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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: Post Office Deliveries
16/09/2021 23:20:26

All seems fine here in South Dorset, but I would expect the sort of problems others report to be fairly local.

Certainly a manual I ordered from Tony Griffiths arrived today only 3 or 4 days after I ordered it - I think he copies them to order so I would expect a little waiting.

Thread: What Did You Do Today 2021
13/09/2021 23:40:53

Thanked the two Forum users who had responded to my appeal for help with a Myford screw-cutting gearbox.

It didn't seem to match the details they sent, but a bit more research via lathes.co revealed the unit is an early version - though in very good condition! Still, the lathe itself is of 1947 vintage, so that's appropriate I suppose.

I was intending to machine the replacement idler-gear for the output side, but instead made and used the drilling & tapping template for the two screw-holes needed in the lathe's bed for fitting the gear-box; and spent a bit of time becoming further acquainted with the thing.

Thread: electronic cylinder indication
13/09/2021 23:26:17

Not sure if a strain-gauge sensor would work in this situation, heat-isolation apart.

The senosr needs a flat frequency-response from a few Hz up to several 100Hz, so that for example the admission pressure reading is equal across the engine's own range from tick-over to maybe the 300-400 rpm on a steam road vehicle.

Even if the strain-gauge itself could follow the pressure-variations it has to be mounted on a substrate or diaghragm that may not be sufficiently linear except at very low speed.

A piezo-electric probe is probably the better bet for higher speeds, and I think suitable ceramics are available quite easily and cheaply. They are after all used in telephones, buzzers, door-chimes, etc. (As a guide the note Middle A at 440Hz - matches roughly the typical full speed rpm of an overtype steam-wagon engine. Or perhaps a miniature loco on a rolling-road?)

It needs a suitable amplifier as the voltage output is tiny.

Nevertheless, an interesting area of experiment and study.

13/09/2021 09:51:01

Fine work, and a very interesting discussion.

I worled for a company making sonar equipment and did ponder the possibilities of a piezo-electric pressure-sensor for engine-indicating. I found that in fact this was being done in the 1930s for testing i.c., particularly large (marine and plant), Diesel engines.

'

Some have mentioned the Dobbie-McInnes Indicator.

In this, the steam pressure acts on a piston against a calibrated spring, and the amplitude of its motion is recorded against the scaled-down stroke on a pro-forma card clipped round a drum rotated by a cord and return-spring, driven from the motion.

To keep the indicator-card and the whole instrument compact but suitable for more or less any engine stroke, the drum cord is not attached directly to the cross-head but via a reducing-lever, either one attached for the test or some point on the lubricator-drive arm.

'

Engine Power:

The diagram gives more than the valve-effects and pressure at any point. The area it encloses leads to calculating the power generated by the steam inside the cylinder, hence "Indicated Horse Power" (IHP) - or indeed in Watts, of course.

Originally the area was detemined by tracing the loop with a 'planimeter', a manual, mechanical integrator; with the card clipped to a suitable flat surface. I don't know the mathematics and programming, but would the electronic system allow this from the transducer and piston-travel data?

(The early electronically-measured indicator-diagrams could be analysed only by connecting the transducer to an oscilloscope, photographing the trace then measuring the print.)

The output power available for the intended work, is the Brake Horse Power (BHP), measured from a dynamometer.

Thread: Maximum number of characters in a post.
13/09/2021 00:31:37

Brevity is the soul of wit, so they say. Of wisdom too.

So some tips that may help you:

I've sometimes prepared long texts in MS 'Word' (which has a word and character counter) then copied the text to the thread.

Ask yourself....

- What are you describing? The system or its every component?

- What do the photos show? Completed parts or detail machining?

- What is your aim? To suggest a lubrication system (with computer control??) in general, or to show your specific system?

- For Whom? Beginners needing step-by-step help, or reasonably experienced model-engineers?

- Would the work be better offered as a constructional series to ME or MEW - the latter perhaps more appropriate?

