A CSB Source book

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Will L
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A CSB Source book

Postby Will L » Fri Feb 28, 2014 4:19 pm

In the past I’ve posted a fair bit of stuff, on a number of threads, about the use of Continuous Springy Beam (CSB) suspension on steam engine chassis. When I wrote it I sort of hoped that they might have some long term value. However if a thread gets many posts added to it can become difficult to find a particular post, and if it doesn't attract additional posts it soon disappears down the list. In either case the information in it becomes harder to track down.

The purpose of this post is to catalogue what I've put up there so it is much easier to find, and, because it sits on my own “workbench” forum, hopefully it won’t disappear from view without my say so. I won’t necessarily be sticking to just my own posts and I expect to cataloguing stuff posted in other threads and websites, so anybody looking for CSB information need only start looking in the one place. Mostly I’m doing this for me, but hopefully other people will find it useful too.

To try and put a little organisation into the information available, I’ve tried to structure things a bit in this post and then use links to take you on to the details which are held in other places. What this means is that to access the information you should always start with this post, the first in the CSB Casebook Thread, and then use the links below to find the bit you want. This is a slight abuse of the structure of the forum, but it is in the spirit of the Scalefour Wiki that Deputy Chairman and low flying motorcyclist Paul has been championing.

7 headings follow, each with a brief explanation of what is under each heading. Click on the heading and it will, eventually, take you to a further summary post which gives information about, and links to, the key posts. In the short term it may just take you strait to the referenced thread but I can’t do everything at once.
This post, and the summaries which will also be held on this thread, will be edited to add additional new stuff as it comes along.

Despite me playing fast and loose with the forum structure there is no problem if you wish to add your own comment/feedback/suggestions to the thread.

Genesis

I didn’t invent CSB’s I've only tried to explain and popularise something that I saw as a real advance in 4mm steam loco chassis design. There is a lot of basic material on the Central Londan Area Group (CLAG) webs site, much of which predates my involvement, and that contains information I have reference over and over again. So before going on to catalogue my own stuff, I give links and a summary to what I consider to be the key CLAG website sections.

Loco Suspension, fitting CSBs
This is the thread where I started. It covers the basic theory although my thinking has moved on a bit since then. The thread is based around a blow by blow account of the conversion of an existing loco (the J10 0-6-0) to CSB's, both loco and tender acquiring new chassis in the process. As well as basic CSB stuff it also covers things like articulated coupling rods and pickup design, and refers back to previous work on the O4 (2-8-0) which was what convinced me that CSB’s were the way forward.

Abstruse CSB Theory

This thread was started to defend the average reader of the “Loco Suspension, fitting CSBs” thread from a discussion about the validity of the software models/spread sheets used to design a CSB chassis. While I found this fascinating there was a danger of suggesting that CSBs could only be implemented by the wielders of some sort of academic qualification. While clearly not true it was worth allowing those, who didn’t want to immerse themselves in theoretical concepts, to avoid having to plough through them. It was this thread which lead to the development of two main “user friendly” spreadsheet tools for designing your CSB chassis.

CSBs and the Single Bogie

Earlier work on CSB’s concentrated on chassis which only carry weight on the driving wheels, typically an 0-6-0. This thread deals with my first effort to apply CSB’s to a chassis in which some of the loco weight needed to be carried on a bogie. The subject was a Bill Bedford C12 (actauly a 4-4-2) chassis kit and the thread covers theoretical considerations on a 4-4-0 chassis, their application to the kit and some practical problems that turned up on the way. It also gives a method for fitting pick ups on a bogie.

CSBs a question of Gravity

This follows on from the “CSB’s and the Single Bogie” thread to develop a generalised way of working out the design of any CSB chassis with, or without, a functional weight carrying bogie. So you can guarantee that the chassis will sit level and determined the weight distribution across all the weight carrying wheels at the design stage.

CSB and tenders

A useful thread which discuses the use of CSB on tenders, and the implications for weight distribution between loco and tender. It also covers the interaction of wheel top wiper pick ups and CSB.

Getting your CSB loco sitting level and the buffer heights right
A 10 point summary of how you achieve what the title says

Edited 31/3/2014 to reference the summary of the “Abuse CSB Theory” thread.
Edited 7/6/2014 to reference a thread on the use of CSB on tenders
Edited 18/1/2018 to reference a thread on getting a CSB loco level and the right hight
Last edited by Will L on Thu Jan 18, 2018 8:48 pm, edited 5 times in total.

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Will L
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Genesis

Postby Will L » Fri Feb 28, 2014 4:32 pm

The CSB Case Book summary page covering items on the CLAG website.

