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Member postings for Sam Stones

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

Thread: The Pitch Drop Experiment
07/01/2021 22:06:06

The pitch was musical after all, Nigel.

Sam cheeky

07/01/2021 21:07:28

A fascinating subject, Michael.

For a few brief moments when I saw your subject title, my mind switched from musical pitch to thread pitch before ….. well here’s my contribution.

In light of pitch’s (historic) use as the thermoplastic (resin) component in dough moulding compounds, pitch is actually extremely brittle at room temperature. [I can’t find its Tg, can you Nick?]

Pitch was stored in large pieces outside at the plastics factory where I began work (1950). Some pieces were as large as footballs. Along with fillers of various kinds, it was steam-heated in ‘Z’ blenders. The fillers provided a support matrix not unlike glass reinforced resin.

In the northern reaches of England on those rare occasions when the sun shone through, the stored lumps of pitch could be heard snapping and tinkling as it/they responded to the changes of surface temperature.


Edited By Sam Stones on 07/01/2021 21:09:13

Thread: Lamp Post Engine
12/12/2020 21:29:32

At about 1:50 into this video, Clive mentions 'side emitting' LED's

Does that help?


Keep safe,


12/12/2020 21:20:45


Try dimpling the end of an LED with a drill point, thus forming a conical concave. It should spread the light sideways.

I think Big Clive **LINK** mentions that they are available (in that form) over the counter. However, without wading through his many videos I can't say where.



Thread: Taper turning
29/11/2020 18:55:12

Not much direct help John, but this home-made taper turning attachment came with my second hand lathe back in the 60's.

A taper-turning attachment

The original owner had used a piece of angle iron to bolt to the four 1/4" BSF screw holes in the back face of the ML7.

Although I only used it once to its full extent for machining some stainless steel coffee table legs, I adapted it as a cam system while machining (and grooving) a brass fusee for my (John Stevens) skeleton clock.



Thread: M42 bandsaw blades
29/11/2020 00:31:35

Many thanks to Peter, Paul, Robin, and Nigel B, your combined responses and links have led me to realise that M42 is the nomenclature for a version of high speed steel (HSS).

It wasn’t, as I was first trying to determine - a metric ‘something-or-other’ or perhaps some percentage-combination of chemical composition, e.g. 18-8 stainless steel.

I particularly find the Lenox **LINK** most valuable, especially their diagrams of shear-plane angles and swarf formation. The video mentioned by Robin is also worth a look.

To a limited degree, I shall be addressing M42 hidden within a subsequent post.

I don't expect to do that for some time yet.

Incidentally, did you spot the Achilles heel?




Edited By Sam Stones on 29/11/2020 00:34:03

25/11/2020 21:25:36

I’ve tried without success, to find the specification for what have been described as M42 bandsaw blades.

What does M42 actually mean/describe?

Are M42 blades always bimetallic with tool-steel backing and teeth tipped with HS (cobalt) steel?

Can blades having carbide-tipped teeth be classified as M42?

Thanks for any help.


Thread: What am I?
25/11/2020 18:29:48

Going alone to start a new business in ’85, I had it ‘declared officially’ from none other than the Australian Taxation Office that I would be listed as a Consulting Engineer.

It was unfortunate however, that it reminded me of a couple of quotes from Victor Kiam’s book …

Going for It!: How to Succeed As an Entrepreneur

His catchphrase was … "I liked the [Remington] shaver so much, I bought the company"

However, I have occasionally pondered another of his quotes that …

consultants are like castrated bulls.


Thread: Strange Word...
15/11/2020 19:30:22


I should have noticed that I'd loaded it twice.

Cud try betta.

15/11/2020 19:23:53

Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

I cdnuolt blveiee that I cluod aulaclty uesdnatnrd what I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in what oerdr the ltteres in a word are, the olny iproamtnt tihng is that the frsit and last ltteer be in the rghit pclae. The rset can be a taotl mses and you can still raed it whotuit a pboerlm. This is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the word as a wlohe. Azanmig huh?
Yaeh and I awlyas tghuhot slpeling was ipmorantt!


Thread: Another way to pass the lockdown time
12/11/2020 18:39:44

For a different reason OM, (I was born near there in 1935) I traced the rough lines of two 'long gone' railways.

farnworth - old railway sites.jpg

They are from an area west of Farnworth (Lancashire) called New Bury. The north south line was from Manchester Victoria, to Great Moor Street, Bolton.

The east west railway was very short, taking coal from Brackley Colliery to George Street depot.

That's some exercise your doing!

Good luck. Keep safe.


Thread: ACME versus Square thread profiles
10/11/2020 00:41:15

Referring to Andrew Tinsley’s thread …

Why ACME threads on leadscrews?


At the time, a CAD image seemed an appropriate method of displaying how the helix angle presents an undercut. It also offered another explanation why lathe leadscrews have ACME profiles.

To digress slightly, helix undercutting can be an issue with moulded external threads, and often influences the choice of thread profile. The angle of the pressure face of a buttress thread is one such instance.

Unfortunately, try as I might, I failed to discover how to manipulate the solids, i.e. subtract the yellow blocks from the helix. I left it looking like this ...


That was back in 2017.

