Here is a list of all the postings SillyOldDuffer has made in our forums. Click on a thread name to jump to the thread.
|Thread: Will cash become obsolete ?|
Government and banks aren't the major drivers, it's what the young folk do that changes the world. They hardly use cash at all. Not for them wasting time counting notes and fumbling with coins - contactless, bang, gone. And in business, the yoof positively dislike cash because it makes life complicated. Cash in at a bank? You must be joking granddad!
Someone complained on the forum that 'Boomers' is now a term of abuse. Kids today have gone soft; in my young day our elders were all 'Old f*rts', even though they were genuine war heroes. Time gets us all in the end. Horrified to find that hotmail accounts are now considered thoroughly old-fashioned...
|Thread: Colchester Student Mk1 Won't Start|
Well done you and Phil!
|Thread: DC-DC converter|
Method in my madness though! I tested my caliper with a linear PSU and 40cm leads and it was all over the place. Previously, I'd powered the same caliper from an Arduino with short 5cm leads and it was fine. (Arduino's on-board linear regulator, my potential divider.)
Thinking about it though the experiment isn't convincing. I ought to repeat it with a battery rather than a mains PSU. If I repeat with battery clean volts and the caliper still misbehaves, it must be noise picked up by the wires?
Induced noise is quite likely I feel because the caliper is high impedance? (I make 6uA at 1.55v about 260kΩ but you know what my maths is like!)
I still think my conclusions about the caliper being very sensitive to low volts are valid though. I found:
My caliper fails absolutely below 1.48V and was reliable only above 1.51V. The SR44 cell produces 1.55V, and this voltage appears to be critical : a drop of 0.05V is enough to upset this caliper, at least with my noisy supply.
No harm in checking again especially as I qualified the conclusion with 'at least with my noisy supply'. Playing electronics is more interesting than tidying, which is what I'm supposed to be doing! I might have a glass of wine and do the experiment in a drunken haze.
Edited By SillyOldDuffer on 07/04/2020 15:45:07
|Thread: Will cash become obsolete ?|
What else is disappearing?
My wife's granny saw a Zeppelin, mine grew up with cobbles and dirt roads - no tarmac. They both knew ragamuffins. My mum remembers horse drawn carts, trams, skies full of propeller driven aircraft and Lord Haw Haw. I remember a working Steam Roller, Buttons A & B, Telegrams, Trolley-buses, Slide Rules, Typewriters, Punch-cards, DA Haircuts, Black and White TV, Factory Chimneys and LSD. Others will have more examples!
On the way out: wildlife and the Great Barrier Reef, Internal Combustion Cars, Cash, Pensions as I knew them, Jobs for life, slow Data Networks, Sodium Vapour street lamps, broadcast TV, cheap oil and a high meat diet. And any job that can be done by artificial intelligence...
Inter-species jumps are difficult - if they were easy, we'd be ill all the time. Infectious diseases are tuned more of less to their hosts by shared chemistry. Anything of a mismatch and the risks caused by bugs plummet. Chemistry obviously matters on a larger scale too: cat fleas dislike human blood, and - even though sheep love it, I can't digest grass. Between 1 and 3% of human body weight is bacteria living in us, fortunately we're friends.
Coranavirus is a common as muck family of viruses that have been around forever. They infect many different hosts including dogs, see Canine Coronavirus, but don't usually jump between species. When they do, immune systems are unprepared. In humans, one member of a large family is causing big trouble. Covid-19 is fairly infectious and mildly dangerous. Covid-19 is a variant that happens to have chemistry matched to human cells. People spread it, not cats, dogs, or red-herrings!
Edited By SillyOldDuffer on 07/04/2020 13:53:06
|Thread: What is it with the fit of old slotted screws?!|
There are standards but they don't help much. The answer is the width of the slot depends on the diameter of the screw and the thread system.
BA slots are specified in BS57-1920 as being 0.2D + 0.1mm, where D is the full diameter of the thread.
