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Member postings for Nigel Bennett

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

Thread: "Invicta"- Photos wanted
20/10/2020 09:36:06

Thanks, Russell; that was extremely helpful. I wasn't expecting to find anything on YouTube! is the one about Invicta.

20/10/2020 08:20:50

Yes, I realise that building a model of an unsuccessful prototype is not the best way of guaranteeing success in miniature. However I hope that I can size the cylinders to the boiler size and get something that will pull me. At least I will have more boiler pressure to work with than the original at 40psi. Will I succeed? That’s the fun of model engineering!

Brian, yours looks like a workmanlike job, but really, Canterbury Lamb by LBSC is essentially a Tich with slip eccentric valve gear, and the whole mangled about to look like Invicta from a distance. For obvious reasons; to make it work!

Edited By Nigel Bennett on 20/10/2020 08:26:52

19/10/2020 09:18:28

I have recently become fascinated by the Canterbury & Whitstable locomotive Invicta, and I'm currently trying to create a 3D CAD model of it with a view to building it in 5"G as accurately as possible. That two-wheeled tender appeals to me!

LBSC, of course, designed Canterbury Lamb in 3.1/2"G, but it's only a vague resemblance and nothing like the real one.

I am considering fitting mine with a marine type boiler, which will look something like its current form. I don't expect I'll win IMLEC with it, but it might just about pull me, and maybe almost equate to the performance of an LBSC version in 3.1/2"G.

So is there anybody in the Whitstable area able to nip into Whitstable museum to take some photos for me? As I live up in Leeds, nipping down there on my bicycle won't be just an afternoon's jaunt...

I'm particularly interested in the arrangement of the cylinders and steam chests, especially at the rear where the exhaust connects to it. None of Mrs Google's holiday snaps shows it very clearly. I have also no idea how the feed pump is driven.

If anybody is willing to help me, I'm happy to reimburse any expenses; PM me and we can discuss. Thank you!

Thread: Copper tube for boiler
17/10/2020 09:42:26

Hello Sam

Table Y seems to list a number of different grades of copper. Ideally you should get BS EN 12449 (C106) Phosphorus de-oxidised copper, which is probably what ME suppliers will sell you.

The wall thickness of a traction engine boiler is more a function of its strength as a stressed chassis; having the machine run over unexpected holes or kerbs when you're driving about is likely to put far more stress on the boiler than its internal pressure. You need a really good throatplate to barrel joint!

2,5mm wall would be about right for pressure purposes at 80psi, but regardless of the working pressure I think I'd want 3mm wall for a road vehicle.

Good luck with it; you'll need plenty of heat when you come to make it. Practice your silver-soldering first on some bits of steel or something so you get the feel for it without it costing you too much in materials. Don't just start on the boiler if you've no experience. There's plenty of literature about (especially old ME articles) on boilermaking.

Thread: Advice on Collets
16/10/2020 18:25:20
Posted by MC Black on 16/10/2020 13:58:04:

I purchased a set of ER16 collets in Imperial Fractional sizes for my lathe.

I was VERY surprised to find that three of the set were actually labelled in metric sizes even though I had ordered Imperial.

The collet in the box labelled 5/32 is actually marked 4-3
The collet in the box labelled 7/32 is actually marked 6-5
The collet in the box labelled 9/32 is actually marked 7.5
The collet in the box labelled 5/16 is actually marked 8-7

I complained to the seller and almost 20 messages went back and forth - but I might as well have banged my head on a brick wall for all the good it did!

I resolved to stop buying things from China if I wanted any sort of Customer Service!


I really don't know what your problem is. 5/32" and 4mm are so close that no collet maker is going to bother creating an imperial version of what would be exactly the same collet - it just does not matter what they are marked; they are fit for purpose and will grip the Imperial dimension stated on the box.

The range of ER collets in these sizes is 1mm as you can see by the marking, and if they cover the Imperial size you need, then why kick up a fuss? If I was that bothered, I'd get a little diamond engraver and etch the imperial size on myself.

I'm so glad the UK went metric 50 years ago.

Thread: Locomotive wheels
05/10/2020 13:27:27

Definitely cone your wheels if you're thinking of running it. On my last three locos I've not had the bother of simulating the tyre - because I've fitted shrunk-on steel tyres as per prototype. I would imagine on a 4-4-0 like Salisbury you'd be fighting for adhesion anyway, due to the less than ideal weight distribution. Steel tyres confer a much better grip.

