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Member postings for Andy Stopford

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

Thread: Back issues & Flash plugin
20/12/2020 20:42:54

For anyone who can't view the older mags in the Linux version of Vivaldi, you need to L-Click the padlock icon in the address bar, choose Allow Flash and reload the page. You may have to do this each time you logout/in.

You may need to have Pepper Flash installed; a script to automate this can be found here:

https://gist.github.com/ruario/215c365facfe8d3c5071

This may work for other Chromium-based browsers.

Thread: How to restore artists' brush bristles
14/12/2020 20:08:50

I agree with the above, always clean brushes thoroughly, and don't expect them to last forever (though you can of course demote them to less exacting duties). For both artistic and other purposes, the synthetic ones are excellent now, and cheaper than sable or whatever.

I'm just posting really, to add that acrylic usually succumbs to meths -you could probably also use IPA (no, not the beer, you drink that whilst the brush is soaking).

Thread: Speed limiters for cars from 2022?
11/12/2020 20:50:12

What's the problem with speed limiters?

Society has decided, for excellent reasons, to legally restrict the speed at which we are allowed to drive. Many people break these laws, most get away with it, some get caught, some have crashes, some injure or kill others.

Excessive speed also wastes fuel, increases pollution, etc.

Why do otherwise law-abiding people want to have the option to indulge in this particular lawlessness? I note someone made a comment about 'Honest citizens' vs 'Pikeys, new age travellers' . Hmm - not too sure what the difference is (New Age Travellers? This isn't 1985 you know).

'So, Andy' you might say 'you've never broken the speed limit then?'

Of course I have, but I've also driven many thousands of miles in speed-limiter equipped HGVs, and I can't say I ever felt that my God-given Right To Speed was being infringed (even though variations in power output, load and gearing make the speed limiter a lot more tiresome than one on a car would be).

Though I must admit, when the company mechanic in a futile attempt to cure an engine problem, disabled the speed limiter on the 17 tonner, it was great late at night on the way home from a Removal Horrorshow to open it up to a meteoric 75 mph.

Thread: Brazing copper
02/12/2020 19:47:17

I've brazed copper using the standard brass rods (I don't know the precise formulation - it was a long time ago), and borax as flux.

It was easy, no problem getting enough heat.

One job involved fixing a wood-fired water heater that someone had tried to repair with a stick welder and steel filler rods(?!). I had no problem building up a nice thick fillet to bury the resulting lacework.

You'd have to check with those who know about suitability for any sort of pressure vessel, though the flanged joints on the boiler of my espresso machine (a La Pavoni P67, for those who are interested) appear to be brazed. That only runs at about 1 bar though.

Thread: Another engineering masterclass
23/11/2020 16:53:49

The piston/turbine compound was the Nomad, the Dagger and Sabre were the H24s.

Some great info on these and many others here:

https://oldmachinepress.com

Thread: Arduino programming?
22/11/2020 21:15:35

For a general introduction to C++, This is pretty good:

https://www.learncpp.com/

Note though that the Arduino uses a special sub-set of C++, and some things are missing, like the ability to find out the type of a variable, which is a pity because this can be a very confusing aspect of microcontroller programming.

Thread: Display for Arduino
20/11/2020 20:18:27

You need the 7-segment display with i2c backpack - that way there are only two data lines to connect up. They are readily available from ebay and look really good. Unfortunately I've only used one with a Raspberry Pi zero, so I can't give you the C code to make one work (I used Python for the Pi, and the libraries are different anyway).

Hopefully the following link to Adafruit's information and instructions won't fall foul of the forum rules:

https://learn.adafruit.com/adafruit-led-backpack/

edit: Sorry, the ebay ones are SPI rather than i2c; they should be similar to get working, but for simplicity, it might be best to use the Adafruit ones - if you're in the UK, Pimoroni sell them - they cost a bit more than the ebay ones, unfortunately. 

