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Member postings for Nigel Graham 2

Here is a list of all the postings Nigel Graham 2 has made in our forums. Click on a thread name to jump to the thread.

Thread: It Is A Steam-Engine... Using the term loosely
15/01/2021 12:23:19

All these replies are re-inforcing my belief that at best, ground-heat systems could provide only modest and very intermittent background warmth to help the homes' main heating system; could serve only a single home with a big garden that faces South and is not overshadowed; and would save far less money or planet than claimed.

Andy -

I don't know how far the heat depletion would spread laterally from a pipe array. Since the heat sources (subterranean and solar) are to all intents and purposes perpendicular to the ground, a row of arrays in a street would receive equal amounts of heat, assuming same ground and shadow conditions for all. I suspect that for most ground neighbouring arrays would not affect each other much provided a few metres separation.

The bigger problem would be for blocks of flats However, I doubt such systems would be at all practical for them because they would need far more heat in total than feasible from what for many such buildings is very limited land area, often in the shade for much of a Winter's day.

I did not mean to imply "freezing" the ground. These systems would not do that. They would simply keep it cold - the plants and wildlife over-wintering in it would not be too impressed, though.


Duncan -

Mean solar irradiance - is that figure of the heat or of the total, energy density? I tried to look the figures up too, but found the presentation fractured and confusing, not really answering the question.

I assume that 3kW/hr is what you need to keep your home comfortable all day and night?

Your performance figures. Sorry, but that so-called coefficient of performance reads to me like heat-pump advertisers twisting what engineers call efficiency, to remove the revealing % sign.

You might obtain nearly 1kW/hr of heat from 1kW//hr of electricity, by direct resistance heating, so nearly 100% efficient. (A small amount of the electricity is lost as light.)

If C of P does mean efficiency, as indeed the figures suggest, the fluid in the pipes absorb only 2% of the sun's radiation hitting the ground; and the circulating pump would take, maybe a 100W?, further nibbling away at the overall efficiency.

It will be at a maximum for only a short time too around mid-day too, even if the garden is not overshadowed, and although dry ground might act rather like a storage heater, the heat actually put into the rooms will be small and might diminish fairly rapidly after dark.

So they are not very efficient systems at all physically, and despite costing little to run, probably not financially either efficient.


Hopper -

Potentially the heat rising from within the Earth is indeed huge, derived from nuclear decay very deep down, mostly far below several tens of miles of Continental Crust. The heat diffuses through that without too much trouble, but then to reach your garden has to fight through a suite of rocks of combined local characteristics and depths of much greater variety than Heinz condiments.

To make life even harder for the heat energy, nearer the surface its path must be influenced considerably, possibly not quantifiably, by the local hydrology.

This means that whilst Duncan's example might suit London's leafy suburbs basking in balmy 1W/hr sunshine, it could be either even better or almost useless anywhere else.

Put it in one area here in Dorset, and its 2% efficiency in the London Clay may be <1% thanks to plentiful ground-water flowing through the Chalk and valley-gravels below thin soil cover. Its springs take the ground-heat way, but they support large watercress farms developed because the water is just warm enough to maintain the plants through the Winter.

Place the same array in a Devon or Cornish garden, and depending on exactly where, it might be 3% or more efficient thanks to small, natural nuclear heat sources within the mass of granite underlying much of that region.

So just taking mean weather and ground figures from a test location is not safe if we want to use the natural warmth of the ground seriously. The potential exists but exploiting it has to be based on thoroughly understanding the intended location's real temperatures and heat-flux from above and below, not the sellers' assumed " co-efficients of performance ".


I have had direct insights into how harnessing "free" energy is by no means as simple as stage-managed teenagers try to claim; and as engineers we know it isn't. My previous home faced SW, theoretically suited to a solar array. My brother, working then for a "renewable" energy company, explained that the small roof area, direction and over-shadowing rendered it not economical.

He had no commercial interest here as he lives and worked up in Scotland. I asked if his company built small-scale hydro-electric plant, in a country ideally suited to it. Such schemes are now quite common in England. He replied that although sound environmentally and potentially as business, the Scottish planning system rendered it uneconomical. I do not know if this still applies.