Thread: 3/16 Cast Iron Rod
28/09/2020 13:09:40

3/16" cast iron would present great difficulty in manufacture, as it would chill spectacularly and you'd end up with something ferrous that would snap if you looked at it. It would also be extremely difficult to machine. It's simply not practical to make it. Having said that, if some multi-national wanted to produce it by the mile, they'd find a way of doing it.

So I'm afraid you're going to be knee-deep in cast iron dust!

Thread: Mounting a collet chuck.
24/09/2020 14:49:42

Hello Andy

I hope the backplate is big enough to fit the chuck!

it's normal to turn the backplate register so that it fits the collet chuck very closely. What is most important is that the front face of the backplate, where the chuck fits, is skimmed absolutely flat to provide an accurate location to avoid wobble. Having achieved a good fit on diameter, you then need to drill and tap one or other of the items to hold them together; using the one to spot the holes in the other is the usual way. Fit the thing together and do the screws up. Job done. In theory...

If the PCD of the existing holes in backplate and chuck don't agree, then you'll have to choose a suitable orientation for them to get some metal in the appropriate positions.

However, it's very likely, looking at your backplate, that the turned register on your backplate could be smaller than the female recess in the chuck. (If it isn't, just turn it to a good fit as above.) It can still be used if it's too small.

Having got the bits together and done up the screws, clock the tapered bore of the chuck with a good clock gauge. Unless you're really lucky it will probably be a little bit out. It's a case then of dismantling, skimming off a small bit on the diameter of the backplate register and re-assembling with the screws gently nipped up. Clock up the bore again and use a soft hammer to bop the chuck true to the clock gauge. This may take some time (and bops) and may even involve skimming off a bit more of the register diameter, but persevere and you'll get there. Tighten up the screws a bit more and re-check with the clock gauge - it may need further bopping. You should be able to get it to virtually zero runout.

Then, before you do anything else, I would then drill two little dimples, one in the backplate adjacent to a Camlock pin, and another on the lathe spindle close by so that you can re-fit it in the same orientation. Fill both with red paint. (I've done that on my Boxford 280 and all my chucks are marked.)

Hope that helps!

Thread: Scrappy Haul (50 HSS Pieces)
21/09/2020 12:40:49

What a haul!

Whatever you do, don't try to use the large end-mills by holding them in a lathe chuck. Cutters that size are nasty, horrible, malevolent things that will try to remove parts of your lathe, job and anatomy with distressing results unless they are properly held. You will need a proper collet chuck and a big milling machine to use them.

Don't ask me how I know...

Thread: Burgess BK3 MK2 capacitor
17/09/2020 21:13:18

It says 4 microfarads on mine.

Thread: Dart 7 1/4 loco Martin Evans
07/09/2020 11:46:01

In ME in 2014 or so, John Smith did an update of the design to make it a lot more true to prototype. Lots and lots of detail work if you fancy that!

Thread: Tender wheels
28/08/2020 16:04:18

I'm sure Mrs Google's holiday snaps will tell you the number of spokes.

However, I suggest you have a look at John Heslop's account of machining his Royal Scot wheels from solid. ME 4033/4035, back in 1997.

Thread: Workshop Equipment
21/08/2020 17:35:21

Hello Pauline

I'm with Leeds SMEE. Sadly we lost our track at Eggborough Power Station last year due to redevelopment, but we're on the hunt for another site. We used to meet at Darrington Golf Club for formal evening meetings, but until we all get vaccinated or something, it doesn't look like starting up again any time soon. Like a lot of clubs, I imagine!

Our website: **LINK**


21/08/2020 14:35:52

Hello Pauline

It sounds as if you've taken on a challenge with your proposed RR aero engine!

A combined lathe/milling machine is very much a compromise, but an excellent one if you're short of space. Having a separate lathe and milling machine is much to be preferred. Remember that a milling machine takes up a lot of room if you factor in the full movement of the machine table.

