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Member postings for SillyOldDuffer

Here is a list of all the postings SillyOldDuffer has made in our forums. Click on a thread name to jump to the thread.

Thread: Lathe Identification
16/02/2019 20:52:03
Posted by Neil Wyatt on 16/02/2019 20:09:53:
Posted by old Al on 16/02/2019 17:24:40:

...

... over half of forum users are under 50!

Neil

What is this, a b....y Youth Club?

Boys under 50 should be in short trousers. Young people today, don't get me started, useless the whole lot of them. What they need is strict discipline and a dose of the birch...

Thread: Hi from Cheltenham
16/02/2019 18:46:54

In a way asking 'is a Myford a good lathe' isn't a good question. The answer is 'yes, no and maybe'. As a breed, they're good, but individual examples might be total junk.

Quite a serious problem with Myford lathes in my opinion is they attract unreasonably high prices. Buying Myford is likely to put a dent in your wallet - fit for purpose possibly, value for money - dubious. A particular problem in 2019 is that many Myford lathes are elderly. Some have had hard lives or been grossly abused. Not good to pay premium money for a crock however impressive the reputation.

Back in the day Myford hit the sweet spot with a decent lathe of reasonable capacity that - for the money - knocked most of the competition into a cocked hat. But, at the time, the competition was thin on the ground. Most of the other lathes available at hobby prices were inferior and Myford deservedly built a high reputation.

Nearly 70 years have passed. Today there are other opportunities. First you could buy a new Chinese lathe - not refined, but very good value, and the purchase is low risk because consumer protection applies. Also, the machines are of more modern design featuring stiffer beds, better motors and electronic control. Second, you could find a second-hand lathe that's comfortably a notch or two above the Myford Sevens. Back in the day rugged well-made high-performance machines made for industry (brands like Boxford, Harrison, Colchester, Raglan and many others) were simply too expensive for hobby buyers. For example, the cheapest Boxford was about a third more expensive than the dearest Myford. To our advantage, industry switching to CNC put large numbers of quality manual lathes on the market at reasonable prices and in good condition. Notably, they can be had rather cheaper than a Myford, probably because they are less well known.

Personally, I bought new Chinese. The main reason was I didn't feel confident I could tell the difference between a second-hand lathe in good nick and a wreck. Appearances are misleading - it's possible for a good-looking lathe to be scrap while it's grubby mate is in excellent order. Safest to walk away from any second-hand lathe that the seller can't or won't switch on and demonstrate! You have to look and listen carefully for wear, damage, and missing parts that might be impossible or gob-smackingly expensive to replace. Once satisfied the machine is working OK, or can be fixed, you then sort out transport and installation.

Another advantage to me of buying new was being able to order the biggest mill and lathe that would fit in my workshop straight from catalogue dimensions. No hoping a suitable pair would turn up on ebay, I just ordered the machines online and they were delivered shortly after. But my fantasy is still being paid £10 by a grieving widow to remove a master-craftsman's carefully maintained collection of classic machines. It does happen!

Might be better to start with 'do I want to buy second-hand or new?'; 'what sort of work will I do' and 'how much space and money can I afford'. Once those questions are answered away you go.

Dave

Thread: Mini Lathe Rear Tool Post
16/02/2019 11:39:10
Posted by Michael Gilligan on 16/02/2019 11:20:49:

Looking good, Ron

MichaelG.

Indeed. Ron deserves a prize for being 'the man most likely to'. He's gone from beginner to 'gosh' really quickly. If only I had half his talent. Bet I could out bodge him in a contest though, bodging is my specialist subject...

smiley

Thread: Warco Super - Major Vario inaccuracy
16/02/2019 10:18:08

Hi Bob,

I hope you don't think the posts questioning your measurements are unhelpful. Rather they are trying to confirm whether you have a genuine problem or not. No advantage to you rejecting an acceptable machine due to a misunderstanding - though it sorts out in the end, the bother and hassle of making a return is considerable!

Background to the questions is a forum history of chaps buying new Chinese for the first time and starting by taking dodgy measurements to prove to themselves the machine is OK. The problem is that taking accurate measurements demands a level of understanding, skill, and technique that not everyone has. It's not easy and beginners often get it wrong. Actually, experts get it wrong too, it's just that they are alert to the possibility and don't automatically trust anything! Sometimes these chaps are right, sometimes they're just torturing themselves.

One hint that mistooks may have been made is posts saying something like "x Axis spot on front to back y axis.008 out". Suspicions of beginnerism arise because units aren't specified, nor the distance over which the slope was measured. Also, there's no information in your posts about the method used to take the measurement, plus a sense of a man in hurry! From my armchair, it suggests - probably wrongly - that your measurement technique might be the problem.