He installed a small solar array at his own home, near Glasgow. On a shed roof, it is rotated in azimuth by a small motor, taking less electricity than the approach gains. I think he also built a small roof-mounted solar water-heater, helping the hot water rather than central heating.

Thread: What Did You Do Today 2021
14/01/2021 18:27:15

Slightly convex... Lengthways or across? Or both?

A stress-relieving effect?

Slight wear dropping the table in mid-travel so that on long traverses, it follows a very slightly concave path (so very slightly less metal removed from the centre)?

I've noticed similar faults and not really been able to pin them down, but my mill may have a harder life than yours.

Thread: Coronavirus death stats
14/01/2021 12:48:46

The Corona virus - more accurately the Covid-19 one - is the last straw for many who are already seriously ill, and I lost a friend to it in that way. It might also weaken people who might otherwise recover, enough to die from a subsequent (not consequent) illness.

However, are we sure that the "within 28 days of a test" used in the News reports, is actually a fair representation of what the hospitals really report? The NHS reports deaths in which Covid is implicated as a direct cause or by taking out the already-ill. I cannot imagine it would really link Covid infections and co-incidental road traffic accidents.

We also know that politicians don't help when they muddle up the facts, because too many of them are as ignorant of anything technical and statistical than are too many journalists.

Nevertheless that question is an important one, and the 28-days move was established as a response, to try to make the pandemic death-rate at least somewhere near correct. However we must be very careful not to seize upon the corollary that would make increasing testing the guilty party.

Thread: What nut and bolt material?
14/01/2021 12:33:18

The risk of galling between stainless-steel fasteners can be reduced further by using differing alloys - possibly easier if one part is to your manufacture under your own quality control.

It is increased by the load concentrating on one thread flank as the assembly is tightened.

I once had an M5 screw and 'Nyloc' nut of the same grade of stainless-steel, seize solid before they were fully tight, on an assembly that prevented any other solution than tightening them until the screw broke. Preferably without locally distorting what they held together: a pair of thin stainless-steel plate rings clamping together the inside flanges of two rubber mouldings forming a toroid. This was at work, so something not to my design.

Thread: It Is A Steam-Engine... Using the term loosely
14/01/2021 12:17:06

Martin -

A good question, and in fact asked in the report. The Dearman company says it buys the gas it uses (a by-product of extracting oxygen from the atmosphere) from a processor using "renewable" energy.

More efficient than direct cooling by the liquid gas? Evidently not, but the system does combine mechanical refrigerating with gas cooling; and maybe relying more on the machine simplifies keeping the temperature constant.

14/01/2021 12:09:20

Hopper & Dave -

With respect although you both explained how it works. you have not answered my question.

I ask, can such a system be relied on for at least some background warmth to a house throughout the Winter without risking depleting the heat energy from its ground faster than it will be replenished?

I am not convinced it could, not to any worthwhile extent anyway.

I do know the difference between heat and temperature, and that the system designers do understand the physics and engineering. Physics is immutable and predictable for all practical purposes - but though driven and regulated ultimately by physics, geological and meteorological processes are extremely variable and a ground-source heating system is very heavily dependent on the variables.


All heating systems are influenced heavily by a factor beyond their control - the external temperature and duration at that temperature. The ground can hold a lot of heat, but the amount and temperature available in a given spot and time are affected by the natural recharge from the surrounding geology and by solar radiation. Both of those variables are very much that - and the sun's contribution is a matter of seasonal daylight and weather (cloud cover and air temperature).

I live on the South-facing, coastal, dip slope of a ridge of various limestone, sandstone and clay strata with fairly thin soil cover. I think it quite possible that a system designed for a house near me would perform quite differently, and have very different re-charge characteristics, if installed in a similar home a mile North, on the deep clays below the scarp slope. Very different again if in a garden in the R. Frome valley 10 miles inland, in wet valley-gravels but North of a higher ridge that creates a distinct " North-South Divide " in local Winter air temperatures and frost.

It might even differ from garden to garden in the same street, depending on overshadowing in low Winter sunlight.

A ground-source heating system moves heat energy from ground to house. If it cools the ground faster than the natural re-warming from the Sun and from a steady but very small, locally individual, heat flux from the depths, its heat output and temperature within the house will diminish. Eventually, at some sort of equilibrium controlled also by the building's primary heating, it would have to stop and wait for Nature to catch up.

