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: CNC Knurling|
Not that it matters for small files, but Dave's example is slow because the file is opened and closed for each append. As open and close are expensive operations involving the operating system in permission checks and resource management, it's usual to open files once at the beginning and close them only at the end.
My example writes 30 'hello' lines to a file once per second. It uses print() rather than write(), which I pedantically reserve for binary output. Omitting file=myFile, or setting file=sys.stdout, writes to the screen, which is useful whilst debugging.
|Thread: Multimeter recommendations|
Rather than theorise about 'quality' here's photos of the insides of an AVO8 (Model B) and an inexpensive Maplin Digital.
The AVO movement and electronics are mounted on a thick plastic front panel backed by a heavy steel box, not waterproof. The electronics are hand assembled from separate components of basic type: wire-round resistors, bent springs, open switches, the whole being much exposed. The construction style is a century plus old, and was pretty sensible because the unreliable components of the day often needed repair. (My meter has a few old repairs.) This type of construction is semi-skilled, labour intensive, and extremely expensive: much of the customers money went on wages, not 'quality'. In 1953, an AVO 8 plus leather carry case cost the equivalent of about £700: only an exceptionally wealthy amateur could afford a new one.
The Maplin meter was built using modern mass-production techniques. Few humans involved: most likely the SMD components were automatically placed on the board by a machine and wave-soldered in the blink of an eye.
The meter's brains are in the Integrated Circuit far right in the photo. The electronics are far more complex than those in the AVO, and also far cheaper. Once designed and debugged the IC can be sold in volume for less than a pound. The other components are also mass produced far more cheaply that their 1950's equivalents. The AVO has a seriously pricey high-end D'Arsonval movement; the modern meter has a Liquid Crystal Display costing a few pence.
Not much difference between brands or models when inexpensive meters are mass produced in this way; the old-fashioned notion of quality that applied to my 1950's AVO don't apply to this class of consumer electronics. It's quite hard to make duds provided the meter isn't too cheap. But beware buying manufacturer rejects, customer returns, and damaged goods from unknown purveyors on the web.
Chasing 'quality' is likely to waste the amateur's money on a grand scale! Going up-market takes one into paying serious money for ruggedisation, high accuracy, and safety features designed to save professional electricians from mistakes made on live switchgear.
If you're the type who enjoys owning feel-good tools, by all means buy an AVO or one of its modern equivalents. Just don't pretend it's a rational procurement decision. (I fancy owning a red MG even though it's daft)
If carrying the meter in a pocket is important, don't buy an AVO! If AC current is wanted, don't buy the Maplin. If safety is important, don't buy either!!!
Good point, which is why I own digital AND analogue meters. I recommend buying one of each!
Digital meters are hard to misread but need time to settle, so best for measuring steady volts and amps accurately. For a bit more money the meter can do frequency, capacitance, and inductance, plus reasonably useful transistor testing.
Analogue meters are easy to misread, but are good for many common situations where a quick check is good enough: continuity ; does a power rail have roughly the right volts on it, etc. They're especially useful for detecting changes like capacitors discharging, batteries and power rails fading under load or motor boating. My analogue meters also detect RF oscillation by going full scale on all ranges by detecting on the movements protective diodes.
I own a genuine AVO, same age as me but the meter is still in good working order. Don't use it much because it's heavy and inconveniently beefy. Mainly valued for it's 10A AC range. It's unusual 27V battery is a mild pain to source.
The analogue that gets most use is an inexpensive rather than cheap 20000 ohms per volt Japanese plastic hobby meter. Fully portable, and - unlike the AVO - can be propped up to ease reading the scale. 30 years old, takes ordinary batteries and accurate better than 3% on all ranges last time I checked.
Otherwise, I have a couple of Maplin digitals. The second was bought because I lost a lead and it was cheaper to buy a new meter than a set of new leads.
My Use Case is electronics, originally valves up to 1kV, but transistors and 240Vac mains only since 1995. These days, lots of 3.3V and 5V microcontroller stuff, all low risk. I would buy a safer meter if I did more than occasional mains work, and the kit I have is definitely unfit for 440V mains. Flimsy leads are the most obvious problem - they bring the operator too close to death - but the meters aren't built to resist internal arcing if the operator makes a mistake.