Edited By Andy Stopford on 20/11/2020 20:27:24

Thread: The Raspberry Pi gets domesticated
02/11/2020 15:23:59

For an 'in-between' option, the RPi Zero W is worth a look; lower power requirement than the other RPi versions, but you can still have a desktop GUI if you want (I run mine 'headless' and connect to it over the WiFi with VNC Viewer, or SSH if I don't need the desktop), and you can run Python programs on it which, for me, saves time v. C++ for an ATMEGA/Arduino/ESP8266, etc., though the ESP is another strong contender for a monitor/controller.

Thread: Why is this guys mini lathe parting off so well?
22/10/2020 21:43:40
[The main issue with my compound slide was that the gib strip was rocking as load came on the toolpost, allowing the slide to lift. The problem (in my case, and I suspect many others) was that the gib adjustment screws were acting too far back from the sliding face of the gib for it to be stable (the gib is too thick for its height). This was compounded by the shape of the adjusting screw tips and recesses in the gib.]

You can also check this by trying to lift the topslide from underneath the dial end - you may find an alarming amount of play.

On my mini-lathe this was due to the cross slide gib being completely the wrong shape in cross section, and not deep enough to fill the space in which it was supposed to work. I made a new one from brass - quite fiddly due to the difficulty of actually gripping the thing - if you're a beginner, you might want to leave doing this for a while.

To be getting on with, if your gib strip is like this I reckon you could probably make it work a lot better by shimming it against the underside of the cross slide - an old beer can is a useful source of aluminium shims. Try to fill the gap at the top as much as possible short of making it jam.

Thread: Big Bang : Tallboy bomb
14/10/2020 21:38:44

The reason the Lancaster was considered as a vehicle for the atomic bomb was that it was originally thought that a plutonium-fuelled bomb could use a similar gun-type mechanism to that used for the uranium-fuelled Little Boy design (used for the Hiroshima bomb).

Plutonium 239, being more prone to spontaneous fission than Uranium 235, required a higher velocity for the projectile in a gun-type weapon, so that the two sub-critical masses formed by projectile and target would come together and attain super-criticality before they had time to start a pre-detonation 'fizzle'. This was attained by lengthening the barrel. The resulting weapon (called Thin Man) could, at the time, only be accommodated in the Lancaster's lengthy bomb bay. Contemporary American aircraft, like the B-17 had a pair of shorter bays, though the up-coming B-29 could be modified to carry it.

Further research revealed that manufacturing impurities in the Pu-239 made it even more prone to pre-detonation than had been supposed and the Thin Man would have to be impossibly long to work. Efforts were therefore concentrated on the more complicated, but more efficient, and safer*, Fat Man implosion bomb.

More here: https://en.wikipedia.org/wiki/Thin_Man_(nuclear_bomb)

*The idea of a safe nuclear weapon seems a little strange, but the gun-type design could be accidentally detonated from a single failure point. Getting the implosion bomb to work at all was sufficiently difficult that it had a degree of intrinsic safety to work with.

Thread: The Apollo Guidance Computer by Frank O'Brien
10/10/2020 21:59:51

I can't help you about the book, I'm afraid, but there's a load of videos here about restoring the AGC:

https://www.youtube.com/watch?v=2KSahAoOLdU&list=PL-_93BVApb59FWrLZfdlisi_x7-Ut_-w7

And a lecture about it here:

https://www.youtube.com/watch?v=B1J2RMorJXM

Thread: Threading trouble
04/10/2020 13:13:38

+1 for zero-to-zero, not quite as foolproof as a swing-up toolholder (I imagine, I've never used one), but close, and the angled feed helps on difficult materials.

Hand Cranking

I made a hand spindle crank for my mini-lathe because I had a some internal 1/2" NP threads to make in stainless steel a while back, and it seemed like a good idea. I have to say, it did not work well.

To avoid work-hardening the steel required a reasonably deep cut, but I found as the thread deepened, there was a tendency for the tool to dig in. Nothing immediately terrible happened of course, but I was then left with a burr in the thread which was extremely difficult/impossible to get rid of before threading could recommence.

