Member postings for SillyOldDuffer

Well, although there was a Whitworth Standard for Screws for Instrument and Watchmakers, it wasn't included in the British Standard (because BA was adopted for that sort of work.) So can't be BSW in the purist sense.

Probably not Whitworth though because the set is American, and they never went in for Whitworth much! I reckon it's ASME, the US National Standard thread form miniaturised for Instrument and Watchmakers.

Can you measure a flank angle? Whitworth will be 55°, ASME 60°.

Interesting find whatever it is.

Dave

Highly unlikely the motor won't work perfectly with a VFD. Possibly the MS2 is extra well-matched to a VFD, perhaps constructed to give a bit more torque at low speed and to run a little faster than a T3A could.

Small differences sometimes matter to industrial users. On a Myford you won't run the motor at top speed in case it damages the bearings, and - if the motor struggles at low speed - torque on a Myford can be got by changing the belt down or engaging back-gear.

Dave

Sadly not - last time I found one for sale it was too expensive. Ought to look again, I'm often in despair! Zero progress today on anything.

Dave

"The T3A power is rated at 0.75 - 7.5; the MS2 is 0.75 - 37"

I don't understand the numbers or see them in the spec. Where did they come from?

Twigged it! It's from the website. Doesn't matter. The T3A series is a range of motors. The smallest T3A is 0.75kW, up to the largest, which is 7.5kW. MS2 is another series ranging from 0.75kW up to 37kW. They both come with 2-4 or 6 poles and with the usual standard footprints The difference appears to be their relative efficiency and power factor - T3A motors are shade better than the MS2, not power or torque, just running cost. On a home lathe, the running cost difference will be tiny. It would show up on a machine that did much more work per day than a Myford.

Practically the 0.75kW motors from the T3A and MS2 ranges are almost identical. Either will be fine.

Dave

I offer a Metropolitan Vickers electric loco, introduced in the 1920s

No 17 above was Florence Nightingale, scrapped in 1942 after an accident.

No 2 was Oliver Cromwell, renamed Thomas Lord in 1953, withdrawn 1962.

Dave

Is 600 - 800mm square the maximum available, or is the table allowed to overhang?

My WM18:

• Stand 400mm wide x 580mm deep
• Tray 600mm wide x 680mm deep
• Table Width 1150mm (including handles)
• Max Right-Left table movement, 1744mm, including handles.

So a WM18 would nearly fit in the space, except the table overhangs by 275mm both sides, much more when the table is traversed. On one side my table projects across a walkway, ion the other it overhangs an area used for storage.

The WM16 and WM14 are much the same design scaled down Can anyone provide their Max Right-Left table movements?

It was size that decided the machine I bought: a WM18 was the biggest I could fit in.

Dave

I was a professional programmer, paid to write in COBOL(s), FORTRAN(s), Filetab, C, C++, Sculptor, Perl, Informix-4GL, SQL, MS-BASIC, Visual-Basic, Pick-BASIC, and Delphi (Pascal-like). Also for my employer, I wrote reports on the applicability of Algol, Forth, BASIC, LISP, Pilot, Pascal, Python and Ada. Plus a comparison of the vices and virtues of the competing RDBMS of the day. Not only can I write BASIC, more than one variant, but I've had plenty of experience with other languages in all applications apart from real-time.

I'm afraid BASIC doesn't fare well in a professional programming environment. One difficulty is the large number of different versions of 'BASIC' - it's poorly standardised, leading to low portability and high re-training costs. There are many other irritants.

Early BASIC was narrowly focussed on allowing ordinary folk to interact with a computer, mainly to hint at possibilities. A simple language with no pretensions, the first BASIC was never intended to be more than a demonstrator. Unfortunately, its simplicity meant BASIC was fairly easy to implement on early 8 bit microcomputers, and it became popular in the hobby community, gradually adding many non-standard improvements.

BASIC's fluidity was no problem for singletons with home computers, but youngsters moved on to Computer Science courses, and started in IT Departments with their heads full of BASIC bad habits, that had to be painfully unlearned. Folk who had started with BASIC didn't make good use of the clarity provided by structured languages : they mangled Pascal by expressing logic in BASIC terms. And BASIC didn't support teams of developers. Meanwhile, computer languages had moved on, introducing features that BASICs haphazardly adopted later in non-standard ways. Although modern BASICs look respectable because they've adopted modern features like structured code and objects, BASIC is messy. BASIC's shortcomings turn nasty as programs grow in size and complexity. OK for small simple stuff. All big systems are hard to maintain, but big systems written in BASIC are extra tough. Trouble is most programs don't start out intending to become big and complex, but they often grow like Topsy as users ask for more features.