I suggest amateurs should never work on the sort of electrics needing a safe meter. The meter won't save an untrained bodger from the consequences of his ignorance. The meter is only part of the safety regime: important to know what you're doing, and to take all the other appropriate precautions, including PPE. The Fluke Website is worth reading, this section deals with hand-held meters. The information is relevant to professional electricians and over the top for me and my Arduino!
If safety is a requirement, buying second-hand online or from a mate probably isn't an option. Although my venerable AVO, is in good condition, I doubt it meets modern safety standards. The same doubt applies to all second-hand kit: brand names do not protect equipment from age, wear and tear, abuse, iffy repairs, or changes in best-practice. Second-hand equipment has to be tested: safety, calibration and functionality cannot be taken on trust.
There's much to be said for buying a modern Digital Storage Oscilloscope rather than a multimeter if electronics is the main requirement.
Oh no, John has unleashed my hobby horse! I submit the word 'quality' has no place in engineering.
Engineers should start by identifying requirements and then select equipment to meet the requirement. The criteria are Fitness for Purpose and Value for Money, not 'quality'.
Spending money without justification is an engineering sin. You have to engage brain to define exactly what's meant by fit for purpose; for a one off, the answer might be the cheapest available. The very best might be essential in a professional setting.
Lasting a lifetime, whatever that means, is rarely a engineering requirement in the way Capacity, Frequency or Induction ranges might be. Does one really want to pay for expensive calibration, multiple channels and high accuracy?
For ordinary workshop purposes a cheap multimeter is more than good enough, and easily replaced if the worst happens. And the money saved could be spent on something useful like an oscilloscope.
Sky's the limit If quality is the only requirement. A £3636 Keithly isn't bad but you can spend more!
Spending money on 'quality'
|Thread: Win 10 back t0 Win 7|
Worth investigating as Bill suggests before going to the painful bother of reverting to Windows 7. As Windows 10 is supposed to handle pictures OK, and most owners are happy it does, I suspect Clive's problem is a mismatch of some sort between his older camera and it's Windows 10 driver.
What's the make and model of the camera? We can check if the manufacturer has updated W10 drivers for it. Also, it sounds as if the photo manager is different, and needs changing. Possibly the camera's memory needs to be reformatted. Fingers crossed, it's an easy fix.
|Thread: RAF to give up flying planes.|
Simulators have been around since WW1; I've got a photo somewhere of a sort of swivel mounted wicker bathtub fitted with a Lewis Gun. A couple of burly blokes bounced Trainees around in the basket as if they were defending a plane. Learning to hit moving targets this way was safer and cheaper than experimenting on Baron von Richthofen.
I suspect it's been technically possible to wholly train pilots on simulators for at least 20 years. They have many advantages such as being able to train pilots to manage fault conditions far too dangerous to try for real, like glide landing an airliner after all the engines have failed.
Ten years ago all the advanced air forces were actively investigating not having pilots at all. What essential function does he perform? In a weapon system the delicate pilot is rather a liability because he can't stand the G-Forces, and requires life support. The man is a problem. To improve manoeuvrability a modern fast jet is aerodynamically unstable to the extent that an unaided human can't keep in the air. Instead the pilot 'flies' a computer system that micromanages the aircraft's control surfaces as necessary to stop it crashing. The pilot is only needed to take command decisions, and with good communications, the pilot might as well be in Wiltshire.
And captured pilots can be the major embarrassment when a military mission goes wrong. In the U2 incident, the Russians didn't reveal Colonel Powers was alive and well until President Eisenhower had committed to denying any and all US involvement, a lie. Only then the soviets put the pilot on TV! (The Soviets were a bunch of hypocrites: Col. Powers was exchanged for Rudolf Abel, a GPU spy caught operating in Brooklyn by the FBI .) Strangely, having a human being invade someone else's airspace is far more politically charged than doing the same job with a drone or satellites.
The need for high performance aircraft waned somewhat with the end of the Soviet cold-war. China appears to be developing an aggressive military stance that may trigger another confrontation, in which case I expect many of the next generation of aircraft will be pilotless. The trend is already evident in the decline of the Flight Engineer: modern aircraft have automated out much of the need to employ one.
|Thread: Threading myth .... busted!|
Horses for courses is my take too, though maybe a bit of a myth has developed due to conservative Model Engineers ignoring tool improvements since the angled method was first developed in the 19th century. We have better horses now!
The angle method dates back to treadle lathes and plain carbon steel cutters. These need all the help they can get, giving angled threading a strong advantage.