Just like the over-drawn water well, and just as affected by location.

A kitchen fridge moves heat from one space and discharges it in another until the desired interior air and food temperature is reached. If left undisturbed, the delay between successive refrigerating cycles is led by the slow return of heat through the walls and door-seal. A ground-heat system's recharge time is the analogical delay, and probably a lot slower.


Hence my concern that however properly designed individually for location and ground conditions, the concept of a ground-source heating system based on pipes under the garden, is essentially flawed.

(Those using direct, high-energy geothermal sources, as in parts of Cornwall and Iceland, are different and a rare exception. I believe there are also studies underway in extracting heat from the water flooding deep, abandoned mines: a reasonably reliable source provided again, artificial scale does not overtake Nature.)

14/01/2021 00:00:02

What was show was a set of large coils laid not far under the ground - probably just deep enough to avoid normal gardening.

It occurred to me to wonder what happens when you are relying on the system most - coldest days and limited insolation in Winter. Surely, unless the system is fitted with complicated thermostats that shut it down to avoid this happening (so defeating the object), it would be possible to draw heat from the ground more rapidly than Nature can replenish it... so defeating the object.

This is analogous to a water well. It is possible without proper control to extract water more quickly than the aquifer can supply it, creating a funnel-shaped volume of dry ground around it.

Also, that heat-pump system would be affected by the thermal properties of the surrounding ground - again analogous to the water-well whose recharge is controlled by the porosity and permeability of the rock. (Rock includes very solid stuff, multi-jointed ones like limestone, practically waterproof clay or water-logged sand and gravel).

You say many of these ground-heat systems have being installed. I wonder what proportion have actually proven their heating and financial worth over long spells of either frost and cold East winds chilling the soil, or slightly milder overcast with no sun but rain transferring the heat downwards?

As I said previously, I may be missing something but I'm certainly not rushing to buy a ground-source heat pump; not without I know the full performance I could expect, both in heat and in financial efficiency. I doubt anyway my garden would be large enough - the feature depicted a 3-bed suburban detached property, not a small Edwardian terrace, with land to match! A air-heat-pump might be more sensible... it might give a bit of background warmth while the ground-source users look out over their expensively-refrigerated lawns, and shiver.

Thread: Is there an easy way to make lots of scale model seats?
13/01/2021 22:16:11

Do you have access to a 3D printer? That would seem one route.

Alternatively, are their shapes amenable to being pressings within range of some die-making and a fly- or arbor- press?

Thread: Another watchmakers lathe
13/01/2021 22:12:56

I would suggest the "poles " with pulleys are parts of a milling-spindle, typically for wheel-cutting on a horological lathe, especially as the spindle clearly carries a dividing-plate.

As well as more complete replies here, try looking at other examples of similar machines (e.g. on the site), and seeing what fits convincingly together, to help sort actual lathe parts from lathe accessories from odd bits that hitched a lift with it.

A " round knurled ring with grub-screws" could be a simple adjustable stop or a knob for rotating a spindle somewhere.

If the "top slide " isn't that, might it be a vertical slide? You describe the second purchase as a collection of parts, so it could be a top slide but from some third, unknown lathe. Possibly collected by the seller who thought he could adapt it for Something Very Useful

I have found old machine-tools seem to lose important or useful bits, but attract mystery bits to sit there and defy you to identify them!

Thread: Cleaning copper rivets.
13/01/2021 21:49:03

Household acids (vinegar, citric acid, de-scaler) all fine but I would stress the point Brian H makes -

Degrease the rivets thoroughly first, as grease tends to protect the metal from weak acid and would potentially contaminate the silver-soldering.

Thread: It Is A Steam-Engine... Using the term loosely
13/01/2021 21:42:18

Gentlemen, I was being slightly tongue-in-cheek with my title.

I am aware that any engine that converts heat to mechanical energy is a heat-engine by definition, but in case I forget I have several of my Dad's old text-books on the subject. Most of their contents is above me I am afraid, as being degree-level mathematics.

What is significant perhaps about Peter Dearman's work is that he has produced a machine intended for genuinely useful work in specific applications.

