Member postings for Kiwi Bloke

Oh, wonderful! This is why this forum is solid gold. There's so much knowledge and wisdom around. Thank you Bandersnatch and Bazyle! It has to be RSS, doesn't it? I found physics, pure and applied maths fine, but statistics and probability calculations caused cerebral meltdown. Why are they so counter-intuitive?

Neil, just getting the mag out regularly must be a nightmare. Well done! Unfortunately, as editor, you get to be the focus of all criticism, discontent, etc., whether deserved or not. Perhaps the occasional praise, if you're lucky, makes it all worthwhile. Proof-reading must be a dying/dead art - or just too expensive. Spell-checkers are no substitute. I have the unfortunate ability (disability?) to spot typos and similar errors almost as soon as I turn a page - except in my own writing, of course... It was useful, professionally, but it's a pain. I also wince when I see misplaced apostrophes. I'm glad to see that MEW is better in this regard, under your stewardship.

Whilst MEW is not a learned journal, it aims to be instructive. Let's hope it retains that aim, and doesn't degenerate into a colour-glossy entertainment rag. It has a responsibility to print correct information (wherever possible). That's a big ask.

I meant to ask 'So, what do you do, and why?', wondering whether any consensus would reveal itself. Even without the intended emphasis, I'm glad that it seems to have generated some discussion. Thanks, everyone - can we keep it going?

I take Mr Stevenson's point, but I suppose I'm questioning the advice, probably repeated regularly, throughout Model Engineer's life, to drill with increasing diameter bits (in appropriate circumstances, material, etc.). As HOWARDT says, trying to open out a hole with a two-flute cutter can be hazardous, leading to the problems explained by Bazyle. Drill guides, or something in the toolpost, pushed against the drill, if drilling in the lathe, help, of course. It seems that lack of power, particularly in the days of treadles, might have fuelled the original advice. Is it still appropriate?

Interesting stuff, but I think the lack of proof-reading &/or printer's errors have let the author down. It's good to see this sort of article in the mag, rather than the all-too-common picture-heavy 'Wot I did on me 'olidays wiv a welder/angle-grinder/'eavy 'ammer' type of article that is not very enlightening.

An explanation of the maths in Table 1 would be appreciated - there are undefined variables, and the formulae are truncated. I suspect there should have been a diagram to accompany the table. Also, I'm sure it's just a slip: RMS calculation (as used for the total error calc'n) requires the root is taken of the mean of the squares, not their total.

They say that the biggest fool can easily ask questions the wisest man cannot answer, so I feel no shame asking this...

What is the recommended technique for drilling holes? No, that's not really the question. What's the scientifically correct way to drill holes, and why?

It's often recommended that holes are drilled, using a succession of progressively larger diameter bits. The diameter increment is usually glossed over. OK, doing this reduces the load on the machine (and workpiece), but it has disadvantages. The major one is the difficulty of getting the 'next size' drill to centre, and not try to start to drill a pentagonal, or other non-round hole (for the well-understood reasons). If you ram the bit into the hole, to get it into cut without it dancing all over the place, the sudden load on the bit's corners can break them off.

I tend to drill in only two steps: first, a small pilot hole, around the same diameter as the final drill's web thickness, then the 'finished' size, but I have fairly grunty machines available.

So, what do you do, and why?

Thanks for all the information folks.

I've just looked at my copy of Tubal Cain's Hardening, Tempering & Heat Treatment, No.1 in the Workshop Practice series (pub. Argus Books, 1984) and lo and behold, Sindanyo is mentioned. So that's where I heard about it... Wish my mental filing system was more reliable...

Currently-produced Sindanyo is asbestos-free, but I'll assume that the casing of my elderly furnace contains asbestos.

The furnace's electrical plate says 240V, 23A, so it should cook breakfast OK. Here in the land of the Kiwi, electrickery is harder to come by - domestic wall sockets are rated at 10A, although 15A sockets are sometimes fitted in garages, etc. Wiring regs are different from UK - power circuits are radial, and most houses have many power circuits, each fed from a fuse or circuit-breaker. Joe public isn't allowed to do much in the way of wiring, unless it's 'signed off' by a professional sparkie. I'll probably have to arrange a dedicated feed from the fuse board for the thing. Oh well, if life were simple, we wouldn't mess around with this sort of stuff, would we?

