Tuesday, February 19, 2019

Tennis ball pump

It may be remembered that I have an abstract interest in pumping up tennis balls.

A plastic tube, all this past fortnight.

This interest resurrected itself when a tubeless tyre refused to hold pressure and I had recourse to the bicycle shop which has a compressor.  There I found a New Device called a flash pump into which we will not go since Google will take us there if we're interested and anyway nobody is. Reading this. Unless I'm sore mistaken.

Persons unknown have made their own flash pumps all over Youtube and you may youtuble them, I expect, if the subject enthralls.

I have confined myself to gluing ends on a bit of PVC pipe, one of which screws off and didn't quite seal on an 80mm O-ring cos I couldn't get enough torsion twixt lid and pipe.  Accordingly I machined a large tight hole in a bit of oak and chopped it in half and got a better purchase on the pipe in the bench vice and that worked: the tyre pressure gauge revealed that 60psi still remained within from Waitangi day until this afternoon, viz., for two weeks.

JE Gordon (p119-123, Structures) told me that the pipe is twice as likely to burst like a sausage than the ends are likely to shoot off, but they - the ends - are a bit bulging and I housed this thing out in the shed in case I got that wrong and it transformed itself into a pipe bomb.  Which is itself stupid: I should have put it in the grapefruit tree and then only grapefruits rather than sheds will be damaged.

The balls were sealed inside and the test to see if some of the 60psi leaked into them was done by dropping them on a concrete floor and seeing if they bounce as high as a new tennis ball. They didn't. Well, one did, but four others were mediocre and one bounced with little enthusiasm. So they're back in the pipe and back up to 60psi for another week and we'll see how long it takes before they all go bouncy.

The pipe, if this is of interest, has an OD of 82mm and a wall thickness of 3.4mm and somehow or other I calculated this would give a safe working pressure of 115 psi but I can't recall what possessed me to come to that conclusion. Was it a website somewhere? Anyway it seems safe at 60 psi. The inlet valve is a Presta valve cut from an old inner tube, sealed on the inside merely with the remnant of the rubber inner tube and the locking ring tightened with pliers on the outside of the end cap. 

What all the Youtublers do is fit a second Presta valve, connect it to the putative tubeless wheel valve with a bit of soft plastic pipe, fold the plastic pipe over and nip it closed with a Mole grip.  The device is pumped to something approaching pressure vs volume, the Mole grips flicked open, and the outrush of air is claimed to seat the tubeless tyre on its rim.  Some Youtublers claim that a plastic fizzy drinks bottle will hold 150 psi and so it might if it's a small one, but I have bitter experience of this and can assure you a three litre fizzy drinks bottle will swell and burst at 130psi and woe betide your hand if you chance to be holding it while this bursting occurs.  Compressed air is a lot more dangerous than folks imagine.

There are so many videos online that I can't be bothered to locate one for viewing pleasure, but the general clues used by Mr and Mrs Google are cheap ghetto tubeless inflator.

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Sunday, September 16, 2018

Foam Chaincase

It will be remember-ed - we few, we happy few, we band of brothers - it will be remember-ed  (no it won't, cos no-one's paying attention and frankly, why should they)  that I built a foam chaincase around my no-maintenance rainbike so I could dose the chain with oil and not worry about it.

Said rainbike started making a whoosh-whooshing noise t'other day and on my return, dripping, I chanced to examine the back tyre and decided, on reflection, that it was probably about time to replace it.

Back tyre. Past its sell-by date

Using the time-honoured method (1) of undoing the LH axle nut only and pulling the frame apart just enough to get the old tyre out and the new one in, I replaced it and found to my annoyance that the chain had come off.  Stuck inside the foam chaincase I couldn't get it back on, so peeling back the foam I discovered that my endeavours had not been entirely successful in keeping the chain oiled and clean and maintenance-free.

So it was an interesting experiment but in the interests of honesty I think we can discard both the chaincase and the idea.  I prefer waxing chains as road dust doesn't stick to wax and a waxed chain lasts longer than oiling it,  but I think this bike can be an exception and since it's made out of old junk and exists solely so I can get my daily exercise even in inclement weather, we'll oil the chain and live with the need of occasional replacement.

(1) As explained to me by Mr. Knight.

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Wednesday, July 11, 2018

Violin mute

It is a truth universally acknowledged that I am a pretty atrocious violinist.  - Actually not universally: only acknowledged by those admitted to the privilege of hearing me play, of whom unfortunately there are all too many lurking in my history. - Luckily in an orchestra you get drowned out by everyone else, and the only way the audience detects how useless you are is when they notice that you're doing an upbow when everyone else is doing a down, except when your bow is jiggling a bit because you're way back on bar 73 and everyone else has moved on to bar 81 which doesn't have any semiquavers in it.  "Ah," say all my devoted fans, "but how come you were outside desk?"  Simple: inside desk, who is a good deal better than you are, turns the pages and then you don't have to hiss "where are we?" quite so often.  If you don't happen to play in an orchestra I will let you into a secret - your inside desk knows exactly how bad you really are.  Never sit next to someone unless you're prepared to share your darkest secret with them.  This is the chief reason I haven't played in an orchestra for, oh, 36 years. Well, that and there not being one. - There is a ukulele band. - I do not belong to it.

