Member postings for SillyOldDuffer

My experimental pendulum reports 21399

It's calculated using the bandwidth definition because logging a pendulum with a microprocessor produces all the data needed to calculate bandwidth. Much easier that measuring decay and, I think, measuring impulsed Q is more useful than measuring free-swinging Q. Clock pendulums are impulsed, not free.

Bandwidth is calculated from the 29.3, 50,0 and 70.7 percentiles.

Easy in Python because numpy has a percentile function. Where tickArray is a list of periods:

h, l, r = np.percentile(tickArray, [70.7, 29.3, 50] )
b = h - l
q = r / b

Usefulness of Q? The balance wheel in a marine chronometer has Q of about 400, that of an ordinary well-made pendulum is said to be about 10000. Best vacuum enclosed pendula, up to about 100,000.

I see Q as a measure of the purity and stability of an oscillator, where high Q means it produces close to one frequency only. Real oscillators do not produce a single frequency, they wobble around it, and they are likely to drift.

I've noticed good long-term time-keeping can be got from a low Q pendulum - less than 5000. I believe it's because wobble errors tend to average out, and aren't obvious unless the clock has a high resolution display. As most pendulum clocks only display to the nearest second or minute, low Q may not matter because the error is invisible and doesn't accumulate. However, high Q becomes important whenever a clock must be high-precision or high-resolution.

I need a high Q pendulum because I'm chasing milliseconds and below, but what I'm doing is bonkers!

One of the other threads asked if Q varies. Normally Q is measured once by simple methods and assumed to a constant. My pendulum's Q isn't!

The data suggests the Q of my pendulum varies between about 15000 and 31000. The red line shows temperature and I think I see a relationship - after a lag, temperature causes Q to vary. Far from convincing though - I don't know what causes this. Hard to think why Q should repeatedly peak over a 100 hour period. Perhaps the moon did it!

Like as not other pendula do the same, because mechanical or environmental changes are likely to affect the purity of the signal. Anyone happy with their clock is advised not to look too closely! That way lies madness. Nature conspires in many ways to subtly alter the period of a pendulum despite the clockmaker's best efforts.

Dave

Well, I type in a sentence that seems completely clear to me and Tim proves it's not!

It was the value of different opinions on art I meant rather than the value of art itself. For example, I hate jazz. In my opinion It's elitist, irritating, self-indulgent, ill disciplined and pointless. Jazz is a waste of my time and the musicians technical and aesthetic skills.

A friend loves jazz. He says improvisation creates pure music freed from stultifying convention, and is the human spirit unshackled. My friend considers jazz 'powerful', which I say is rubbish because power is measured in Watts not Armstrongs per Hour.

My point is that neither of us is right or wrong about the value of Jazz because it can't be quantified, it's subjective. Since there's nothing to measure, my friend's opinion of Jazz is just as good as mine. The danger is that we are fanatics and prepared to force our ideas on others.

Engineering value works because it can be measured. Thus a tool made in 1975 is great, whilst its makers hair-style, moustaches, flared trousers, platform shoes, and loud shirts have all proved ridiculous! Anyone prepared to share photos of themselves from 'the decade that style forgot'? Not me!

Dave

The numbers aren't good. With a ⌀25mm test bar my Chinese lathe and chuck run-out is 0.06mm at 50mm out. It was a little better when new. The exact figure varies a little depending on how the chuck is tightened.

My chuck is inexpensive and tightening it feels gritty. The scroll is not as well-finished as it might be, and could be soft. That my run-out is slowly getting worse is probably due to wear on the scroll and jaws. I'd expect a more expensive chuck to achieve noticeably lower run-out from new, to turn more smoothly, and to resist wear for longer, but they don't last forever! Don't forget a second-hand tool may have been worked hard or abused by previous owners.

I suspect your chuck is worn. With luck it's just the jaws, which can be reground or replaced, but maybe a new chuck is required, the headstock is out of alignment, or the spindle or bearings are damaged.

