Member postings for Kiwi Bloke

Thanks everyone for your input. It's strange, isn't it? The problem with so much teaching and knowledge acquisition is that the 'whats' are taught, in preference to the 'whys' - because it's easier, and the teacher can be a regurgitator, with little understanding.

The 'anti-dig-in' idea sounds reasonable, but does it withstand close scrutiny? A tool on centre height still experiences an outward force. I suppose 'dig in' susceptibility depends on the geometry of the deflection of the tool bit, holder, tool-post, slides, etc. With a weedy Myford (for example), a dig-in is an unstable condition, the bit 'nodding' further into the work. It's not pulled in, it's pulled down; the whole tool support assembly effectively pivots somewhere near the topslide base, and this pushes the tool inwards (Long ago, I applied forces and measured deflections, then calculated effective centre of rotation of tool tip). In this case I don't think that an above centre-height setting would help. But - this may have been the original idea, because I'm sure I have an ancient book (somewhere...) that believed that the forces on a lathe tool pulled the cutter towards the centre. Similar thinking may be the reason why some old lathes (and the current Cowells - it's a living fossil...) have the carriage gibs at the front. I wonder whether the high setting results in a little burnishing of the cut surface, which was thought to be better cutting?

By the 1930s, South Bend lathes were pretty hefty, and well designed, albeit with plain spindle bearings, so lack of rigidity should have been less of a problem.

However, none of this musing really explains why the texts advocating a high setting for parallel turning set this aside and allow geometrical considerations to demand on-centre-height setting for tapers. Inconsistent information worries me...

(edits for two-fist typing - and before coffee, too)

Edited By Kiwi Bloke on 21/04/2023 22:47:15

Pete, you're quite right, distilled water is best, and cooking up the nasty soup is best done outside, standing upwind...

You mention a deep blue colour, seen in a picture. Yes, this is common, and an attractive feature of Smith & Wesson revolvers. Colt's revolvers look blacker - at least to my eyes. But the range of near-black shades on different guns is quite considerable. I once handled a S&W revolver that looked oddly 'wrong': it was too black. It transpired that it had been worked on and re-blued by the local, friendly gunsmith who showed me, and used, the method I described. The different recipes in Angier's book undoubtedly produce different 'colours', but their ingredients look like curry recipes, and are, I'm sure, more the result of 'ancient knowledge' than proper chemical research.

Well, it depends on what is meant by 'true up the lathe'. If going through a full set-up process from scratch, it's quite involved, as are the tests (eg Schlesinger). However, for a final test of the machine's ability to turn parallel, a couple of turned collars on a length of bar, held in the chuck is absolutely fine. The chuck need not hold on centre, or truly axially, but must hold without slop. I've seen a video on the unreliable net that suggested that the 'two collar test' be done with tailstock support. Oh dear...

Terminological inexactitude abounds!

R H Angier's 'bible' on the subject is titled 'Firearm Blueing and Browning'. It was published in 1936. It seems that chemical browning dates back probably before the 1600s, and seems to have been a refined form of rusting, coating the iron with red/brown ferrous oxide. 'Temper blueing' was also used around the same time, the colour being produced by heating, giving the progressive oxide film build-up that we're familiar with - and as used by clock-makers - to get a distinct deep blue colour.

Nowadays, the commonest gun finish is chemical blackening, but it's still often loosely called blueing or browning. This finish can be obtained by boiling a rust-browned part in water. This converts the red/brown oxide to black oxide. Traditional rust-browning - or blueing - is a very tedious process indeed, but it's safe, for instance on shotguns, which are traditionally soft-soldered together.

Currently-available 'Cold blues' are commonly based on Selenium salt deposition, but are not durable, and the colour depth is often poor. However, it's a useful 'touch-up' process.

Angier provides numerous recipes for chemically colouring iron/steel, but most of them sound more like alchemy than elegant chemistry. Many are based on, or contain, arsenical or chromium compounds, and other nasties.

