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Member postings for Kiwi Bloke

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: Guess the Chemical?
28/07/2019 09:36:07

If it's whisky - or indeed any other alcoholic beverage - I shall continue to use it in the manner to which I am accustomed, DIRE WARNINGS notwithstanding.

Thread: Setting wheel train on ML7
26/07/2019 01:44:50

Glad you're now all geared up. My apologies, my chart in fact suggested a 55T idler, not 50T as I said. I should have gone to bed instead of posting when tired...

Cutting the thread is easy enough - don't be scared. There's plenty of info out there. It's best to ensure that the cut is made primarily by only one side of the tool, either by making a small lateral movement for each in-feed, or by feeding down the flank of the screw, by setting the topslide round by half the included angle of the thread. Take a very shallow cut first, and check the pitch is what you intended, then gently does it...

Good luck.

Thread: Permission to Copy
25/07/2019 22:09:31

Brian Perkins' VW was published as a construction series in Strictly IC Magazine (USA), Robert Washburn's excellent mag. Sadly, I believe that both gentlemen are no longer with us.

Thread: Setting wheel train on ML7
25/07/2019 11:20:22

40T driver. This meshes with 38T, which is keyed to 20T, both on 'first' stud. The 20T wheel lies outboard of the 38T wheel. The 20T meshes with a 50T 'idler' on the 'second' stud, which in turn meshes with 50T on the leadscrew. My chart suggests a 50T idler. You have a 55T idler, which seems OK, if it fits - obviously, the number of teeth is unimportant. The first stud is on the higher slot on the banjo, the 'second' stud on the lower slot. So your setup looks nearly there, the driver seems to be where it should be, so it's just a matter of getting the 20T and 55T into mesh.

Meshing adjustment. Slacken the banjo clamp nuts, and swing the banjo downwards, to give you 'wriggle room'. Get the mesh of the idler 55T and leadscrew 50T wheels correct, then the mesh of the 20T wheel on the 'first' stud with the idler, then swing the banjo up to get the mesh of the 38T correct with the driver and clamp the banjo. To align with the idler, the leadscrew gear will have to be spaced outboard with a spacer or small dia. gearwheel acting as a spacer (you seem to have done this).

Don't mesh the gears 'tightly', but allow a little backlash. Some advocate a strip of thin paper between gears when setting up, to ensure some clearance. Lubricate the gears. Slideway oil is good - it doesn't get flung off as readily. Lubricate the studs too.

Hope this works - working from charts and memory, and haven't checked the maths (it's getting late). I have the luxury of a gearbox, so haven't done this very much since the gearbox arrived...

Edited By Kiwi Bloke on 25/07/2019 11:25:51

Edited By Kiwi Bloke on 25/07/2019 11:27:30

Edited By Kiwi Bloke on 25/07/2019 11:31:19 (I said it was getting late...)

Edited By Kiwi Bloke on 25/07/2019 11:38:37

25/07/2019 10:58:23

Walk into Comwell Tools or Buck and Hickman. Branches throughout UK. Both have web sites. 'Burrs' finds the things within the sites.

Thread: How to cut metric threads on an imperial lathe and vice versa.
25/07/2019 10:01:27

After all that there has been written about threading calculations, confusion persists. The dissenters are correct. Perhaps gear trains and their calculation confuses people. Although Pete and Duncan have already explained, and not wishing to steal their thunder, let's look at it another, possibly simpler, way.

Say you have a lathe with an 8 TPI leadscrew. Each leadscrew revolution moves the carriage 1/8", or 25.4 X 1/8 mm. Multiplying top and bottom by 5, to get the calculation into whole numbers, gives 127/40 mm. So, in order to cut, say, a 1mm pitch, the leadscrew must revolve 1 / (127/40) = 40/127 revs. This must, of course, happen each spindle revolution. This is where the changewheels come in, but we don't need to bother with that complexity. The problem is closing the half-nuts at the right spindle and leadscrew relationship. The point is that 40/127 is inconvenient because the smallest whole number that can be used to multiply this fraction by, in order to get a whole-number result, is 127. Only then will the leadscrew and spindle be correctly synchronised. So, the suggested method would work if one had a 127 tooth pinion on the thread dial indicator...

Edited By Kiwi Bloke on 25/07/2019 10:02:20

Thread: Wiggler or edge finder?
22/07/2019 09:16:57

Clive. 'I suspect that your stiff "General" brand edge finder was intended to be used with the light line method rather than the kick off method.' Well, of course, it could be used this way, and perhaps it should be, as it's the most sensitive method. But my point was that the manufacturer's instructions are as I quoted, and they seem bizzarre. I'd be interested to know whether anyone has used General's method.

