Member postings for Nigel Graham 2

Michael -

I can assure you I've not listed you - or anyone - as "Ignore"!

I'll have a look at that link you cite.

Sorry Chaps - you've lost me with that abbreviation - MOI?

I'm not trying to place " constraints " on anything. Nature does that, imposing learning limits as natural as height or eye-colour. I do not choose mine, but wish they were a lot wider.

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" 3D in MOI is really a case of imagining your model/structure... [of a subject] ... defined by a plan view ... "

I understand that, probably true of all 3D packages.

I can imagine the subject, both in three dimensions and in plan.

I can't understand how to turn that 3D mental image into the 3D CAD model version; i.e., with using the software as I had hoped possible!

Another thread shows how to model a tool-post key in 3D in FreeCAD. I could do the same in TurboCAD, without minor details like chamfers; but only because it is 5 symmetrical elements I can join on one axis by co-ordinate calculations. Such sums are theoretically not necessary; but anyway impracticable for drawing the model dinghy or aircraft wing.

(By "minor details" I meant minor only on the drawing - the real thing needs the chamfers, but if unable to draw them I would use text descriptors instead.)

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" ... would not meet BS308 standards... "

If I had to meet such artificialities, I'd be a fully-trained professional who obviously always found CAD very easy to learn!

However, I would like to be able to do things like adding automatically correct dimensions to useable drawings of correctly-sized objects; rather than having to use guesswork, text-editing and untidy, mis-aligned dimension lines.

(TurboCAD lets you Snap dimensions to their true points, but it doesn't let me do that. I can only use the cursor only, by eye. So the objects are accurate, but their dimensions very inaccurate and untidy; even when I carefully follow an introductory exercise. Nothing indicates what I may have missed, mis-read or mis-set, when or where.)

Yes - that's a classic example, R Johns!

I'm surprised someone managed to put the tool the wrong way up though. Was it just the cutter the wrong way round in the collet, or the entire collet chuck upside down?

Gary - thank you for your very kind offer!

Unfortunately I live in South Dorset.

I'd stick to TurboCAD - having made a little progress and started using it to help me design my steam-wagon engine it would not really help me to try to learn a very different package. I did briefly try Fusion but with no success. The snag is that there is an entire mint of pennies to drop, and none are at all intuitive.

The TC User's Forum Gallery shows very many wonderful brochure-quality pictures, both engineering and architectural, but I think they are all by full-time designers who use TurboCAD professionally.

I don't know anyone locally who uses TurboCAD, who could help me.

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Blowlamp - I think you're right, at least as far as 3D CAD modelling goes, but I would like at least to make ordinary orthographic workshop drawings with it. I am not bothered about those brochure pictures, but I'd hoped to be able to learn the 3D mode as an adjunct, for such things as assembly-drawings.

I read the above with interest to see if FreeCAD might just possibly be simpler than TurboCAD.

However I saw that, Dave Smith 14, your remark,

" I particularly hope Nigel Graham2 reads this and has a go following the guide lines you have described. It is not rocket science using 3D modellers,... "

No it isn't - and the designers of Yuri Gagarin's capsule had to make do with their People's Glorious parallel-motion drawing boards, like the one likely to remain in my dining-room for my benefactors.

Unfortunately my experience with TurboCAD and brief excursions into other makes shows 3D modelling is literally too much for me; in quantity as well as difficulty. It's unlikely then I could follow your third-party suggestion.

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TC differs from Alibre, FreeCAD, Fusion etc. in giving a direct 2D or 3D, choice. I think you can take elevations from its model views, but I don't know how.

I can use TurboCAD enough for rather rough orthographic drawings, manually editing the approximated dimensions so they read the right values on prints to anything but scale.

I don't normally find 2D drawings the perceptual problem others claim justifies CAD 3D pictorial models, unless the elevations are particularly complicated. I am used to many years of reading orthographic engineering drawings and Ordnance Survey maps. However I first encountered at work, the 3D picture on the workshop drawing to help the machinist visualise what the CAD draughtsman thinks feasible to machine. Hemingway Kits do that too - but on designs feasible to machine!

I am aware of the trap of mixing First and Third Angle with the risk of mirror-imaging or similar errors. (Hence the convention of a simple cone with end elevation in the drawing's title block.) I expect CAD holds its own traps for the unwary though.

Alibre's at it again - e-posting me things I can't use! This time I'd left Atom loaded, but when I tried to open the simplest of several exercises they'd sent, Alibre told me (more or less), "SHAN'T! Licence expired!".

