Member postings for Sam Stones

In several of his YouTube videos, watchmaker Roger W Smith mentions black polish.

**LINK**

Where can I buy some, or should I stick with elbow grease?

Sam

Your point is taken about talc as a filler, Russell.

An ‘ash content’ test (better conducted under safe laboratory control) would establish the presence of particulate/fibrous mineral fillers, e.g. talc, calcium carbonate, glass, etc.

However, and although I’m not completely convinced from Choochoo’s photograph, since the fracture appears striated/delaminated, this emphasises the probability of contamination with incompatible polymeric/non-polymeric material. Phew!

Drifting off ABS into plastics in general and having been sensitised to looming problems of stress cracking, the aspect of frictional heat generation is challenging, and from personal experience, acrylic in particular may need attention.

Referring to ... **LINK**

scrolling down the page to the paragraph commencing …

On a totally different subject, ………….

I made a note about underlying stresses and their release as micro-crazing.

In particular, the paragraph …

By the way, I have occasionally noticed this same stress-cracking effect has introduced crazing to the edges of acrylic security screens, where human body oils and other substances have made contact.

This incipient problem was also reviewed in my 3 Part article of Model Engineer reference …

Making a miniature changeover valve in plastics

#4555 – 3 Mar 2017, #4557 – 31 Mar 2017 and #4559 – 28 Apr 2017

Sam

As is becoming my habit, I’m a bit late in the day, Choochoo.

I must ask … How many of these mouldings do you have to drill? If just a couple or three, then ignore my initial comments about the material.

Like Andrew, Eric and Murray however, my first reaction was – ABS ??? Surely not!

The sample in your photograph displays characteristics of serious contamination as observed by Murray. Second grade, off spec. and regrind are one thing, but this stuff is delaminating.

Virgin ABS doesn’t do that.

I suspect the inclusion of incompatible, perhaps none polymeric (floor-sweepings) material. Without extensive/intensive mixing, contaminants will striate and delaminate as seems to be the case. Such materials should be destined for the bin or moulded into plant pots.

It was practice in certain establishments to have a moulding machine set aside for chuffing out plant pots. It would sit alongside another machine moulding drip-trays for those other (moulding) machines which leaked oil badly.

Along with previous recommendations especially securing the work-piece, machining thermoplastics requires recognition of their low thermal conductivity and therefore their propensity to melt. Mr Hancock mentioned this in his contribution.

In this context, I would add; use sharp cutting tools (e.g. for woodworking), and cut slowly.

Have fun,

Sam

Frances, You got it in one.

That's about the time I started buying Model Engineer.

Well done that man!

Steve,

I meant to show this when your thread appeared.

It must have been back in the late 60's that I saw something like this in Model Engineer. I can't be sure.

I also had a piece of bronze bar from an earlier project which became the bearing and a means of gripping it under the ML7 tool post clamp.

As you would guess, a round cutter was inserted into the thing on the left.

It went out the door with most of my other equipment.

Regards,

Sam

I couldn't resist doing one of those multi-exposure pictures.

Photoshop of six (video snapshot) images.

Nothing to write home about, but fun to play with.

Sam

Expected top temperature in Melbourne today ... a sweltering 14 degrees (that's C folks)

Neil wrote ... By heck Sam, you seem to have your camera upside down

Well it just goes to show Neil, that the earth is, indeed flat, double sided, and not very thick.

Having made the (antipodean) trip a few times, it's a bit scary as the plane flips over the edge.

Sam

Eclipse - South east of Melbourne - Didn't get the lot and not the ideal camera gear.

These taken at about 05:30

Regards,

Sam

See my album for a bit more detail.

Moon and Mars

Edited By Sam Stones on 27/07/2018 23:53:21

Hi Frank,

Lead sounds like a (slightly) better option to plastics, certainly in terms of its melting point (327°C for pure lead). Not many thermoplastics resist melting at those sorts of temperatures.

However, since I/we are talking about creep, I imagine that those better qualified are already raising an eyebrow in relation to the viscoelastic properties of lead, pure or alloyed.

As a demonstration to students, I fashioned a coiled bed spring from 3 mm dia tin/lead solder. Its purpose was to display the material’s minimal elasticity and low resistance to creep.

Unaided, the spring collapsed completely during my talk.

Sam

Google … Spring and dashpot for further entertainment.

Hi Alan,

Right now, down here in the antipodes, it has been a bit chilly. However, we do get warm weather.

In a thread about my use of fishing line for clocks, (04/07/2014) of this (lengthy) …

**LINK**

fellow Victorian and Forum contributor John McNamara drew my attention to the Gremlin called Creep.

It left lots of egg on my mush. Marinated in design applications for years, a knowledge of empirical time/temperature/stress curves was essential. I had simply taken for granted that fishing line was a sufficiently tough monofilament (molecular orientated) to resist creep.

