Member postings for Kiwi Bloke

...and replying to your post above.

Interesting approach. No doubt your approach will work fine. Whether it will continue to do so as it wears remains to be seen. Realistically, it isn't going to wear much is it?

However, a few things to consider:

1. Tilting the strips will tend to cause line contact, which will be associated with greater wear. Don't forget that a softer material can wear a harder one if it gets embedded with abrasive - as in a lap. These strips need to be 'sacrificial'.

2. You could use Belville washers (or other spring washers) under the retaining screw heads to achieve preload. (IIRC, Emco use wavy spring washers).

3. The strips will certainly not float on a film of oil (hydrodynamic bearing), unless you make the gap large enough (and the saddle whizzes along) - and we don't want a gap, for obvious reasons. At the low speed a saddle will travel, and the loading necessary to pull the saddle down, even boundary lubrication is optimistic. There will be metal-to-metal contact.

4. Don't lose sleep over it. "She'll be right", as they say here in NZ.

...carrying on from my post on your other thread (confused? So am I...).

The important thing here is, I believe, preload. It's difficult to arrange and control preload when a system is too rigid. Hence my belief that, counter-intuitive though it may be, Emco got it right. Or, at least more so than Sieg.

The Sieg approach looks attractive at first sight, but I suspect that it's another example of their blindly copying design ideas rather than thinking things through thoroughly. Compared to Emco's design and manufacturing integrity, I consider the Sieg machines to be seriously inferior in many areas. (I'm probably going to cop a lot of flack for that remark, and don't wish to start a war, so let's just leave it as a statement of a personal opinion...).

OK, I took a guess as to which thread I should aim my reply - and got it wrong. (Life can be so confusing...).

Please see other thread.

As Michael Gilligan has pointed out, scaling things can cause problems. Remember that, as linear dimensions increase, mass increases with a cube law. Even though a larger lathe can take heavier cuts, I don't think cutting forces, which have to be reacted by saddle, etc., will increase at anything like the same rate. Therefore, in large lathes, the saddle's weight is a major component of its location and stability.

A little U3 is, one might say, too lightly constructed, and is not gorilla-proof, and nature's scaling law works against it. As Graham Meek has pointed out, the Maximat 11 has plastic anti-lift strips. I think the V13 also has. Neither is adjustable, IIRC. They probably contribute little to the stability of the saddle (under normal conditions).

On the U3, however, the anti-lift strips are vital, because gravity isn't doing enough to locate the saddle. They are non-adjustable (unlike the Sieg - interesting...), and it appears that saddle manufacture has, in their location surface's regard, wide tolerances.

This long preamble is to justify my belief that the choice of a plastic material by Emco is intelligent, not negligent. The strips are almost certainly designed to be elastic, so that they are in a sprung, pre-loaded condition when tightened down. Of course, when the saddle has been incorrectly manufactured (or horribly worn), there's no pre-load, nor even any contact, so they are ineffective. So the strips must produce a sufficient force on their ways to pull the saddle down onto the bed ways, doing the job that gravity can't.

Lubrication in this position is going to be hit-or-miss, so an inherently 'slippery' plastic is better than metal. Also, the increased stiffness of metal means that it won't act like a spring. Sieg's adjustable strip approach is necessary for metal strips. Emco provide no adjustment, so flexible strips are necessary in this application. Metal may be OK, if carefully fitted, but wear will destroy the fit.

Think in terms of pre-load. No movement is possible, until the pre-load force is exceeded, even if pre-load is provided by something floppy, like a rubber band!

Bottom line - stay with plastic, but make sure it is adequately pre-loaded!

Update. It was mechanical, after all. Following a quick clean and lube, things looked good. Then, a couple of days later, the motor wouldn't start. Poking the fan (power off) revealed that it wouldn't initially turn easily. Then it would, apparently freely. Today, complete strip down, including motor. No corrosion, but what lubricant there had been was gummy or varnish-like. So, acetone wash, brushing out bushes, etc., and gun oil to the bearing felts, reassemble. Now the fan spins really freely! Switch on and it goes like the clappers! Happy wife, who no longer resembles a couple of chapel hat pegs when she gets out of the shower (unheated houses are miserably cold in NZ winter!).

Moral. Simple things shouldn't be discounted, diagnostic examination should be careful, even on a rush job, and assumptions are dangerous...

The Gibraltar was Tubal Cain's.

As has been said, it depends... The Myford Super 7 topslide, with Dickson QCTP is not a rigid set up, and using a parting tool in it can be hair-raising.

