Here is a list of all the postings Kiwi Bloke has made in our forums. Click on a thread name to jump to the thread.
|Thread: Brush motor repair|
Agreed, however isn't that true of almost all 'consumer goods' these days? In fact it's worse - the wretched junk we have to choose from is carefully designed to fail. Marketing + Accountants - Engineers + Necessarily Passive Consumers = The Unacceptable Face of Capitalism?
|Thread: Burgundy finish to tools with wooden handles?|
I wondered about that. Can you easily (in a factory setting) get a fairly thick coat with shellac?
|Thread: Brush motor repair|
Well, I feel a bit let down. So much knowledge and wisdom here, but no-one's waved a magic wand and told me how to fix this wretched armature wire. Come on you lot! Please!
The winding is looped around its connection to the armature bar, a radial extension of which is bent over the loop, trapping it, and peened flat. I've managed to lift the peened-over bit, and release the loop. The break is just at the side of the armature bar. There is no slack, and only a few mm of wire to play with. I think that mechanical connections, perhaps with added solder for electrical integrity, are the way to go. I'm thinking of squashing a small brass ferrule around the wires, with a new length of wire going to the commutator, but it won't be easy...
At the moment, the whole thing has been put aside in the 'lacking inspiration' basket. Has anyone any better idea for a method of repair (inspiration isn't happening...)?
|Thread: Burgundy finish to tools with wooden handles?|
Whatever the coating is, it's brittle, and eventually flakes off in nasty, sharp-edged 'splinters', revealing uncoloured wood. I assumed it was just a coloured old-style varnish (whatever that is).
I broadly agree with Martin Kyte's posts. Here is some more confounding stuff.
Arguments about the efficacy or wisdom of lockdown are, at present, not likely to be rational. The data simply isn't there yet. Comparison between countries is also unhelpful, because of the wildly different counting strategies used, and the amount of testing, to name just two problems.
When a novel infective disease appears to be spreading, it is naturally the worst cases that get identified. Those infected, but who just have a sniffle, will be overlooked. Therefore, it is a natural tendency to think that the disease is more dangerous than it will turn out to be. I think this is called 'ascertainment bias'. It was this that made the death rate seem scarily high at first, in some locations.
Pehaps governments were alerted to Bill Gates' TED talk of 2005, in which he pointed out that the world was completely unprepared for the next pandemic. SARS and 'bird flu' had been scares. This lack of preparation, and the human desire to 'do something' might partly explain governments' apparent panic over-reaction, although some countries chose to wait and see what would happen.
Three public health priorities are pretty obvious: 1, protect the population as a whole; 2, protect the individuals; 3, protect the health service from being swamped. Essentially, 1 involves the isolation of infective people, 2 involves people staying away from infective people, and 3 involves slowing down the rate of spread of the disease. Lockdown and quarantine clearly attack 1 and allows 2 and will help with 3, but it isn't as simple as that.
It has become clear that this disease is tricky because it is very easily transmitted and perhaps the majority of people who become infected have no, or minimal symptoms. Unfortunately, infected people appear to be most infective a few days before symptoms develop. Naturally, asymptomatic people don't seek medical help, and generally won't get tested, unless a screening programme is in operation. Therefore, if they are allowed to, they will, unknowingly, infect other people, and may be the major vector. Ill people typically don't stagger around infecting others, but take to their beds. So it is clear that aggressive testing is of little use, unless the population is locked down.
Relying only on the isolation or quarantining of infected people after they become symptomatic therefore removes only a proportion of the spreaders from the vulnerable population. Therefore, lockdown is, perhaps somewhat accidentally, a very good idea. It is a specious argument that lockdown is pointless because it's too late (it should have been sooner and more aggressive in UK and elsewhere) - everything helps.
Infectious disease epidemics have a tendency to fizzle out, apparently even without sophisticated medical or social intervention. The development of herd immunity (and the assumption that there is a high proportion of asymptomatic infected people) is a component of this fizzling out, but there are other mechanisms. Natural selection favours less lethal strains of infective agents, and many viral epidemics seem to have followed this, with the population of viruses becoming less dangerous with time. At present, it is not clear whether herd immunity is, or will develop for this virus. It's not safe to rely on it. We will see what happens in Sweden...
If transmission continues, because isolation of, or avoidance of spreaders isn't successful, the proportion of the population which becomes infected may reach the level it would have done without any social limitation measures. This is not a reason to abandon lockdown, etc., because it ignores the possible explosion of severe cases leading to health care overload.