Today there's no call for BASIC in the world of jobs or academe. BASIC's main benefit is for hobbyists who started with on a ZX80 or BBC Micro, who want to do similar hobby programming on a microcontroller. Fair enough - it reduces the learning curve. But taking that short-cut ain't smart for anyone who wants to earn a living as a programmer, is serious about getting the best out of a microcontroller, or is starting a large project.

Under no circumstances should youngsters be encouraged to start by learning BASIC. In an IT job interview they will be asked to explain why they chose BASIC. They'd better have a good reason, and I don't believe there is one! Choosing BASIC means you don't understand the history, or why other languages are more suitable, or didn't question what their misinformed Elmer said. Being easy to learn is only one factor - grown-up programming needs much, much more. For example, BASIC is inferior to:

• Horrible old COBOL for Data Processing
• FORTRAN for Maths
• C/C++ for system, embedded and software tool programming
• Javascript & Java for web work
• C# for smart phones
• Python for general purpose computing

I see in the 2022 IEEE list of Top Programming Languages that only one BASIC is listed: Visual Basic is 29th between VHDL and Labview.

The only good reason for using BASIC today is you already know it and don't need better. Good choice for tinkerers who already have BASIC skills, bad choice as a starter language for everybody else.

Dave

Rawlings (in The Science of Clocks and Watches) discusses bob shape in Chapter 4 (Dissipation of Energy by a Swinging Pendulum), and DA Bateman adds a useful section in which 'The objective was to discover which shape would give the lowest air resistance for a given volume, and hence the largest Q for a given mass and density.'

In short:

• The bob should be made of a high density material such as Tungsten
• Swinging inside a case reduces Q compared with swinging in open air
• in DAB's comparative experiment
  • A 3:1 cylinder was worst - Q=1845
  • Next up, a sphere - Q=2946
  • Best performer, a 2:1 parabolic spindle - Q=3375

My pendulum has a mild-steel cylinder bob, not a good shape and it might rust, but I plan to swing it in a partial vacuum. As my ancient vacuum pump only gets down to about 600mb, I might try to improve the shape by rounding the ends into a "cylinder with hemispheres".

Cylinders are easier to make and balance than other types, which is a practical advantage.

I guess Joe's bob shape isn't the absolute best possible. However, still hot stuff - better than a sphere, and much better than my cylinder.

I don't think Rawling's mentions polishing. I'd expect a highly polished bob to perform better than a rough one.

Dave

The Graces Guide entry for John Harris Tools includes this advert:

Dave

I thought M20 x 1.75 was extremely unlikely too, except the thread is a perfect match to 1.75 on my thread gauge and the male is very close to 20mm.

And, although M20 x 1.75 isn't listed as a fastener thread, it must be used for something because taps and dies can be bought for it.

I always assume all metric threads must follow the fastener standard, but it's not true. As the thread I measured is for a pipe fitting, not a fastener, possibly it's right. Maybe M20 x 1.75 and M20 x 1.5 are legal in some 'not a fastener' standard we've never heard of.

It is odd though! I'd expect a drain-plug to have one of the usual threads, yet mine seems to be a weirdo.

Dave

I think the photodiode's black colour is more a nod towards filtering than effective! Better than nothing.

Yes I looked for jitter by triggering the scope on both input and output. I couldn't detect any jitter with either arrangement except on the falling slope of the output when the comparator is rapidly triggered by a short input pulses, say 3uS wide input pulses every millisecond. A 1mS wide pulse repeating every 0.5s doesn't cause any jitter.

On this module only the RISING edge is reliable, but it seems very good. I use the RISING edge to count period, and time the FALLING edge to guesstimate relative amplitude, which, fortunately, is less critical!

Good idea about Standard Deviation and random walk - I'll have a go later.

Dave

The tray and drain is for suds rather than clearing swarf. Not big enough to wash away swarf which often comes in bundles.