Time marches on. The value of angled cutting became questionable after lathes beefed up to drive HSS cutters. HSS revolutionised metal turning because the alloy's improved heat-hardness can remove metal 5 or 6 times faster than a Carbon Steel cutter. After about 1900 lathes became much more rigid to handle the extra strain. However, many small workshops were - and still are - equipped with relatively light machines, ½HP being typical fdr many years. And even with HSS and a hefty lathe, there are times when angled threading is worth it.
Time marched on again. Carbide can remove metal 10 to 20 times faster than HSS, and - provided the machine has sufficient power and rigidity and the work can take the strain - cutting threads straight-in is fast and efficient. VFDs have made it possible for hobbyists to own seriously chunky ex-industrial 3-phase machines so many have the wherewithal for brutal cutting.
I don't think the border between angled and straight threading is clear cut; it depends on what you have My 800W mini-lathe could thread straight-in with a carbide insert but I felt more comfortable using the angled method. Mini-lathes aren't tough guys. Since upgrading to a WM280, about 3 times bigger than a mini-lathe, I almost always thread straight-in with carbide inserts because the bigger machine handles it well. But I still angle cut occasionally - mostly slender work, exactly as Martin says.
Horses for courses.
Edited By SillyOldDuffer on 05/09/2021 12:25:55
|Thread: Machine Lamp Recommendation?|
Not 'best practice' though, and leaving the key in an innocent chuck might turn into a bad habit. Although a key left in a rotary table chuck won't become a missile, they can jamb the table which might damage the gears if a slow-witted operator forces it.
The case for the defence! Nothing is as it seems. At present my workshop is unusable due to being full of empty boxes pending daughter leaving home*. Not possible to turn the mill on and it's being used as a shelf. Stuff had to be moved to take the photo.
Good news. My lathe's chuck key is almost idiot proof. It has bright red handles and an ejector spring ...
* Don't get me started on solicitors. Is it just me or are they all slow, expensive and error prone, happily performing entirely to their own satisfaction...
My experience for what it's worth! I experimented with two types and decided neither did what I wanted. More on that at the end!
To my lathe, I fitted a magnetic sewing machine light, like this one but cheaper.
Prices range from about £5 to £40. They come with either a plastic clamp or magnet base, making them easy to fit to most machines, moveable, and they produce a reasonable white light. The swan neck isn't long enough, and, more important the electrics may not be fit for purpose. (The more expensive versions might be: my cheap lamp was cause for concern.) Problem is sewing machine lamps aren't designed for rough workshops, exposed to knocks and fluids, where the user is dangerously well earthed by big metal machines and concrete floors. The circuit that powers the LEDs is safe enough on a sewing machine in a dry internal room, but risky as a machine lamp. The same concern applies to other domestic lamps; are they electrically safe in a workshop?
My mill is fitted with a proper machine light, electrically safe and mechanically robust. It contains a 12V power supply driving a quartz halogen car headlamp bulb. Fixed to the machine with four bolts, so attaching it may be problematic, particularly as gantry movement limits where the base can go. From memory, about £60.
Neither lamp is satisfactory in my workshop. They both create unhelpful deep shadows and bright reflections. So I upgraded my workshop's general lighting instead. Squeezed into a single garage, after painting the ceiling white, I fitted three pairs of diffused 60W fluorescent tubes - 360W daylight total. The lamps are positioned to brightly light everything underneath evenly: no shadows and reduced reflections.
So although occasionally useful on the mill, I don't need a machine light. Not perfect, as soon as the fluorescents pop their clogs I shall upgrade to LED - the light is better. The change was so successful I wondered if machine lamps are bygone hangovers from when factories were relatively dimly lit - 100W tungsten bulbs are about 2.5% efficient, compared with a strip lamp's 20%. My garage is brightly lit!
|Thread: Parting off help!|
What I like about the forum is it's willingness to answer questions - enormously valuable when I was a raw beginner, less now I'm no longer a virgo, but I'm still learning new tricks.
The forum isn't an organised reference source like Wikipedia, and it doesn't have a first class search either. It has a Question and Answer format, which can be repetitive. Inevitably the same subjects come up again and again. I don't mind - helping people get started by answering their questions keeps the hobby alive! Newbies arrive on the forum, are educated, and move on to greater things.
Sad state of affairs if a primary school teacher like William told new classes to use their common sense just because he was fed up teaching the same material year after year! William may get bored repeating himself, but his job benefits different children every time. Although a river looks much same day by day as it rolls to the sea, the water is different: just like life.