The CLAG website home page

This is a fascinating web site which documents all sorts of interesting stuff from the Central London Area Group. It contains articles from many authors and it ably tied together by Russ Elliot. There is much more here than Just CSB’s. My selection of the bits which do relate to CSB follows.

Scalefour Digest 41.0 - The Principles Of Model Locomotive Suspension

This is one of the Scalefour Society digest sheets, and this particular one is "hosted" on the CLAG site. (Hosted = internet speak for were its kept.) This is a seminal work by Russ Elliott on model rail vehicle suspension, or lack of it, which must be of interest to anybody who wants to do any more than guess if his model will work. It predates the development of CSB’s which are passed over with the comment that working out the fulcrum points is a bit complex. None the less it contains much basic stuff I needed to know.

Deflection of beams – menu page
A series of articles about springy beam suspensions. CSBs are not the only way. Some are more digestible and relevant to CSBs than others. If you don’t feel the need to read the lot then the following two are the most important to the understanding and development of CSB suspension.

Continuous springy beams

This covers a great deal of the CSB groundwork, and other springy beam configurations. It gives many worked examples for fulcrum point placement for common and popular prototypes and it continues to be updated with additional examples. If you read nothing else, read this. Contains links to all the software tools.

Suggestions for the setting out of the vertical position of the fixed fulcrums on a CSB chassis

Details from Ted Scannel which explains how to do what the title says.

Other interesting stuff

The CSB spread sheets

The links to the three available spread sheet tools are contained within the “Continuous Springy Beam article” above but this link will take you strait there.

CSB gallery

A collection of Pictures showing CSBs implemented by a number of builders. New examples continue to be added.

Fitting a CSB to a High Level Models Pannier chassis

An expansion of the article which appeared in Snooze 182. A good blow by blow account of fitting CSBs to a good kit not originally designed to have them. Copiously illustrated and authored by Mike Smith, James Moorhouse, and Russ Elliott

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steamraiser
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Re: A CSB Source book

Postby steamraiser » Fri Feb 28, 2014 5:38 pm

Will,

Your heading grabbed my attention.
Is there any chance of a CSB book / booklet sponsored by the Society?
This would be a much more user friendly source to have on your modelling bench.

Gordon A
Bristol

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LesGros
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Re: A CSB Source book

Postby LesGros » Fri Feb 28, 2014 6:44 pm

Will,
I applaud your effort, :thumb and agree with Gordon about the desirability of it leading to a publication; a worthy project.
LesG

The man who never made a mistake
never made anything useful

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Will L
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Loco Suspension, fitting CSBs

Postby Will L » Fri Feb 28, 2014 6:46 pm

Loco Suspension, fitting CSBs
CSB Source Book Summary of this long thread which, while based on the construction of CSB chassis for a LNER J10 0-6-0 loco and tender, touched on many other topics along the way. This is early work and some of the thoughts given here have been developed further in later threads.

Background Issues

Loco Suspension, Why and How
Basic suspension issues, comparing rigid compensated and sprung chassis

So why CSB’s
An explanation of what CSBs are, where they came from and what convinced me they were such a good idea. Also pictures of my first CSB loco and tender chassis (the O4)

Setting out a chassis for CSBs
Applying the lessons in the previous post to the J10 tender chassis to produce a set of chassis frames.

Constructing the J10 tender chassis

Part I
Applying the lessons in the previous post to the J10 tender chassis to produce a set of chassis frames.

Part II
Constructing the tender chassis, including do it yourself horn blocks, producing the frame spacers so they allow the CSBs to pass, and assembling the whole thing.
Sorting out the fulcrum points

Four posts which tell you all you need to know to design the fulcrum points for a chassis

Part I, An Introduction
An introduction to the process of calculating the location of CSB fulcrum points. It introduces Russ Elliott’s seminal work “Continuous springy beams”, and the Roger Wyatt spread sheet. When this was written only Roger’s original spread sheet was available.

Part II, What does the Spread Sheet do
Explains how the original Roger Wyatt spread sheet goes about its business and what the inputs it requires are.

Part III, Understanding the answers
Explains how manipulating the location of the fulcrum points affects the results and what we are aiming for. Points out that there is no one right answer and gives a diagram to illustrate where all the best answers are to be found. Shows how the chosen answer for the J10 tender fits into this. It also explains the implications for cases, unlike the J10 tender, where the wheelbase isn’t symmetrical.

Part IV - In summary
Introduces my version of the Roger Wyatt spread sheet which, hopefully is rather more user friendly, and does allow you to calculate results for 2 3 and 4 axle chassis. The latest version of this spread sheet can be down loaded from here and is also available from the CLAG website, see the Genesis page of this thread.