I have an old Gallenkamp muffle furnace. The outer casing is made of a dense manufactured board, which contains glistening material, possibly mica. (Hope it's not densely compressed asbestos...). I'm sure the name of the stuff is somewhere in the back of my head, but it's rather cluttered in there, and finding things keeps getting harder...

Several ventilation holes, approx 1' dia., have been machined through the board, showing that it machines well. It seems that various fittings are secured to the casing by screws, apparently tapped into the board. I now want to remove some of the screws. Some come out OK, others are reluctant. I suppose, if they are in tapped holes, the hole's thread will strip. Well, that's if I'm lucky - one screw sheared off...

The questions are 1) Any idea what this stuff is called? 2) Does it destroy taps, because of abrasive content? 3) Might Helicoils work?

Nicholas Wheeler makes some good points. I'll have to re-think some of my prejudices. However, I still don't want the hassle of protecting myself from isocyanates.

Hammerite? No thanks - hated the stuff, both original and politically-correct, emasculated versions. The original thinner (a now-vilified chlorinated hydrocarbon, if I remember correctly) was too useful in the 'shop to waste on the ghastly paint.

If I were back in 'the old country', I guess I'd be trying Tractol, but I don't think it's available here in NZ. Sparex tractor paint is available, however - anyone know anything about it? We enjoy(?) a very restricted choice of many things here. (Thank goodness the craft beer movement is really taking off, so the choice of beverages is much better now!)

No-one's yet answered what the traditional materials would have been. Some of the old machines I've dealt with seem to have massively thick (original) paint, which is hard and somewhat brittle, and comes off in large flakes, rather than peeling off. Would it have been simply many coats of a tough type of alkyd paint?

I've been following, and admiring, Damian Noble's account of his Senior rebuild. Very impressive!

These days, at least in NZ, and I'd guess worse in UK, it's getting difficult to get hold of old-fashioned paints containing the not-quite lethal solvents we loved to breathe in. 2-pack polyurethanes and epoxies are nasty, expensive and also difficult for privateers to get. Myford's exhibition finish used Trimite polyurethane, from memory, but I was told that the stuff wasn't available to the public.

Eventually, I intend to rebuild some old machines - some from WWII era - and would like to mimic their original finish. They will be used, so the paint must perform well too.

What were the traditional materials used for machine tool painting, say 40+ years ago? I assume they would be some form of alkyd resin paint (= oil-based enamel?), but these can be pathetically fragile. Presumably there were tough versions available. What filler/surfacer would have been used on castings? What primers?

If it's pointless trying to source semi-obsolete paint types, what would you suggest? If there are any Kiwis out there, where do you go for a good selection? Mainland paints in Chch looks promising; anywhere else?

...oh, and another thing. 'Hydraulic oils' typically contain anti-foaming additives (not relevant here, of course) and corrosion inhibitors. Esso Nuto H32, or equivalent, as advised for Myford lubrication (but not slideways), is a nice oil to have around the 'shop - light, and suitable for general purposes. Automotive engine oils typically contain detergents, which messes up their water-displacement properties. They are not good for corrosion protection, although no doubt there are exceptions. I believe that automatic transmission fluid is OK - perhaps it's similar to an hydraulic oil.

ACF-50 is indeed excellent. Even better, I think, is the imaginatively-named Corrosion Block, from the same manufacturer. It's more viscous than ACF-50, and hangs around much longer. I believe that ACF-50 slowly evaporates. Just a wipe with a rag impregnated with the stuff is all that's needed - a smear goes a long way. It's also an impressive penetrating oil.

Does M&W manufacture in UK these days? I thought their clocks and electronics had been oriental for years, but don't know for sure.