There's more - much more - of course, and one thing's sure - it ain't simple. Governments had to make tough decisions when the hard science was deficient. Epidemiologists are taught that they should be very cautious about making predictions, however 'good' their mathematical models appear to be. In retrospect, many decisions will prove to have been poor, but we may be very grateful for others. In cases of life or death, it seems to me to be better to err on the side of caution.
UK's figures are distorted because the prevelance of the disease isn't known, partly because testing has been so limited. Death certification mechanics have been changed, and it seems that deaths are frequently registered as being because of Covid-19 when, in fact, there is only a suspicion. I may be wrong, but I believe that a large number of people have been registered as dying from Covid-19 without having been tested.This seems to be common in residential homes. So the number of deaths is inflated, and the number of cases is too low, so the 'death rate' in UK appears artificially high. It isn't surprising that the disease has spread rapidly in UK - people are so highly 'connected' and there have been many persisting infection 'hot spots', eg the tube continuing to operate makes a mockery of lockdown.
|Thread: Method of joining for chuck key?|
Robert Atkinson beat me! Dental X-rays won't penetrate - they are too low energy. Also, I think you'd need higher energy photons than general medical diagnostic X-ray gear provides. You could try your local radiotherapy centre, perhaps. You'd need an energy where the attenuation coefficients of Fe and Cu/Sn were sufficiently different to allow them to be distinguished. I once had a cello put through a hospital CT scanner - that was interesting, but another story!
Three things to consider (out of many more, of course)...
1. Until the number of infected people is known as accurately as the number of deaths from the disease, the true population death rate from the disease can't be calculated. Because there seems to be a large proportion of infected people who never get diagnosed, partly because disease screening isn't being done and because not all infected people develop significant symptoms, the prevalence of the disease remains unknown.
2. An individual's risk of death depends greatly on the individual's circumstances, and isn't simply related to the population's death rate.
3. The old and infirm seem to be at greatest risk of death. Countries in which people tend to die before they get old, or have a 'young' population for whatever reason, or who don't survive infirmity, can be expected to show a lower death rate than, say, UK, where the wonderful NHS keeps old wrecks going far longer than they might in countries without universal high-quality health care. So, a country's death rate (from coronavirus) may tell you more about the population's characteristics, or the way data is collected, than it does about the intrinsic lethality of the disease, or the adequacy of available healthcare. Or not - you just can't tell, because the data isn't there yet.
Apologies to any old wrecks reading this - no offence meant.
|Thread: Machine Tool Peripheral Hoists|
I don't want to watch the video - it sounds like a horror movie...
|Thread: Method of joining for chuck key?|
Tapered, square-section shaft and hole, round shaft end peened over, to hold it in?
|Thread: Brush motor repair|
Quite - my worry too. I was expecting to have to bind any soldered joint. 'There has to be some way of fixing this,' he said, in quiet desperation...
Hi Folks, anyone got any good ideas? I'm hoping to resurrect the YDK motor in a Dyson DC14 vacuum cleaner. It's only 15 years old, and on its second set of brushes, so it's too young to let die... If I can repair it, I might be able to offset the brownie points earned against having to use the horrible thing, so it's worth a few hours of cursing.
I've discovered that an armature winding wire has broken, just at its junction with the commutator. Of course, it has to be one of the wires that lies in the inner layer of the obliquely-orientated wires to and from the commutator bars, and there's no slack. Assuming I can extract the armature, I may be able to winkle about 1 cm of the broken wire out from under the others, into an accessible position, to graft on a short length which can then be joined to the commutator.
It looks like an awkward job, requiring micro-surgical techniques. Has anyone any tips or suggestions relevant to this sort of endeavour? Should I attempt to make a mechanical junction at the commutator (if possible), rather than, or in addition to, soldering the new wire in? It looks like the winding wires have been connected to the commutator by crimping or, possibly, spot welding (difficult to see with the armature in situ, but no solder evident).
|Thread: ER collet adapter|
I'm not doubting your observation, but I'm struggling to understand how. [I like to understand things - it's a failing...] The supply of obviously defective screws with the kit would raise my suspicions to danger level, and I'd be going all over the thing with an impressive array of metrology gear. Or wondering whether to return the thing...