For BSF and Whitworth, slot widths are listed in a table. 8 different slot widths are listed for the 12 screw diameters between 1/8" and 1".
For extra confusion, the depth of the slot is related to it's width and possibly also to the type of head. For example, BA slot depths vary depending on whether the head is Countersunk, Instrument, Round, Cheese, Filister Capstan or Connection.
Metric and other standards follow similar rules.
In theory a different sized screwdriver is needed for almost every type and size of slot-head screw; i.e. dozens of them.
In practice, if the correct sized screwdriver isn't in the toolbox, one can either be ground to fit or the job can be bodged by attacking the screw with whatever is handy. Judging by the number of old machine screws with chewed slots, most of the work in the good old days was done by lazy apprentices rather than master-craftsmen!
|Thread: DC-DC converter|
I guess what's going on is the caliper expects to run off a cell and they are as electrically pure as you can get. There's no need for the caliper's electronics to have any protection whatever against spikes, ripple or voltage variations because - in normal operation - there are no long leads to pick up mains hum or other interference, and battery DC is clean.
Adding an external power supply opens the door to a bunch of nasties, which the caliper isn't equipped to deal with. Putting a capacitor across the battery terminals will decouple the caliper, which is good. Putting it at the power supply end won't have the same benefit.
Another easy thing to try is making the power leads into a twisted pair. Twisting wires together reduces external noise by balancing it out.
|Thread: Borehole pressure vessel change|
I doubt the walls will be particularly thick especially if the container is steel. My wild guess about 3mm, could be wrong!
15bar is about 220psi, which isn't far off the working pressure of a model loco boiler made of relatively thin copper. Cylinders take a lot of internal pressure: a 2 litre lemonade bottle bursts at about 12bar, and the plastic is about 0.23mm thick. The pressure vessel will be proportioned to take a working pressure plus allowance for heat and pressure cycling (if any), and probably corrosion. (Does the cylinder have a specified life like rechargeable gas bottles?) Then multiplied by a hefty safety factor. For ordinary items x2.5 is common, x5 if safety is involved, and x10 or more if safety critical.
I know absolutely nothing about boreholes!
|Thread: Will cash become obsolete ?|
I'm reminded of the late George Best “I spent a lot of money on booze, birds, and fast cars. The rest I just squandered.”
Seriously though, despite being convenient for small personal transactions, cash has many disadvantages.
Try buying a new car in cash - asking will be an embarrassment for all concerned. Even worse, offer to buy a house in cash. Special arrangements will have to be made to move the money securely, and expect awkward questions about laundering, proceeds of crime, and tax evasion! Many purchases are impossible in cash - for example, online sales are all electronic.
Cash is completely unsuitable for buying anything really big like railways, motorways, airlines, shipping, armed forces, power stations, and the health service etc. Trade in goods, services and commodities is enormous - in 2019 Australia exported about $50Bn worth of coal and $75Bn Iron Ore. They weren't paid in cash!
Cash suits criminals because it's hard to trace. As they are the main users, the assumption now is a bag full of €500 notes is unlikely to be legitimate.
Managing cash in volume is a major risk due to crime, fire, flood and fraud. Payroll and bank robberies with violence were once commonplace. Even disposing of worn-out paper money is dangerous - Jack Mills never recovered from his injuries. Looking after cash costs a lot of money - safes, guards, armoured vans, bank vaults, alarm systems, cameras, spot checks etc.
So cash has been replaced gradually since about 1700 with 'instruments'. Once mainly high-finance, they're now common in ordinary life. Most of them today are electronic. Like cash, they are just promises to pay. Electronic money is a form of paper money - neither are actually valuable like Gold.
Electronic systems are safer than cash because they can be backed-up, traced, and are accountable. Cash kept under the bed is gone forever if its owner falls for a con-man. If the bank fall for a con-man, your money is safe. Electronic money transfers are much faster and far cheaper too.