An easy, proper, black oxide finish can be got with a mixture of Sodium Hydroxide (8 parts) and Potassium Nitrate (5 parts) in water, the parts being boiled for about 10 minutes in it, at about 140 C, the boiling temperature determined by the mixture's water content. It's a nasty, hot, dangerous, corrosive mixture, so be careful, especially if needing to add more water, and good luck getting the chemicals. Needless to say, everything must be scrupulously cleaned and de-greased*. The coloured finish is then oiled and perhaps waxed. It's really the oil or wax that slows down any subsequent rusting process, because the oxide coat alone is porous.

(Neither I, nor the management of this forum will take any responsibility for anything that occurs as a result of this posting, and Angier's dead. You know the drill...)

* and if anyone thinks that a wipe down with acetone will properly de-grease a surface, they are sadly mistaken!

I've just picked up a copy of the well-known - and respected - book "How to Run a Lathe", published by South Bend Lathes, this the 34th edition, of 1938. Like several other, older books I have and have seen, it advises: 'The cutting edge of the cutter bit should be about 5 [degrees] above centre, or 3/64 in. per inch in diameter of the work... for ordinary straight turning.' It then advises that, for taper turning, threading, and cutting 'tenacious metals', the cutter should be exactly at centre height - as we'd all expect. The accompanying illustration is of what looks like a small HSS bit in a substantial toolholder (standard industrial practice) - but not a spring tool holder.

As far as I'm aware, the 'above centre height' advice is now obsolete (except, perhaps, for some boring operations), but I don't understand why it was ever advised for 'ordinary' turning. Any ideas?

Armchair theorist Alert! I've no experience of trying to colour stainless steel(s), but have messed around with Se-chemistry products for touching up firearm finishes - with very variable results. Have a look at Wikipedia - 'Black oxide'. It seems that some stainless steels will colour satisfactorily.

Excuse a slight detour. Rather than standing, stooped, with aching back, at a machine, I (now) prefer to sit. I'm of average height, but my back still complains. Therefore, I like to mount bench machines on a bench/stand with knee-room below the machine. An office chair with quick-action height adjustment, and on wheels, is added luxury!

Oops, double post. Is there any way of deleting an entire post?

Edited By Kiwi Bloke on 11/04/2023 03:28:12

Before you lose hope and commit to digging ugly big holes in your beams, it might be worth living a bit dangerously. try cooking the exudate with an hot air gun. Heat the mess up to just below the temperature at which the wood chars (that's the living a bit dangerously part). With luck, whether it's uncured epoxy or resin, it will harden to the point where it can be chipped or scraped off (when cold). Alternatively, you could try rubbing the stuff with rags soaked in acetone. Happy birthday!

Edited By Kiwi Bloke on 11/04/2023 03:28:50

Why do you think that? I'd have thought that the NPL would have considered quercus robur their 'default' oak.

At the risk of flogging a moribund nag, like I said, it's complicated... And there's a lot of misinformation being perpetuated.

Timber is largely composed of cellulose, a polysaccharide, and some of its sugar units are acetylated. These can react with water to produce free acetic acid. Timber is consequently acidic, some more than others: oak, sweet chestnut, western red cedar and Douglas fir are particularly acidic. Acetic acid is volatile, so a closed wooden box, with timber containing any water, is very likely to contain acetic acid vapour, and this will corrode the contents. This is a risk for many metals, including, perhaps surprisingly, lead, not just Fe-based materials.

Corrosion can also occur by contact with the timber surface, and this appears to be a particular problem with tannin-rich timbers, such as the oaks. The corrosion is caused by acetic acid, not the tannins. Acetic acid is a stronger acid than tannic acid. Nomenclature is often muddled in source material: quercitannic (sic) acid is a tannic acid found in oak. There are other tannic acids, and tannic acids are a sub-set of the tannins.

Tannins are a major component of some 'rust stabilisers', the ones which don't remove the corrosion, but turn it black: the red rust is converted into black tannate, which protects the substrate from further rusting. Tannates are also oxygen scavengers, but I don't think this attribute is important here. However, what this means is that, (if there's moisture around), steel in contact with oak may develop characteristic black corrosion damage. Tannins are not volatile, so this blackening shouldn't occur without contact. Tannins will also cause dark blue discoloration of non-corroded metal. The timber may also be stained around steel fasteners, for example, which will also corrode. Again, it is the acetic acid that causes the corrosion, but the tannins that turn the rust black. I suppose that when tools rust in association with other types of timber, it's generally thought to be 'ordinary', moisture-induced corrosion, and the contribution of acetic acid is not appreciated.

