Sunday, 22 December 2013

Teenagers - Con Rods Part 2

This shedweek I have mostly been playing with my milling machine. If you recall from last time I had made three of the four con rod ends, I now need to make the middle bits to join them up. I had initially intended to get Kung Fu Pete to weld up the joints but having investigated welding 4140 and then having it nitrided afterwards I've had second thoughts. The weld in such a thin section would be hard and possibly brittle so I had a chat with the man at the SSM and he said that in theory there is no reason why I can't braze the assemblies and then have them hardened. The brazed joints and indeed the entire centre sections can be masked using a special high temperature paste. Nitriding takes place at 570 degrees celsigrade which is a little too close to the melt temperature of the silver solder I have been using, so I'm going to braze them with CZ6 Silicon bronze instead. This melts between 875 and 895 degrees which will give me a bigger margin. A brazed lap joint will be as strong as the parent metal if I follow best practice and make the overlap 4 times as long as the thinnest section.

First thing to do is to sneak into Pete's shed and "borrow" a section of rigid angle to use as a brazing jig. The centres of the con rods are 8.5" and each side must be the same otherwise the levers will have a different  range of movement per side.

The holes can be accurately drilled to be 8.5" apart on the mill table by moving the bed along on the dials.

I've made a series of accurate buttons to take up the gaps between the con rod bearings and the 
bolts so that when the con rod ends are bolted down the centres will still be accurate.

Use them to bolt the ends down and mill the first part of the lap joint.

Then with  the ends bolted down I can accurately measure the gap... 

...and turn a bar  between centres of the correct diameter and length.

Mill the top flat.

Mill the corresponding part of the lap joint.

And finally mill the bottom to thickness.

The middle part then sits nicely in the gap ready for brazing. 
I'll probably put a bolt through the lap joints beforehand. 

The oiler holes still need to be drilled and tapped and I'll file the correct profile after brazing. The gear side con rod is different in that it holds the planet gear rigidly without allowing it to turn. I can make this in two pieces instead of three using one of the ends already made.

Starting from bar stock of the correct size centre drill each end and mill the bar to thickness again.

Then mount between centres and thin down to size...

...before turning the taper. My topslide only has 3" of travel so I had to take two bites at this. 
I'd like a taper turning attachment, sigh.

Next week, I'll finish off the drive side side and get them brazed up.

In other news, we now have a teenager in the house. My son turned 13 today. I took him and some equally excited friends paint balling this morning. I can now report with a high degree of accuracy that getting hit by multiple paint balls simultaneously from several directions is fairly uncomfortable. Having a group of young teenagers gang up on you with mildly offensive weapons is one way to spend a morning I suppose. Actually it was really good fun and I gave as good as I got.

In more other news, this thing arrived yesterday. One of my friends in San Francisco will know exactly what I'm going to make out of it.

Happy Christmas to both of my readers once again.

Thursday, 5 December 2013

Nailed It - Con Rods Part 1

After weeks of painting, plating and making things look pretty I've finally got back on the machine tools making swarf and thoroughly enjoying myself.

Isn't it pretty? Even my lovely wife think so. 
I caught her showing it off to some friends the other day.

The gear guard in place for the first time.

It took me several evenings to get it back together, I didn't rush it and only got the one deep gouge in the paint where I had to spring the forks to install the front wheel.

I seem to be rapidly running out of bits to make which is both good and bad. Good because the bike is nearly done and bad because the hardest bits are still to come. I'm going to make the connecting rods next. Everybody knows what a con rod is, it connects a piston to the crank shaft. Well so do these con rods if you think of your feet on the end of the levers as pistons and the crank as erm... the crank. Even though the ICE wasn't yet in wide use, it had been around for years and the term would have been familiar enough to the makers of the geared facile, Ellis & Co, to use it in their catalogs. But I digress.

This page is from the 1884 Ellis & Co. catalog from my own collection. 
Email me, using the link at the right, if you'd like a complete scanned copy.

Ellis and Co. have used at least two styles of con rods on the geared faciles. Early ones such as the Percy Nix machine in the Coventry museum has tubular arms, later ones are solid and much more slender in section. I'm going to be making the later style.

The Percy Nix machine from 1888 (second year of production) has the earlier, tubular style of con rods.

The later style are solid and much more slender.