To add to my Emco comments in another post: the Emco QCTPs offered for the U3 and Compact 5 are a poor design. The mating faces are tangents to a circle, and their included angle is too large, resulting in very poor kinematic location about a vertical axis. I think Harold Hall's design, with a little tweaking, looks like an excellent, and easily made, QCTP design. One day...

Well, thanks for the thanks Julius. It's always nice when there's evidence that one's posting has helped (or even been read and understood...).

I wouldn't bother changing the strips. Just flatten them with a fine file. Beware abrasive paper, in case grit gets embedded. I would imagine that the material was chosen so that the strips could be tightened down in a loaded condition, without too much worry about seizing because of poor Not many people would boast about their expensive disappointment, would they?lubrication.

It does seem ironic that it's not always easy to find complaints about machines' shortcomings, and grumbles about machine design, manufacture and performance before one buys a disappointment. (See also Ford Ecoboom thread!) Perhaps few people like to admit even to themselves that they've bought a lemon. However, once there's a trickle of discontent published, it's sometimes followed by a torrent...

One could completely fill the forum with fully-justified gripes about Myfords, Emcos, Cowells, Fobcos and other 'well-respected' makes, but their owners seem to prefer to keep quiet - although freely making disparaging remarks about far eastern built-down-to-a-price-and-down-to-an-even-lower-quality machines. Not many people would boast about their expensive disappointment, would they? I'm impressed by the number of Cowells lathes that turn up for sale in apparently almost-unused condition. I wonder why. I could fill pages with my criticisms of the machine (if anyone's interested)...

Sadly, there are plenty of areas of design and manufacturing weakness in Unimat 3 (and other Emco) machines: the U3 saddle 'lift strip' arrangement and the vertical quill's bearings have been discussed here, and Graham Meek and others have worked wonders on various improvements. With suitable attention, U3s can be made into useful, although very limited machines. But 'fresh out of the box', they are a gamble.

Thanks Robert, great info. So it seems that these devices are so gutless that they have terrible speed regulation, and will 'slip' increasingly, as load is applied. Is this correct? However, they may not be damaged if they stall - also correct? Just for info, there's no external evidence that this motor has been cooked.

If it seems to be misbehaving in the future, I'll bite the bullet and pull the rotor out, with the intention of frightening it with a punch.

Around the time Fobco ceased trading, I saw a turquoise-coloured, apparently factory-fresh example. Its ball handles looked a bit rough, and the quill rattled horribly in the main body. I wondered whether this was a trial model from a cheap-labour contract sub-manufacturer, or whether Fobco cobbled together reject parts to flog off. If that was the best they could do, the world's better off without them. Pity, because the cream-coloured ones were good machines, although I thought the belt section was too large for the small pulleys. I would very much have liked the bigger model...

When things go OK, you tend to ignore them. When they don't, you suddenly pay attention - but can easily imagine their behaviour has changed in ways it hasn't...

A fan heater seemed to start running hot, with visibly red elements (simple coiled type), and its cylindrical fan seemed to be going slower than usual. Dismantling revealed the expected eiderdown-full of fluff and muck, but the fan and motor rotated very freely, with no evidence of unexpected friction. After cleaning the inaccessible nooks and crannies, and sparingly lubricating the motor bushes, it all seems to work OK, with barely-red elements (never noticed them red before, but never really looked...), but am I imagining that the fan is slower than it used to be?

Excepting mechanical causes, can the simple type of shaded-pole motor partially fail, so that it runs a bit more slowly than intended? I think I understand how they work, and can't imagine how this could occur...

Possibly a glitch at your end of the download - it's all present and correct in my copy. (Bloody computers!)

"Because we can" is NOT a justification for doing something! I suppose that if there were more of these engines failing in litigious USA, there would have been a class action against Ford by now. In the distant past, the AA acted in suppost of motorists. Now it sells insurance and promotes holidays...

Good find, Michael, thanks for sharing! Page 20 is there in my .pdf download (but I haven't checked that all the pages are there...)

Edited By Kiwi Bloke on 13/06/2023 01:51:00

Some years ago, I obtained an apparently unworn, probably barely used, U3, in a grubby, but not rusted condition. After a complete strip-down and clean, I tried to turn some approx. 3mm dia. MS stock. It was hopeless! It transpired that the mating surfaces of the underside of the saddle held the 'lift strips' a tiny bit away from their ways on the bed, so the saddle could move vertically. Some careful blueing, and needle-file work on the saddle soon had them snug. Problem solved. Check yours!