Really, a few carefully-chosen photos and brief notes on pipe sizes, fittings etc. should be sufficient to help others wishing to build their own version, remembering their possibly quite different machine-tools and facilities from yours. Reserve deeper detailing for the more complicated, specific things built for it, such as any pump, filter, etc.

You mention software. I am not sure where that is needed in what I take to be a machine-tool oiling system, but a programme listing might be better as an appendix, second article or offered directly by e-post.

Thread: What Did You Do Today 2021
13/09/2021 00:00:59

Thank you for the photos etc of Wortly Top Forge , Bazyle. That lathe has some very fresh-looking swarf in the buicket under it!

I do like these smaller, volunteer-run industrial museums as they lack the pickled-in-aspic-and-ignorance feel of one or two of the Big-Name places I have seen.

If you are Down South, in Somerset, Weston Zoyland Pumping Station Trust's work is worth seeing - and it does run its engines on steam, supplied by a large Portable Engine uinder an adjacent lean-to. Pride of place is its original, in-situ, Amos engine and centrifugal pump. The site was originally for fen-land drainage, on the Somerset Levels; and the modern pumping-station (not publicly accessible) is adjacent to the museum.

Though only open occasionally, there is an intriguing small-scale water-works museum just outside Sherborne (N. Dorset). The water-supply pumps were water-wheel powered and have been partially rebuilt to show this; but the museum also has a fine Hindley mill-engine rescued from another water pumping-station in the area, and run from a vertical boiler. The point this museum emphasises is the site's role in fighting the water-borne enteric diseases, especially cholera, that were as rife in small rural towns as in the the Dickensian, East End of London.

SE Dorset has its famous Corfe Castle ruins overlooking the restored Swanage Railway with its new, SR-trim, Norden Station serving a Dorset Council run park-and-ride. Between car-park and station is a small museum devoted to the local ball-clay mining, with a short represantative level. The site itself was not a clay-pit but was instead the transhipment point to the national railways for clay brought there by various narrow-gauge railways from pits in the surrounding countryside, and the museum's short 2ft-g. railway gives a somewhat limited and unfortunately not emphasised flavour of this.

While for the military-minded, Bovington Tank Museum is not ever so far from there.

++++

Me Today?

With Thanks to my appeal on the Wanted Classifieds -

I started sorting out the pre-loved gearbox I bought, err, a while ago, for my Myford ML7. I found the parts I feared lost, and identified the gears therein.

These included the output-side idler with several teeth missing (appropriate for me... ask my dentist!); and a brand-new stock gear I assumed the seller had intended modifying as its replacement.

So last thing this evening I made a split-collet from an oddment of aluminium scaffold-tube, for holding that wheel in the 4-jaw independent chuck.

Prior to closing up for the night and ensuring the cask ale in my local is up the scratch. It was.

Setting the wheel central and boring through for a bronze or 'Oilite' bush is the next task.

Thread: origin of CAD
12/09/2021 11:58:02

It is true by basic geometry that a line has no width or thickness, but it is not necessarily true that a line cannot be used to form a thin wall in CAD.

It requires simply giving the line a specific width, which may be only a very small fraction, effectively turning it from a geometrically pure line to a rectangle, for example.

In TurboCAD at least - which unlike as some people seem to imply, IS 3D-based - that is one of its ways to produce an extruded "solid"; but with two important caveats. Firstly the location is governed by the wall's neutral axis; secondly if the line is a full boundary such as a circle or polyline, the extrusion is "solid".

So drawing our example mug from a library cylinders or extruded circles, still requires creating a solid cylinder then subtracting from it a concentric inner one, stepped up by the base thickness.

'

One point about TurboCAD and I do not know if this applies to other CAD makes, is that it seems to use at least three ways to generate solids, giving each different characteristics hence different, often unexpected, reactions to subsequent editing.

To be fair though I say "seems" because I have probably missed something by very rarely using 3D CAD anyway. Wasting 100s of hours trying to learn it to no more than a very basic level made me realise it is both a major, very advanced computing skill, and of very limited, practical engineering value to me.