I suggested earlier that you test the machine by cutting metal and looking at the results. The advantage is cutting shows what the machine is actually capable of rather than inferring what it might be. Also this type of simple test is less error prone. Of course, if the machine produces poor results, then you measure the machine to identify the cause.

None of this questioning means we think you are wrong, only that it saves you a lot of bother by confirming you're right. It's entirely possible that your machine is faulty or out of adjustment. On first installation, adjustment errors do happen as a result of transport, lifting into place, operator error, or a problem with the stand. These can be fettled. But although Chinese machines seem to have improved over the years they aren't assembled or inspected to high standards making it possible yours is a wrong-un.

The best resolution is that an ordinary non-intrusive adjustment fixes the problem. Second best is Warco replace a faulty machine with one that's within spec. Third best is you get your money back and start again.

If your measurement is correct, then the tilt is about 7x what it should be - not good.

Dave

Thread: Submitting Articles to Model Engineers' Workshop
15/02/2019 20:28:36

Is it only me who misread 'Wet transfer' and assumed it to be a euphemism...

Thread: Warco Super - Major Vario inaccuracy
15/02/2019 19:59:26
Posted by Robert Askew 1 on 15/02/2019 17:58:09:

Lower at back higher at front

.004” low at back .004 high at front

sorry but not exctable to me

Bob,

Before condemning the machine on the basis of measurements, try cutting metal with it. Note John Haine's comment that the machine may be intended to bend. It might not be as bad as you fear in practice.

You may have a more serious problem though! I see from your other posts that you've been a machinist for 40 years and use a Bridgeport VMC1000 at work. As such it may be difficult for you to cope with the gap between the machines you are familiar with and what a private individual can afford. Typically an industrial machine is 6 to 20 times more expensive than the hobby version. The Super Major is a decent hobby machine, but it's definitely not industrial quality.

It may be that Warco can provide a Major with better figures, but generally hobbyists make do within the limitations of their equipment. For what I get up to my Chinese machines are adequate, but I don't work at high speed, I back off when the machine shows signs of stress, and I change the way cuts are made to compensate for known shortcomings. I also keep a close eye on adjustments, things like gibs, backlash, and tram can wander. My work-rate is slow and it involves a lot of thinking around obstacles. Although it keeps me amused as a hobby, this way of working might well annoy the hell out of you, and it certainly won't do if you intend seriously using your mill productively or to make money.

The alternative to a new Far Eastern hobby machine would be a new Far Eastern industrial machine, or - perhaps more affordable - a second-hand ex-educational or industry mill. The main issue buying second-hand is finding a good one - condition is everything because spares and refurbishing are expensive, maybe beyond your worst nightmare. With time and luck it can be done though.

As it's important to be happy with tools, keep looking for what you want but be aware cost might force compromises unless you have deep pockets stuffed with cash. Much depends on what the machine is for, how you intend using it, and what you can live with!

Dave

 

Edited By SillyOldDuffer on 15/02/2019 20:01:52

Thread: Modern equivellent idea's please
15/02/2019 17:01:47

Unless you're keen to save money or retain original parts for nostalgic reasons, how about replacing the motor and switchgear with a VFD and 3-phase motor? Unlike horrible bumpy single phase motors, the 3-phase type are smooth enough not to need resilient mounting. Motor vibration can spoil the finish. In addition to being smoother, more efficient, and with better torque, 3-phase motors are also more reliable - no start and run windings, capacitors and centrifugal switches to go wrong.

Single-phase motors are a sad compromise on most machine tools - their only advantage is they run on ordinary domestic electricity, making powering them easy. Everything else about them is inferior. When Myford 10s first appeared it was intimidatingly expensive to convert single phase to 3-phase in a home workshop. Very few could afford to do it. That's changed - the electronics needed to create 3-phase from single phase is now commonplace and affordable. What you get is a better motor with speed control, reverse, soft-start and emergency stop built-in.

Going 3-phase makes most sense when an old motor absolutely has to be replaced. But if you can afford it, going 3-phase would be a worthwhile improvement now.

Dave

Thread: Tube Seam
15/02/2019 15:11:32

I don't think it matters in a small low-pressure wobbler boiler but seams are best avoided in pressure vessels. Longitudinal seams are by far the most vulnerable with many fatalities due to full size boilers failing along them.

