Member postings for julian atkins

Hi John,

Thank you for the above very helpful posts and detail. One of the most interesting and informative series of posts I have read on this forum.

Mike, good luck with the clock!

Cheers,

Julian

With the greatest respect there is no evidence that what Sean is proposing to use is silver steel!

There are various simple tests for silver steel.

If Sean's material is not silver steel then a lot of the above is academic, as is Sean's aim to harden and temper the material he has.

Cheers,

Julian

Hi Stewart,

My advice would essentially be the same as that provided by Simon Collier - join a decent club and get involved.

The questions you posed are very broad.

If you ask a room full of model engineering club members the same questions you will probably get a different answer from each of them.

If you want to build a miniature loco to do a job of work and haul passengers rather than for display or just as an engineering construction exercise then you really do need to join a club.

Firstly you will need to run the loco somewhere when completed.

Secondly the condition of that club's track will have a bearing on what loco you choose to build - the obvious factors being whether ground level or raised track and the gradients.

Thirdly you may not like it! Operating a miniature loco requires a great deal of heavy lifting usually and a suitable car. You may find that leaning over a tender to get at the controls is uncomfortable. You may not like inhaling large quantities of smoke. You may not like all the mess and muck associated with running a miniature loco.

As for choice of loco and gauge, it is no secret on here that I would never suggest anyone build LBSC's Tich, and I would never advise anyone to build Martin Evans' 'Simplex'.

For a beginner I would suggest avoiding anything with a tapered barrel boiler and belpaire firebox, avoid anything with a combustion chamber, and avoid anything with piston valves. I also dislike sloping grates, marine type boilers, and anything with a long tender.

Certain well known designs have well known faults, and are best avoided unless you are prepared to depart from the drawings. Certain designs are not really suitable for a beginner and some are considered very poor.

So, I would stay clear of anything designed by Greenly or Jackson/Clarkson. I would stay clear of some of Keith Wilson's designs.

Also consider designs that have a construction series in ME/EIM/LLAS.

Have a good look at Don Young's designs (see Reeves website). Usual disclaimer.

Cheers,

Julian

Edited By julian atkins on 18/12/2017 08:47:32

Hi Dave,

You have to bear in mind that when Hackfly was published in ME, Martin Evans was desperate for any miniature loco articles to fill the pages.

Issue after issue contained articles and letters by K N Harris, who at every opportunity criticised LBSC.

K N Harris and Turpin were friends. Turpin himself had written about his 5"g loco 'Hybrid' in 1956 in a manner that was not exactly 'modest'!

Note that K N Harris acquired 'Hybrid' from Turpin.

LBSC was very well informed and knew of the link between Harris and Turpin.

LBSC was wrong to resort to personal criticism of Turpin, but that was LBSC!

Cheers,

Julian

Hi Dave,

Hackfly was indeed an atrocious design. It was perhaps the worst point in the history of the ME magazine.

It was atrocious and awful in virtually every design detail.

Given that 'tyro' model engineers often build miniature locomotives that are not the best designs and end up disappointed after spending a great deal of money and spare time, I think LBSC was quite correct to criticise the design. He did exactly the same some years earlier when Jack Austen Walten described with drawings a boiler that would have been quite unsafe for 'Twin Sisters'.

Anyone can look at the Hackfly drawings in ME and would no doubt completely agree with LBSC's criticisms, as I do.

Cheers,

Julian

Hi John,

I have sent you a PM.

Cheers,

Julian

Hi John,

Don Ashton's book is available from Camden Miniature Steam Services.

On pages 28 and 29 you will find a worked example that would fit your requirements. Lap is 0.120" and note it is not necessary for the steam port to open fully to incoming steam so valve travel is a bit less than your 5/8"

In Don's example the eccentric throw is 0.460"

Cheers,

Julian

Hi Duncan,

I think you need to consider the SMEE Journals. C M Keiller was a SMEE member.

He provided his formula to Martin Evans when Evans was writing his book on boiler making in the 1960s.

Jim Ewins had his own views which were also published in the SMEE journals and also the Maidstone MES newsletters which have been archived. They are also in Evans' book.

The fullsize formula is in Jos Koopmans' book 'The fire burns much brighter' available from Camden.

I have always used generous tube diameters via length for both ordinary flues and superheater flues.