By the by I strongly suggest there's no such thing as common sense. Everything has to be learned...
|Thread: 5” Rotary Table/Tailstock/Chuck Kit Info/Questions|
My advice is not to get wrapped round the axle worrying about the quality of hobby tools. If the best possible rotary is really needed (and I suggest it's not), then buy an industrial model. It will cost a few thousand pounds, and although it will be somewhat more robust, don't expect it to be bullet proof. Many a well-made rotary table has been wrecked hacking out big wheels for model traction engines!
Most hobby rotary tables are of the HV6 design. A worm drives a cogged wheel and turns the table on a simple plain bearing. Though obviously made down to a price, they're reasonably accurate and sufficiently sturdy for most amateur purposes. They're aren't high-technology, nowhere near as difficult to make as a computer hard disc.
The buying strategy for this class of affordable tool is quite different from the good old days. Until about 1960, tools were so expensive it paid to get the best one could afford in hope it would last a lifetime. Not a good idea to buy cheap back then, because there was a sharp divide between well-made and cheap and nasty. There were brand names that could be relied on, so what grandad said about them was worth listening too. This world has pretty much gone.
Today the world is flooded with mid-range tools, affordable rather than excellent. Not intended to last forever, they are nonetheless generally acceptable for the light duty found in typical hobby workshops. Many products come from similar anonymous factories, and are rebranded by a local seller. But be aware that some versions are too cheap, or customer returns, or manufacturer rejects. The customer probably has no idea who made the item, or even which country or countries it came from. And for this class of kit, it rarely matters. The customer isn't looking for 'quality', he's after 'value for money' and 'fit for purpose'.
So, rather than spend ages looking for a magical brand-name, I suggest a more appropriate procurement strategy is to:
'It won't last' scream the old-school! True, nothing does. The point is, at the moment, hobby-market Rotary Tables and the like don't have to.
Main exception to value for money purchasing is bragging rights: you can't boast about Far Eastern hobby equipment! Don't care myself because tools only have to do what I want of them, and that doesn't include impressing the neighbours!
|Thread: Scribing with verniers|
Asking 'does it harm them' implies a simple black and white answer, when it might damage them. The question is better put in risk management terms:
Given tool A, costing £B, is it worth the risk of damaging it by action C? The correct answer depends on your particular circumstances: what is the risk; how likely is it to happen; how severe are the consequences; and how happy are you to pay for any consequences?
As the answer varies, it pays to think about internet advice on the subject. No particular reason why Jeff Bezos shouldn't use certificated digital calipers to open cans of paint but in my experience Model Engineers are notoriously careful with their money!!! For that reason, although I'm content to pay the price of damaging my Lidl caliper by using it as a scribe, I choose not to risk my Absolute zero Dasqua.
Photo is of my inexpensive scribe, a tool specifically made for scratching lines in steel.
No doubt here, but even a scribe isn't expected to last forever. And unlike a Mitutoyo this one came with a spare carbide tip...
More dubious advice. As Digital Calipers are made of stainless steel, I confirm its OK to stir Sulphuric Acid pickle with them. Not having to find a plastic spoon will save loads of time, but who wants to take the risk...
Edited By SillyOldDuffer on 01/09/2021 15:46:55
|Thread: Overheated Drill|
Letting the tool do the work is perhaps the single most important workshop lesson I had to learn. Not as easy as it seems: hard pressed power tools mince their own swarf, go blunt, wear their brushes and burn out their motors. More haste, less speed! But slowing down too much is just as bad: when a cutting edge rubs it soon goes blunt, causing more havoc. Surprisingly easy to blunt tools by rubbing.
The material makes a big difference too. The sweet-spot between not too fast and not too slow is quite narrow on work-hardening metals. RPM, cutting pressure and edge condition are critical on some types of stainless steel: far more awkward to cut these than leaded mild-steel.
I had to learn to position my technique between namby-pamby wimp and bad-tempered gorilla. By nature I tend to over subtle, but turn quickly into the Incredible Hulk when frustrated. Neither extreme does good work...
I suspect many workshop skills depend on learning the sweet spot and then staying in it consistently. Any other examples come to mind?
