Member postings for SillyOldDuffer

How about extruding the 2D L by only a nanometre. Then the answer will be only slightly wrong...

Dave

A sensitive variant of this is burning a Joss Stick and watching what happens to the smoke.

I'd have thought the source of a rapid loss of steam at 80psi would be fairly obvious, in this case is it all blowing up the chimney? Mention of springs makes me suspicious of the valves. D-valves are supposed to be held down by steam pressure. Could there something be wrong with the assembly allowing them to lift, such as being fitted upside down. (A wild guess!!!)

Nah, don't beat yourself up! Threads are foggy.

Although engineering is standards based, the history is pretty complicated, and there's still plenty of opportunity for confusion. For that reason most of us own small reference libraries!

As professional engineering books are inclined to be dry and mathematical, they aren't beginner friendly. Fortunately, books have been written for us. Sparey is excellent on lathes, though he assumes Myford and wrote in 1948. Our very own Neil Wyatt has an up-to-date book on the Minilathe. And Jason Ballamy has covered Milling. The Workshop Practice Series are good too. Faced with a new problem, I often save lots of time by buying a book.

Last but not least are the magazines. Model Engineer is a good way of picking up information on methods, tools, materials, clubs, exhibitions, and problem solving. I found Model Engineer's Workshop even better, because I'm not really a Model Maker. I do experimental, and MEW focusses better on my need to improve workshop technique. I get value from both magazines, and after 10 years in the hobby am still learning from them. The forum is excellent because it supports Question and Answer, and members with a multitude of experiences all know their stuff.

Dave

Always happy to be educated!

In this Fluke diagram showing how to measure AC current, it's explained you can't put the clamp over Live and Neutral:

This I understand to be because the AC current flows one way in the Line wire and in the opposite direction in Neutral. The two generate magnetic fields that cancel out, so the clamp meter reads zero. Highly misleading.

However Live leaking to earth is a different case. The current flowing in Live is not equal to the Neutral current, so the magnetic fields don't quite cancel. A sensitive clamp meter will measure the difference, which is equal to the earth leak current.

Chris has me worried though: if the clamp is put over LN and E and the leak is due to a suppressor, the clamp won't detect it because the 3 magnet fields balance. It will detect a leak due to faulty insulation and a damp floor, because then not all the leak current goes back along the earth wire. Is that right?

Can anyone design a circuit that would reliably show how much current a device was leaking under all conditions?

I don't believe the debate alters the advice given to John.

Dave

I shim up 10mm on my WM280. I guess it would take 12mm but that's bigger than I need. I find advantage in smaller tools for fine work - the lathe is loaded with 8mm tools at the moment. Main thing is ensuring the shank is small enough to position the cutting edge at or just below centre-height.

If the lathe was delivered strapped with steel-bands, save it! Makes good shims.

Dave

Experts may not be infallible, but faulty logic to think they can be ignored because ignorant guesses are just as valid, They're not - experts are more likely to get it right than anyone else. Judgement beats luck on average, which is why I don't waste money on lottery tickets. Experts tell me the odds against winning big are about 14 million to one; the fact that one person wins does not alter the fact that there are also 13,999,999 losers!

I prefer Clive's earlier comment: 'If you have pure compressive stresses its at least as safe as the original casting. Any tensile or bending loads and you are in the lap of the gods. It will be stronger than the cracked casting but no way of knowing how much by as the bond made on the first puddling layer must be weaker than a deeper adhesion from a brazed or more sophisticated weld. Never as strong as a good casting would have been.'

Experts can't recommend the technique because it doesn't handle common stresses, and is unreliable to boot. If cast-iron has to be repaired, they would argue, why not do it properly? The answer is that gambles are sometimes worth trying, especially at home. If a chancy repair works, hurrah. Otherwise no worse off than before.

But thanks to Clive's explanation, I'm now more expert than I was on puddling! The education makes it possible for me to better judge if the method is worth trying should I need to repair cast-iron.