If you are as bad as I say I am, and let's face it you are if you're me, the only way you can play a violin is with a mute. And there's the prob.  No mute.  I had one: indeed I had two.  I had a proper black one made of soon-to-be-extinct ebony, and I had one of those wire plastic rolly-onny-thingies that sit behind the bridge on the squeaky bits of string, and now I have neither.  I have searched my violin case.  I have searched John's violin case.  I have searched his old ¾ case and I've searched that wooden Antonius Stradivarius case which contains the instrument with several wormholes and the date 1776 which means he was still making violins forty years after his death.  (It does have a nice tone though.)  But no mute.

My Stradivarius with home-made mute

 Don't believe me? Antonius Stradiuarius Cremonenfis

Faciebat Anno 1776. Absolutely genuine.

Accordingly I had to make one. This isn't as difficult as making a bicycle, but it does rather undermine your case for prevarication when your daughter asks you to fix one of those things to a coat that she's made, you know, one of those press things that don't have a name.  So you acquiesce.  And a good job too.  She opens the packet and works out which of the four bits goes where and you lend her a punch to make the holes in the cloth and she gets the tool (supplied) and whacks it with a hammer (yours) on the tiny anvil (supplied) and the clicky-onny-bobble works perfectly.  But the clicky-tooey-bobble doesn't work at all.  The smart whack with the hammer flattens the sticky-outy-tubey-thingy into the concave recess of the anvil, and ten minutes and your 2½ x magnifiers are required to work out why, and you realise that the tools supplied aren't up to the job and she really needs a tiny supporting anvil, not a concave one, to prevent the sticky-uppy-tubey-thingy collapsing while being whacked.  So you find an old bolt picked up from the road - one always collects bolts and this is why - half an inch in diameter and chuck it in the three-jaw and machine a 6mm OD base 0.7mm high with a 3.3mm OD point 2mm high to support the thin sticky-uppy-tubey-bit and you hand her a centre-punch for the initial belling of the last-mentioned-thingy and then a small ball-bearing and behold! your anvil works perfectly.

All the tools required for dressmaking.

"So when they sell snap fasteners in Spotlight for needlework, they should mention that all you need is a hammer and an engineering lathe."

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Friday, March 9, 2018

Mr English's tandem

Mr. English has been for a visit. He came once more on his recumberent tanderem which, it may be recalled, was not unlike the machine they were a-riding four years ago.

He had balanced his wife on the back of this recumberent tanderem, but without too much difficulty I tipped her off and occupying her seat, obliged him to pedal me up Marahau Hill while I amused myself by making encouraging comments and pointing out objects of interest at the wayside.

Normally I manage the steep bit to the grey box in seven minutes but Mr. English managed it in five. It takes me a minimum of thirteen and a normal of seventeen from there to get to the summit, but Mr English managed it in eight, whereafter he was a little puffed. The whole ride, which I have once (but only once) done in one hour and twelve minutes, he did in one hour and nine. Towards the end of the ride he tried to break away, but he was unable to drop me. This may be attributed to my Youth and Superior Musculature. I considered overtaking him on the final stretch but thought it might cause him to lose control, which would be unkind.

This warmed us up to a small degree so off we went to Stephens Bay for a swim, and Mrs. English did not fully believe my warning about the stingray, so afterwards we walked to Apple Tree Bay and peeping down from above saw two of them after which she was
1. convinced and
2. nervous.
"I'll wait till we get to Auckland before I go swimming."

Next day off they went to Golden Bay, taking 1 hour 40 minutes to ascend the 791 metres of Takaka Hill, I daresay taking sips of water from time to time

After they'd had their fill or Takaka, which means to say sampling the tofu, they returned and I snuck a number of pictures of their green bicycle for the purposes of Industrial Espionage.

Then, amid the precursor to the rainstorm that placed eight inches of rain on top of New Zealand and caused one or two problems to those motoring over Takaka Hill, off they went to Auckland. Where Mrs. English went swimming. And where she didn't meet with a stingray. Rather, with a great white shark.

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Saturday, February 24, 2018

Binocular collimation

It has often been averred that I am a genius. Admittedly there is only one person doing this averring - viz., me, but that doesn't detract from the frequency of the observation.

Today's observation concerns fixing a pair of Swift Audubon 7x35 roof prism binoculars which were out of alignment. Nice optics for each eye provided t'other was closed, but that reduced them either to a heavy monocular with a spare attached, or attached monoculars for two viewers having Very Narrow Heads.