Cheers,

Julian

Hi John,

There are a significant number of designs where Martin Evans made a hash of the Stephensons valve gear (and also Walschaerts). Don Young always made a number of errors on his Stephensons valve gear when using loco links as he drew the gear out incorrectly and didn't understand what he was doing. Keith Wilson was ok doing the classic Churchward GWR arrangement of Willie Pearce's gear for Stephensons which is less indifferent to scaling down, but when Keith tried other arrangements he was seriously out of his depth. I dont think that Keith ever understood valve gears properly.

LBSC made serious mistakes on all his 5"g valve gear designs except his Joy valve gear Minx and Maid of Kent.

What we know now thanks to H S Gowan and Don Ashton really only was made public from circa 1974/5 onwards.

Don't worry. What you decide to do can easily be checked on a valve gear simulator program these days before you cut metal.

I have been involved in re-designing a number of well known ME loco valve gears in recent years for various builders. John Baguley has done the same. The understanding of the niceties of Stephensons valve gear is a fascinating topic and can become an obsession. If correctly applied and understood the superlative performance on the track is well worth the time and study involved.

Cheers,

Julian

Hi John,

We briefly discussed this earlier this year on one of your other threads.

I think the simple answer is no, you cannot scale down the fullsize Stephensons valve gear but this must be qualified as it depends on the loco and arrangement of Stephensons and much else besides.

One of the classic 'cock ups' was Keith Wilson's 5"g 'Bulldog/Dukedog' valve gear - which is also relevant because it is pretty much the same arrangement you wish to copy. Direct drive Stephensons with loco links and slide valves below the inside cylinders. No way does the gear produce enough travel for the valve events required.

So unless you are vary careful and are aware of the pitfalls you could end up in the same mess Keith Wilson landed himself in.

Neil is absolutely correct that miniature locos require or ought to have greater travel of the valve than what would be scaled down from fullsize.

You start with the cylinder block and what width the steam ports and exhaust ports will be. (Only the width of the steam port is relevant for valve travel). Then how much lap do you want on the valve? Then in fullgear (say 78 or 79% cut off for a 2 cylinder loco) you can calculate the required valve travel required.

Then you have to consider the type of expansion link employed (launch type or loco links) and within reason you can predict the eccentric throw required.

Note with slide valves (outside admission) loco links are preferred with direct drive, and launch type links with indirect drive. In each case there will be a small suspension offset and a small amount of die block slip so the eccentric throw need only be a tad more than calculated.

If you have loco links with indirect drive, or launch type links with direct drive (for outside admission/slide valve) the suspension offset will be considerable to achieve equality of valve events and there will be considerable die block slip which also requires a greater eccentric throw and larger expansion link to compensate/accomodate the excessive die block slip.

Note Martin Evans used direct drive and launch links on Princess of Wales with slide valves and specified a totally inadequate amount of suspension offset.

Fowlers Fury mentioned LBSC's Pansy. I can state quite categorically that Pansy has a very poor version of Stephensons gear, but can easily be rectified.

John, you also have to consider the expansion link suspension and whether centrally suspended or suspended by the top of the link if loco links.

Anyway the first thing is to decide on the cylinder block and whether for a 5"g loco the size of Super Claud you have say 5/32" or 3/16" steam port width.

Cheers,

Julian

Hi Jon,

If you are interested in a narrow gauge loco...

Conway is a freelance design by Martin Evans. For a little bit more effort you could build a copy of the Hunslet 'Quarry' design. Don Young did a 3.5"g version called Hunslette. Far superior to Conway IMHO. Hunslette also has balanced slide valves (optional) which give a very free exhaust.

From memory there is a problem with Conway's valve gear as it uses launch type links with direct drive.

In the case of both Conway and Hunslette (and Juliet) the wheels can be turned from steel blanks which also provides extra adhesion compared to ordinary cast iron wheels.

Personally I would go for gunmetal cylinders despite the extra cost - though in 3.5"g you may not have a choice anyway.

Cheers,

Julian

Hi Jared,

A long straight edge, vice, set square, and files and some decent light.

I have never milled any loco frames, though some have been of quite complicated shapes plus all the cut outs in the frames and lightening holes/openings, plus of course the openings for the horncheeks which must be done very accurately.

I rivet the 2 frames together before commencing any of this .