I guess faulty heat-treatment was the problem with the Kurtis' casting. Large, complex, thin castings are likely to develop internal stresses if they are cooled unevenly. Who knows, perhaps in the factory it was last out of the oven at close of play, and was brought out 20 minutes early so the shift could go home. In the rush to leave they may have dropped the temperature extra quickly by opening all the doors on a cold-day.

We live in an imperfect world. Remember the British workers who faked Nuclear Fuel certificates so they could watch football on TV?

Dave

Yes, but I'm glad of all the clarifications. My understanding wasn't good enough! I assumed current in the earth cable should be measured, now I know better.

Dave

On the bright side, this is all a fantastic learning opportunity!

In addition to US, British, and Metric thread systems, they all support different classes of fit. Ordinary threads are made to fit loosely - cheap to make, quick fitting, but not full-strength. Closer fits are used when strength and vibration resistance are important - more expensive, slow fitting, and easily cross-threaded. This is in addition to damaged or poorly made threads or other difficulties.

Thread-locker is another possibility: it's a type of glue used to stop vibration unwinding threads. Comes in mild and medium strength forms, not too difficult. However, the strong variant may require heat to undo it. Thread-locker, gummed up oil, dirt, and rust all make nuts and bolts unexpectedly difficult.

As iffy threads are quite common, it's useful to own a tap and die set, just to clean them up. Running a tap through a thread easily fixes burrs and other problems, thus avoiding lots of bother. Lidl often sell cheap metric sets plenty good enough for this. Otherwise ebay etc. Worth investing in better made taps and dies if threading is going to be a regular job.

Thread gauges also save a lot of bother. As superficially similar nuts and bolts don't fit, identifying what the thread is with a gauge saves a lot grief - guessing is painful!

Grips almost always damage the work. Useful for rough work, such as removing jambed nuts that will be replaced anyway. Normally use the correct sized spanner, buying in when necessary. Adjustable spanners aren't as good as fixed spanners, but better than grips. Ditto screw-drivers, because the wrong size or type will damage screw heads.

Don't be discouraged - you're making good progress.

Dave

A sound engineering explanation for why heating and cooling systems often contain water!

Not the whole story though. Water being liquid adds an extra problem, which is the need for leak-proof containment. That bumps up the initial cost and adds a maintenance problem. In contrast glass doesn't require a well-made container, the system is low maintenance, and sand on the carpet is trivial compared with hot dirty water. However, for a little more dosh, cast-iron or fire-brick store more heat than glass, which might be important.

Solid heat storage systems create a new problem: how is the heat to be transferred to where it's needed? Hot water can be piped through radiators. Solid usually means fan-blown air, requiring trunking etc. Despite needing a fan, the system is much more reliable than gas central heating, which might be more important.

Which brings us to the cost of fuel : gas is cheap (at the moment), electricity expensive (at the moment). Coal is messy hard work and has to be delivered into a bunker. Oil is cleaner, fairly cheap (at the moment), and has to be pumped into a large storage tank. Wood is hard work, needs dry cover, and the cost depends on where you live.

My view is all heating systems have pros and cons, making it unwise to generalise. Engineers have to understand the full requirement and come up with a matching answer. Considering the full requirement often changes the answer, for example, Vehicle Diesel Heaters come with a long list of disadvantages making them inappropriate for heating homes. In the same way, the clean convenience of electricity often outweighs the advantage of cheap fuel, and costly but reliable local fuel is a better bet than unreliable cheap imports. There are many possibilities, and few shortcuts!

Dave

Q. So how do I create a new screen short-cut for Alibre, please?

The usual way is to click the Start button bottom left. This should open a panel with all the applications listed. To create a shortcut, click and hold down on the Alibre icon then drag and drop it to the desktop. Entering Alibre in the search may help if the Application list is huge.

Double clicking the Alibre icon from the Start menu should also launch it.

Dave

I can't see where ArcEuro say their nut is both 14mm and 9/16 UNF? I did find 'The Model 100/111 Tool Post Stud is threaded M14x1.5 at the top with a ø14mm shank to match the tool post bore and is threaded M12 at the bottom for the SC4 lathe’s compound slide.' in their 111 for SC4 fitting instructions,

I think root cause was buying a post from Little Machine Shop in the US. American customers would expect the 111 QCTP to be fitted with a UNF nut. Not so in Europe. Here, metric is far more common than UNF, making it likely ArcEuro sell the same QCTP apart from the post having a metric thread (M14x1.5) Not normally a problem unless a European customer buys from the US or vice versa.

