fizzy,

beware, if you make a Speedy boiler. One of the members @ my club was building one and showed us all a small problem. He said there was insufficient clearance between the undersides of the bottom row of flues and the throatplate flange. He had filed small scallops of metal from the flange to accomodate those boiler tubes. Obviously, I do not know if he had followed the drawing exactly, as he said he had or if he made a small error of which he was unaware or if drawing was at fault. All I`m saying is just be aware and check very carefully. Godd luck.

John

Hi Fizzy,

Whoops! Just had a look this morning + notice I failed to proof – read my rotten typing last night. That was meant to be…………….good luck!

1. Speedy boiler builder now dead so cannot question him further.

2. As far as I know, it was his first attempt @ boiler building + therefore relying on experienced club member boiler makers rather than own experience. What I saw of his work, it was good.

You just need to be very careful in cross-checking dimensions on any drawings. Worthing club members did a joint effort build club loco – "Nigel Gresley"(?) design by late Martin Evans and they had long conversations about how certain parts fitted together.

John

I know what you mean about buying a boiler. I find myself in the same position.

I may be saying the obvious but are you aware that your boiler inspector will need to see your work at several points throughout the build. Best to check with your club inspectors from the start of the project. Also many older drawings are out of date in the size of materials and in some cases even type of material. Again you inspectors will correct and update for you.

Best of luck. Chris.

Funnily enough I was gazing into the depths of a FS smokebox this morning – more or less. A couple of rather sorry boilers at the Ruddington Workshops at the top end of the Grand Central Railway. Only the cafe open But a good chat about full size steam, watching the engines from Barry Yard top the huill in front of our house when I was a boy and big plate of egg, chips and beans.

They've got a Ruston diesel, full size, about as big as a Luton van!

The Nottingham SMEE have a mighty fine track too anyone from there on here, so to speak?

Neil

Craig,

Some will, some won't. If your design is so near to an existing design that it makes little difference you might get around it that way.

Some inspectors will give your design a fair chance,wanting to see drawings and calculations if you've gone for something a bit different, otherwise if fairly run of the mill you may be OK simply by quoting good examples of the sizes and thicknesses of material etc used in existing designs.

Some i am afraid though will only consider published designs.There is only one way to find out for sure and that is to ask.

May be worth noting that in industrial pressure equipment practice, the Design Verification Engineer and the Inspector are likely to different individuals with quite different qualifications/experience.

A Design Verification Engineer can check that the Designer has used a sensible approach or complied with a recognised code. The Inspector will check that the finished item matches the (verified) design. I would not necessarily expect either to be competent to do the job of the other.

Typically it is all to easy to overlook something in your own work (not that I'm suggesting you have) – that is the main reason for independent verification of designs.

The best article I've ever read about boiler design is entitled Safety of Copper Boilers by Kozo Hiraoka, I suspect it has appeared in several publications including his book Building the New Shay:

**LINK**

In the above book it extends to nine pages with graphs for:

(1) Minimum staybolt diameters;

(2) Maximum allowable pitch of symmetrically arranged staybolts;

(3) Minimum thickness for a cylindrical shell under internal pressure; etc. etc.

In terms of authorship per se, never mind the subject of the book, I suspect those familiar with Hiraoka's books might concur that they are amongst the best ever produced for the model engineer. The quantity, clarity and the draughtsmanship of his drawings/illustrations are a revelation.

It has to be said that his paper has been produced to meet American Society of Mechanical Engineers codes/regulations but I would find it very difficult to understand why a British boiler tester would fail a boiler produced to the exacting ASME standards.

The book is expensive so I would suggest a visit to your local public library.

Martin Evans book does not contain any formula on unsupported boiler areas that I can see. It only has one formula that refers to pitch of stays limited by the strength of the stays only, and independent of sheet thickness.

I'd be interested to see a calculation of max unsupported area.

Edited By robert mort on 15/06/2013 21:54:31

Thats a nice touch – bush stamped with thread used – no guessing etc

Edited By DMB on 16/06/2013 12:27:05

Roger,

The WDSME member I was referring to, was I believe, making his first loco. I think his job was a "chippy." I dont think a Speedy boiler is a beginners but he seemed to have done some nice work. I would think that a boiler like this with tubes so close to the "outer skin" calls for the essential use of only pre-treated water to prevent furring-up with chalky deposits. This could build up very quickly in a really hard water area like Sussex south coast – Worthing/Brighton. Prevention is very much better than attempted cure for this problem. Back to prev., he used a round file to put a couple of small scallops in the flange. I am not aware of any other probs. with this boiler and I believe he died before completing the engine and I dont know what happened to it so cannot comment further on success of test or running performance. Can only say its a shame LBSC apparently left black holes like you mention and very often in valve gears of a number of his designs. He did however say that his published VG designs left out a small detail so he always had an ace up his sleeve.

John