Perhaps the first choice is not of CAD make, but basic type. It is not a fashion-statement, so however heretical this may be to some, you may need or merely want for your own engineering an advanced isometric-first package, or a reasonably comprehensive orthographic-only version.

Then you need consider if you will be able to learn it. You may find it very straightforwards or an uphill battle, depending on the programme itself, the embedded, supposed "Help" menu, the available tutorial material - and your own ability especially if a CAD first-timer. I found the basic teaching material sold with the software very good - not a wretched video of an expert showing off, but a proper pdf manual, on a CD.

My choice? A programme whose big advantages over other makes, include giving both options very easily. So I occasionally try very simple isometric drawings as academic exercises, but use its direct orthographic "side" for all real, practical purposes.

'

Remember though, it's what we make that counts. The lathe is necessary, but the CAD programme may help.

10/09/2021 13:02:11

Interesting history and thoughts.

Dave -

I would take issue with one point you make. It may reflect what you and I were taught at school (or anywhere else) but the A-Level course I took did include two 3D representations.

Bearing in mind that whether T-square and paper or computer screen the image is physically 2D anyway, these were:

- Isometric projection (CAD packages seem to call it just "3D". Awkward and long-winded manually, but ideal for assembly-drawings and the like.

- "Lines in Space" - relationships between oblique lines that cross with or without touching, in three dimensions; and typically, determining the shortest line linking them. Our teacher warned us that if you don't grasp the principle at the start, you will find it very difficult. He was right there!

Coming to CAD from years of being accustomed to making and using only orthographic drawings, it is not easy to think in the isometric "model" first approach; and it can place a massive barrier to producing the orthographic drawings you need actually to make the item. (Assuming non-CAM methods.)

Consider what happens between idea and rough pencil sketch, and cutting the material.

Manual draughting requires a grasp of basic geometry and knowing the conventions for line-types etc., but the technique is relatively easy and intuitive; with a reference-book for the occasional, more difficult aspects like interpenetrations and developments.

CAD requires learning a far more complicated technique, specific to the particular make of software, albeit that it will draw things like interpenetrations far faster and more accurately than possible by hand.*

Depending perhaps on the make of CAD you use, learning to draw isometric models to any meaningful level is formidably difficult; and you still need the dimensioned orthographic drawings for the workshop. I use TurboCAD - which unlike Fusion and Alibre which I have also tried, gives direct isometric / orthographic choice; but I have not discovered if it offers othographic views from isometric models.

(TurboCAD also comes as a one-off, full purchase at a reasonable price, not costly subscriptions!)

.

Maybe it's a matter of realising that the drawing is as much a tool as the lathe.

We don't build a miniature engines or clocks, say, because we have a lathe. We buy the appropriate lathe because we want to make engines or clocks. Also, it is clearly better to have the tool capable of reasonably more than we will use it for, than find it disappointingly lacking for the occasional more complex or larger item.

Similarly with CAD. It makes sense to buy the most sophisticated you can sensibly afford - professional quality even if a lower-priced edition - reasonably confident it will give you everything you will need for your engineering in your workshop. (Some of the beautiful pictures on TurboCAD's Users' Forum suggest pure art, not to guide making the items!)

'

You say "design" is hard. It can be, but CAD is a drawing tool that helps us design the thing. We still need understand engineering principles; but I submit that learning the electronic drawing tool is a separate and very advanced skill.

I do not agree that it is harder to convert from orthographic manual drawing to CAD modelling, than to learn full CAD without previous experience. If anything the latter ought be harder. Whether meeting CAD as engineering-draughting "virgins" or orthographic "old hands"; it is still a new, highly-specific, extra skill; but if already having engineering-drawing experience we need "only" learn the specific CAD edition.

'

What counts too is our ability to learn that CAD package; and what we hope it can do for us.