In the event no-one is able to gift a 9/16" UNF from their junkbox, I'd buy a full nut from a UK supplier and put a washer under it. (£2.55 from Westfield) When the tool post is working, not too difficult to make a flanged 9/16" UNF on the lathe.

Dave

I recommend buying a copy of Tubal Cain's "Model Engineer's Handbook" (Link is to Waterstones' - other suppliers available. Many 'what-nots' are explained!

Margaret has bumped into the 'which standard system' problem, and it's worth thinking about. Briefly:

• British Engineering was originally based on the Inch, and standardised on Whitworth Threads. (aka BSW). Later BSW, which is a coarse thread, was found wanting for many purposes and the system was expanding by adding a fine series (BSF). This too was found unsatisfactory for Instrument and Electrical Work, so a third system, not remotely Whitworth, was added - BA. None of these are interchangeable.
• In the USA, also based on the inch, it was immediately noticed that Whitworth threads are over complicated, so the Americans adopted a different standard - the National Thread. Their system also added finer threads later on. National and Whitworth threads are similar but not compatible.
• The rest of the world went Metric, based on the metre, and produced a third system of threads. These don't match US or British sizes.
• During WW2 considerable trouble was caused when it was found British and American fasteners were incompatible - Margaret's QCTP incompatibility problem on a grand scale, with Tanks, Guns, Aircraft, Ships and machines of all types out of action due to minor technical differences. By agreement, the US and UK both adopted the Unified System, which is mostly the US National System, based on the Canadian Industrial Inch, which was 25.4mm. Almost universal in the US, and for a short time, UNC and UNF became common in the UK.
• After WW2 it became increasingly apparent that the Metric system has many advantages. Thus almost the whole world went metric apart from the USA. The UK chose to metricate slowly, gradually abandoning BSW, BSF, BA, UNC and UNF. Extending the pain badly damaged British industry. Most British engineering was exported because the UK domestic market is quite small. Foreign customers were not impressed by the mix of Whitworth, Unified, and Metric components sold to them by the UK, whilst confused standards reduced productivity and made it difficult to modernise. Today the UK is mostly metric. New design has been metric for about 30 years and it's slowly but surely becoming difficult to source older components.

So British Model engineers setting up a workshop have choices! My view:

• If the work is restoring old British manufactured items, go Imperial.
• If the work is building models from classic plans, go Imperial. This is especially true of steam locomotives and traction engines because so many good designs are pre-metric.
• If you inherit an Imperial or US English workshop, stay with it.
• Everything else, go Metric. Metric is generally cheaper and easier to source, and the trend will continue. US industry is the last bastion of English measure, and even they are slowly but surely metricating. Inches are a disadvantage when selling equipment outside the US. In the UK importing nuts and bolts, or anything else, from the US is extra expensive - avoid!

Pays to standardise if you can. In practice, it's hard not to work with all these systems occasionally. I do experimental work, where Metric is wonderful, and almost everything I own is standard metric. Imperial repairs aren't the end of my world, except I have to recognise what's needed and do the conversions. However, Imperial is a time-waster compared with the same job in Metric, because I often have to buy or make stuff specially. Metric jobs turning up in Imperial workshops are a similar nuisance. Whatever you do, don't get Metric vs Imperial vs US substantially the wrong way round!

Dave

PS Flange Nuts are ordinary nuts with a built in washer, so you don't have to worry about losing the washer.  If a flange nut can't be found, a washer and ordinary nut work just as well.   Also, flange nuts often come with ridged bottoms designed to grip: don't use this type on a QCTP without a washer underneath, or file the ridges smooth first!

Edited By SillyOldDuffer on 24/09/2023 14:38:48

The RCD "Residual Current Device" disconnects when it detects an imbalance between line and neutral currents. The imbalance means current is flowing to earth. To an electrical engineer used to managing power, earth current indicates an electrical fault. RCDs are quite sensitive, set on the assumption that the fault current is flowing through a human being, and because 30mA is dangerous to health, they disconnect quickly - a few tens of milliseconds.