Check the chuck and spindle are OK before assuming collets are the answer. It's easy to waste lots of time and money fixing the wrong problem. You can guess how I know!

Dave

Big money and foreign investment have indeed failed to stop unprocessed sewage being dumped, but the problem pre-dates them. The Victorian approach to effluent produced on an island was was simply to dump it into the sea, often via a river or canal. Public health improved enormously when they realised the need to keep it away from sources of drinking water, often achieved by by piping sewage to the seaside rather than pouring into rivers.

At first the Victorian system worked quite well because there was much more sea than sewage and not many people went swimming. However, as towns got bigger, it soon became obvious that more needed to be done. Adding sewage farms to the system was a considerable improvement because they process effluent in various ways to render it less dangerous. Their output of a comprehensive treatment plant is safe to drink provided the system is in good order, and working within it's operating limits.

Most of Britain's sewage system was built by local government, funded by rate payers plus central government grants. The problem with government funding is that no-one likes paying tax! Therefore governments constantly look for ways to 'save' money. Ideally savings are made by improving efficiency, but this is easier said than done. In consequence 'savings' are achieved by 'stretching the assets' - reducing maintenance, delaying replacement of clapped out equipment, and/or overloading existing assets. Gradually, the system degrades. The policy always ends badly - discovering that 70 years of neglect means the entire system is trashed, and that the cost of fixing it is enormous. Sewage systems fail by releasing part-processed and raw effluent.

When the problem reached crisis point in the 1970's government dealt with it by privatising the system. New money was made available, not borrowed by the government which makes the books look good, but still borrowed - by water companies. The public still pay. Improvements were made, but companies are in business to make profits, and they too are struggling to do all that is needed. Private companies believed to be more efficient than public services, but this is rarely true. When underfunding is the root cause, public services are inefficient because they can only operate within a budget, whilst private companies are inefficient because they have to achieve profit margins. In both cases, whoever is in charge is forced to "stretch the assets". Wildlife are a long way down the list of considerations!

Everything humanity does has an impact on the environment. The issue is how bad the damage is. No doubt building the Severn Bridges meant hundreds of tons of nasty rubbish ended up in the river, but the disturbance is tiny compared with building a tidal barrage.

Today the population is larger than a century ago and we have much richer lifestyles. In the past, mankind lived without causing serious damage to the environment, and greedy freedoms were safe enough. Easy to generate wealth when there's no responsibility for depleting natural resources, wildlife, or other people. Not now! Human activity is seriously damaging our eco-system, and, unless the problem is managed, the consequences will be appalling. No good naively pretending it's still 1955 and most of the planet hasn't been exploited. - that innocent carefree world has gone.

Dave

Might be good evidence that AI is getting more human, not necessarily a good thing!

Humans make up "facts" to produce answers, and also make false sexual harassment complaints. Slander and libel keep lawyers well paid, we fall for scammers, politicians love propaganda, civil servants are 'economical with the truth', newspapers are biased, people believe in cults and ridiculous conspiracy theories, cock-ups are covered up, and toddlers plastered in chocolate deny they ate the cake.

Although recent AI developments are a breakthrough it has a long way to go. Filtering fact from fiction is particularly difficult - look at how bad people are at doing it!

Dave

Getting exciting. Watch this youtube video in which ChatGPT writes Python. There are other examples...

Even expensive 3-jaw chucks in good condition are a poor choice when repeatability matters. Griptru maybe, which are adjustable. A 3-jaw is speedy, but the price is repeatability, which drops off as the jaws, slots and scroll wears.

Better alternatives available. I put an independent 4-jaw chuck on when I need repeatability, because the job can be accurately centred with a DTI. Some machinists always work with a 4-jaw, because, with practice, work can be centred quickly and repeat error eliminated. Collet chucks are the bees-knees for certain workflows, I have an ER32 collet chuck which is very useful at times, but if I was serious 5C collets are better because they can hold shapes other than round. A full set of 5C collets is expensive.