Over the years a lot of inventors have tried assorted wheel re-inventions but without succeeding. Not perhaps in the League-of-Hopelessness of perpetual motion, but not really thinking of applications or even basic physics. I had a partial copy of the description of one such, and the waffle failed to disguise as new, a simple rotary-vane motor; but as far as I could glean about the working fluid and energy source, that didn't give us anything new either. (I think its heat source was the Sun.)

Back in the 1980s or so, agricultural academics were studying growing suitable crop-woods (species of hazel and willow, I think) for the raw material for a form of producer-gas that would fuel conventional petrol-engines modified to burn gas. Their idea was a power-source for places like remote farms - assuming the space and conditions for the trees of course. I do not know how far that progressed; nor what "green" types now would say about it. So nothing new in the equipment; but possibly not very much thought about application and need.

What Dearman has done is use the familiar and well-tested in an unusual combination to solve a particular problem. In other words, seen the problem and looked at how it can be solved by ingenious use of the readily-available and adaptable. Not tried to alter the familiar or fight the physics, call that novel then try to find uses.


Recently my local paper gave a splendid diagram showing how the heat is harvested for a household ground-heat pump: fluid circulated through a large array of pipes at shallow depth below the garden. I thought, unless I am missing something, you need only school-level physics to see the obvious flaw.


This all reminds me of an amusing spoof published in one of the railway "glossies " (an April edition?) back when BR was throwing its steam-locomotives away as fast as you could spell Dai Woodham. Illustrated by a line-drawing of a bizarre confection of Pacific wheels and motion turned end-for-end under the superstructure, coupled to half of a diesel locomotive body on a tender chassis, the mock-scientific text told us all of a hush-hush R&D project by British Rail(ways still then?) as a replacement for the steam loco. Allegedly the secret machine would evaporate a special fluid at high temperature and pressure, and by suitably conveying the vapour to the power-cylinders....

Thread: Manual threading on the lathe - problems
13/01/2021 00:38:50

How are you holding the die?

Although it is possible to use the tailstock as a makeshift die-holder guide / pressure pad (I have done it), it is not very reliable for very accurate work (I know - I've tried it).

Your second best bet to screw-cutting is to use a tailstock die-holder, and that will probably give you as good a result as you are likely to expect or need.

Is your difficulty compounded by expectation? You seem to mean this is for a piston simply screwed to its rod. Whilst I don't know the specific engine, it is usual to not rely on the thread alone for concentricity. Instead, the assembly should include a register, at its simplest a plain section of the rod fitting a reamed portion of the hole in the piston.

Many builders also leave the piston a tiny bit over-size then skim the last few thou off with it finally assembled to the rod, held between-centres or by other means to ensure concentricity.


Can you cut BA threads? Well, they are metric though not obviously so; to a geometrical progression.

5BA is of 0.59mm pitch, or 43 TPI., and 0.014" (0.355mm) deep.

If you screw-cut it about 0.7 thread depth, you can die-cut it to size and profile by die, and on a thread of less than perhaps 8 or 10 turns the pitch error is likely to disappear in the cutting tolerance. Anyway, a slightly tight thread is probably an advantage on a piston-rod.

The awkward bit is grinding the tool accurately without a basic tool-&-cutter grinder.

' '

If your lathe is to Imperial dimensions it is possible, using spread-sheets, to find combinations of its change-wheels that will theoretically generate some close-match mm / BA threads for short, though useful, distances before the accumulating error prevents correct finishing with a guided die.

Edited By Nigel Graham 2 on 13/01/2021 00:42:16

Thread: It Is A Steam-Engine... Using the term loosely
12/01/2021 23:32:27

BBC R4's current series 39 Ways To Save The Planet (1.45pm week-days) on "green" alternatives yesterday looked at the Dearman Engine, a British invention and company, whose present primary application is to replace the small diesel engine that drives the refrigerator-compressor on a refrigerated-goods lorry trailer.

They didn't go deeply into the mechanical details, but it soon became clear that Peter Dearman has adapted simple steam-engine principles to work on high-pressure nitrogen. The programme seemed to imply it runs on liquid nitrogen, missing the point that the liquid is the source of gaseous nitrogen, boiled as with gases like propane, by release and expansion through a regulator.