When I use the long straight edge (for many years a long builders level owned by my Dad), chalk marks were put on the frames that needed attention.

Cheers,

Julian

Hi Phil,

Thanks for that link! I had quite forgotten about it!

I would add as an aside that after constructing my own Railmotor I later re-built Don Young's original Railmotor for it's new owner after Don's death. I lifted it out (on my own) from the boot of my old Vauxhall Chevette Saloon circa 1996 to display at an IMWES monthly meeting.

The following day my back completely seized up and required treatment. I have suffered from back problems ever since.

So I would not suggest a 5"g Railmotor is a one person lift.

I think the HSE guidance is 25kg for lifting and 15kg for carrying or perhaps it is the otherway round.

In any event all 5"g locos are over 25kg, and most 3.5"g locos too.

I cannot lift my own unfinished 5"g Stepney (my own version of a 5"g Terrier ala Martin Evans' Boxhill) unless the boiler is off the chassis.

If lifting a loco is a consideration then 2 persons for the lift are required.

Jon - I don't think I would want to attempt to build a miniature loco on an old Myford ML4, but in the 40s and 50s many did!

I think a 3.5"g LBSC Juliet should suit your bill with full valve gear. I would regard this as a much better proposition than 'Tich' if you plan to run it. The construction series is in ME and all castings etc are available and the boiler is a piece of cake to make yourself.

Cheers,

Julian

Edited By julian atkins on 30/10/2017 23:54:41

Hi Simon,

You have done extremely well there and I very much enjoyed watching the youtube clip.

There have been many Springboks built to Martin Evans' 5"g design, which was a very early design of his circa 1960, and you deserve considerable praise for having noticed fundamental errors in the design/drawings and resolving them.

I remember one particular Springbok built by the late John deBank of the IWMES on it's first few steamings on the track and it seized up solid.

On the other hand I remember driving Alan Killick's Springbok at Beech Hurst (SMLS) and you could drive it on the reverser with an open regulator - a rare treat. Alan's example was not built to the drawings I gathered!

With a Jos Koopmans draughting and Don Ashton input into the valve gear you have something quite special there plus your excellent workmanship!

Cheers,

Julian

I am grateful to Ketan's post.

I have crossed swords with John on many occasions in quite forthright PMs and on here on occasions.

All good wishes and prayers.

Cheers,

Julian

The OP is referring to the Clarkson drawings not anything else!

My 3.5"g GWR King is built to Jackson/Clarkson drawings. The drawings are very difficult and a great deal of knowledge of the fullsize locos is required to interpret same.

I think any Clarkson drawings are really only for the experienced model engineer with a detailed knowledge of the fullsize loco in question.

Not sure if this helps.

Cheers,

Julian

Hi Howard,

There is some disagreement over the following but for boiler bushes such as dome and regulator bushes (large bushes) , and for that matter any smaller bushes, do not use leaded phos bronze. Although some suppliers state their leaded phos bronze is ok to silver solder (eg Colphos) silver soldering a boiler involves long heat ups, and I have heard of all sorts of disaster stories of leaded phos bronze bushes. I have never used leaded bronze and to avoid any confusion have never acquired any.

I have also never used gunmetal castings for bushes.

If you go to a dedicated non ferrous supplier they will cut you off accurate slices of cored phos bronze which saves an enormous amount of machining and cost. I have used C Rees of Cardiff for the last 16 years (which is local to me and I can pop in and select what I want from the racks and shelving) usual disclaimer.

Cheers,

Julian

Hi Peter,

Generally wheel balancing on a 5"g loco is ignored. If your wheel castings have balance weights cast on them leave them as that.

The Metro boiler is a smallish 5"g boiler though the belpaire firebox makes it more complicated. There is no reason why it should not be built single handed.

Cheers,

Julian

Hi Peter,

The crank pin on the wheel should be 180 degrees out of phase to the position of the crank axle pin nearest that wheel.

(If the on the same phase you have what is known as Stroudley balancing which is quite rare and in fullsize required excessive balance weights on the wheels).

Cheers,

Julian

I have restored a number of English dials.

I dont think your original is beyond hope or needs replacement. To retain the original dial restored would be the ultimate aim I would suggest.

I dont think this is very difficult.

You just have to understand how these dials were made originally.

Cheers,

Julian