Bottom line: all timber is suspect if there's moisture about; keep things dry, sealed from any acid vapour emanating from the timber, and out of contact with the timber, particularly if it's a tannin-rich timber. Closed boxes are bad, boxes sealed in plastic bags are worse. Now that there are alternatives, perhaps timber storage boxes, drawers, etc. should be avoided.

Did you read the paper, particularly section 2.3? Clearly, it's a rather complicated subject...

National Physical Laboratory. Can't get much better than that... I had hoped that the URL would reveal itself in my post, but I presumably did something wrong <sigh>.. (Like others, I like to see links spelled out as plain text in posts).

My reading is that, after some (unknowable) time, oak's liberation of acetic acid will drop to an insignificant level, rendering it 'safe'. Still seems risky to use wood, though...

JA I hadn't realised this topic had been done to death already...

I didn't wish to hijack a thread, so started this. There's a lot of 'traditional knowledge' around in long-established trades, crafts, etc., and it's perpetuated by constant repetition and 'teaching', but a lot of it is little more than dogma: it hasn't been scientifically evaluated.

Oak is often demonised as being the wrong timber to use for instrument cases or tool cabinets, because it causes terrible corrosion of the contents. It's explained that it's the tannins that are responsible - or is it the acids, and if so, which acid*? Sometimes oak boxes are a problem, however oak is commonly used for this purpose, without any problem. In fact it may be one of the best options. So, it seems that oak can be very risky, or hardly risky. Why?

All(?) is revealed here:

**LINK**

* acetic, actually

Well I never! Isn't this forum such a wonderful mine of information! I thought I knew my way around a Fobco...

Theo - either oil would be OK for the quill feed, but slideway oil should hang around for longer. If you're an oil-every-day person, or even every week, hydraulic oil should be fine. The better stick-slip properties of slideway oil aren't really important here.

Regarding your previous post... Oiling the column is presumably because you wish to avoid the risk of corrosion. Hydraulic oils contain corrosion inhibitors, but, unless the drill is in a horrible environment, almost anything would do, except detergent oils (most engine oils). Detergent oils can absorb atmospheric water, which may cause corrosion. This isn't usually a problem in an engine, where the oil gets hot enough to evaporate off the water.

Motor mount pins. I'd suggest moly grease. Clamp screw threads, hardly critical, but moly grease again.

Generally, ISO 32 hydraulic oil is a good general-purpose lubricant, formulated with anti-foaming and anti-corrosion additives. It's good for spindles and gearboxes, although a heavier grade may be specified for the latter. Free from detergents, fine particulate contaminants should settle out into the base of a gearbox, rather than be kept in suspension.

Slideway oil is for ...slideways, because it doesn't readily slide off surfaces, and is formulated to reduce the problem of 'stick-slip' friction that can be a problem with tight-fitting, slowly moving bearings. In such bearings, there won't usually be a complete oil film separating the opposing surfaces, so the requirements from the lubricant are rather different from high-speed bearings, where a relatively high-pressure oil film is built up by movement.

Edited By Kiwi Bloke on 20/03/2023 11:23:00

[more edits - typing with fists again...]

Edited By Kiwi Bloke on 20/03/2023 11:25:00

Terribly late to the party, sorry...

Buying things these days seems to be a lottery. Too many brand names have been bought by profit-takers who don't care about the products. China seems able to supply everything, at all levels of quality, and with any name you like. Problem is that you can't tell which is going to be good, before you purchase.

I bought an 8" Starrett digital caliper. It's horrible - clearly not from Scotland or USA.

Even though home use is unlikely to wear out an indicator, accidents happen. I'd take my business to a manufacturer which offers service, repair and spares. They are confident to stand behind their products - but perhaps not their low-cost lines. Some of the big names still do, but good luck with Chinese, no-name stuff.

