't get in for the full length with the hacksaw. A Dremel with mini metal cutting discs made short work of this and I was able to get an accurate slice removed.

Next the gap was squished closed, this is a simplification since it is important that the round profile is maintained for the length of the taper. Simply squishing the gap would result in a sharp V at the joint, not satisfactory. Also the springy nature of the 4130 made this an interesting exercise.

Squished gap.

Then take the squished tubes into Christchurch to go and see Pete the welder again. Pete is one of the few people that I am confident outsourcing work to, I know from past experience that he understands my level of desired quality and he always delivers.

Welded gap.

I ran a little silver solder down inside the ends to disguise the inner seam of the weld, at the same time I normalised the weld zone since these will be repeatedly under stress cycles. Time will tell if they prove durable.

Finally dress off the welds and cut to length. 

Now we can see what the finished profile with a dry fit of all the parts so far. 
I can see a brazing day in my near future.

These handlebars have been something of an ordeal to make, probably the item that has caused me the most difficulty so far. Certainly they have proved very costly in terms of time and money, I am glad that they are done.

In other news, some weeks ago I read with great interest that the SOLO project has officially gone live. SOLO being "Search Oxford Libraries Online". And as everybody knows, The Bodleian is an Oxford library. I'll leave it as an academic exercise for the reader to find the appropriate link but suffice to say, there is now a wealth of down loadable material at your fingertips. For example, I have increased the number of Bicycles and Tricycles of the Year (Harry Hewitt Griffin) in my collection from 7 titles to 12 as a result. Happy hunting. Incidentally, last year I had a very rare opportunity to purchase an original pair of H H Griffins from 1883. They are both in excellent condition and in due course I will be duplicating them for general consumption. I had never previously seen the copies from 1883 before and I was tickled pink to find them. Coming soon to a blog near you...

[1] Thanks to Christian R. Conrad for correcting me. I erroneously assumed that it was in Germany. It isn't.  For some reason I am unable to respond to comments, I'll need to investigate this. But thanks, I do appreciate the information.

Thursday, 8 November 2012

Mill Mantling

This week I have been more excited than a dog with diphallia. Allow me to explain.

Some time ago I was given a milling machine. Specifically a 1976 Mk1 Dore Westbury. The mill has only had one owner from new, that owner being a retired professional engineer who had built the mill from the basic kit of castings. And a fine job he had made of it too. I just needed to go and pick it up and bring it home.

Which is a problem if you happen to live in New Zealand and the mill is in England.

My father had been given a much larger Bridgeport and had no need of the smaller mill so asked if I wanted it. I enjoy a challenge (if you hadn't already noticed) and since I know the mill well and know it's history, it was worth pursuing. So during my recent museum leave I took time out to arrange the shipping. Now, getting a 76kg lump of iron around the planet is a non trivial task which is compounded by the strict MAF regulations here in NZ. I'm not complaining about those regulations by the way, I like NZ the way it is and support efforts to protect our biodiversity. The upshot is that I couldn't make a crate myself since all the timber has to be treated and stamped and certified and documented etc, etc, etc. It turns out that there are companies that specialise in moving lumps of metal about. I used Oakbridge because I happened to see an advert in one of the classic motorbike magazines that litter my parent's house. They were very easy to deal with and for a price, happy to take on the job. That price being somewhat less than an equivalent mill would cost here in NZ. I have seen several other Dore Westbury mills for sale here but they all seem to be either badly built (they were a kit, remember), badly abused or an interesting combination of both. None of these options appealed.

I took the mill apart, thoroughly cleaned it and arranged pick up of all the pieces. That was 3 1/2 months ago. Since then the mill has been on a long cruise and I've been wading through customs and MAF forms. Actually that's a lie since a local agent handled all that for me, I'm not good at paperwork you see.

Then on Saturday, this turned up.

Inside it was this. 

When my daughter saw the pile of bits, she asked if I was going to mantle it straight away. I liked that. It isn't one by the way, I looked it up

I just needed to paint the castings, Dad never got around to it

And put it back together. The quill is a little tight and I need to take it apart 
again to remedy this, I've probably got a little paint around the edge of the bore.

I only had the one piece left over at the end which was good. 
Dad, what is this bit?

I still have to bore a hole in the top of the workbench to allow the column to drop through. And to bolt the base down. And to route the switch cable properly.

In other news, I have been in touch with Norman, a fellow old bike enthusiast from England who has been following some of my ideas for making stuff. Norman has just started a new blog to document his own experiences and I urge you to go and have a look. In particular try and help him out with an identification for his latest project.