I'm like Jason and Dalboy except I don't bother with a cooking tray. I remove largish bundles of swarf with a gloved hand (lathe switched off) and/or magnetic swarf rod. Finer chips are occasionally collected with a bit of hardboard. Once in blue moon, I vacuum clean the whole lathe and swipe with a cloth.

I don't care about the paintwork!

The thread in my WM280 drain appears to be M20x1.75, which is odd for a hose fitting. Might be 1/2" BSPP and 14tpi, which is close to that size.

Dave

Wot, not even Yamaha? I think they do!

Imaginative talented customisation is a very good thing, but it's not to be confused with engineering design from first principles. Try this for size. Move into an unfamiliar branch of engineering, perhaps electronics. If that's genuinely new territory, please design an electronic ignition system for the XS 650. All your own work please - do not attend a class, consult books, search the internet, or ask anyone else. We'll mark the result!

Engineering from scratch is very difficult to do without plans, drawings, education, a good library, skilled support, prototyping and plenty of hard maths. Mostly done by teams, not individuals. Can take a long time too - about 200 years to get steam engines working at peak efficiency...

Dave

It's often hard to follow forum threads because after someone makes a point like as not many other unrelated posts intervene before it's addressed. Confusing

This one touches on my wandering clock rate, which SK (who is experimenting with a laser), believes is due to my basic beam and sensor. He could be right because, as part of the experiment, I deliberately chose to repurpose an Arduino module. I assumed the module would work reasonably well, and - so far - haven't proved it's unsuitable. Rather late in the day, I've run some tests and discovered the module has shortcomings!

Having wondered if I could approach the performance of a 1922 Shortt-Synchronome with a home-made pendulum and modern electronics, I decided to see what could be done with hobby technology. The idea was that anyone who wanted to copy what I was doing could do so easily. My clock isn't best practice, hence much messing about from which I've learned a lot and kept myself interested.

I've got a big list of improvements. Not least the TDc7200 TDC and OPB960-11.

Dave

Though what's considered bad practice varies.

I was brought up to treat the humble flat-bladed screw-driver with great respect, never using them as crowbars, chisels, scribes, stirrers or wedges. Soon realised that screw-drivers are excellent for all those jobs, and collected a bunch of battered old ones for what I call bodge-driving. Now when the old ones are past it, I'm happy to buy new screwdrivers specifically for abusive work. I think it's OK as long as I never use my bodge-drivers on screws!

Dave

Pedantic I know, but I read somewhere low voltage thick filaments also reduce 50Hz flicker because thick filaments have higher thermal mass than thin ones. Though I've not noticed much difference myself, I guess 50Hz flicker could have been a problem on a large shop-floor lit entirely with filament bulbs all flickering together at the same time.

Agree care is needed, especially with lamps in a workshop. The cheap magnetic 2-pin work-light my daughter added to her sewing machine is safe enough because the sewing machine is double insulated and operated on a table in a dry indoor room. I wouldn't use the same lamp in my workshop because the risk of a serious shock in there is much higher. My lathe isn't double insulated, I stand on a concrete floor that might be damp and sometimes splash water about. The lamp is exposed to higher levels of vibration and  falling into the chuck could break the insulation. The environment has all it needs to make an electric shock much worse than it would be in a dining room. Special rules apply to bathrooms, which are dangerous for similar reasons. Mains electricity in a workshop requires a few more precautions, like avoiding cheap 2-pin work-lights!

Dave

Edited By SillyOldDuffer on 21/08/2023 11:32:15

Don't get me started on change management! My experience echo's Duncan's.

After building up an enormous problem by taking the easy way out for decades, the board often wake up in the Last Chance Saloon with no practical way of untangling a complicated knot. Staff who don't see the accounts think everything is fine, and see no reason to change anything, or they've been suffering for years and have no faith management will ever operate in their interests. Under pressure to deliver existing commitments with what they have, middle managers barely cope with day-to-day problems and have no time for bigger issues, even if they were listened too. (Middle managers upset the board by bringing bad news and making strong technical objections to grand visions; best not to ask them anything!) Senior managers focus on the 'big picture', and rarely understand how the business works in detail. They don't know how to re-engineer a large organisation haemorrhaging money because its riddled with thousands of minor inefficiencies.