More than one reason for seam failures. Seams are always weaker than solid metal, even when well-made. Even with good workmanship there's a risk the seam won't be perfect throughout. Then, in use, the seam acts as a stress concentrator that fatigues the adjacent boiler wall every time the boiler expands and contracts. This it does when heated up and cooled down and as steam is consumed by the engine. The seam also provides a focus for corrosion, which weakens the joint. Add to this the difficulty of inspecting seams inside a boiler and it's not a good combination! Unlike most other problems developed by ageing boilers, fatigue and corrosion are difficult to spot, making the eventual failure a surprise.

When longitudinal seams were unavoidable during construction of a big boiler, best practice reduced stress concentration by not overlapping the edges, and by placing the joint so it was easier to inspect. Later, continually extruded parts or carefully welded joints were preferred.

Seams running around a boiler drum are less subject to these problems and hoops are easier to make strong.

As off-the-shelf extruded pipe also makes it easier to build small boilers, it makes sense to use it.

Dave

 

Edited By SillyOldDuffer on 15/02/2019 15:13:44

Thread: New coffee maker - disgusting taste!
15/02/2019 14:28:00

No one's mentioned the great British love affair with Instant Coffee yet. What do the team think of instant coffee, especially decaffeinated or Camp...

Thread: Stepper Motor Controls
15/02/2019 11:55:14

Part Two:

Although intimidating at first sight, taken one at a time, the controller is rather simple to use. The DC Power Input and motor are connected here, in the red box:

stepmotorconns.jpg

This particular controller works with between 9 and 40V. Check your motor's specifications for it's upper limit but generally stepper motors will run 'better' fed a high voltage rather than a low one. But they work across a wide voltage range - it's the current that matters. For the same reason it's 'better' to use a crude unregulated DC power supply than a fancy regulated unit; regulated power supplies tend not to perform well driving pulsed loads. However, I didn't understand that when I built my rotary table and it works perfectly well with a cheap 12vdc regulated LED power supply.

If you whack a lot of volts into the motor there's a risk of of heating it due to exceeding its power limit (again see spec for the maximum current a particular motor will take.). To avoid damage the controller provides switches (marked SW1 to SW6) that can be set to limit the maximum current delivered to the motor. Given an unknown motor, you can start with the lowest setting and move up the range until the motor works properly, ie turns without losing steps.

 

stepcurrent.jpg

The number of micro-steps needed for the motor to do a full revolution motor is set in the same way. The ends of the switches can just be seen in the red box at top of photo. The number of micro-steps is a compromise that depends on the application. Generally it is set to the lowest number of steps needed to achieve the required step accuracy. No point in simply going for the maximum number of steps, because there is no such thing as a free lunch. At high micro-step settings the motor is more likely to lose steps under load and the rpm is lower.

stepsteps.jpg

Finally the control connections. These occur in pairs working in the opposite sense to suit the electronics used to control the controller.  By convention these can either signal 'ON' by putting 5V on a connection, or signal ON by grounding a connection that has 5V on it already.

ENA is enable. The controller won't power the motor unless this is ON.

DIR is direction. When ON, pulses are generated to turn the motor clockwise, when OFF the motor turns anticlockwise.

PUL is Pulse aka Step. Each pulse applied to this input moves the motor one micro-step.

ENA and DIR can both be set with ordinary on/off switches but PUL requires a stream of pulses. These could be generated with a simple chip like the NE555 and a speed pot.  More likely something sophisticated like an Arduino or PIC micro-controller would be used. They can be programmed with whatever the user wants to do. For example, an Arduino could calculate the number of pulses needed to rotate the motor by an angle input by the user, then enable the motor, set direction, issue the right number of step pulses, and then dis-enable the motor. By keeping count of pulses and direction changes the micro-controller always knows where the motor is. A more sophisticated controller could translate G-Code to drive several stepper motors on a CNC machine. Controllers can be bought ready made in various shades of complexity.

What could possibly go wrong is another question!

Dave

Edited By SillyOldDuffer on 15/02/2019 12:03:46

15/02/2019 11:54:24
Posted by ChrisH on 14/02/2019 19:44:40:

Electronics is one avenue I haven't been down for 40 + years, so stepper motors and their electronic control has passed me by. However, I now see a need to know some more about that latter subject as I can see an opportunity to employ a stepper motor drive.

I have been looking on the internet for information on stepper motor control but either what I have seen asks more questions than it answers or, more usually, the authors seem to be writing in another language!

So, can anybody suggest an idiots guide to stepper motor control, along the lines of "idiot to expert in no time at all", written in plain English to be readily understandable to someone without a degree in electronics and electronic control and a lifetime's experience in the subject. And I mean idiot!