I was wrong.

Therefore, it seems clear that your shelf fastenings have suffered a similar outcome.

Stay cool

Sam

My sympathy Ron, and to others who suffer gout.

When it is far too painful to walk, I get relief from taking a couple of prescribed cortisone tablets. For what it’s worth, I haven’t eaten red meat or chicken for more than forty years, and for a couple of medical reasons, alcohol is off the menu.

Another less afflicting discomfort is having trigger finger in both index fingers.

**LINK**

Although less painful than gout, the pain increases overnight but, unlike gout, it eases throughout the day.

As Ady1 mentioned, lying on the left side in bed certainly works, although in my case I'm talking about reflux.

Here’s an ‘engineering’ type solution which you can try. I noticed the problem while watching the nursing of my infant son fifty years ago. It dawned on me that ‘winding’ him over the shoulder didn’t match how ‘gas’ was caught in his stomach. My suggestion to his mother was to tilt him to his left.

What I find surprising is that although this works every time for me, no one has ever mentioned it for winding babies. If you’ve not already tried it, lean to the left at about 45°

Sam

PS – I love grilled salmon.

Edited By Sam Stones on 16/07/2018 23:22:53

I can't find words enough to describe this.

**LINK**

Although there was no risk of fire, this reminds me of a school excursion to a horticultural property in Hutton (Lancs).

We were encouraged to climb to the top of the ten-foot ladder of a steel structure to examine one of these.

**LINK**

That was in the late 40’s, and even now would be quite a novelty, recording Lancashire sunshine.

Sam

Edited By Sam Stones on 09/07/2018 01:53:42

Same source of material, perhaps Neil?

Coincidentally and way off topic Trevor, it might be useful to know that a buttress thread is a highly recommended and much used thread-form for plastic materials’ applications. The reasoning relates to radial creep.

By the way, I admire your tenacity with regard to winding those fine wire coils. I recall my electrician father claiming that he was the only one in the workshop with the patience to handle the extremely thin wire. Besides suffering numerous wire breakages, other maintenance chaps who tried came close to nervous breakdowns.

Only wish I could help with the half nut problem.

Sam

A word of WARNING.

Without even reading through the entire method for forming (pressing) threads into Delrin (polyacetal), which is clearly a smart way; just a word about applying heat to this material.

The fumes from over heating are extremely noxious. Get a whiff and you'll never forget it.

Good luck with your 1/2 nuts.

Sam

Nice lathe, Neil.

Having the ability to drag this topic further from its original title, at some time around the 50’s, a likeable old chap called Fred joined the toolroom and put in charge of the 24” shaper. There was a story, perhaps invented to impress us apprentices that he had once worked for RR.

Already in his 70’s, he was heavily into chewing tobacco. Some of the lesser respectful, suggested that he had an A/H at both ends. Even worse (?), especially for the labourer who had to sweep up everyone’s swarf, he regularly aimed his excess spittle into the pile of chips building up in the guard surrounding the business end of the shaper.

Spittle-quenched chips of blue?

So that I haven’t killed off Ross’s thread altogether, here’s a rhetorical question …

Is the (lathe/shaper/milling) tool cutting or pushing?

Sam

In the toolroom alongside Joe the shaper’s machine, he had a large box of nuts, bolts, and a range of clamps.

As a quite young and clearly insufficiently experienced apprentice, I was helping myself to some bolts from the box, presumably because I was using the other shaper alongside Joe's machine.

Something landed on top of my head as I was bending down, and not realising what it was, I tried to brush it off with my hand. Silly me!

It was a very hot piece of swarf fresh off Joe's machine. It neatly wrapped itself around one of my fingers so I couldn’t brush it off.

Oh the pain, the pain!

Like this.

https://www.youtube.com/watch?v=L-I2xcpWzEM

Here's a bit more Chris,

Another issue came to mind, particularly with what can happen when machining BDMS (bright drawn mild steel). Skimming a surface of a rectangular bar of BDMS can release built in stress sufficient to cause the bar to bend. Insufficient hold down force would allow the steel to lift towards the cutter.

That aside, and since we are talking about an electromagnet, I can’t resist describing the situation in the tool room back in the early 50’s. There were three surface grinders. The chucks on two were electromagnetic, and the third had a chuck with permanent magnets.

The shop’s workhorse surface grinder (with an electromagnetic chuck) was driven from a counter-shaft running the length of the shop. A 10 hp electric motor at one end of the shaft provided the power. Imagine, in the middle of grinding a workpiece, the urgency when there is a power cut. It happened on more than one occasion.

One chap was grinding a line of steel inserts secured to the chuck when the power went off. The chuck let go, and the still spinning grinding wheel propelled the line of inserts against machine’s end guard like bullets from an automatic machine gun.

More food for thought eh?

Sam