Not realising productivity is maintained by good-will and arrangements evolved over decades, the board launch an ill-judged untested change programme. It's probably naive, seriously under-resourced, poorly planned, and has no fall-back. It will be dumped on a stressed workforce in hope they can solve a mass of unidentified complicated organisational puzzles and make it work. The attempt will cause a lot of waste and failures when the board are having a very difficult time negotiating money with banks, share-holders, investors and government.

Doesn't always end badly but it's not unusual for entire organisations to be demolished and restarted from scratch. Rather than sort out shattered labour relations in a tiny Victorian factory full of obsolete equipment, it's easier to build a big new factory abroad, fill it with all the latest equipment, and recruit new staff locally who can be trained to implement current best practice without having to deal with the sins of the father. Or sell the brand-name, turn the factory into a car-park, and reinvest the money in bit-coin.

'Big picture', back in the UK, staff released from the thrall of a dying organisation, are re-employed on more productive work by an up-to-date employer, who isn't burdened by what went wrong before. Whilst it works on average, the process is unpleasant: people suffer when it happens to them, in terms of stress it's up there with life-threatening illness. I had many friends who worked for the GPO / BT when it transitioned from copper and Strowger to fibre and digital. Although redundancy was generous, no joke for middle-aged men to find themselves looking for new jobs in a market that didn't value electromechanical communications skills. Horrible.

Today, young people do not expect the job security that became common after 1945. Many of us had it easy!

Dave

"Is a hammer on a surface plate worse than leaving a chuck key in?"

Correct answer is 'No'. Injuring people is usually far more expensive than damaging objects.

Putting a hammer on a surface plate only risks damaging a physical object that can be replaced or repaired. Yes it's bad. but only in the way scratching a car with a supermarket trolley is bad. Leaving a chuck key in is worse because it can damage people as well as the lathe and job. Very bad in for the same reason a car crashing into a crocodile of schoolchildren is bad.

Dave

I set up an experiment to test the performance of the Arduino Infra-red Obstable detector I'm using to measure the period of my pendulum. One of these modules, with the photodiode and IR LED extended on leads:

The test set-up is a 100MHz oscilloscope and a 60MHz Function Generator. The Function Generator is set in pulse mode, and it's output was connected to an MPSA06 transistor used to switch the IR LED on and off. To keep light out the IR LED and IR sensor were mounted inside a brass tube made on my lathe. (It's not all electronics!_

The arrangement lets me pulse the IR LED over a wide range of pulse widths and repetition rates and to measure how accurately the comparator responds to the detected signal.

Results are more complicated than expected.

The shortest input pulse that can be detected depends on the repetition rate, this graph is for input pulses repeating every 20mS:

Although the comparator switches on quickly, 9.4uS after the transistor base is switched, it can take a long time to turn off after the input pulse ends. Next graph for slower millisecond pulses repeating every half second:

Good news, no no sign of noise being introduced by the IR beam. Next step is to break the beam with a real bob and look for noise due to diffraction as the bob flies slowly through the beam. And to buy a Sharp opto to see how that fares.

Bad news, that the comparator stretches pulses means my relative amplitude calculation must be off because the sum is based on the length of time the beam is broken. Probably harmless because relative amplitude is only used to detect an arbitrary trigger point.

In doing the experiment I noticed yet again that sunshine causes real trouble.

Conclusion: the beam sensor is flawed, but not badly enough for me to rush to upgrade it. The way the beam sensor misbehaves when pulsed electronically doesn't explain why my clock rate wanders. I don't expect diffraction to explain it either, because surely any error diffraction causes must be constant?

I may take even more radical steps to keep sunshine out of my clock.

Dave

A sensible observation. My workshop rarely allows the fast heavy cuts typically needed to optimise carbide. I mostly work on fist sized objects using not particularly fast, powerful or rigid hobby machines. Difficult to get high surface speeds on small diameter work, so sharper carbide inserts often cut better than blunt efficient ones.

Boring is on my list of difficult operations. The biggest problem I think is boring bars tend to flex and chatter because they have so much overhang.

For convenience I prefer carbide boring to HSS, but getting good results can be fiddly, maybe swapping inserts, and often having to try different combinations of RPM, Feed Rate, and Depth of Cut. Fast and light cuts generally, but much depends on the material and the depth and diameter of the hole. I find it easier to get good results on larger diameters and deep holes are harder than shallow.

Dave