When an RCD triggers, it's important to ensure the earth fault isn't genuine, perhaps caused by the failure ancient rubber insulation, damp, frayed cables, broken connections, or other wiring faults.

However, the problem can be innocent. Enter villain stage left. It's an electronics engineer! He has a legitimate need to bleed small currents to earth. All electronic devices in the home will be fitted with suppressor capacitors, arranged to short interfering high-frequency currents to earth. Unfortunately, suppressors also allow a tiny amount of 50Hz current to flow as well. As a modern home contains dozens of electronic devices, it's possible for them to collectively leak tens of milliamperes and take the RCD close to it's trigger point. Powerful electronics, like microwaves and VFDs leak more earth current than tiddlers like TV sets, and are therefore more likely to pop the RCD.

I suspect the friend's house has an existing high level of legitimate earth leakage, and switching on both VFDs takes his RCD over the top. Proper EMC filters leak more current than basic suppressors.

I thought some of the newer cheapo mains testers measured earth leakage, but I couldn't find one on Amazon. Perhaps I dreamt it! Looks like a more expensive clamp meter is needed. Positioned on the device's earth wire, it will show if the problem is local. Positioned at the consumer unit it will show total leakage. The most leaky devices can be identified by unplugging them.

A 'competent person' could do the tests by wiring in great-grandad's AVO. Not recommended - it's the sort of dodgy job that zaps professionals. Clamp meters are much safer!

Dave

Edited By SillyOldDuffer on 24/09/2023 12:42:39

I recommend Stewart Hart's PottyMill as a starter project. It's been discussed many times on the forum, for example here, and the plans are widely available on the internet. I built mine from this version, which is rather cramped and unconventional in glorious technicolor, but I found no mistakes. Stewart is a forum member and a PM to him (see Inbox in Green Banner above), might get you a copy of his conventionally drawn originals. Stewart's version is a good example of a typical model engineering plan. It's worth studying both!

For Stirling and various other engines, try Jan Ridders. (His website starts in Dutch, so press the 'English' button top left.)

Dave

Artificial Intelligence might well catch that disease. It's pandemic because most humans prefer opinion and hearsay to fact. Not only is collecting and understanding evidence hard work, but people reject difficult truths that upset them. Be interesting to see if AI becomes as dishonest as humans!

I'm surprised ChatGPT didn't suggest EDEN as the answer to Amundsen's forwarding address. Amundsen disappeared in 1928 on a rescue mission, suggesting God called Amundsen home because He loved him too much. In comparison to a clear case of divine intervention is it likely a Norwegian knew 'mush' was the 'go forward' command given in Canada to Huskies? I don't believe Amundsen ever said 'mush', or that his hounds knew what it meant...

Dave

I had 3 colleagues who'd been laid off by Xerox when times changed. They'd all enjoyed being 'Xeriods', and are probably still calling themselves that!

My dear old dad was entangled in converting US English into British English, and made heavy weather of 'Earth' and 'Ground'. Either his employer had a low opinion of their workforce, or their electricians were extremely thick, or perhaps just a bunch of old-fashioned jobsworths!

In my youthful experience Earth and Ground were synonymous, and I expected to everyone to be keen to explore Vcc, Vee, Vss and other mysteries. Not so apparently: any electrician who read the word 'Ground' was expected to have a nervous breakdown.

That the manuals described an exceptionally complicated system seemed not to matter. My theory is the boss men focussed on the only thing in the manuals they understood - Americanisms - and wasted everybody's time by fixing an irrelevant problem.

Dave

Edited By SillyOldDuffer on 23/09/2023 11:55:14

Nothing wrong with stoning HSS lathe tools because they are easily reground, at least by experienced operators with a good eye. And stoning twist-drills for a special purpose is respectable too. But the idea of stoning a milling cutter upsets me! To my mind the sharp corner edges of a milling cutter are its most precious asset, to be cosseted as long as possible. When they're damaged the cutter loses much of it's utility, and needs to be replaced or sharpened, both a bit painful!