Clearly one department not knowing what the other's done. Mind you, the exercises all looked far more advanced than that scribing-block in the MEW series.

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Tried again following the introductory exercise on the introductory CD issued with the TurboCAD programme itself. At least it uses step-by-step instructions, not a wretched video of an expert showing he finds CAD easy. At the dimensioning stage it all went to rats as every attempt to dimension it as it told me, failed on an error message about no snap points or something. I found I have to dimension objects only approximately, by eye, then edit the value texts to the right numbers; so defeating one of the programmes' main features.

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So what now?

Obviously, I can't learn 3D modelling. Unfortunately though, nor can I learn 2D (orthographic) CAD drawing beyond a very basic level.

Is CAD for me?

Well, yes, but only at a very primitive level of rough, single-layer, 2D drawings with semi-manual dimension and line-type editing, and non-scale prints. Its only advantages over manual drawing are such as easily copying objects around the image.

Possibly, Neil, if it's a gear- rather than centrifugal- pump.

Another reason may be the material used for its bearing. Some plastics are hydrophilic, tending to swell slightly, so though otherwise suitable for low-cost bearings might bind on the shaft.

Or, much simpler, it might contain mild-steel in a combination that would simply corrode rapidly in water.

Assuming nothing as simple as the device being partially choked by scale or water-treatment additive. Also assuming the water-inlet strainer is not choked enough to starve the injector under full draw:

My first thought is the injector is taking in air through that leaky water-valve. The valve will emit water when the injector is off, but being on the suction side of the device may allow enough air in to stop the injector's action.

Ditto anything else on the water line. You don't say what this injector is on, though seems directly on the water-tank. It's not easy to determine from the photo, so I took the liberty of copying it to be able to enlarge and rotate it to view from different angles; a bit puzzled by what's "below" it in your original.

If as seems the installation is directly on a tank wall, it ought be almost as reliable as if actually inside the tank.*

Next, try the condition of the overflow valve in the injector itself. It is in the suction half of the injector, depending on the depression in the combining-cone to close it.

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Repairing the valve may be possible depending on its design. It looks like a plug-cock. Leaking past even new O-rings suggests a worn spindle. Refurbishing the plug and bore may be as straightforward as lapping them together.

Is the plug retained by a nut and washer on a threaded tail? Also a potential leak-path though not so likely because the main sealing surfaces are the plug and taper-bore walls.

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Finally, the control-rod connection looks quite rigid. It may be better if slightly flexible so any slight misalignment does not put unfair radial strains on the plug and seals.

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*I asked because if on a loco or traction-engine with a water-tank in a tender or driving-truck, I'd suspect also the flexible hose needed in the water line. As I think DAG Brown points out in his book on injectors, the simple hose pushed onto the pipe-end can allow very fine air-leaks not obvious if the valve is upstream of the hose. One cause is the hose material stretching and age-hardening slightly.

Earliest fictional amphibian I recall was Freddy the Frog, in a children's comic otherwise long forgotten to me!

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I forget where, a geology text-book probably, but I once saw a reference to a very early (BC?) Chinese seismometer whose ornate indicator was based on bronze frogs that dropped balls from their mouths. I don't know if the number of disgorged spheres related to the severity of the earthquake.

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Likewise Brian - I thought Martin was studying this for his forthcoming best-seller, The Development of the Railway Point From The Mines Plateway Stub to the HS2 Diamond Crossover.

Right then, who's going to risk it, buy some of these various blades, and review them for us!

I think I have some of the Vitrex abrasive blades and Abrafile clips, somewhere(!), and when I'm recovered enough I'll given them a go on off-cuts of steel.

Regarding the Japanese blades being for a particular saw-frame, I would not think it too hard to make adaptors to suit an ordinary hacksaw. Or for a power fretsawing machine?

Following that, and more generally, it's worth building a reasonable library of model-engineering reference-books.

Some will give you the appearance of trapping you into making machine-tool accessories for ever more, but collected in a reasonably discerning way, they accumulate a wealth of valuable information on techniques, materials etc directly relevant to us in our own workshops.

The Workshop Practice series is very good, and I have about 10 selected by relevance to my workshop and projects. They are clear, concise and each details a single field of skill. Those by Harold Hall on machining techniques do use specific projects but to help you both master the methods and equip your workshop in a reasonably no-frills way.

Another single title is Geo. Thomas' The Model Engineers' Workshop Manual - though at first sight this looks like the tools-to-make-tools sort aimed at very experienced model-engineers, it contains a lot of valuable information, thread-tables, etc. (To be fair this book does address that reputation!)

