Member postings for Andy Stopford

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.

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.

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.

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

+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.

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.

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.

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.

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

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.

@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.

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.

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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:

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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?..

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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.

Just a couple of points:

You can program a bare bones ATmega using the Arduino IDE just as normal - if you've burnt in the Arduino bootloader it is an arduino, effectively.

But, you won't be able to do it using USB, unless you add a USB-UART chip (and socket) which of course complicates things a bit; if you go down this route it's worth designing a custom PCB and getting it made in China (£10-ish for 5 boards from a company called Elecrow - others available, but I've found Elecrow good).

A simple way to get round this is to use the DIP package with the appropriate socket. You can then swap it for the one in a standard Uno, program it, and return it to your project. It's not ideal, it's fiddly, the pins are easily bent, but OK for something where you've got it working how you want it using a test setup with an arduino, and now you want to complete the 'production' version.

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.

+1 for using a 328 on its own; if you set it to 8 MHz it will be stable at 3.3V with a usefully reduced power consumption. They come in a variety of packages, both DIP (solderable with a standard iron) and SMD.

Depending on how you are using it, you may be able to let it sleep, to be woken up up when required by an interrupt from some other device. Since you mention using it for a clock, then a Real Time Clock chip, e.g. an MCP7940N, could provide the interrupt, as well as providing your clock functions.

Also, you don't actually need the crystal, the ATmega 328 has a built in crystal, which is adequate for timing its own cycle, though not for external tasks, like making a stopwatch.

I would thoroughly recommend this guy's website if you haven't dipped into stand-alone ATmegas:

http://www.gammon.com.au

These are good, and don't break the bank:

https://www.chronos.ltd.uk/product/new-3-8-sq-shank-clamp-type-parting-tool-with-4-1-2-m-35-hss-chipbreaker-blade/

I think you probably need to get the dedicated holder for them to locate properly. No need to grind the top face of course, which makes life easier.

I recently bought one of these:

https://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Lathe-Accessories/Tool-Posts/Model-000-Parting-Tool-Holder-Horizontal

If you already have, or are thinking of getting, the appropriate QCTP, then I'd thoroughly recommend getting one to go with it.

I have a Fairway Taxi (the old-school London cab). Some previous owner, possibly the first, had it waxoyled in a totally futile attempt to prevent it rusting to bits.

I keep a small trigger spray full of water to hand during its yearly appointment with the oxy-acetylene torch, to snuff the inevitable waxoyl fires emanating from whatever box section is currently subject of attention (you don't need to be able to see the fire - just misting into the box section through some convenient opening towards the top does the job, a bit like putting out a chimney fire by throwing a cup or two of water on the hot grate).

Re. petrol tanks: in theory the mixture inside the tank is too rich to ignite. Furthermore, petrol is non-conductive (a dielectric I presume?), so I suppose there's no need to insulate the terminals of pumps, etc. - though the submerged pumps that Jaguar used on early Mark 10s were quite carefully earth bonded to the tank if I remember rightly.

Slightly OT, but for water-based paint, Albany (Brewers own brand) will give a true gloss (I hate fooling around with horrible, stinky solvent-based* paint and refuse to use it now).

*Yes, I know water-based paint has water as the solvent - or does it? Are these paints solutions or emulsions?

I don't think Hylomar is intended for metal-to-metal joints, I always assumed it required some kind of gasket and then it would work quite well. It was about the only thing which would make a reasonably oil-tight joint on the card gaskets of the old (pre- 1969-ish) Jaguar polished alloy cam covers. Smearing it on the copper washers for the hold-down nuts of same didn't help a bit though.

For sealing threads like this, I'd use PTFE tape - easy, no need to degrease, and non-seizing when you need to disassemble.

You can get different kinds of PTFE tape - the stuff for gas fitting is thicker, which is handy for larger clearances.

n.b. if you need to seal threads on oxygen fittings, you must use PTFE tape made specially for the job. The ordinary stuff contains a lubricant which might just turn your oxygen bottle into a rocket...

My opinion, both from doing the Xmas postie thing, and 20 years' experience in the removal business, is that if you need to write "Fragile" on a box, you haven't packed it properly.

(OK, if I'm doing a packing job, I do write "Fragile" on glassware etc., but mainly because the customer likes to see it)