My hex collet block iand 3-jaw are moderately repeatable, but test yours to find out how good or bad yours is in your chuck. I don't think scraping the block is a good idea, because repeatability depends on what's wrong with the chuck : probably better to replace the chuck, or the jaws, or grind the jaws.

Main use of hex and square collet blocks in my workshop is moving work between mill, lathe and bench, not overcoming of my 3-jaw chuck's limitations. Good for what it does, but that doesn't include accurate repeatability.

Dave

The problem is a combination:

• There aren't many places in the world where a tidal barrage would work well. The Severn Estuary is one, the Thames Estuary isn't.
• The stress on the environment is enormous. A barrier changes the entire nature of the area from a sea-way and river to a lake.
• The sea-way services a major port, and several small ones. How there are affected depends on where the barrier is built. The sea-way is also used to dispose of sewage from 3 large cities and many towns
• The river is a major source of drinking water
• The Estuary provides coolant for a large Nuclear Power Station
• A barrier is a seriously massive engineering project - it has to be strong enough to manage the weight of millions of tons and water, and cope with Atlantic scale storms, including severe storm plus high-tide plus a low pressure depression. In the worst case, failure of the barrier would be off-the-scale expensive : think flooding from Newport Cardiff and Bristol into the Midlands.
• The size of the barrier means it will be expensive to build. This means it has to generate a lot of energy before it's worth building. At the moment it's not competitive with other renewables - maybe later
• Tidal ebb-and-flow means the energy available rises and falls on daily and annual cycles. Inconvenient rather than a showstopper, but another reason for seeking alternatives.

Wave energy is promising, but the engineering is difficult and looks to be high-maintenance. It's easier to build large towers with a wind turbine on top, they're easier to maintain.

Geothermal is also promising with challenging engineering - a couple of wide-bore holes potentially several miles deep, penetrating into the magma to create super-heated steam. The theory is straightforward, but we don't have the technology or need yet.

I don't think the issue is lack of expertise at the top. We're talking big money and significant change versus vested interests and a lot of people who fear losing out and don't understand the science. They think it's a political argument, when the Laws of Physics are in charge. Thermodynamics aren't influenced by human opinion. Add more heat to the environment, and what happens next follows physical laws, not human wishes. It's a nasty situation: those who understand the science know full well bad things are happening and have several ways of reducing the damage. Unfortunately, they haven't been able to persuade those who don't understand the science, and those who don't want to. It's a mess. Regret to say that those who don't understand have so far won the argument, and not enough has been done. In consequence the original target of allowing a 1.5°C increase in average temperature is now unachievable, and the new target will be between 2 and 4°C.

Things will change, because we've gone beyond warning of trouble ahead. Now, man in the street is starting to notice something odd is happening to the weather. Climate is difficult for individuals to comprehend, but rapid sequences of record breaking rainfall, storms, heat-waves, freezes, droughts are harder to ignore. Reality always wins in the end.

The danger is public opinion is swinging far too slowly to avert seriously rough times ahead. Politicians fail because they can't afford to upset their supporters, even if they know their supporters are completely wrong. The Laws of Physics care absolutely nothing for human affairs, left or right.

Dave

Drivers are a problem! Or maybe not. Proprietary print drivers are slowly being driven out by standard interfaces like the Internet Printing Protocol, which covers AirPrint, Mopria, Wifi Direct and others. With luck you can't find a Linux driver for your Epson because it doesn't need one!

IPP is supported on Linux by the Open Printing Project. Their front page links to 3 databases of IPP compatible printers including Epsons. If your Epson supports IPP, it doesn't need a driver. Instead your Linux needs IPP.

I'm not sure what has to be done to get IPP working on Linux: seems just to be installing a CUPS plug-in, so probably not difficult. Can't try it for you because my basic Brother HL1212W doesn't support IPP.

Dave

Dave

A hole, usually straight through because it's hard to route a cable inside a finished cavity wall.