Much older books can be useful too, because they were written to show how to make things with quite limited equipment, as was common in their day.

Also look for books on model locomotive building and operating - not ones specific to individual projects though they can be helpful, but more general ones.

Have a peruse of TEE Publishing's web-site. They usually have a stand at the major exhibitions, too.

I can understand wanting to reduce weight for transport reasons, but is the locomotive really front-heavy? I'd be very surprised, since considered just as a dead-weight the cylinders would be balanced very much by the firebox.

Looking at photos of this loco, it seems already rear-heavy by having the cylinders behind the smoke-box and leading wheels, with the much of the load including the cylinders carried on the rearwards-set coupled wheels.

I would think its weight is quite well balanced, but on a miniature, aluminium cylinders might not be significantly lighter than bronze or cast-iron ones with excess metal cut away; as part of the loco's total weight..

Besides, the loco needs to be heavy for adhesion.

Not dimensioned, but labelled sections of both the drain-cock and the operating-valve in the Handbook for Railway Steam Locomotive Enginemen, British Transport Commission, 1957. There is very little text with it, the diagrams being sufficient.

It's quite an elaborate device considering it simply sends steam to the drain-cock itself, and releases it on closing.

I've scanned it and would include it here if I had any idea how!

The Japanese blades advertised by Axminster look like copies of the Bestway product, but note the small-print on the Axminster site: "... case-hardened..."

That suggests they are made from mild-steel, and intended for cutting only thin wood.

"Vitrex Radial Hacksaw Blades" are the TC tools made and sold for cutting tiles, and readily available from builders' tool stockists. They are abrasive, not toothed, so might not be suitable for metalwork, certainly not softer metals that will just clog them.

Does anyone know if a pond pump would work as a suds pump, or whether, as possible, it uses natural-rubber parts that the oil would attack?

I do have a Stuart circulating-pump saved from the skip, but that was made for, and only used for, water. I'm not sure of its type: peering into the outlet, the impeller doesn't look like a conventional centrifugal type.

In which case, oh dear!

It's the root diameter of the existing thread in the nut that would count first.

8BA - 2.2mm nut root

3/32" - 2.4mm screw OD (neglecting crest rounding, probably insignificant.)

So if the intended fitting is indeed 3/32" BSW with only 0.1mm (0.004" a side you'd be heavily "modifying" rather than replacing the existing thread, which suggests having to replace one of the two fittings to be sure of a secure fixing.

Likewise.

They seem no longer manufactured, and the nearest available now, at least easily, is the abrasive type intended for cutting ceramic tiles, and a lot shorter than the original Abrafile.

I have not experimented with cutting metals with them. They may be all right on steel. may be fine on harder steel like gauge-plate and might even cope with tool-steel, eg for roughing out an HSS blank.

I think they would clog very rapidly on aluminium alloys, copper and its alloys, and plastics.

I seem to have less difficulties with high speeds as low ones. There are times I want the machine to run ate less than its available speeds.

I've fitted 3-phase conversions to the Myford 7, Harrison L5 and BCA jig-borer, will be fitting one to the Myford VMC Mill; but these systems want the motor to run fast so even on the lowest pulley or back-gear sometimes the ML7's speed dial is verging on the yellow.

The problem is greater on conventional machine like my Meddings bench-drill if I want to use something like a hole-saw, or even its largest twist-drill (1/2" in steel. The answer there is an old, very care-worn Progress 2G drilling-machine, dedicated to slow-speed work, but I've to find room for it yet. At the rate I'm going the workshop won't have room for me to do any work in!

When it's the Denbigh horizontal mill's turn for returning to service, that will have a conventional single-phase motor but large reduction, possibly by gears as well as belts. (I bought it with a ramshackle confection of motor, old car gear-box and improvised chain-drive on an angle-iron tower straddling the mill itself.)

The SFM guides are generally drawn from trade practice yes, but they also tend to assume large, very rigid machines many of us don't have. They can be useful guides, but I regard them as maxima more than optima.

They also assume self-acting feeds to keep a consistent cutting rate that can be difficult to achieve by hand on long lengths or across large diameters.

If you obtain good results with what your are using and doing, stick with that; but there's no harm in upping the speed for small diameters and for drilling small-diameter holes; in free-cutting materials. Use lubricant where appropriate though.

Incidentally when I am turning, I listen to the cutting as well as watching it, especially if I'm brushing on a lot of coolant that obscure the revolving cut surface. it's highly subjective, but I find if the cutting starts to sound a bit harsh, it may mean I am forcing it a bit and tearing the material, or the edge of the tool has begun to dull. Or both.