The other day a friend of mine mentioned that he had made some cast iron half-nuts to fit a new 12x2mm ACME leadscrew for the lathe he was refurbishing. The nut halves were a tight fit on the leadscrew so he decided to lap them using a leadscrew offcut. After lapping the thread of the half-nuts he discovered ‘… the fit was too good and was making it difficult to engage and almost impossible to disconnect under load.’

It was time for me to fire up the seventeen year old CAD package and search again for a way of generating a solid that I could manipulate. After squinting at and dabbing icons for a while, I suddenly spotted one I’ve used many times.

Create Swept Solids.

This was one of several dropdown windows exposing blocks of icons. There, amongst the block of six was …

‘Create a solid by Sweeping a Profile along a Helix’

We were in business, and soon I had four images showing the extent of interference, bearing in mind that I was using size for size, i.e. no clearances and no radii etc.


Travelling perpendicular to the thread axis, you can see how the undercuts interfere.

This issue has clearly been known since the late 1800's, yet I can't find a link. What do you people think?


Footnote: Usually, half nuts are less than half. Is that intentional?

Thread: PC unable to read PNY flash card
06/11/2020 19:25:45

Good news!

Overnight, with the help of his son, my friend loaded the files into Dropbox. This morning while still bleary-eyed, I managed to down load all that was necessary.

Thanks again for all you help and good intentions.

Keep safe.


05/11/2020 20:55:46

Thanks for all the advice so far gentlemen.

For clarification, here are a few more notes regarding the USB card and (I presume) its contents …

  • The images were taken in the UK and posted to me in Australia,
  • I have no idea what camera, computer, or software he used*,
  • My desktop PC runs Windows 7 Home Premium,
  • My old IBM ThinkPad laptop runs Windows XP Pro V 2002,

It looks like incompatibility is high on the list Dave (SOD)!?

I had noticed that the USB plug wobbled relative to the black injection moulded body of the device. It had spent 26 days in the postal system, which raised a couple of questions …

  • Was the device damaged physically?
  • Was there a broken connection?

I decided to pull it apart, only to find it was intact. See this ‘top and bottom’ image.


Holding the ‘skeleton’ by its PCB edges, I again plugged it into the PC (and the laptop). That was when the LED revealed itself, flashing in a typical pattern and then remaining lit.

Plugging the device into both PC and laptop this morning showed the same symptoms, i.e. the rapid flashing lasts about five seconds when plugged into the PC, but only about one second when plugged into the laptop. The same (error) message appears briefly on the laptop.

The LED, visible on the RH edge of the PCB (top image), didn’t show through the black moulded case. Now it does, through a 2mm hole I drilled in the case.

*With such bad news about the CV19 spread, I’m worried that I still have had no response from my UK friend.

Many thanks for your help so far.


PS Dropbox it'll be next timedevil

05/11/2020 02:51:32

Thanks for your prompt reply Paul.

I'm guessing my UK friend still has all the photographs on his computer. If all else fails, he might have to send them as email attachments.

Meanwhile, I'll look for some recovery software.

Thanks again,


05/11/2020 00:44:43

A very helpful friend in the UK sent me a bundle of his workshop photographs on a PNY 16GB flash card.

Although my PC says the card is OK; beeps when I insert the card into the USB socket; and the card’s LED flashes, nothing shows up in my MS Outlook 2010 file manager.

I then checked with one of my own cards and that was fine.

When I plugged the PNY card into my old (IBM ThinkPad) laptop the LED flashed as before but then reported …

‘A problem occurred during new hardware installation. Your new hardware might not work properly.’

Returning the card to my PC produced the same results as above, i.e. it beeps and the LED flashes.

Is there a simple solution?

Thanking you in advance,


Edited By Sam Stones on 05/11/2020 00:45:21

Thread: Newton's 3rd Law
31/10/2020 00:25:49

Without the skateboard, steering on castors would be near impossible.

I’m with Pete and assert clearly it's reverse thrust.


Thread: Which ball turner?
30/10/2020 03:56:24

From the dark distant past. That's a lump of bronze in't middle.

spherical turning attachment.jpg

I can't recall using it for much more than a couple of handles, as on the turret here ...

A six-way turret



Thread: Arduino Pendulum Clock Design - Comments Welcome
26/10/2020 18:22:56

Roughly 1/8 as stiff?

i.e. D^4

However, I can't be sure about resin composites.


Thread: Stellite 98M2 tools
26/10/2020 00:29:45


I cannot recall the grade of Stellite used for the triangular drills in our toolroom. The drill tip had a (very) negative rake. The three notches are about how I remember them, although they may have been a bit wider.


As an apprentice in the early 50’s I had the task of drilling through the nitrided skin of the cavity of a compression mould.

Once through the skin the rest of the drilling exercise was with a conventional HSS twist drill.

The operation required that enough downward pressure was applied to the drill to virtually melt the mould steel. Drilling was more about pushing the metal out of the way. A quick Internet scan shows that nothing seems to have changed to the drill-tip geometry .

Worn screws and barrels of plastics extruders can be restored in a process called ‘hard-facing’. Stellite and other hard materials sprayed onto surfaces replaces in particularly, worn screw flights.

I find it hard to believe it's more than 65 years ago, and carbide was beginning to appear.

Keep safe people,


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