Straight through doesn't mean it will be easy to trace though. Might be hidden on the inside behind skirting or whatever.

The so and so who installed the TV coax drop cable from my loft to living room socket 40 years ago looped it round a batten mid-way. The git turned a simple cable replacement job into a major works project because the cable can't be pulled through and is deep inside the wall.

Dave

If value means anything, Warhol paintings have sold for over $100M!

Just after WW2 a British major comedian said he'd established the value of his autograph. He always paid the bill in pubs and restaurants with a cheque. If the bill was below a certain value, the cheque was framed and hung on the wall to show that the star was a patron. He got a free meal because the cheque was never cashed. Above a certain value, the cheque definitely would be cashed, thus establishing the big stars actual monetary value. From memory, he was worth about £4. I think it was either Tommy Trinder, Max Wall or George Formby. Anyone know for sure?

Another interesting point: the value of art depends entirely on personal opinion. Art can't be quantified and checked against a specification. That means everybody's opinion of it is of equal value. There is no objective right or wrong. Nonetheless, people are often enraged by art or feel obliged to die in a ditch defending it. Emotion rules.

Engineering, Science, Maths are quantifiable, and can be checked against a specification - there is an objective right and wrong. Although Art and Engineering often overlap - Spitfires look good - it's important not to confuse the two.

Economics follow basic logical rules and outcomes can be predicted with fair accuracy. Except economics has a high emotional content. It's strongly influenced by group behaviour, even when that behaviour is daft. When it became apparent COVID was dangerous, a large proportion of the population broke the system by panic buying. Allowing emotion to trump logic created an unnecessary artificial shortage of Toilet Rolls! I think humans are driven to compete ferociously for Toilet Paper and Warhol paintings by the same primitive desire: it comes from the greedy animal part of our brains, not the clever bit.

Before deciding anything, give the clever part of our brains time to think. Allowing gut feelings to rule when facts point the other way is always a mistake. Even if the facts are unpleasant. I expect Lee would be delighted to buy a genuine Warhol at a car boot sale for a fiver, and would then do everything in his power to get the maximum he could by selling it. I would! For $100M dollars I'd say anything, even untruths, to persuade customers that Warhol was the best artist ever.

Dave

Edited By SillyOldDuffer on 07/08/2023 10:28:06

I like it. Depending on circumstances I use 3 methods:

1. Nipping a strip against a rod held in the chuck (when the rod is going to be turned)
2. Setting against a rod turned to a cone held in the chuck (for accuracy)
3. Setting against a column carefully turned to height that stands on the ways. (for accuracy when a job is already in the chuck and a tool needs setting.)

Sonic's idea is an improved column. Better because my column is easily knocked over and last time it fell on the floor the reference edge was damaged. Sonic's version has a nice base, is shorter because it reaches over from the cross-slide, and can be reset after accidents.

Dave

Three wrongs in one sentence! I won't explain why because Brandolini's Law applies.

I'm confident Martin can't justify his claims, but I sure we all want him to try. Watch this space!

Dave

No need to be sorry, I have the same reservations. It's all too possible that some of the assumptions behind my ideas are wrong.

I lack the maths and evidence to prove it's all good, and, as I'm operating on the bleeding edge of my understanding, someone who knows could turn up and demolish me. I'm hoping to get more conclusive evidence.

The case is open - so far no-one is convinced, but no-one has raised a rock-solid objection either. Could go either way, but I am nervous.

Dave

Tricky territory! I think Tony's Show needs to define what it means by a 'handicraft'. Personally I expect it to mean hand-made with only the simplest machines and no power tools.

As a judge I'd reluctantly accept items made on a treadle lathe, but submissions with any hint of a motor would be rewarded with a flogging!

Marks for:

• original design (don't care if CAD is used)
• doing all the work yourself
• Hand tools only
• Home-made tools and
• Home prepared materials

So an LBSC loco finished by a small-boy using grandad's Colchester, Bridgeport and plasma cutter and standard stock metal would be marked down severely compared with a shapeless hand-knitted cardi made from home-spun wool plucked from a sheep by a ten year old girl.