'Mentioning GHT reminds me that his analysis of how the things operate is wrong. Nothing to do with tilt. Just a matter of generating enough force between probe and ball for it to drive sideways along the surface. Once its moved a fraction off axis centrifugal force takes over and it flies.' I don't remember GHT's explanation. I'm not sure that I understand what you mean by 'enough force between probe and ball for it to drive sideways along the surface.' I may have misinterpreted what you meant, but, to avoid confusion, the probe's ball or cylinder does not drive itself along the surface it is contacting, as a result of friction at this interface. The sideways force is generated by asymmetric forces between the chuck and the ball end of the probe sitting in the chuck, once axial alignment is lost. Experiment confirms that the tip of the probe is driven sideways, from the chuck, but doesn't pull (or push) itself sideways. If centrifugal force deflects the probe, things may have got rather hairy. Better to arrange things so the probe doesn't whirl free, if possible.

Thread: Dangerous 2" Scale BB1 Boiler
21/07/2019 11:55:37

May I suggest that the above extract from the boiler regs is published regularly in ME? Whilst I would expect boiler inspectors to know this, how many builders would know to first pressurise their newly-built boiler this way? Not me, certainly - although I'm not into steam.

Thread: Wiggler or edge finder?
21/07/2019 01:49:33

Here's another twist. From an estate sale, I got a 'General' (General Hardware Mfg. Co., Inc., USA) 'Universal Wiggler and Center Finder'. It's of the spring chuck / collet / multiple probes type in appearance, but is intended to be used differently.

Its instructions state: 'Insert the large ball of attachment into spring chuck. With the spindle turning, make the ball run true by holding any blunt object against it. Apply a thin coating of layout blue on the ball and feed the work up to it until the blue is barely wiped.' Note, layout blue is specified. I suppose you're supposed to use a small brush, and ensure the probe is not deflected. No alternative method of use is given.

The chuck can be tightened, but, even at its slackest, it holds the probe fairly stiffly and 'roughly', and it's not suitable for use with the usual wiggler kick-off technique. How one is supposed to get the ball to 'run true' accurately, by the suggested method, is beyond me, but, since the thing is surplus to my requirements, I've never bothered to try seriously. I find it difficult to believe that this method is used, if for no other reason that one needs to be able to have a very good, close-up view of the probe in action. Anyone ever come across this method in use?

I have a flaky memory of GHT commenting on a 'stiff' wiggler that didn't kick-off consistently. He considered it useless, until someone pointed out to him that it was not supposed to kick-off. Memory thinks one was supposed to look for disappearing light between probe and work, so the probe had to be set running true, as above. Could be mistaken - memory nearly full, and stuff is being dumped to retain a little capacity...

The 'General' set also contains a cranked 'probe', intended to hold an indicator, which can be held stiffly enough by tightening the chuck. Perhaps those sets containing such a 'probe' are intended to be used as above, and not to 'kick-off'.

Thread: Surplus subjects learnt at school.
20/07/2019 10:46:21

In retrospect, none of the subjects were 'surplus', although it didn't seem like it at the time. Some of the teaching was, however, dire: how is one expected to learn a language from grammar text-books and vocabulary lists? What is the point of being expected to be able to recite 'the dates' of the kings and queens of England? However, I wish I'd paid more attention to the non-science subjects that didn't come easily - they seem so much more interesting now. I was told to 'try harder', but what did that mean? No-one ever explained...

Edited By Kiwi Bloke on 20/07/2019 10:47:18

Thread: Crucible for annealing cast iron piston rings
19/07/2019 23:01:30

Oops! Too late to edit a slip-up in my post. Correction: Chaddock's method described in 1967, not '57.

Thread: Angle grinders - Dangerous or not
19/07/2019 06:05:48

Nasty, dangerous and scary machines, but I'll continue to use mine and hope to get away with it. The alternative doesn't bear thinking about.

In Oz & NZ, Jaycar sell a soft starter kit for power tools. I've just bought a second one. I think they are running low on stock. The design was published in Silicon Chip magazine, July 2012. It reduces the start-up kick quite well. The design is, I think, unnecessarily complex. In essence, a NTC thermistor, with a cold resistance of about 20 Ohm, is in series with the load, until it's shorted out after about 0.5 second. Not only is the kick reduced, for the benefit of the operator, but the inrush current is severely limited, which may be helpful in some electrical installations.

Thread: If it ain't broke don't fix it - or should I?
19/07/2019 05:54:02

Probably would have been better with lubricant, assuming tool geometry and all other variables were OK. It's often helpful to bore with the tool 'upside down', working on the 'back' of the bore - the surface furthest from you (perhaps you did...). That reduces the risk of chips getting dragged between tool and work and spoiling the finish. Also, the feed is applied by conventional and familiar use of the dials, rather than having to subtract. But if it works OK, why bother?