After a while I gave up and completed the rest of the job under power with no problems. I guess that with such a small lathe, there is insufficient inertia to overcome a slight dig-in when turning slowly by hand. A more aggressive approach might help, but then I'd probably be concentrating so much on cranking, that the tool would collide with the end of the bored hole.

Thread: Home workshop accuracy & tolerance?
23/09/2020 21:34:04

Industry cheats there too. The chinese optics manufacturers effectively beat the rest of the world by high volume output and then measuring and grading what came off the line according to quality with the best lenses and mirrors commanding the highest prices.

The same sort of thing is done in the production of computer processors: many blanks are sawn from a large disc of silicon, the ones from near the edge* can be run reliably at a higher clock speed, and are sold as the top-level, high performance, premium price model.

You can 'over-clock' the cheaper version, it is after all the same thing as the posh ones, but it may cause errors (which will usually result in the system freeze- or exiting).

*Or the centre, I forget which.

Thread: How to move a Colchester Student ?
04/09/2020 21:11:17
Posted by Durhambuilder on 04/09/2020 20:11:56:

And definitely an example of how not to do it

https://youtu.be/dHpCJKXB0YI

Well, you've got to admire their, er, bravura...

He's right about using rollers though; on a flat surface it's surprisingly easy, if foolhardy to attempt single-handed.

04/09/2020 20:57:21

I moved my Harrison L5 several times (including to Portugal and back) dismantling it each time. Yes, it's a nuisance, but if you take the opportunity to give all the nooks and crannies a thorough clean it sweetens the pill, and it is much easier (and safer) to handle in this state. If the access is awkward it may be little slower than doing the rollers thing. You can have a beer whilst cleaning it of course - try to avoid taking a gulp from the paraffin can though.

One thing to take care with - if it's like the Harrison, the headstock is rather oddly balanced.Have two people lifting it with a bar through the spindle, and, ideally a third to help balance it as you lift.

Thread: Elliot 10m shaper weight
13/08/2020 19:13:16

Very useful machines; I used to have an Eliott 10M. I only got rid of it because I was moving back to England from Portugal, and I had nowhere to keep it.

I sold it to a local mechanic. Most Portuguese are short, but this guy was a giant. I'm 6' 3" and he towered over me.

I went to start my lorry so we could use the crane to lift the shaper onto his trailer.

"Não precisa" (No need) he said, picked it up in a sort of bear hug, carried it over to the trailer and plonked it on. Cranes are for wimps.

Edited By Andy Stopford on 13/08/2020 19:13:54 to remove errant smiley

Edited By Andy Stopford on 13/08/2020 19:23:20

Thread: Rotary Table Choice 36:1 o 90:1
11/08/2020 21:09:31

I've got the 90:1 - bearing in mind the low power and lack of rigidity of the SX1L (not a criticism - its great for what it is), the slower feed rate is probably desirable if you're using it to radius corners and the like - you do have to baby it a bit for that sort of thing.

With regard to the worm mechanism - it's pretty robust, you don't need to worry about that at all with a mill of this size.

As far as I can tell, you're on your own if you want to have a division plate set-up. I was part way through designing such a thing for mine when the need for a 63 tooth changewheel became urgent, so I went for the cheap and cheerful approach of printing a strip of paper with the appropriate divisions marked on it, and taping it round the circumference of the table. Eyeballing alignment with the index mark on the table worked fine - it may not be super precision, but my Imperial threads screw into existing fittings without a problem (and the 63-tooth method isn't perfect anyway).

The only slight irritation with this method is that the strip is 319.9 mm long for my table, so you have to print it at 33 degrees to fit it on a sheet of A4 - it would have been nice to have printed a whole lot of them on one sheet for different tooth numbers.

Thread: Arduino low power alternatives
09/08/2020 20:24:51

@SOD

Atom/PlatformIO seems to work now if upgraded to version 1.49.0. Mine wasn't set up to automatically update and was still on V 1.39. I used the method shown on this page:

https://flight-manual.atom.io/getting-started/sections/installing-atom/

And followed the instructions to add the repo for my OS (OpenSuse 15.1).