I recently got a new, genuine Starrett 8" digital calliper, unseen. Brand loyalty, you see. The price seemed almost too good to be true. It was. Nasty oriental quality. It's accurate (so far...), but can't really be used sensitively because of the poor, gritty feel of the slide. So much for brand loyalty.

Re battery life. Note that SR44 (=357) cells are silver oxide, with about twice the energy density of LR44 lithium cells, and need not cost significantly more. Some sellers don't know the difference and think you're being awkward if you refuse a lithium cell. The button cells supplied with new devices from the darker corners of the orient are often junk.

I apologise for appearing to accuse MEW of not reliably paying its authors. I was merely passing on what I'd been told, and explaining what was the sticking point. I'll see what I can do to help find the overlooked payment. Hopefully we can then be treated to a fascinating story of engineering precision and ingenuity in what must have been rather difficult circumstances in those days on the other side of the world.

I know this machine's 'brother'. There are five or six in the family. Their history is fascinating and may be published in the future in MEW. The machines are derived from a non-commercially-made-in-NZ 'prototype'. Five sets of castings were obtained by the person whose name appears on the photographed machine in the late 1940s. The patterns were made by his father. These were then made up into complete machines by various people, incorporating various different features. The lathes were not commercially produced. They contain no proprietary parts, apart from ball races in some of the headstocks and, I suppose, some fixings. The T-slot on the front and rear face of the bed was intended for accessory attachment. The whereabouts of all but one of the machines is known and the 'missing' one is thought to survive not too far away. Kiwi ingenuity at its best!

The owner/builder of the lathe I 'know' has prepared an article, with photos, all ready to send to MEW. He tells me that he won't send the article until he's been paid for a previous article published in MEW over a year ago!

I can't reveal any more - let's hope the story will be published. It's just a matter of payment being made...

The owner/builder/author resolutely avoids all contact with computers. It's a real pity, because he posseses enormous theoretical and practical engineering knowledge and has made several superb machine tools and accessories - some in partnership with his late father. If only all that information could be extracted onto a (large) hard drive...

Do yourself a favour, and use a push-button starter with no-volt release. It might save fingers, one day. You can easily add a reversing switch and panic-off buttons. However, if you insist on using the Dewhurst, the thing connects as follows. Terminals are numbered, left side, 1-4, from top to bottom, and, right side, 5-8, top to bottom. (1-2-5 means these terminals are all connected to each other.)

FORWARD: 1-2-5, 3-6-7, 4-8

OFF all disconnected

REVERSE 1-5-6, 2-3-7, 4-8

Assuming a capacitor-start, single phase motor, connect the supply to 1 and 3, RUN winding A1 to 7, A2 to 5, START winding Z1 or Z to 6, Z2 or AZ to 2. So the run winding is connected the same way to the supply in forward and reverse positions, but the start winding is reversed for direction change.

If it's not a single phase motor, ask again - these switches can cope with many types. Note that it's rated at 0.75 hp at 200-240V.

Thanks Martin for pointing out that the expression I derived can be simplified - much more elegant! So I too am guilty of cumbersome maths! Also, I am guilty of a typo in the third-to-last line! (Couldn't edit the post once it was posted and I noticed the error - too late!) Mea Culpa. I'll go away and sulk, whilst remembering not to throw stones in glass houses...

(Real) Kiwi Bloke.

Edited By Kiwi Bloke 1 on 08/01/2016 11:14:11

What a lot of cumbersome maths!

The easy way is to look up in an engineers' reference book the relationship between pitch circle diameter and the distance between vertices. This is typically used when one has to set out the vertices by co-ordinates. This is usually given in the books for many regular polygons. For an equilateral triangle, the PCD multiplied by 0.86603 gives the distance between vertices, to a good-enough approximation.

If we are to be treated to a mathematical tutorial extending over two pages, let us at least have an elegant solution. A little geometric insight shows that the PCD = 4/3 X Square root (3/4 X D^2), where D is the distance between vertices. No need for a calculator with trancendental functions!