You can see from the photo above that three of the ends are identical (apart from oiler placement) which means I can make all three at the same time. If I had access to a big lathe, I'd simply make each con rod from a single piece of stock and bore each end at a time. The centres on the con rods are 8.5" and I would need a fairly hefty lathe to swing that, even in the gap. I don't have access to such a machine so I'll do it in sections on my trusty little Myford and then join them up. The right hand con rod will be made in three sections, both the ends and a centre section. The left hand con rod will be made in two parts since the top end doesn't need to be turned. I'm having a dilemma about how to successfully join the sections. I could ask Pete the Welding Ninja to TIG them up for me or I could silver solder them with a lap joint. The difficulty comes from the need to harden the bearing surfaces. I'm going to have to think about this. As usual, here's a stack of photos.

Calculate the minimum size of bar stock required and mill a flat on each side.

Then saw it into the three pieces and mark out the shape of the end.

I'm going to bore the holes and bearing surfaces in a four jaw so I need to remove as much material as possible from the stub to prevent vibration when running off centre at speed.

Mill the sides so that the stub is at the correct width. 
Roughly file the fillet from the stub to the body and mill the corners off 
so that the shape can be held securely in the four jaw.

Repeat with the front and back. 

I've left enough material to produce a nice fillet between the end and the shaft.

I've needed to make a parallel spacer out of some scrap tube
 to ensure that the work sits square in the four jaw 

Centre on the marked punch and drill and bore the central hole 
Also clean up the outer face. I can't profile the outer edge at this time as I need
 the flat surface to align square against the parallel spacer when it's turned around.

Rough out the shape of the bearing surface at a 45 degree angle...

...and use the profile tool to machine the bearing. Then polish the surface.

Then flip over, re-centre on the bore and repeat.

Next mount on a mandrel...

...and machine the edge profiles.

Then mount on the mill and clean off all the 'corners'. I would like to use a rotary table 
for this but I haven't got one so I use my dividing head instead.

Finally give them a little tickle with a file. I'll wait until I have the centre section made 
before I profile the stub that attaches to it. As I said I need to have a think about it first.

In other news, I did a most stupid thing this weekend. When Pete (hired muscle) came and Kung Fu'd up the old deck, we just threw the wood into a heap behind the facile factory. I'd been meaning to do something about it ever since but my lovely wife forced my hand this weekend and made me do it. The old deck boards had many rusty old nails sticking out at all sorts of dangerous angles. I laid the boards down and knocked the nails flat with a hammer before sawing the timber up for our wood burner this winter. The timber is untreated hardwood so useful as fuel. I thought I'd got all the nails done and went inside briefly to answer the phone. Afterwards I ran down the back door steps and put my full body weight on the one remaining nail that I'd missed. It pierced the sole of my shoe and then carried on through my foot and came out the top. Of course the nail was a special deck nail with annular grooves that made it hard to get out. I had to put my other foot on the board and yank my crucified foot off the nail. Being male, I naturally didn't go to the doctor until it had got properly infected and had gone an interesting colour. I thought I'd had a tetanus when I had my spectacular crash two years ago but apparently not, my last recorded one being in 1993. Probably best that I don't put a photo of my foot up I think. It does mean that I'm having to soft pedal with my right foot and standing on the pedals is out of the question.

An annular grooved nail, yesterday.

Wednesday, 20 November 2013

Collecting velodromes - and some pin striping

As I mentioned last time, I've spent this shedweek painting some pin stripes. Although I greatly admire the old guys who could do this free hand, I don't. I use a tool to do the job, the same as Raleigh were using at 7:20 in this film from 1945. I'm sure you've seen it before, but I love that film although the working conditions were terrifying. I've used a few tools over the years and I can save you some time trying to find one that works. Don't be cheap, just go and buy a Beugler. Easily the best tool I've used and although requiring practice and a reasonable degree of manual dexterity, it's possible to achieve good results quite quickly. Alternatively sent it to me with some cash and beer and I'll do it for you. I've developed a system that works well and requires the minimum number of sessions to get the paint on. I can't paint all the lines at once or both sides at the same time so it has to be done over several evenings. When not in use I wrap the tool in cling film or glad wrap as it's known here in NZ. This prevents the paint inside the tool drying and I only need to clean it when all the lines are on. For paint I use those little pots of enamel for model making, Humbrol or Revell are both equally good. I've found that some colours are easier to use than others. Primary colours go on the best and gold and silver are the hardest to work with. So of course I'm doing my lines in gold. A long time hobby of mine is to photograph original pin stripes on bicycles whenever I find a new pattern. Genuine Victorian examples are rare and disappearing fast as the bikes get over restored. I hate that but then I don't own them.