Some will find it easy to learn and soon knock off the complete set of workshop, orthogonal parts prints from their full-coloured G.A. "model" of their intended 7-1/4" 'Britannia' or 19C-pattern Regulator Clock.

Others may take a little longer.

Others still, may like me find the pictorial option so difficult that we waste valuable workshop time trying, so are better sticking mainly to the relatively simpler orthographic "side" the programme offers.

'

I have been haughtily told that I am not using CAD "properly" by drawing directly in 2D although TurboCAD is a comprehensive 2D/3D programme.

Rhubarb! I am using it properly, but keep the 3D side only for very occasional, very simple tasks (one was a geological diagram!).

I can manage rather rough drawings dimensioned accurately but printed not-to-scale: adequate for my projects in my workshop with my equipment. If others use the 3D-model first route, fine. I acknowledge and respect their greater abilities, but this misses the point:

... That however we draw things, it's the physical objects we make that count.

''''

* (I don't know if TurboCAD can plot developments of interpenetrations it can certainly show in 3D Model form. Investigating for my wagon boiler's cladding, two cylinders forming a 'T'-piece, I could see only having to adapt the manual technique shown in a 1930s text-book.

I considered calculating the co-ordinates by spread-sheet, but though I can translate Algebra into Excelese, designing the Algebra would be impossible. I'd need calculate only one quadrant as the joint is symmetrical, but think each edge-point a 3D co-ordinate set from its own sextext of simultaneous, trigonometrical equation

Thread: Cutting a 1/2" bsp thread on Harrison L5 help
10/09/2021 10:14:43

Thank you Jason -

Just dug out my copy of the manual.

What confused me was that the top shaft wheel on my L5 is of 20T and appears not removeable as the book suggests it should be, whereas the table in the book is for a 40T top shaft wheel for 14tpi.

It gives 40 - 100(idler) - 70 then gearbox position A... 2:1 reduction; but for my lathe I need 20 - idler - 70 and C (1:1).

Fizzy -

The plates on top of my lathe are all worn away too!

Though not cheap I suggest you buy one of Tony Griffith's (lathes.co.) facsimiles of the L5 manual. It is a very comprehensive operating and servicing book, and includes the change-wheel tables for both imperial (any thread-form) and metric threads. If you are going to do a lot of screw-cutting it would be worth hanging copies of the tables up by the lathe - you could laminate the copy or protect it simply with a polythene bag.

09/09/2021 23:37:58

Jason -

The leadscrew on an L5 is of 1/4 " pitch, not 1/8" . At least on mine it is.

Verify the tooth-count on the spindle pinion: on my lathe it differs from that given in the manual.

Otherwise, depending if a 40T or 20T pinion and my arithmetic not being all up the creek:

4/14 = 40/140 = 20-idler-70

or perhaps 40 - [70+30] - 60 (compound).

The leadscrew gearbox should be on the 1:1 position (I think that is "A" ).

Thread: Why do designers do this!!
07/09/2021 18:27:56

With cars of course the value-engineers have had their go at at it, and the stylists have to - well, are paid to - make the exterior look as snazzy and saleable as possible. If their unholy combination results in having to take half the bodywork apart to change a lamp.... tough.

I have a Renault Kangoo and have just had to pay a lot of brass better spent on model-engineering to replace the worn-out, possibly original, HT components (now at >50 000 miles). A task that years ago would have been obvious to diagnose and a couple of hours' work for any motorist with basic maintenance knowledge. And as for the so-called "cabin air filter".... Goodness knows where and how that's hidden! I found several amateur videos showing the secret but they revealed only any edition of the Kangoo except mine, and all different.

Ironically the bureaucrats keep insisting on tighter and tighter "type approval" rhubarb, but the concept of making it easy for the owner to keep the car legal even when on a cold, wet dark Winter Saturday night, and far from an over-priced main-dealer, seems lost on them.

Thread: Good workshop practice? NO.
01/09/2021 17:02:56

Using pump pliers to turn a die can easily result in snapping the die in half, which won't help.

I'd suggest you obtain appropriate die-holders and tap-wrenches for the tools you have.