As I have suspected for a long time, it turns out that fiddling with old bikes in sheds is rocket science. Well sort of.

Monday, 29 October 2012

Braking News

These past few shedweeks, I've been making a couple of pivotal components for the geared facile.

Specifically the two pivot mounts for the brake lever and the spoon brake. As mentioned last time, these were almost certainly off the shelf items supplied by Snell & Brown. I'm slowly making all the bits necessary for the handlebars to be brazed up, without actually making the handlebars, I'm still pondering on that chewy little problem. The success of a project like this is in the small details and as mentioned last time, I enjoy small details. Little bits like the lever mounts have to be accurate for the machine as a whole to be accurate.

The lever pivot would originally have been a casting and most likely from gun metal rather than steel. The original I am copying has traces of verdigris on this pivot indicating a copper content. Mine will be machined from 4140 steel, mostly because I have a suitable lump handy but also because machining this from solid will be quite wasteful and anything containing copper isn't cheap right now. Or probably ever again.

In contrast the original spoon pivot is certainly made from steel, it is a tricky little thing and while I don't need it in order to finish of the handlebar assembly, it makes sense to make it at the same time.

Notice the greenish verdigris on the lever pivot and the rust on the spoon pivot.

As usual here is a photographic recipe for cooking your own lever pivots.

Start with a suitable lump of 4140 and mount it eccentrically in the 4 jaw to bore the off centre 0.75" hole.

Then shape the sides to form the start of the convex bulge and define the width of the clamp.
Flip it around, re centre on the bore and machine the other side.

Then saw away the excess, this is the bit that would have been wasteful if using gunmetal.

Mill the upper and lower bounds.

Mill the clamp height and the excess from the round bulge.

Drill a pair of holes, one being threaded, the other just to help with metal removal.

Rough out the slot in the clamp with a saw.

Mill out the clamp slot and finally finish off with a hand file

The spoon pivot is based upon a 0.75" steel ball. On my latest trip back to Blighty just a few months ago, I purchased a ball turning lathe attachment for exactly this job and I've been itching to use it since.

Turn a piece of 4140 bar down to the rough shape.

Start turning the ball, my word, this was fun.

Thin down the threaded section to 0.25" and rough out a 26tpi thread,
this is so that the die will start straight as I'm unable to use the die in the lathe.

Then without removing from the chuck, remount in the dividing head 
and drill and tap the cross through hole at 0.25" cycle thread.

Counterbore for the screw.

Then index a quarter turn and rough mill out the slot from either side. 
Also mill through at the base of the slot.

Remove from the chuck, and saw out the narrow bridge remaining.
Saw off from the barstock and run a 0.25" cycle thread die down it.
Remount in a suitable fixture and mill the slot to final size.

Finally make the two screws for the pivots, first rough out the screw before cutting the thread.

Make a suitable arbor to hold the screw whilst the head is machined, 
first cut the dome, this is cut using the same settings as for the round ball so that it matches the profile.

Then cut the slot with a slitting saw.

The completed pivots.

Phew, that was a lot of pictures.

In other news, I've been exorcising my demons these past few weekends. Last Monday was labour day here in NZ which means a long weekend. Hoorah. The whanau decided to spend the weekend in Akaroa doing exciting holiday things. I decided to ride over following the route of Le Race. Now, I'm not as fit as I usually am at this time of year. This sorry state is due to a number of things that I'm not going to go into, but suffice to say I've been drinking a little too much as a result.

The climb up from Little River to Hilltop was OK and then the summit road was OK to. The steep bit around the back of Duvauchelle was hard but then it always is, the difficulty came on the final descent down Long Bay Road. If you recall, the last time I rode this, I liberally smeared a percentage of my skin down parts of the tarmac. I had no desire to repeat the experience and descended like a very slow descending person. I was pleased to get to the hotel in one piece.

Then this last weekend, we headed up to Hanmer Springs for the night. I usually take an offroad bike and do the loop straight up Jack's Pass, along the Clarence River and then back down Jollie's Pass. Riding up Jack's Pass was relatively hard due to the strong Nor'Wester headwind, I was blown to a stop and then forced backwards three times on the way up. Remounting on such a  steep hill into a headwind proved quite difficult, the whole time getting sandblasted by the gravel. Just before the summit of Jollie's Pass my seat post snapped clean off at the point where it enters the frame, it was a typical aluminium fracture with no prior warning. I rode the final 11km including the steep descent and back into town standing up, my thighs were burning when I got back. Nothing that a quick dip in the hot pools couldn't sort out though.

A breaked aluminium seat post, yesterday.