If finish on a large scale was important, I'd prefer Andrew's approach - buy a cutter designed for the job.

Of course being an amateur, I buy inexpensive cutters, use them for roughing out everything from squishy Aluminium to chilled cast-iron, then expect them to produce a mirror finish from fine cuts, and I'm certain they're rubbish unless they last at least 30 years. My mill's not very rigid either!

My first question is, how bad is the problem and does it need to be fixed. Andrew Skinner's photo is visually flawed, but could be acceptably flat (mostly).

Flatness can be established by shining a light on the back of a straight-edge and looking for light escaping between the work and the edge. Also possible to detect tiny ridges by feel - fingertips and nails are remarkably sensitive to surfaces.

Milling cutters almost always leave characteristic marks. They're obvious in Andrew J's excellent copper plate example, which is probably very flat and has classy finish with strong mirror effect. The example is as good as can be expected from a well-adjusted stiff milling machine, set up correctly with an appropriate cutter, and driven by a skilled operator.

The remaining milling marks are unavoidably tiny. If a better finish is needed, change technique. Usually polishing with a succession of ever finer emery paper, and then buffing.

When milling I try cut in parallel straight lines because changing course leaves deep marks. Also use the largest diameter cutter available. Fly-cutters generally produce a better finish than other types but are slow. And an HSS fly-cutter can be stoned without upsetting me!

Dave

Kurtis is impressive. I've watched many Cutting Edge videos in hope of catching him do something unwise; no luck so far. Really knows his materials and methods, with none of the incidental blunders and bad practice that spoil lesser Youtube efforts.

I guess Karen is the talent behind filming and editing because the videos are so well-made too. Not many can do tasty engineering and make a slick video as well.

My only complaint is the dog! Far too well-behaved, plus I'm a cat person...

Dave

I'm afraid Clock Polisher's positive experience doesn't prove that PWM can speed control all types of single-phase motor. Might be worth trying though.

Have I mentioned before how much I hate single-phase motors? Only about 500 times! One reason I dislike the beasts is the number of different ways clever chaps have come up with of making them spin, none of which are entirely satisfactory, and many truly horrid compromises. Murky engineering, making it hard to say what will work or not.

Like as not both motors on Clock Polisher's Unimat were the Universal type. These have brushes, run on AC or DC, and can be speed controlled with a rheostat or PWM driver. As their efficiency is low, it's unusual for them to be much bigger than 250W. But for intermittent low and medium power work they do a good job - my old Black and Decker drill had one. Less common today because DC motors and PWM or Brushless do much the same and are more efficient.

No idea what sort of single-phase motor is on a Sealey BG150WL bench grinder: might be a Universal too.

Moving away from Clock Polisher's good luck, the assumption that frequency has to be altered to speed control an induction motor isn't quite true. For example:

• A Triac chops a proportion of an AC waveform off, so the motor gets shorter pulses at 50Hz. It turns, but with reduced power, such that any load partially brakes the motor and it loses speed. Is this yuk? Yes!!!
• Another way of speed-controlling a single-phase motor is to arrange the windings so that the phase between them is altered by adding capacitors or tapping into the inductance. Altering the phase between windings causes a loaded motor to slip, - it's like controlling the speed of a car by slipping the clutch. Again, not efficient, and mostly found on constant load motors like fans. Is this type yuk too? Yes!!!

That said, these methods allow some single-phase motors to satisfy a few useful speed control requirements. I might think the methods are all bodges, but hey if it works, why not?

By far the best way to speed control a single-phase motor is not to. Instead speed control the output with pulleys or a gearbox.

So, though electronically speed controlling single-phase motors is possible, it depends on the type of motor - some will, some won't, and even if it does work results are likely to disappoint. Three-phase motors with VFDs are in a different league - much better.

Is the band-saw designed for woodwork? Metal is fussier than wood and prefers lower speeds.

Dave

In the editor, try clicking the button marked 'ABC' and then 'Disable SCAYT'.

If that doesn't work, you may have a mis-configured Browser checker. As all Model Engineers know, nothing is ever easy...

Dave