Edited By Kiwi Bloke on 24/05/2020 10:47:45
Perhaps I'm being a bit thick, and have missed something important, but I would expect this set to be designed so that the collet body is kept in radial alignment by a register on the adaptor. I'd expect the user to have to turn the register's diameter down to size, and also to face the adaptor. Then, surely, even 'wobbly' screws - if they fit the holes - will not derange alignment.
|Thread: Logging in|
Just adding to the evidence base, should anyone be trying to get to the bottom of this issue. Never had a problem, although I don't log on all that often, and stay logged-on for only as long as it takes to make a couple of posts. Using Linux, Firefox, AdBlock plus, NoScript. I disallow third-party cookies and clear cookies between sites. Only script allowed is from ...model-engineer.co.uk. Therefore, for me, there's no evidence that this site is misbehaving.
|Thread: To grease or not grease|
Grease is fine for low(ish) speed applications, in which dirt can be kept out. Too much grease and/or too high a speed will cause the bearing to run warm or hot. This isn't going to happen in this application, in which retention of lubricant is probably the prime concern. Oil has a habit of dribbling away. So grease is good.
Oil is good for high-speed bearings (eg high-speed spindles), particularly if it circulates. It will carry heat away from the bearing, and, with luck, muck too. But few machines we are likely to come across will have oil pumps...
|Thread: cross slide dept stop|
It was Tubal Cain (TD Walshaw, not the YouTube yank), and probably more than 30 years ago. (Why does time accelerate as one ages?) He described a click-adjust cross-slide stop, primarily as an aid to screw-cutting. Really neat idea, especially as the concept is easy to implement. Cross-slide stop and swivelled top slide (for down-the-flank feeding) speeds up screw-cutting and makes it less demanding of dwindling attention...
OK, I admit it - I'm feeling grumpy, but I wasn't until I read this thread.
This discussion has surely been done to death several times already on this forum. There are two camps. One advocates expensive lubricants, designed for high-performance internal combustion engines, or high-duty transmissions, and also favours chain-bar oil 'because it's sticky'. In the latter case, why not use strawberry jam or honey? The other camp patiently repeats fact-based rational arguments. It's like Trump versus the scientists.
I'd imagine that the machine tool manufacturers and lubricant blenders know more about machine tool lubrication than anyone on this forum, so why not take their advice? The lubricants are entirely appropriate and are not expensive. There is no convincing argument to do otherwise.
You could probably get away with using anything vaguely oily in our little, lightly-stressed machines, and this is why the 'I've used old sump oil all me life and it's fine' type of argument gets rolled out tiresomely. However, if you have well-fitted, correctly adjusted slides, the advantage of proper slideway oils, which are designed to minimize the stick-slip phenomenon becomes apparent. A sometimes dramatic example of where this can be very important is in a shaper's ram. And the argument, previously made, against detergent oils is to be emphasized. So it's 'hydraulic' oil and 'way oil', as has been detailed previously. OK?
Edited By Kiwi Bloke on 16/05/2020 12:56:44
|Thread: Tig Welder recommendation|
Consider the service back-up, spares availability and warranty. These considerations probably push you towards a big name, rather than an outfit that gets his oriental supplier to slap a fancy brand label on a device of unknowable provenance.
I think I made a mistake when I decided not to spend more on a AC/DC machine. Now I'm frustrated by not being able to glue ally bits together. I'm glad I bought a foot pedal and a box with (albeit simple) pulse operation.
The torch is very important, not least because it's the bit you wrestle with. My impression is that the torches that come with many machines are big and clumsy and obviously have to withstand full-current working (for a bit, depending on the duty cycle). If you're considering doing delicate work, Have a look at CK torches, and consider a wieldy low-current one, if you're not welding bridges together. Rapid Welding sell 'em (and everything else).
|Thread: Needle File Recommendations?|
I think it's a good idea to define your problem before spending money on a solution. Sets of files (anything?) may seem attractive, and may appear to save a little money, but will you end up with several things in the set which never get used? With files, I think you need a range of cuts at least as much as a range of shapes, and the sets of needle files that I've seen have been of one cut only. I have bought my needle files individually, as needed, and am particularly glad to have been able to get No 6 cut Vallorbe files here in NZ, where it's often difficult to get things that aren't of indifferent quality. And, as others have suggested, you need to keep separate files for ferrous and non-ferrous application. As usual, buy cheap, pay twice...
|Thread: Thermal fuse reliability|
Yes, they age and fail. Often, they are hidden in the guts of the device, so elude initial (visual) diagnostic attempts, and then one often finds them unlabelelled. Probably a cynical attempt at getting the punter to buy a replacement, i.e. designed to fail.
Bad design seems to accompany thermal cut-outs and thermostats. We have fan heaters, in which the thermostat turns off the element(s) and the fan, so heat-soak from the elements progressively cooks the entire device, presumably shortening the life of the mainly plastic components. Our cooker has a thermal cut-out 'protecting' the oven. It may be defective, because we can't use the oven at high temp. long enough for some applications. It's across the mains, so the entire cooker is disabled for ten minutes, until the thing re-sets. Brilliant.
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