Emco may have cut corners occasionally, for the accountants, but I think they usually had a good reason for most design decisions. They were not averse to using MS gib strips, so I'd think that the plastic (glass-filled nylon?) was chosen for an engineering reason, rather than cost. Perhaps because of the difficulty of ensuring adequate lubrication? The material is quite hard and stiff, and is secured close to its working surface, so I suspect that cases where they seem defective is the result of the manufacturing fault I've described, or wear - or even simply being loose.

With a well set-up lathe and properly fettled tool bit, it is possible to take off a couple of 'tenths' (or less) at each pass. Lapping is a good idea, but very slow. A hand-held hone, such as those by Delapena (probably no longer made...) or, IIRC, a similar pattern by Bruce Engineering, is quicker. These three methods will ensure roundness, whereas filing and emery paper won't correct a lobed surface - common on centreless-ground stock.

...often called 'Uni-mic' (or 'Uni-mike'...). Possibly a name originally used by Mitutoyo.

Interesting discussion. However, it's a discussion about solutions and wish-lists, before the problem has been defined. What will be manufactured is what will sell. Are we specifying the ideal lathe, the beginner's lathe, the affordable lathe, the best value, the best quality, one on which you can mill, swing huge diameter flywheels, what?

I don't suppose Myford (MkII) or Cowells sell many machines. Each serves a rather odd niche market, which seems satisfied with machines that are essentially 1930s solutions to the amateur user's requirements. In those days, the lathe may have been the only powered machine in the workshop, so versatility was paramount. Myford certainly achieved that, especially with its range of accessories.

Interestingly, Myford bought out, and closed Raglan, which made rather better lathes, and a milling machine. Perhaps these didn't sell as readily, I don't know. But Myford was cheaper and more versatile. Also, decades ago, a purchaser was much more likely to have received at least rudimentary workshop training, at school.

Now, however, imported machine tools cost a much smaller proportion of earnings, and amateurs' workshops often contain multiple machine tools. Sadly, as is evident from some postings on this forum, inexperienced and poorly-informed folk will happily spend a lot of money on machines, yet have little idea of how to equip and operate them. Their requirements are different from typical purchasers of decades ago, and they influence the market. The market is less discerning and less well-informed. Today's kids want a machine on which they push buttons and out comes a finished item. Will the 'screen generation' want manual machines?

Much as I hate to say it, I think Myford and Cowells have had their day. Leave them to the shrinking niche they occupy. They are terribly old-fashioned, but will never be fundamentally updated. Comparing current mass-production to them isn't very helpful.

So, what's on my wish list? I suppose the machine will be made in the Orient - pity, but it seems there's little realistic alternative. However the Orient can make stuff to any level of quality that can be paid for. So, number one on my list is for quality of design and manufacture to be improved - considerably. Number two is for the machine to be modular, so it can be added to, as requirements change and funds allow. I'm nervous about the long-term reliability of electronics, so keep it as 'mechanical' as possible. For amateur use, belt-moving to change speed isn't too bad, is it? The KISS principle is pretty sensible, at least in the home 'shop. And then all(?) the other suggestions, already made, can be considered - but as add-ons.

Good grief! That's a picture of a gib strip? Clearly, the thing's been thrown together by ignorant minions, employed by crooks and charlatans, and sold by deceitful people (I was going to say something much worse...). Fight to get your money back, and don't waste time on a heap of junk that may have many more problems waiting to reveal themselves!

The boiling point of the salt bath discussed in this thread rises as water is boiled off, hence the bath will get hotter with time. Adding water is dangerous, because the water can/will boil explosively. However, significant water loss shouldn't be a problem, unless you're doing a long run of components.

The idea of treating a rusted surface with 'converters' may work OK. As far as I know, these converters (mostly?) contain tannates, which 'convert' the red rust oxide to blue-black tannates. But why bother with the expense? If you lightly wire brush the rusty surface, to get all the friable, loose surface off, and then boil the part in water, the red/brown oxide will convert to black oxide(s). Re-doing the rust, scratch, boil cycle a number of times, until the colour is satisfactory, is the centuries-old, traditional gunsmith's colouring technique. Oil, and perhaps wax, afterwards, to inhibit further (red) rusting. However, it's a slow job... The rusting can be speeded up by suspending the parts over a saucer of strong acid, in an improvised polythene tent.

Can any passing chemist please explain why acid 'fumes' cause oxide formation, rather than acid salt formation, as the liquid acid would?

^^^^^ Agreed!