Thread: Crucible for annealing cast iron piston rings
19/07/2019 05:46:17

Trimble wrote up 'his' method for piston ring manufacture in Model Engineer V153, No 3735, 17 Aug 1984 and later in Strictly IC V2, No 7, 8, 9, 1989. The method is very similar to that written up by Prof D H Chaddock (of Quorn fame) in Model Engineer V133, No 3319, 21 April 1957. I don't remember Trimble's ME article, but I'm pretty sure that he did not acknowledge Chaddock in his SIC articles, although it seems rather unlikely that he was unaware of Chaddock's method. Another example of Americans thinking they invented everything first (computers, powered flight, "Moore-pattern" scraping, etc., etc.)? I wouldn't be surprised if they claim to have been first to set foot on the moon... cheeky [with a nod to a recent thread, I should explain that this unnecessary, silly image is included for those who can't appreciate innocent tongue-in-cheek comments and sarcasm without help.]

A useful overview, which hopefully gives the information you seek, can be found at **LINK**

Thread: A little rant about Emojis and their kin
17/07/2019 11:40:14

Don't despair, Dave. Wisdom comes with age. We can cast our pearls and smile at the antics of the young. They don't know any better, poor, semi-literate dears, although the arrogance of youth blinds them to this. I note that these ridiculous pictures-instead-of-difficult-words have been inflicted on the world by Apple. Well, you don't have to live on Planet Apple...

Thread: The Chocolate Fireguard as designed by Mercedes Benz
17/07/2019 11:27:06

MG. Good question; where indeed is the evidence? IQ scores are often glibly stated (= assumed) to follow a Gaussian distribution, but it's very hard to track down raw data or to discover the characteristics of the study population. It's a mess and is probably too PC-sensitive anyway. I'd put good money on the distribution having a fatter tail of low scores - the result of developmental defects, injury, illness, etc. Quite a lot of brains get damaged by unfortunate events, but few of such events increase IQ. It's unfortunate that many (most?) medical data is assumed to follow a Gaussian distribution when it doesn't. This is assumption is really for the convenience of stats calculations, and, of course, is 'good enough' because it covers the majority of the population.

Thread: Different ways of boring a hole
14/07/2019 11:15:34

Good question. I suppose the answer is 'It all depends...' Major determinants will be the configuration and size of the job and the relative accuracy and suitability of the machines to hand.

One consideration. If you want to make something like a machine spindle housing, or quill, with a bearing housing at each end, a between-centres boring bar in the lathe can bore the central hole, be adjusted to bearing housing dia, then bore each housing, by swapping the bar end-for-end, with guaranteed concentricity of bores, all without having to change the set-up of the workpiece. I can't think of another way to do this so simply (and am happy to be corrected...).

Edited By Kiwi Bloke on 14/07/2019 11:18:53

Thread: Microns ...
08/07/2019 10:22:38

Michael, we seem to crossing swords today - not my intention at all. I admire the nm-resolution (and, presumably, accuracy) of the gizmo, but was suggesting that, unless the rest of the apparatus was remarkably stable, such resolution was wasted, and the achievable performance would be determined by things other than the gizmo. A bit like putting a micrometer head on a micrometer frame made from rubber? Incidentally, could the system be used to check gauge blocks - simpler than optical interferometry, I'd imagine?

Thread: Phillips vs Pozidrive and portable drills
08/07/2019 10:11:03

Michael: earlier, you asked why I found it difficult to believe that the 'camming out' was designed in. I was answering, not arguing with you. My original scepticism was in response to MK_Chris' post.

Wikipedia suggests that the 'camming out' was not a designed-in feature, and cites references. I think this is another instance of the harder you look, the confuseder you get...

08/07/2019 07:18:55

Dave (SOD). Wikipedia says 'The Pozidriv was patented by GKN Screws and Fasteners in 1962'. (So you see that I'm just recycling dubious info. found on the web...). I skimmed the patent to which you linked (how does anyone read this stuff?), but wasn't clear that it was put into production.

Michael G. To design a screw/driver combination to 'cam out' at a desired torque seems pretty heroic, given that the applied axial force, let alone the alignment of the driver to the fastener can't be controlled in the field. And then the driver wears and it all goes to hell. The taper of the driving flanks (ignore the point angle) is, to the Mk 1 eyeball, far shallower than a Morse taper, so one might hope that the screw jams onto the driver, rather than it being a self-releasing taper. I just don't believe that the tiny flank 'slope' will produce a big axial force from reasonable torques.

Anyway, for whatever reason, Phillips and Posidriv drivers can 'cam out', although leaning on an unworn driver with sufficient determination seems to be able to frustrate the (Phillips) designer's supposed intention. If the designer really didn't care about the need for subsequent screw removal, then I still would call him an idiot. There's a lot of them about - especially in the auto industry, where dismantling for service and repair is commonly frustrated by lack of thought - or Machiavellianism.

Grinding a bit of the point off drivers is often worthwhile, allowing better driving flank engagement.

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