Edited By SillyOldDuffer on 01/09/2021 11:38:41
|Thread: Scribing with verniers|
There's a hint of bad fish whenever an expensive tool is misused without good reason! Adapting and overworking tools is OK after engaging brain for deliberate benefit, but spoiling tools due to laziness, ignorance or bad internet opinion is surely to be avoided.
Presumably people cough up serious money for Mitutoyo verniers because they need the tool's extra features. To me, it's odd to spend big dosh and then risk damaging an expensive tool when a decent digital vernier suitable for scribing and other rough work can be had for under a tenner. Unlike a Mitotoyo, inexpensive verniers are disposable - replace when damaged. It's what I do.
I mark out much less often than I used to. Getting more confident in myself, the DRO and the dials seems to have reduced the need for sanity check marking, though I still do it when accuracy is critical. I mostly use a scribe and spring calipers plus a cheapo vernier for marking out. I don't expect the same vernier to measure accurately and scratch steel.
|Thread: Looking for a compact and safe mains lead connector|
I like the IEC 'Kettle' connectors as used on computers. They normally plug into a bulkhead socket but flying males are easily had, this example is wired up as an adaptor:
I don't care for anything more delicate on 240v mains wiring but could be prejudice!
|Thread: Purpose of screw on keyway|
Just a thought, but the wedge and screw imply to me that the joint is meant to come apart without too much bother for adjustment or maintenance. For that reason not many engine parts are permanently fixed. Although blown head gaskets could be avoided by welding the head to the cylinder block, makes it very difficult to replace piston rings, or regrind valve seats etc. Engines are designed with maintenance in mind, though judging by what's under the bonnet of my car, home maintenance comes bottom of the list.
I suggest although the coarse wedge is tapped in tight, the joint can be broken if need be. It's like a Jacobs Chuck taper; semi-removable. The screw protects the wedge from coming loose due to single-cylinder vibration, which has a powerful loosening effect on joints.
On a lightly loaded model engine fired up occasionally for amusement rather than hard work, the precaution is probably unnecessary but I'd put thread-locker on the screw if the engine was going to be run for more than a few hours. Scale matters: many design features make more sense on a full size engine than they do on a model, and vice versa!
|Thread: Help with choosing thread cutting inserts|
I'm self-taught, which means book learning supplemented by experiment corrected by much help from forum. Great fun, but self learning leaves a multitude of gaps!
Is there a good reason for threading up to a shoulder?
My reading suggests, and what I've always done, is to start by turning down the blank (hex or round stock), to thread diameter and then cutting a slot as deep as the thread at the shoulder with a parting tool. This creates start or finish space for the threading tool and much reduces the chance of a collision.
I don't believe the slot makes any difference to bolt strength, so why not always make one?
On the subject of collisions, I always thread away from the chuck in reverse like Jason. Possibly I learned the trick from him! However, reverse threading isn't a good idea if you're unfortunate enough to own a lathe with a screw-on chuck...
|Thread: Protractors scaled in Radians|
Horses for courses:
|Thread: small white spots|
I'm using Firefox on Ubuntu 18.04, and 21.04 without white spots.
Before reinstalling the whole of Ubuntu I'd remove and reinstall Firefox: could be Firefox is corrupt.
Hold down Ctrl, Alt and hit 'T' to get a terminal.
In the terminal, at the $ prompt, type:
sudo apt-get remove firefox
Hit return, enter password, and a stream of removal messages should be displayed. When finished, type:
sudo apt-get update
This makes sure your computer is synchronised with Ubuntu's internet software repositories. Then, type:
sudo apt-get install firefox
Although rebooting isn't necessary, it does clear everything out, so worth doing whenever corruption is suspected. Cross fingers. restart the system. then and test the Green Banners.
Postscript: there is a more nuclear version of the remove command. remove doesn't delete user configuration settings, cookies etc. If you don't care about them, replace:
sudo apt-get remove firefox
sudo apt-get purge firefox
|Thread: Mill vise and rotary table|
Like Andrew I find having both on the table wastes so much space, it's rarely worth doing. The Rotary table is usually the wrong way round too; horizontal when I want vertical and vice versa.
So, unless I've planned a work-sequence specifically to use both, which is unusual, the rotary table is normally kept in it's box. As always much depends on what you do in your workshop. I suppose 75% of my milling is done in a vice, 10% rotary table, and the rest on a angle plate or clamped direct to the table.
Apart from keeping the ways clean and gently oiled, I don't worry about wear except when grinding or machining cast-iron. The machine only has to last longer than I do!
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