Thread: Stringer EW lathe
31/08/2021 18:02:23

Nicely set up, Jamie.

One point to note... a contributor much earlier mentioned "self-act". The facsimile literature from Tony Griffiths stresses that the EW is not intended for that in its standard form. Its change-wheels are for screw-cutting "only", and theoretically only to TPI standards.

Yet it did me proud when I used it to make a special CO2 cartridge connector having a non-standard metric thread!

It also came into its own even before I'd mounted it on a bench with motor etc. I needed to make a strainer from PVC pipe, by hand-drilling over 100 holes, with a battery-drill, through a guide-block clamped on the cross-slide; and indexed for both radial and length by sighting to felt-tip pen marks on a large change-wheel.

Long prior to buying a similar QCTP set I made a set of tool-holders from m.s. rectangular bar, to take bits ground from broken or worn-out centre-drills and the like. Though not having the QCTP repeatability it still saves a lot of shim-shuffling at each change.

No-one seems to have the change-wheel guard on theirs. Nor does mine although I have all the rest of the listed extras. It could be that few people bought them new so the ones we find never had one in the first place!

Mine lives on a trolley made from angle-steel topped with a sheet of a very hard material rather like one of the Tufnol SRBP range, an off-cut from a laboratory bench at work. My 18th birthday-present and second-hand then, it too is intended as the "indoor lathe" when the nights are too dark and cold to encourage an expedition to the workshop; but the poor old thing needs some serious attention to bring it back into proper trim.

Thread: Bassett Lowke "Eclipse"
31/08/2021 17:30:57

Good to see these old designs given a new lease of life.

It's a simple, attractive design and one open to all sorts, such as making a twin-cylinder version.

How did you convert the numbers? Simply by remembering as I do several nearest equivalents (e.g. 5/16" ~ 8mm) then basic mental arithmetic for the in-betweens? (5/32 ~ 4mm, etc.) A lot of the BAs have close though not exact M equivalents too. (5BA ~ M3).

Thread: Sheet metal saw.
31/08/2021 17:05:44

I've found that too, and it seems tightening to just under flexing the plate is the only option. So I'd be glad too if someone can give us the proper solution.

Thread: THE NUMBER 9 !
24/08/2021 21:54:34

Thank you Duncan.

I'm glad I was not the only one who'd not spotted the invisible brackets that make it work. 

I've never seen a clock like that previously.

Anti-clockwise clocks yes.

A clock with its otherwise plain dial given coloured segments to show pub opening times, yes.

A clock with fancy single-digit sums though.... No. I like it!

Edited By Nigel Graham 2 on 24/08/2021 21:55:11

Thread: What Did You Do Today 2021
24/08/2021 21:45:27

Completed, apart from painting, the upper part of the choke for my steam-wagon's chimney.

I had sought advice on here ooh, quite a while ago now, about designing these things so thank you to those who responded!

Time will tell how effective it is, but it's a fabrication of thin sheet-steel (ex- central-heating boiler panel) for the cone, a top ring and flange, both turned from solid; the latter for screwing it to a flange on the of the petticoat pipe.

MIG-welded together. Sort of. Luckily it will be concealed in the depths of the high "stove-pipe" outer chimney.

'

Then a pleasant evening at the club track. The evenings are certainly drawing in!

Thread: THE NUMBER 9 !
24/08/2021 15:04:06

Hee-hee! I like it!

I'm baffled by the 5 o'clock one though.

How does the square-root of 9! = 6 as I read it; or come to that the square-root of 8! = 5?

Nor does it work by the factorial of the square-root of nine.

Thread: Brainteaser
24/08/2021 14:56:02

You don't need apologise, Michael! I was not offended or anything! smiley

24/08/2021 11:54:19

Michael -

I know the word sought had nothing to do with engineering.

Splitting co-gnoman into cog-noman is a typical cross-word play on words, in this case using the mechanical suggestion as "A submarine specimen misleadingly listing to port"!

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