All suggestions will be gratefully appreciated! Thank you.

Chris

 

Edited By ChrisH on 14/02/2019 19:46:22

Do you want to understand how they work, or just enough to use them? The former is difficult, the second a good deal easier. The same is true of most types of electric motor - not many on the forum could give you a detailed explanation of how AC motors actually work. Much more common is people who've learned enough to wire them up. I know this because I'm one of them.

A basic stepper motor has two windings. The motor isn't fed ordinary DC or ordinary AC. It works by applying particular sequences of DC pulses to both windings.

The motor doesn't turn smoothly, it steps. It can do one of three things per pulse-combination;

  • step one notch forward, or
  • one notch backwards, or
  • lock in the current position.

The number of pulses needed to make a single revolution vary, but 200 steps is common. However, another feature is that by manipulating the pulses fed to the motor, it is possible to move and hold the motor in small steps between the natural steps. A 200 step motor can be manipulated to take up to 6400 micro-steps per revolution.

The motors have good turning power and the spindle can be moved fairly accurately to any angular position. RPM is rather low compared with other motors.

It is not necessary for the user to understand the nature of the pulses, or how they are generated. This is done with a box full of rather complicated electronics like this:

 

 

stepunit.jpg

End of Part One

Dave

 

 

 

Edited By SillyOldDuffer on 15/02/2019 11:56:04

Thread: New coffee maker - disgusting taste!
14/02/2019 21:49:51
Posted by mark costello 1 on 14/02/2019 18:01:46:

At the risk of a public flogging, I have a question from across the pond. The only Tea I have experience with is Lipton, is that anything remotely like what You Chaps drinkg?

Although Lipton is a long established British brand I've never tried it! Not knowingly anyway. Teas here vary as much as coffees, with a huge range of flavours, strengths and qualities. Cheap tea is usually disappointing, and for the aficionado there are many different speciality teas, most of which I don't like at all.

Most tea drunk in the UK is made from blends similar to your Lipton's but people tend to have their particular favourite amongst the several main brands available. On top of that, some like it made weak, others demand full strength 'Ginger Tom', drink it with or without milk and, with or without sugar. At the moment I'm drinking Yorkshire Tea. Tea is sensitive to the type of water it's made from. Originally Yorkshire Tea was formulated to suit hard Yorkshire water, but now its sold in soft water areas as well. I'm not certain the Yorkshire Tea I buy in Somerset is identical to the Yorkshire Tea sold in Yorkshire! For the same reason, US Lipton may not be quite the same as UK Lipton.

Problems with tea made abroad include: water not hot enough and fresh (low chlorine, high oxygen), tea left to stew, and wrong type of milk. Fresh cow milk only, not goat, soy, powdered, or UHT! Also while cream in coffee is good, creamy tea is horrible.

Dave

14/02/2019 18:47:36
Posted by Samsaranda on 14/02/2019 16:50:10:

Clive, thanks for your response, always wondered how the bromide was administered, again I served 22 years and likewise never noticed any adverse effects. ...

Dave W

Um, I'm not convinced Bromide was ever put in the tea! I suppose it might have happened in the dim and distant past, but surely if it was common practice it would be well documented? My father-in-law served in the Army Catering Corps for 30 odd years and administering bromide didn't figure in any of his many stories. (Like him pissing in soup served to unpopular officers...)

More likely Bromide is an example of service humour. It winds-up new boys while suggesting old-soldiers are so virile they have to be sedated to protect passers-by. Actually the historically high number of military personnel treated for ignoble wounds inflicted by Venus suggests their manhood wasn't chemically compromised.

On the other hand, water-softener, table salt and water-purification tablets were certainly added to military tea water. Water has to be boiled for up to 10 minutes to kill bugs so it was and is common to chemically treat suspect water before feeding it to the men. Even so pretty much every foreign posting involved risk of picking up the unique local tummy upset. They had names like Dehli-belly and Malta-dog. Anyone remember any others?

Dave

Thread: Boxford machinery auction
14/02/2019 17:15:27
Posted by Tony Pratt 1 on 14/02/2019 15:40:58:
Posted by Andrew Evans on 14/02/2019 13:45:34:

Moving manufacturing abroad makes sense with Brexit. If car makers are planning to do it after investing billions on UK production lines then moving manufacturing of something relatively simple probably makes even more sense.

Shame for any workers losing jobs.

Oh for gods sake give it a rest, manufacturers have been moving abroad for years!!!!