People will argue ad infinitum as to the merits of this or that machine tool. Assuming it's big enough, any half-decent tool can turn out excellent work if the operator is up to the task! If you buy a new one from Chester/Warco/Axminster or whoever, you'll have some sort of comeback if it turns out to be a "Friday Afternoon" machine. Second hand, it's a bit of pot luck, but doing some kind of test piece on such a machine should help to assuage doubts. You are allowed to walk away if it doesn't suit!

You need to consider what you are going to make and how big your components are likely to be, but remembering that a bigger machine can do smaller stuff.

Having selected the sort of size of machine that you want, then that narrows down the choices. I would agree with the Davids above that a DRO on a milling machine is an excellent investment - I wouldn't be without mine. (I have a Chester Lux mill and I've been very happy with it.) You are really likely to reap the benefits from a DRO if you're making aero engine parts - especially if it's a V12 or something...

I think you will find that you will use the milling machine far more than the lathe for your projects, so that's the one to mull over most of all.

As an aside, I'm in Garforth to the east of Leeds, so if you need an extra pair of eyes to look at something with you... PM me if you would like.

Thread: Who trains these ideots?
18/08/2020 16:08:20

Our plumber, on the other hand, is magnificent. We called him out a while ago because there was no heat in several radiators. He had a wander round, gazed hard at a section of floor in the landing and said, "It'll be there. Blocked up with magnetic particles." We pulled up the carpet to expose the floorboards, where many years ago I had drawn a circuit diagram of what pipes were underneath. We unscrewed a floorboard - I always use screws when I'm replacing floorboards over pipes. He pulled out a magnet - and it stuck to the copper pipe. Quick job with a hacksaw, blowtorch and some new fittings and bits of pipe and job's a good 'un. THAT'S what you pay a plumber for!

"Can I have a look at your engines now?" he asked when he'd finished...

Thread: Copper boiler plate flanging, or not?
09/08/2020 20:14:28
Posted by Paul Kemp on

As an aside I have heard more than once the simplex boiler was not compliant with the Australian code but do not recollect a definitive reason why not. Does anyone have a definitive explanation as to why it does not comply? Too low FOS may be due to many reasons, plate thickness, joint design, stay size and spacing or type etc. Where exactly does it fall down?


It’s the crown stays; the Australians don’t allow girder stays. Despite their use in full size boilers, particularly road steam and portable engines, they insist on rod stays between firebox crown and outer wrapper.

Thread: Training school auction
06/08/2020 12:49:52

Gosh! There's a hell of a lot of stuff there. With so many identical bit-too-big for the average model engineer lathes for sale, I can imagine they'll go for peanuts and then be shipped overseas. I do wonder about some of those cupboards plus contents, though; if you bid and won one, how much of the contents would you actually get?

Thread: Starting Small Holes
30/07/2020 09:56:21

I've had a job of drilling 1/32" holes in the end of 1/8" dia brass bar, in the lathe. Normally I would start with a centre drill but the smallest centre drill pilot is to large.

Why is it too large? It isn't necessary to make the centre drill open up the hole to its full pilot diameter; all you need to do is to make a small dimple, slightly smaller than the hole size you want. (Same with spotting drills.) If you make the dimple slightly larger than the final size, you'll be left with a tiny countersink around your final hole size.

Thread: Bar clamp
25/07/2020 15:36:24

Hello Tony

What's the application? Is it something you will adjust frequently or is it a fit and forget job? How much time and effort do you need to spend on making it?

Slitting the "dark" is a good way but be careful if using cast iron outer and the bar is a loose fit as it may break when you tighten it up.

There are quite a lot of ways of "claiming" the bar; I suppose the simplest was of clamping is a grub screw or similar. However unless you take precautions it will mark the bar, and it will also tend to force the bar slightly out of axial alignment - how much will depend on the clearance between the parts.

I imagine by your "2 part cotter pin and bolt" that you mean those split clamp affairs. They're good, and give excellent clamping. They don't mark the bar, but again they do tend to force the parts out of alignment as the grub screw does.

Another way is some kind of collet arrangement; tightening this up will give an excellent grip and maintain concentricity if you've made it correctly.

Thread: Making sense of big numbers
25/07/2020 09:28:08

I liked the story about a chap (It may have been a story on Monkey Cage) who was explaining to his audience that the sun was going to envelop the earth in a few billion years.

One chap stuck his hand up and asked, "Did you say billion or million?"


"Oh - phew! Thank goodness for that. I was sure you'd said million."

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