Other way round at a model engineering show, where different rules apply. There I would expect much of a Gold Medal engine. I'd check the loco's authenticity in detail - counting rivets, period correct colour match, and proper oil-lamps etc. Also apply a hydraulic boiler test and dynamometer run! If suspicious the model will be dismantled to prove it has no commercial bearings, fasteners, or plastics. O-rings in the pump, black mark!

Not important to me what technology was used to build it. That leads to endless complications. For instance, if technology were important, it would be essential to apply a handicap to anything made from British rather than Chinese equipment. Obviously anyone building an engine with inferior Far Eastern tools had to work much harder to get decent results. Their extra skills and dedication compared with well-equipped builders should be acknowledged. I'd reduce a Myford owner's score by 25%, more if they said their lathe was the best ever!

Dave

Edited By SillyOldDuffer on 06/08/2023 20:09:12

I got fed up with Inkjets of any make and replaced mine with a Brother HL-1212W laser. Very basic, works with Windows, Linux and Apple, came with a lifetime supply of toner cartridges. Ok rather than wonderful but fast and reliable.

I notice chaps are keen to select printers by brand-name when they should be worried about printer technology and how well suited it is to their needs. Brand name is a poor guide because all manufacturers produce equipment ranging from almost toys to professional grade. They all have good kit, but domestic users dislike the prices!

The usual domestic InkJet is rock-bottom cheap, and ink is very expensive. Suitable for frequent low volume printing. Not mechanically tough enough for big print runs. and - much more serious - if not used almost daily, they gum up. They un-gum by forcing ink through the pipework, wasting lots of precious ink, and a serious blockage is fatal. Good for printing a few letters and photographs every day, otherwise avoid.

Office inkjets are much cheaper on ink, and strongly built, but again have to be used frequently. Costly for home use and likely to disappoint if the ink congeals due to low usage.

In short, InkJet technology is cheap to buy, but I don't think it does a good job unless what you need is a close match what they're good at.

Lasers are good for infrequent use because there's no ink to gum up. Basic models like mine are very cheap, and are uncomfortable doing large print runs. Tens of pages rather than thousands. Small Office and Office printers are beefed up, often considerably, and the price reflects this. Black and White is cheaper than colour.

Colour lasers have similar characteristics but are more complicated, hence pricey. They too vary from cheaply made for low volume home printing up to super luxury-yacht expensive for industrial-grade printing.

As I don't print enough to keep an Inkjet in reasonable fettle, I switched to laser. For cheapness, black and white. When I need a colour print, I nip to my local print shop with a USB stick, or send the files off to a print service. Convenient though it would be to have one, I don't do enough printing to justify buying a colour laser, especially not an office-grade machine.

Dave

It's the "if true" question that's captured my interest & why I'm developing an experimental pendulum.

A good way of solving problems is to copy previous work, doing better by implementing best practice in new ways. Knowing how much weight a bolt needs to support, choose a standard size and type. Don't design a new fastener or anything else unless essential. Avoid Experiment.

I'm taking an experimental approach. If I only wanted to build the best possible clock, it wouldn't have a pendulum!

My interest is in seeing how good a pendulum clock I can make with modern methods, a hobby. So far measured two prototypes & measuring is difficult in itself. The second prototype tackled flaws revealed by measurement.

An important principle is that I fix big problems first:

• Basic mechanical issues, mainly in my over-simple poorly-made suspension
• Changing temperature causes major errors that must be managed
• A surprise, changing humidity caused significant errors in a carbon-fibre rod used experimentally as a combination rod and suspension spring. I believe humidity alters the rod's flexibility rather than its dimensions.
• air-pressure causes small deviations, and has to be managed too

All that done, I still have detectable errors. In particular my pendulum is 'noisy', that is its period varies slightly beat by beat. In a mechanical clock, the escapement and impulse are likely suspects. My escapement is an Infrared beam. and the impulse is applied by an electromagnet.