Edited By Kiwi Bloke on 20/03/2023 10:58:47

My commonest, recurring error is to ever so carefully and methodically, machine some detail to exactly, but completely the wrong dimension. And it's always in the irrecoverable direction, like the diameter register on a chuck backplate being exactly 0.100(0)" too small. I still don't know how to avoid such f-ups: I suppose sometimes it's failing to count handwheel turns correctly, sometimes mental arithmetic failure, sometimes just having tunnel vision, and a lack of awareness that things could be going well, but have been wrong from the start.

And then there's just plain stupidity. I had a tall, narrow-based component standing up on a Jones and Shipman 1400 surface grinder, intending to take a tiny lick off the top. It was the inner part of an Albrecht chuck, so valuable. I had arranged support blocks to try to stabilise the set-up, and knew it looked a bit risky, however... I was bending down, to get a closer look, to see whether the surface had cleaned up enough, when there was an almighty bang. Yes, you guessed it, the wheel had shatterd, driving the work into the mag chuck, leaving an unsightly dent, embedding grinding wheel particles into the workpiece and bending it out of shape. Proper, kite-marked safety glasses are a Good Thing!

Kiwi Bloke's elaboration of Murphy's law: the probability of irrecoverable error is in direct proportion to the importance of the job, multiplied by the care taken.

(edits: more f-ups...)

Edited By Kiwi Bloke on 10/03/2023 00:29:41

Edited By Kiwi Bloke on 10/03/2023 00:31:34

I can't bear to look into this at all. I used to be a petrol-head, but now cars are just a nuisance, and one is held hostage by incompetent srevice agents and by the manufacturers' walls of secrecy surrounding any technical information you want. To answer: yes, this is progress - progress to hell. It is driven by idiots who think that 'because you can' is sufficient justification for doing something, and, of course, by the dead hand of those whose only interest is the financial side of a business. It's ghastly!

Edited By Kiwi Bloke on 03/03/2023 09:47:23

Confuius, he say "The wider you open the window, the more the muck flies in." I'm beginning to wish I hadn't asked, or even thought about this. In the public library today, I riffled through a number of motor vehicle and tractor manuals. Lips to air-side is certainly stipulated in some cases, but only occasionally in hubs with no provision for in-service grease addition. So I'm fairly confident that my memory of fitting hub seals lip-to-air-side is correct - in some cases. And I would think that the seals were of a somewhat different pattern to today's common double-lip seals. Things change...

Thanks everyone for the thoughts and info. The garter springs on the new seals I have are almost certainly Zn-plated steel, and there's no realistic possibility of adding an additional trash shield to the air-side of the seal. I think the bearings will outlive me on a single charge of grease, kept in with the seals fitted lip-inwards, as seems commoner. I'll ignore the grease nipples...

Yes, exactly my thoughts. Beware the farmer with No. 8 wire. He's almost as dangerous as his mate with a stick welder. They both think they can fix anything, and to hell with doing it the 'right' way!

Hopper, thanks for a quick reply. My belief is that it was common practice to fit hub bearing seals with the lip & spring on the air side of the hub, even if there was no facility to feed the hub with grease. This is certainly the case for Massey-Ferguson 165 tractor front hubs, as printed in the manual. In that application, the hubs are supposed to be fed liberal quantities of grease regularly, presumably to flush out any muck that gets past the single-lip rubber seal. I'm pretty sure I've fitted seals in various cars this way round, but it was a long time ago...

I'm aware of the dangers of over-packing anti-friction bearings, but I suppose that in such low speed applications, it's acceptable to drown them in grease. I agree that a single charge should be good for years, so I suppose the provision of grease nipples is for 'muck-flushing-out', rather than lubrication. The application in question is for the wheels of a gang mower, the hubs carrying grease nipples, and for which the manual is hopeless, so no help there...

I'll bet that a lot of similar stuff comes out of the factory - or the repair shop - with seals fitted the 'conventional' way round (my tractor's were the wrong way round) - but is it 'correct'? Does it really matter? It would be nice to know...