I've had another look at (VS-) Code, and I think Atom is more user-friendly (or at least less user-hostile).

It's a tricky one, simplicity v. all-singing, all-dancing complete solution. Much of the time I think poor documentation is the problem, as you've mentioned.

Of course, in the world of 'real', physical devices, simple isn't necessarily easier; my first lathe was one of these*:

https://store.lathes.co.uk/adverts/for-sale/antique-brown-brothers-lathe

It's a lathe, it turns, faces and screwcuts, but with no graduated dials, thread-dial indicator, on-off switch(!), etc., it wasn't exactly an ideal beginner's machine. Character-building, you might say.

* If the link disappears, it's a rather agricultural flat-belt driven machine by Brown Brothers of Great Eastern St., EC, dating from around 1900(?). Mine didn't have the power cross feed, countershaft or most of the other accessories.

08/08/2020 20:35:34
Posted by Versaboss on 08/08/2020 14:39:05:
Posted by Andy Stopford on 07/08/2020 20:53:10:

Lastly, do yourself a favour and ditch the Arduino IDE - there are much better, easier to use alternatives, with full code completion, hints, colour coding, etc.

I use PlatformIO; it's available as a code editor plugin. I like the Atom editor, but you can use it with VSCode, and, possibly, others.

Hi Andy,

as a sometimes Arduino user I'm always interested in such stuff. However, all is not so easy. I managed to install the Atom editor, and then tried in vain to cooperate it with PlatformIO. What I now have, if I start Atom, is a black screen with a menu bar. There is also a menu point for PlatformIO. But after say a minute I get the message 'editor isnot responding.
I deleted Atom and re-installed it, with the same result.
And btw, IF that system would work, how could one compile the code and load it up into an Arduino? Copy/Paste to the Arduino IDE?

Regards,
Hans

Hi Hans,

It looks like there might be a problem with the latest version of Atom (always a possibility with actively developed Open Source stuff), see this thread:

https://github.com/platformio/platformio-atom-ide/issues/2377

As suggested in the 3rd to last post there, it might be better to use the VS Code version, which being a Microsoft product, is likely to be more reliable than Atom. I shall have to look into that.

Anyway, in either case, it will compile and upload your code in the same way as the Arduino IDE, and it has a Serial window which you can read, interact with, etc if required, again like the Arduino one.

08/08/2020 20:20:21

#####################

Posted by Joseph Noci 1 on 08/08/2020 08:21:54:Posted by Andy Stopford on 07/08/2020 20:53:10:

Just a couple of points:

********************.....

Lastly, do yourself a favour and ditch the Arduino IDE - there are much better, easier to use alternatives, with full code completion, hints, colour coding, etc.

I use PlatformIO; it's available as a code editor plugin. I like the Atom editor, but you can use it with VSCode, and, possibly, others.

I just spent near 2 hours digging into 'PlatformIO'...I think its a little presumptuous to just tell folk to 'ditch' the Arduino IDE...

....

In the two hours I could not fine what the minimum software overhead is when running this system on 'my' board - is there a bootloader? What size is it typically? How does it affect run-time measurements?..

####################

Steady on Joe, I'm just venturing my own opinion; people are free to make of it what they want. You will find many complaints regarding the Arduino IDE in the Arduino forums. It does not make life easy for the beginner, which surely is the point (and was my own experience when I first got an Uno).

As it happens, I totally agree with you regarding the PlatformIO website. It's a model of corporate BS which seems designed show how much money they can afford to waste on some wacky web developer with a mission to put interested punters off.

However to make it clear - it is just an IDE, like the Arduino one, but with some bells and whistles to make it easier and more convenient to use. It doesn't run on your board, it doesn't have a bootloader, though it could be used to install one in conjunction with one of the Nick Gammon scripts I linked to.

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