Tony

True, but we now have Nissan, Toyota, Ford and Jaguar Land Rover all saying they are backing off in the UK directly because of the impact Brexit is having on their business. The problem is that the European Union is by far the biggest market for UK car exports - 57%. Without some other counter-balancing advantage why would a car maker take on higher tariffs and more uncertainty when both can be avoided simply by moving a factory?

The leave side won the Referendum. The time for rhetoric and emotion is long over. Now it's all about delivery. At this stage it is unwise to deny there are real problems and risks. When manufacturers and services start voting with their feet, jobs will be lost unless some advantage is offered to keep them here.

No politics please, what's needed now are clear objectives, honest analysis of issues, practical solutions, and good management.

Dave

Thread: New to metal lathes - bore sizes?
14/02/2019 16:19:19

Bigger ones!

To get an idea of the relationship between size and bore in Far Eastern lathes have a look at Warco's website. If you click on a lathe's photo it will take you to its specification including the spindle bore. (Scroll down to the table at bottom of each lathe's blurb.)

I think the first Warco machine to meet your criteria is the WM290. At 230kg it's the largest of the 'Variable Speed Lathes'. After that, look at the Gear Head machines which go up to 80mm but weigh about 2500kg.

Dave

Thread: Holding in headstock
14/02/2019 16:02:20

Worth mentioning the possibility that long items held through a lathe's spindle are liable to whip unless constrained. . Damage to both job and operator is likely because the amount of energy pumped into a whip is dangerously high. I use a Black & Decker workmate to clamp a length of 2 by 4" with a hole in it at the right height and then pass the work through the hole. A long flexible item may have to be supported in more than one place, for example by passing it through a length of plastic pipe.

Jeff's method avoids the risk of whipping and if necessary you can remove the tail-stock to make more space on the left.

Dave

Edited By SillyOldDuffer on 14/02/2019 16:03:35

Thread: New coffee maker - disgusting taste!
14/02/2019 10:26:31
Posted by David Standing 1 on 14/02/2019 09:18:38:
Posted by Neil Wyatt on 13/02/2019 22:42:14:
Here's a Teasmade on Amazon UK, genuine Swan and a lot cheaper then 300E - buy it before the channel becomes and impassable barrier!

Neil

Isn't that straying into politics? wink

Maybe, maybe not. Almost everything is tinged by 'politics'. Why people think Brexit is a good idea or not is clearly politics. But, the legal, financial, investment and commercial consequences of leaving are factual, and therefore not political in themselves.

I didn't see Neil's point as political. The truth is lack of progress on trade deals makes it likely there will be a period of adjustment until normal service is resumed. At the moment no-one knows how long that might last, which is awkward for businesses involved in import or export. Forum members thinking of buying from abroad during the period of adjustment should surely be allowed to know the purchase will be riskier than it is at the moment, or will be after the dust has settled.

Dave

Thread: Overload trip
13/02/2019 22:05:01

Posted by Stephen Spice on 13/02/2019 19:39:08:

...

My photo's will show ...

Stephen S.

Nice clock! I particularly enjoyed this touch:

Must be a grasshopper escapement...

smiley

Dave

Thread: New coffee maker - disgusting taste!
13/02/2019 20:53:58
Posted by Russell Eberhardt on 13/02/2019 19:49:51:

It's not anything to do with the temperature of the water. If I pass water through the machine with no tea or coffee in it and let it cool enough to taste I get a very strong acrid taste in the water. I suspect it is a plasticiser leaching out.

...

You're probably right but could something temporary in the water be coincidentally making it worse, like chlorine or rust due to local repairs?

Dave

Thread: Buying lathes direct from China
13/02/2019 20:20:16
Posted by Neil Wyatt on 13/02/2019 19:36:53:

Posted by SillyOldDuffer on 13/02/2019 18:56:43:

For example, if the lathe were shipped direct from China to the UK, then I wouldn't expect any delay or tariff snags.

Not many people appreciate that Brexit may mean trade deals with third parties like China fail because those are actually deals between China and the EU not China and the UK...

N.

Yes that's true, I didn't mean all was well between the UK and China whatever happens next! What I meant was an order placed directly between the UK & China before March 29th would complete normally provided the shipment didn't go via Europe. To deal with that situation, the UK and EU have to agree a new arrangement.

The situation if you want to buy from China after March 29th, isn't clear either. The UK has no trade deal with China, so -at best - rather complicated WTO rules would apply until something else is sorted out.

Complicated and uncertain, which is why I suggested waiting before buying anything significant direct from China (or anywhere else!) In comparison buying from a UK supplier is much less risky.

Dave

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