Focussing on the electromagnet, it's clear from my measurements that over powerful impulsing always disturbs period. More, is it best to apply the smallest possible impulse on every beat, or to minimise shock by applying a larger impulse every 'n' beats, and letting the pendulum swing free as much as possible? My results are contradictory: first prototype was best impulsed every beat, but the second works best impulsed every 'n' beats. Don't know why.

Moving on, I believe most of the noise in my pendulum is due to a mistake! The sensor holder is too short & the IR detector isn't triggered until the bob is a few degrees past dead centre. No excuses, George Airy proved about 1830 that the impulse must be applied at dead centre, but experimented with a gentle magnetic pull at top. Having decided George was right, I messed up the 3D-CAD model so the real clock is wrong.

Next step is to rebuild the clock, hard work because I shall add the vacuum plumbing too. Delayed due to illness.

However, at this stage, I've no evidence that the IR beam in my clock is causing any trouble. As the beam uses ordinary components, wouldn't be surprised to find noise due to mismeasuring, but so far not detectable. Why not? I posit any beam outperforms a mechanical escapement simply because no force is applied to the pendulum. Also, beam noise may not matter if the electronics are reasonably consistent. Beam engineering can't be ignored - was necessary to shield the IR receiver to avoid false triggering due to light & reflections.

If the next rebuild shows the beam is causing trouble, that part of the clock will be upgraded. But I've plenty else to worry about before needing to spend time and money on it. And I want to measure just how good or bad a basic IR beam is before moving on.

FGPA and similar suggestions aren't attractive yet. At present, applying FGPA to my clock would be a lot of effort for not much return. I have to find and fix big errors first. I'll die happy if my clock performs so well that FGPA is needed to improve it.

Quick explanation of FGPA! A digital computer can emulate any logic function by applying a sequence of instructions to data. Very flexible because the instructions can be changed at any time. Not all rosy though. Though fast, the electronics in a computer have to do a lot of time consuming work - read next instruction, decode & execute. Therefore plain electronics are faster than a computer programmed to do the same job.

Unfortunately hard wired electronics only do one job and are expensive to design, build, and debug. Change very difficult.

A Field Gate Programmable Array is a good alternative: a gigantic chip stuffed full of logic circuit blocks that can be interconnected in any way. Connections between blocks are programmed, perhaps by blowing fuses to disconnect unwanted circuits, producing a configuration that does a single complex function at high speed.

Blank FGPA are mass-produced and applying them to a problem is more like computer programming than assembling conventional components. Very common now for electronics to be built from a mix of microcontrollers, FGPA, &specialised chips. The combination is fast, affordable, and mostly programmable. A few clever folk understand it all, but development is mostly done by specialist teams. I'm probably too old to tackle FGPA now, but it's good stuff.

Dave

Whoops. Either I'm going potty or the forum skipped a post. I won't put it to the vote!

Dave

Not rubbish at all because it gives direct access to all the pins. Downside is having to build the support components already on the Arduino board - more work. I don't calibrate the resonator with an OCXO, it's currently done with GPS, but see my reply to John's comment above. Good idea: might try it.

Dave

Great minds think alike! That's where the photo of a Nano and PP6 on the same breadboard came from. The pP6 sent software serial to the Nano, which read a BME280 and added environmental data to the pP6 string, before sending the whole via USB to a PC (actually a Pi)

At that point I discovered I could do PET and collect environmental data with the Arduino alone, advantage being it eliminates a serial hop, and moved on, missing a trick. At the time I didn't have an OCXO, and it's only just occurred to me after reading your post that an OCXO/pP6/Nano combination is a winning combination!

Clearly my claim to have a 'Great Mind' is flawed.

Life dominated by a family crisis at the moment but I should be able to build one later. Not difficult to program and I could use it to measure how good my GPS + ordinary oscillator technique really is.

Ta,

Dave