The patterns seem to have got simpler over the Victorian age, Early bikes could have designs that to our eyes look really quite gaudy and over the top with lots of swirls and flourishes. Later designs were less flamboyant. Since I've never personally seen a geared facile in original paint, I don't know what the design was like. The catalogues merely tell us that plain lining was 5 shillings and gold lining 10 shillings. That price difference suggesting that gold paint was more expensive and as I've found, more difficult to put on successfully.

I've chosen a double box design that I'm going to put on the forks front and rear only. Less is more with pin striping and as this is a later machine, entirely appropriate.

Here's how I do this design. First spend some time thinking about where the design is going to go and the extents of the lines relative to components that are going to be bolted to the frame. For example, on the facile the lines on the left side shouldn't be hidden behind the sun gear. The design is asymmetric with the ends of the boxes further away from the axle on the left than the right. If it was symmetric the result would look odd. You need to think about access with the tool, you can't get into tight corners with it and you may need to have a rethink or be prepared to do a few lines free hand. The disadvantage with using a tool is that if (when) you make a mistake, whilst you can wipe the paint off, it will also mark the surface you are painting on.

With the design worked out, place low tack masking tape across the ends of the boxes.

Then run the tool down the tube and onto the tape, these are the outer lines.

Remove the first piece of tape.

Then run the tool down the inside of the first lines and at the correct distance from them. Run onto the tape again.

Remove the second piece of tape and allow to dry for a few hours.

Then using small pieces of tape, place them outside the lines you just painted. 
Mark on the tape with pencil where the lines across should go. 
Take great care placing these bits of tape and pencil marks as 
they will define how sharp the corners of the boxes are.

Paint both cross lines, starting and finishing on your pencil marks on the tape. 
This is relatively hard as you have no guide to follow. I have a little trick to do it accurately every time.

Remove all these little bits of tape and leave it to dry.

It's important not to wear long loose sleeves when doing stripes as it's easy to brush across a perfect line and ruin it. Also plan the order of the stripes so you don't have to lean over one you've already done, you can always come back later when they're dry. If your corners aren't perfect, you can always join up any gaps with a tiny modellers paint brush. Any lines that are too long can also be trimmed back with a scalpel very gently scraped on the excess bit. Don't polish aggressively as you'll polish the young paint right off, however you can 'age' new lines by doing this.

I'm now at the stage where I can clean up the unmasked threads and put the whole thing back together, how exciting is that?

In other news, Pete and I drove down to Oamaru on Saturday to watch the penny farthing racing. We took a couple of racing bikes down and rode the safety events. I was using my 1906 Royal Enfield road racer and I bent the handlebar at the start of the 200m sprint. Hmmm, I'm going to have to have a good think about this as the bike is pretty much 100% original components all stamped with the Royal Enfield name and serial number. I can easily make a new set of bars to the same pattern but that's not the point. Due to my fear that the weakened bars would break, I was unable to unleash my fearsome gallop in the 4 lap race and Pete cleaned up. That's my excuse and I'm sticking to it..

1906 Royal Enfield Road Racer earlier today. 
It doesn't go around corners very well, has poor brakes and is too highly geared. I love it.

Now with added handlebar bend.

We drove back the same day and on the way home we collected velodromes. That is to say we called in to see all known velodromes between Oamaru and Christchurch. It's another hobby of mine. The rules are simple, the velodromes do not have to be in use and in some cases are simply banked grass tracks. If there is no trace remaining we can't count it.

We collected 6 out of a possible 8

Waimate: sealed asphalt, good condition.
Temuka: sealed asphalt in a D shape, OK condition which could be ridden but it had a game of cricket going on at the time.
Tinwald: sealed asphalt, good condition, highly regarded, active club.
Leeston: banked grass track, not in use
Halswell: banked grass track, not in use
Denton Park: Concrete, built for the 1974 Commonwealth games.

We missed Rakaia and Timaru and we couldn't count English Park as there's nothing left. I think I know where one was in Oamaru as well but we'd gone past it by then. If you know of others, I'd love to hear about them.