There are lots of internet articles on collimation and any amount of discussion but the problem is always finding how the wonky binoculars in the hand are originally aligned. Some have cunning screws hidden away to tweak the prisms. Some have eccentrically mounted objectives. Those before me turned out to have one eyepiece adjustable for focus, and the other eyepiece loose and rattly and only held in place by three dabs of glue and an eyepiece cap screwed firmly on top of them. Indeed I was a bit startled, unscrewing the wobbly one, to find the objectives were covered with flat protective glass.

Anyway the problem with a loose eyepiece is that of holding it in the right place while tightening the cap to hold it in the right place. If you point them at the communications mast on the skyline down the valley you have to levitate the lens by mystical powers inside the eyepiece cap, powers that I do not yet possess.

So I made a little wooden box with two holes in the top for the binoculars to sit on, and took the mirror off the bathroom cabinet and propped it under the holes at 45 degrees, pointed the apparatus at the horizon, and managed the job in a couple of minutes. The errant eyepiece lens obeyed Sir Isaac and sat where I prodded it while being clamped into place.

There, another averral of genius. Unf. still by the same person. Unf.ier, I didn't put dabs of glue in place, so I 'spect it will come loose rattling around under the driver's seat of the car.

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Sunday, December 3, 2017

Tandem repair

Came a phone call from Carl: could I fix his cracked tandem frame. He brought it in his van, and here it is:

Built without a top tube it would have been perfect for a couple of mice provided they had long legs - say, a pair of jerboas - but Carl is heavier than a mouse, and he told me an equally heavy dentist occasionally rode on the back, and I can imagine even his children tugging away on those stoker bars. Anyway, it had, as he said, cracked the captain's seat tube exactly where every engineer in the world would predict there to be a stress concentration.

Carl being mostly composed of leg, I thought it wouldn't be a bad plan to extend the frame's seat tube and then brace it. If I retained the original clamp, there could be two seat post clamps and that would use some of the strength of the seat post itself.

First I pulled the seat tube straight with a sash cramp and welded the crack closed.

Rummage in the bike heap for a seat tube top, add an inch of oversize tube to match the existing seat clamp diameter, drill and plug-weld the two together only at the front. Cut a slot in the back so as not to interfere with the existing seat clamp.

Insert another seat tube to keep everything in line.

Poke into frame, and weld again only to the front.

Clearly this is a bit of a feeble joint, so weld a bandage to the front of the joint, top and bottom.

Now for some bracing. The top tube should be in compression, so the welds ought to be okay without gussets. Lop a couple of top tubes off donor frames, preserving cable clips where possible.

Sit back, admire, and telephone Carl.

With a bit of luck that'll prove adequate, and the jerboas can retire in favour of weightier crew. My only concern is in the 700c wheels, which have but 36 spokes each, none of them especially tight. I suggested he take it off to see Ross (warning: Facebook), who is blessed with both enthusiasm and knowledge for and of old bikes. I think this takes the town's total to five tandems.

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Monday, November 27, 2017

Tallbike painted

So, cousin Kate is going to marry Angela Merkel, is he? Well if you can't be king of England you might as well be chancellor of Europe.

Where were we. Yup, the tallbike is even finisheder. It got racks welded on and it got painted. It can now stand innocently until the tyres go flat or I think of a use for it.

Still no triangulation of that whacking great big unstable parallelogram. We shall see if we ever need it. Unlikely if it never gets ridden and becomes a mere shed encumbrance.

Moving on, a big fat German plumber came to stay with his slender wife and tiny child and demanding activity after he'd eaten two dinners and helped himself to several evening beers and smoked a cigarette in bed, all of which made me wonder who won the war, and lacking a baby seat we had recourse to phoning Suzanne, who volunteered either of her machines, one a huge Dutch bicycle and the other a perfectly good gentleman's mountain bicycle, if I'd fix the seat of the one and the tyre of the other. Nothing loathe, since the option was watching the perfumed plumber (he'd occupied the bathroom and emerged leaving behind such fumes of eau de cologne as would eliminate borer insects deep in the beams) eat his way through bacon eggs tomatoes sausages ("The German are better, English no good, like their cars. My Mercedes van has 130 horsepower, nothing it can't conquer." - Oh,thank you for that enlightening discourse. Anything else you'd care to tell at me?) several times, I walked down to the wharf where Suzanne lives and located the bikes and effected the one repair with nothing more than a track pump, and the other by riding it home on a wobbly seat and welding reinforcements to the whateverit'scalled gizmo atop the seatpost. Here's a before and after:

 Before. The cradle thingy for the seat rails bent, as you may imagine, where those thin bits either side of the hole lie.

After. 3mm steel welded in place and left untouched as much as possible to give vertical strength. Not much to show for three hours of a Saturday morning. Still, one hopes it works.

When the plumber went off in his camper van to Picton normal service was resumed, which is to say Carl the electrician telephoned and suggested I repair his tandem. This will have to wait till another post gets itself blogged.

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