Unfortunately, nothing is perfect. Banks are run by fallible humans. Greed often leads people to make foolish decisions and tempts them into crime. A common mistake is assuming a financial bubble like sub-prime mortgages must grow forever just because it paid a big bonus last year. Pop! A disadvantage of modern money methods is the system is much bigger and faster than before. When it crashes, it's likely to be on a large scale.
|Thread: Myford Mk1 Super 7 restoration|
I agree with V8 and it's all easily fixed. In addition to the dodgy fuses and exposed wires, the earth is a tiny rusty bolt and the cables look like rubber. Never trust old rubber...
|Thread: Which Lathe???|
Yeah, but no, but maybe! Broken teeth are a common problem on Myfords. It's because screw-on chucks tend to jamb over time and unwise attempts to get them off is likely to break something. Another major disadvantage is they come undone when the lathe is run in reverse. Though screw-on chucks give good service, I feel a fixing method with two faults can't be ideal.
Bolt on chucks cure both shortcomings. And being able to run a lathe safely in reverse is useful. There's no risk, for example, of crashing into the chuck when screw-thread cutting in reverse away from the headstock. I do all mine that way at high-speed.
Screw-on and bolt-on chucks are both inexpensive compromises rather than the best available. Camlock chucks can be reversed, don't jamb, and are super-quick to change. Shame about the price!
A good reason to be wary of bolt-ons is lack of room behind the chuck. People with big fingers hate them!
But can you name a no-good lathe being sold in the UK by a reputable supplier? (Internet purchasing from abroad is different.)
The Chinese lathes don't meet Paul's criteria. Although they're built to a price and assembled in a hurry, they don't win any beauty contests, and they can produce decent work. No one claims they are a good choice for a tool-room.
Well made lathes hold their settings better, have a smoother feel, and generally save time. They make life easier for the owner. But their motors aren't magically more powerful (though may be continuously rated for sweat-shops.) The dials might be more accurate, but dials aren't essential to accurate work. Low backlash is good, but backlash can be worked around. Thread precision depends on gear ratios, not how polished the change gears are. Being more rigid might allow heavier cuts, but again not essential to accuracy. And lathes all work in the same way: cutting is relative to a spinning axis, which means lathes as basic as a watchmakers turns can still produce accurate work.
In a blind test I think it would be impossible to tell the difference between sample rods turned on a random mix of Super 7s, Chinese, and other machines. Easier to detect the difference between experienced and inexperienced operators.
Knowing how long it took to make each item would be a better guide to the quality of the machine that made it: I'd expect the better lathes to be easier to drive and therefore more productive. But even that's dubious, - a fast Chinese machine with carbide inserts might well leave an Super 7 an HSS in the dust.
It comes back to what individuals want their machines for. Horses for courses...
PS Though not essential, I bought an extra-comfy chair for armchair engineering.
Since you ask, yes, that's how tarts think!
What do you want a lathe for? If it's for cutting metal, almost any machine will do. For rough work, badly worn classic machines and rough Chinese can both perform. In skilled hands it's remarkable what can be done.
In 1947, Myford released a hobby lathe that made all the others look dated or inadequate. It included many modern features - like guarded gears - and was well made. It struck an excellent balance between quality, size, functionality and price. Price was vital, because, although an expensive stretch for most, Myford lathes were just affordable.
Most other good lathes were aimed at the professional market. The cheapest Boxford was about half as expensive again as Myford's dearest machine. Other makes were seriously big money. Mostly bigger and heavier than the Super 7 with complicated 3-phase power requirements. They were bought by schools, colleges, universities, garages, workshops, and factories for whom Myford lathes were too small and on the delicate side.
Time marches on!
From 1980-ish onwards CNC made most manual machines obsolete. Many were and are sold in excellent condition, often much cheaper than a Myford. Myford have a deservedly good reputation but part of it is suspect. Model Engineers had spent 40 years telling themselves that Myford made the best lathe in the world, which was only true while the alternatives were unaffordable.
As VFD's have solved the 3-phase problem and second-hand professional lathes are being dumped by industry and education, its realistic for hobbyists to go up-market from Myford.