Friday, 15 November 2013

Pedantically Painting Parts

Painting takes a long time you know. I certainly don't claim to be an expert coach painter but I do admire their old ways of doing these things. About a hundred years ago I painted a few vintage motorcycle petrol tanks using some of these techniques. The results made an impression on me and when an antique bike requires painting, I use the same method. Incidentally, I need to state that I much prefer to leave the original finish intact if possible. Indeed if the bike is Victorian and has any original finish, I will leave it alone. It's a judgement call of course and you may like the wet, shiny look of modern clear coat on your antique bikes. I don't and I'll explain why. The only suitable paint for an antique bicycle is enamel. Not acrylic, cellulose, two pack, clear coat or powder coat. All of those finishes can be excellent and I own bicycles with all of them, but they are all much younger machines where the finish is appropriate. Enamel has the one major advantage over these finishes, it is possible to cut the finish back and polish it to a deep lustre without any loss of colour or fear of breaking through the clear coat. Coach painters, proper coach painters will spend more time taking the paint off than putting it on. The only trouble is that it is getting harder to get proper coach painting enamel due to valid concerns about VOCs. However saying that, Resene have just introduced a new low odour (read low VOC) formulation for their enamel and it is excellent, I'm genuinely impressed by it.

Painting is all about preparation, it's a little like plating in that the finish you get is entirely depending on the substrate finish. Clean and free from rust, dust, oil and other contaminants.

These following steps are the way that I paint, it's not necessarily the best way or the easiest to get right but it works for me. It's certainly not quick but then I've already spent over two years on this so a couple more weeks won't hurt.

first step is to fill any pits or depressions, I use a modern two part epoxy system and slap it on quite liberally, you don't need to spent too much time at this stage as most of it is coming off again anyway. Then when quite dry, use a block and sandpaper to remove the excess so that the blemish is gone. I only needed to apply a small amount of filler at the cut and welded splits on the lower fork legs and backbone. The actual amount used was tiny. You're aiming for a feather edge that when painted will not show through. You can repeat as necessary.

Next step is to mask off all the bits that you don't want to paint, in my case this was all the bits that have been plated and all the larger threads that I don't have taps for.

Next I apply a coat of primer with a spray gun, this is just flashed on to get an idea of highs and lows.

I don't spray in the workshop, I just hang bits up to dry.

When dry, it is rubbed down to key for the next coat, more filler can be added to any lows remaining. For these initial coats I use Scotch pads rather than wet and dry paper, these pads come in a wide variety of grades.

Some Scotch pads, yesterday.

Then apply another coat of primer and repeat the rubbing down. At this point I would normally apply an undercoat but this new formula of enamel doesn't require one so it's straight to the first topcoat. This can be either brushed or sprayed on, it doesn't matter since the finish from the brush or spray gun isn't the final finish. Leave this for few days in the sun to harden then cut it back with a scotch pad, you don't want to break through to the primer or undercoat at this stage.

This is black but rubbed down.

Then apply the first final topcoat candidate. I say candidate because bicycles are tricky things to paint and any undetected runs will need to be sorted out properly and another coat put on top. If you do get runs, wait until very dry for a week or more and use a block to remove the run, this may break through to the lower coats requiring another topcoat.

It's not a garage darling, it's my spray booth.

I like to let my freshly painted bits dry for a day or so in a dust free environment, then hang them in the sun for a week.

Hanging out to dry.

At this point, I then cut back the finish very carefully. I use 1200 grit wet and dry paper which has been rubbed on itself to make it even smoother, you want to remove as little paint as possible. Then using lots of water and a bar of soap rubbed on the paper, very gently and carefully go over the entire finish. This takes time. You are trying to remove as little paint as possible whilst achieving a flat surface. You have to be very careful about contamination of the paper as any grit will cause swirl marks in the finish. I also do it entirely by hand as the paint is still young and relatively soft. Then hang it up for another couple of days to cure this new outer surface.

Finally polish with a gentle, very mildly abrasive polish. T-cut is too much and you'll tear through the paint with it. Take your time and do it in good daylight. The finish will be a deep, smooth lustre. Of course this is almost impossible to photograph successfully so you'll have to take my word for it. The paint will continue to harden over the next few months so treat it carefully.

Mmmm, shiny.

Mr Middleton berated me once for having 4 molecules of paint out of place, it won't happen again I tell you.

Next week, I'll paint some pinstripes on it.

In other news, I am very pleased to announce that the deck is finally done. All that remained for me to do this week was to apply the final coat of stain. In sharp contrast to the care taken to apply the paint to the bike, I just slapped the stain on with a big fat brush. It was excellent and I now have stain all over myself and a cat that was a little too curious.

In more other news, this week I celebrated my birthday. We went out for dinner to the children's favourite restaurant, Tutto Bene. I think the kids like it because it's a loud, lively very Italian restaurant and I can't tell them off for shouting. The food and service were excellent btw.