So it's a " steam " engine, only it's very cold " steam ", but its great advantages are of course no pollution, and it being naturally very quiet.

' ' ' '

Today's was about another British invention - greatly increasing a solar array's efficiency by incorporating a second layer whose different semiconductor material can use the higher light frequencies to which the conventional p-v cell is insensitive.

' ' ' '

I wish these all success!

" Save The Planet " ... It's not the planet we need worry about, but what's on it!

Thread: Free inserts.
12/01/2021 22:54:33

Blimey, is this the new bit-coin? Along with numbered Swiss files?

12/01/2021 22:51:33

Royal Mail also has the advantage of local sorting-offices (obviously under heavy restrictions at present) and post-offices to help if a delivery is missed: it is set up for domestic as well as business post, after all, whereas the commercial carriers are really designed for business-to-business premises manned throughout the day.

Thread: Anyone made an exhaust flapper for one of their models?
12/01/2021 22:45:23

They are an internal-combustion device. You see them, with or without the little counter-weights, on lorry exhausts that point vertically upwards above the cab roof.

Thread: 3.5 gauge Juliet no.2
12/01/2021 22:39:40


Interesting, use of Baker gear. The original Juliet had inside Stephenson's Gear, but the smaller Tich was all outside with Baker Gear. I wonder why LBSC chose that - it is a modified Walschaerts, but the latter was much more common in British practice.

LBSC's original application of Stephenson's Link Motion to Juliet had a flaw. He guided the valve-spindle by a single-sided swinging-link working on a pin secured to the adjacent frame-plate - an arrangement susceptible to serious wear debilitating the loco in frequent use. Fitting trunk-guides on the frame-stretcher instead, will " teach it manners " , to use one of Lawrence's favourite phrases. (My club did that to its 7.25 " g version.)

I think K.N. Harris did similar among his modifications to LBSC's original valve-gear design for the 5" g. Maid of Kent.

I am not sure about the former engine, but I am pretty certain LBSC designed Tich with a slip-eccentric option. That's OK if you are using it on a continuous track but not very practical for up-and-down lines, and of course it doesn't offer the opportunity to drive it fully, combining regulator control with notching-up.

Since both designs were freelance, representing small industrial locomotives but not modelling a specific one, there's plenty of latitude. I wonder if the Mann [sliding-eccentric] Gear could be used on the inside-cylinder versions?

Edited By Nigel Graham 2 on 12/01/2021 22:40:12

Thread: Juliet no 2
10/01/2021 23:02:28

I for one was not thinking that!

Juliet but with outside valve-chests and Walschaerts (or Baker, like I think her 'Tich' sister uses?) Gear, too. Neat alteration and oh so much simpler for oiling round and maintenance.

Did you have to make many modifications other than rotating the cylinder blocks and designing the valve-gear, to use that configuration?

My society built a Juliet X 2 (a 7.25 " g.) version - in his original introductory instalment of the building series in ME, LBSC remarked quite a few readers had asked about that, and he wryly suggested it be called Julia!

The problem we met in service was that Mr. Lawrence's original design for suspending the inside Stephenson's Link Motion was inherently weak even when doubled up, not suited to the rigours of heavy portable-track use, and eventually we had to rebuild it with big valve-spindle guides.

Thread: Key Cutting
10/01/2021 22:34:34

Michael -

Sorry, I mistook the location of the photo, and for some reason the newness of the lock photographed didn't make me look twice.

Jason -

That message, saying it's a sash lock, had not appeared when I posted mine.

Thread: peatol/taig parts
10/01/2021 18:54:01

Richard -

" The thread form for a Peatol/Taig spindle nose is 3/4" x 16 tpi (60 degree inclusive thread angle), used to be known as UNF Not sure what they call it now. "

Errr, UNF! The thread is still known as UNF.

If you still need make a back-plate or other fittings, taps and dies for the American UN range are readily available. Tracy Tools, for one, lists them.

Screw-cutting the threads would be facilitated too, by the 60º being also that for standard metric threads.


(UNF and UNC became common in the UK with American car manufacturers taking over ours, and by the ranges being for a time at least, the main system for NATO-standard military equipment.)

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