At the same time, Far Eastern makers started producing lathes of more modern design. Easier and cheaper to manufacture than a Super 7, and - for the hobby market, made down to a price. They're a bit rough, but despite numerous minor warts, my WM280 is 'better' than a Super 7 because it's bigger, and cheaper, and does all that I want of it. (26mm spindle bore) True it has no charisma, but I bought it to cut metal, and don't mind fettling it myself! Not clear exactly were the Chinese designs came from; the general approach reflects European and USA thinking developed during the 1950s, which recognises the foolishness of paying for unnecessary quality.
When Chinese lathes are discussed on the forum, we mean the hobby machines. As far as I know, no-one on the forum has ever bought an expensive Chinese lathe. If you have £10,000 plus to spend they do some nice machines...
30 years ago, telling beginners to buy Myford was good advice. Dubious today because the machines are 30 years older and there are far more alternatives.
In the end, it's what you want. I don't care my lathe is warty, others are thoroughly irritated by minor issues. I wanted to buy a lathe to fit the space available, have it delivered, and be able to return it if it was a dud. At the time I wasn't confident I could check out a second-hand lathe, and I couldn't travel far to look at candidates. But that's just me, you might enjoy the hunt, and value pride of ownership.
Do you like a sparkly clean tidy workshop? Mine's a disgrace. Your goals, interests and psychology matter.
|Thread: Todays news -- well done|
The purpose of the lock-down is to minimise contact between people. Those who isolate can't catch it or pass it on to someone else. Therefore the less movement the better.
I see three categories of thinking causing people to break the lock-down:
It's very difficult problem to manage. The government are trying to balance the painful measures needed to control a major health crisis against cost and the need to maintain normality. People are dying of the disease while others lose their livelihoods. Hospital, care home and other workers are courageously putting themselves on the line day after day after day. I'm not aware that any club has suffered due to reduced care-taking; surely in comparison to everything else, looking after a club isn't a priority?
Good result Keith, and exactly how I would have done it.
If you'd hit bother, I'd have said nasty things about turning rebar. Apart from the need to hack back to a smooth surface, the specification of the steel is unknown. Whatever grade of steel is in your particular example, it's structural, not meant to be machined. Using it is a bet, not a safe engineering choice.
The gamble paid off, but poor choice of metal can cause awful grief! I advise against beginners turning scrap because they can't tell if bad results are due to them, the lathe, tool-settings, or duff material. Easier to work with scrap after building experience with friendlier metals intended to be machined.
I had a bad experience early on - unknown to me all the scrap in my junk box was Awkwardcussium. For a while I thought my lathe was incapable of cutting metal. So much more straightforward when I defeated my mean streak and bought suitable Aluminium, Mild Steel and Brass from my local emporium.
|Thread: Which Lathe???|
Tricky one, but despite objections to Chinese, one of them may be the answer. Going 'English' reduces the available choice particularly if a good condition big bore must fit into a small space. It may take a while to find a suitable classic machine, especially if metric is also important. (Buying second-hand, condition is more important than make and model.)
Myford suffer from the name attracting premium prices. If money is no object Triona list a Connoisseur at the moment. It's said to be in unused condition. Price on Application; no harm in asking, but make sure your pacemaker has a fresh battery!
Health emergency apart an important advantage of new Chinese machines is they're available off-the-shelf in a wide range of different sizes. The machine that fits best into the available space can be picked out of a catalogue.
Edited By SillyOldDuffer on 05/04/2020 16:37:18
|Thread: The Workshop Progress Thread 2020|
Are you sure the cases were all Aluminium? Some hard drive cases are Magnesium, as are many laptop bodies.
Magnesium and Aluminium look similar and melt at about the same temperature (650C vs 660C). The easiest way to tell them apart is to measure their density; Magnesium at 2.7g per cc is heavier than Aluminium at 1.7g per cc.