This type of trivial and badly edited article does MEW no favours. The mathematical approach is clumsy and makes the subject intimidating for novices. For non-beginners, there is no need for articles teaching Grannie to suck eggs, either. (The triangle is equilateral, not isosceles and the plural of 'apex' is either apices or apexes, not apeces, as printed. I was pleased to see evidence of apparently improved proof-reading under the new editor, but standards seem to have slipped dramatically. In a publication with an international readership, it is important to maintain high standards of English usage, spelling and punctuation. Sadly, the correct use of the apostrophe seems to be a vanishing art...).

MEW seems to be becoming an an organ for entertainment, rather than authoritative information. It may be interesting some to learn how the editor mucked about with welding equipment, but an article telling us how to do it properly would be infinitely more useful. Please can we have no more articles of the "Wot I did on me 'olidays" type?

OK, there's more than one way to skin a cat...

This is a complex subject and many methods of making rings have been published. Some are very much better than others. The method of manufacture described is designed to produce a circular outer surface, but what about the inner surface? Does the resulting ring produce a constant radial force on the bore (as it should), all around its circumference?

I'd guess that most readers are already aware of Prof. Chaddock's seminal writings in ME about piston rings. A good overview of this complex subject can be found here: **LINK** and it's well worth searching out the source documents to which the author refers.

Paul, I don't know how 'assembly paste' compares with CV joint grease, which is pretty special stuff, compared to 'ordinary' moly grease.

Graphogen is a trade name of the graphite-loaded one I have used. The MoS paste I use is Australian, Molybond GA 50. I think Rocol have a similar product, but haven't noticed it in NZ. The GA 50 blurb states: '...containing 50% molybdenum disulphide powder in a lithium based grease used as an anti-seize and anti-scuffing compound for metal parts. It has an extremely high load-carrying capacity and a wide temperature range of -10C to 150C (suitable for use up to 400C as an anti-seize compound). This product does not contain copper, nickel, aluminium or graphite.' So it sounds like the answer to a maiden's prayer, doesn't it? I think its solids content is much higher than (most?) other moly greases. It really is useful for all sorts of things, particularly highly-loaded sliding surfaces of similar metals.

Incidentally, scroll chucks benefit from intelligent lubrication, not just any old oil or grease. Their clamping force can be dramatically increased by using such a lubricant, or a ferociously expensive one, Kluber Altemp Q-Paste NB 50, as specified by a European chuck manufacturer. I had to lie down for a bit, after buying some, years ago. I don't know if it's still available. Worth it though - it goes a long way.

Here, in unimportant New Zealand, it's still possible, having satisfied the various legal requirements, to be granted the privilege of an appropriate licence to own and use most types of firearms, including semi-auto pistols. Home manufacture is also possible. I heard a story, which I have no reason to doubt, that an experienced shooter and toolmaker, having completed a competition target pistol, woke up to the fact that he should get it registered with the police. Of course, it had no serial number, so he stamped it with his initials, followed by the last two numbers of the year of manufacture (it was in the '90s). When the Firearms Officer saw the number, he nearly fainted, and spluttered "Crikey! How many have you made?" They had a good laugh about it, and all was well.

It will, I fear, only take one idiot to ruin this freedom for us. Whether that idiot is a criminal, or in the government (not mutually exclusive), remains to be seen...

Well done - it's satisfying to resurrect the dead, isn't it?

As far as I can remember, all the micrometers I've had to lay hands on have been lubricated with a smear of grease, but of what type I know not. I've found that, after a thorough clean, light oil can result in an inconsistent feel, particularly when the thread-closing collet nut has been tweaked enough to provide enough drag for the ratchet to work.

I recommend what's known as 'anti-scuffing paste' or 'assembly paste' or similar. It's a grease, heavily loaded with either molybdenum disulphide or graphite. It offers protection from thread galling, especially when, for example, steel runs against steel. I prefer the MoS version. It has innumerable uses in the 'shop. Available in tubes, from engineers' merchants. A tiny amount goes a long way. You can use a drop of oil as well, if the grease is too 'draggy'.

Edited By Kiwi Bloke 1 on 22/11/2015 10:05:01