Whilst Aluminium is safe to machine, Magnesium swarf is rather too easy to ignite. It burns with an intense bright white flame and the fire explodes when water is poured on it. Great fun! Magnesium is used because it casts and machines better than Aluminium and is stronger, but it has to be handled with care.
Magnesium and Aluminium alloy together usefully. Commercial alloys go up to 15% Magnesium, which casts well and is strong. Alloys with less Magnesium machine better but aren't quite so good for casting. On the down side swarf from Magnesium/Aluminium alloys catches fire much more easily than ordinary Aluminium alloy swarf. It's not as bad as pure Magnesium, but still risky.
Once started metal fires are more dangerous than ordinary fires, chances are an ordinary workshop extinguisher will make them worse.
Magnesium is top metal for machinability - it's easy to cut, dimensionally stable, and gives excellent finish with no bother. Better than all other metals. Not used as much as it might be because the fire hazard always has to be managed, both whilst cutting and then handling and storing the swarf.
This Youtube Video shows what to expect. I'd cheerfully work with it, but would take care to clear swarf often and have the right sort of fire extinguisher ready to go.
|Thread: Making Progress with TurboCAD|
Me too, which is why I use QCAD for 2D, and FreeCAD for anything 3D that doesn't require assembly. (I go Fusion 360 for anything that needs Joints. I like Fusion, but not the cloud model.)
I noticed tuning into how CAD software works isn't easy, especially in the early stages when one's mind is liable to be filled with preconceptions and assumptions about how CAD ought to work rather than how it actually does. Also, it's hard for beginners to see the wood for the trees because CAD packages are packed full of non-obvious features such as different workbenches, special tools, and expert facilities. Intimidating, and easy to get hopelessly lost especially if you like to learn by clicking buttons randomly to see what happens!
As CAD is beginner unfriendly I wrote a Getting Started with FreeCAD thread last year. I attempt to explain the difference between 2D and 3D thinking, which is often a major learning obstacle, and then try to get a model engineering beginner going as quickly as possible with the appropriate part of FreeCAD. Simple step-by-step examples moving up to more complex objects.
There was also a magazine series and thread covering Alibre, which some might prefer, because FreeCAD is a bit experimental, guv. Alibre, FreeCAD, and Fusion360 have many similarities. AutoCAD and TurboCAD take a somewhat different approach. Which best suits an individual might depend on previous experience and mind-set; despite knowing my objections aren't logical, I don't get on with AutoCAD.
|Thread: Gear Cutting - Pressure angle.|
Neil's not alone, here's my crude version for making Meccano compatible gears,
The rack cutter cuts an involute because the cutting teeth either side of centre shave off material from adjacent flanks whilst metal is being crudely removed by the centre cut. The amount and placement of adjacent shaving depends on the angle of the gear blank, which changes as the blank is rotated. The shaving effect progressively improves tooth shape towards a perfect involute. It's not like a form tool or gear-cutter where the tooth shape depends directly on the tool and can be cut in one go.
|Thread: BBC Micro Boxford TCL125|
The subject has come up before. There are a few mentions on this forum, and there used to be several websites where chaps described how they did it. I found this one on mycncuk fairly easily and also Johnsmachines, but not much else. I've an idea there was a Yahoo group, goodness knows where that's gone.
Anyway, it's not a simple rewiring job. While the lathe and motors are good, the electronics and original computer controller (a BBC Micro) aren't Mach compatible. (The BBC Micro is long obsolete.)
So the approach seems to be to replace the electronics with modern Mach compatible motor drivers and to dump the BBC Micro in favour of a PC. A tricky project to tackle on your own without electronics and computer experience.
Although Neil's suggestion of an Arduino converter has legs, it would have to be programmed by someone who understood Boxford and Mach control languages, and the difference between the BBC and PC parallel ports. Looks like a rich mix of easy and difficult, I think easier to replace the old electronics, which is what John' did. It cost him $AUD 800, about £200 today.
Best hope for an easy answer is to find someone who's done it already and copy them! They do exist, try asking on on the forums.
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