For those not comfortable using spread sheets this thread also outlines a paper and pencil method of working out a “good enough” set of fulcrum points.

J10 Blow by Blow

Back to the J10 – the existing loco
Shows the J10, A DJH cast kit, prior to modification, the various parts expected to go into the loco (some expectations are not always met!) and the Fulcrum point calculation.

Jointed Coupling Rods
A diversion covering details of how to convert Gibson universal coupling rods, which are designed to articulate about the centre crank pin, to proper knuckle jointed articulated rods.

Horn blocks
This post gives an overview of the Highlevel horn block frame assembly, then details of actually preparing the horn blocks for use. It includes a method of overcoming the difficulty of getting a gear box between Highlevel horn block assemblies by making thin axle baerings . This predates the introduction of especially thin ones by Highlevel. Diversion on the topic of identification marks for chassis parts to ensure each part goes in the right place on assembly/reassembly.

The Frames
A description of how the pre-cut Gibson chassis frames were marked out and drilled for the CSB fulcrum points etc, and the profile modified to suit the existing cast metal loco body. It also explains were the axle centre line goes on a chassis with standard 6mm by 7mm horn block cut outs. This predates the Highlevel CSB jig which also does this job. It then covers fitting the horn blocks to the frames using a Chassis Pro jig, and finally there is a Diversion on the use of Seconds files.

Assembling the Chassis
This discusses the form of L shaped frame spacers used on the chassis and how they were designed to suit CSBs. It moves on to making them and assembling the chassis side around them. It also covers the use of a blanking piece of boiler profile fitted to the chassis to plug the hole in the bottom of the boiler needed to allow the motor to fit.

A Gearbox for the J10
This post explains how to reduce the width of a Highlevel LoadHauler Compact + Gearbox so it will fit between the horn guides/axle blocks/CSB wires on the drive axle

Wheels for the J10

Part 1. Preparing the wheels
This explains how I prepared the Gibson wheels, and dealt with the fact that these happened to be of the ex Studiolith variety which don’t have the hole for the crank pin moulded in.

Part 2 - Assembling the wheels
Using the GW quartering jig

Part 3- Fitting the wheels and CSB wires
At last

The J10, A Rolling Chassis at Last, Fitting the Coupling Rods
Or Wheels for the J10, part 4

Pickups for the J10

Part 1
Explains how the tender pick-ups for the J10 were fabricated

part 2 Matters arising
Explains the rationale behind my pick-up design, including how they fit in with CSB use, and illustrates the pick-ups from the loco.

Other asides and relevant posts that occurred along the way

Modifying Brassmaster Hornblock for CSB
3 Posts suggesting ways of modifying Brassmaster horn blocks for CSB use.

Discussion re us of CSBs just resting on axle bearing top
This and the next 11 posts suggest the possibility of the CSB wire resting on the top of the horn block, rather than being tethered to it as they are when using Highlevel horn blocks. N.B some later Bill Bedford Loco chassis are like this (the J72). Also includes this post from Russ giving a way of modifying Sharman circular flexi chassis bearings for use in this way.

An Aside About Knobs
A discussion about which size of handrail knob makes the best fixed fulcrum points.

O4 Developments
A diversion relating to real life experiences with the O4. Mostly of interest because it points out the need to get the loco CofG in the right place and the potential role of Heavy Metal loco Crewe in achieving the desired balance point.

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Will L
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Re: A CSB Source book

Postby Will L » Fri Feb 28, 2014 6:53 pm

LesGros wrote:Will,
I applaud your effort, :thumb and agree with Gordon about the desirability of it leading to a publication; a worthy project.


Very kind but its taken me months to get this far and I'm not finished yet.
Last edited by Will L on Fri Feb 28, 2014 10:01 pm, edited 1 time in total.

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David Thorpe
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Re: A CSB Source book

Postby David Thorpe » Fri Feb 28, 2014 8:22 pm

I have to confess that I found Will's postings on CSBs so useful that I have already edited them into a 39-page illustrated A4 booklet.

DT

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Re: A CSB Source book

Postby Flymo748 » Fri Feb 28, 2014 9:37 pm

Will L wrote:
LesGros wrote:Will,
I applaud your effort, :thumb and agree with Gordon about the desirability of it leading to a publication; a worthy project.


Very kind but its taken me moths to get this far and I'm not finished yet.


Hopefully the moths haven't eaten your notes, as well as your Sunday best suit!

In all seriousness, if Will is willing (excuse the pun) and the other parties (I'm looking at CLAG here, as they have been such a profound driver on the whole CSB cause) don't mind the use of their inputs, then I'm sure that the Committee will give such an idea a very serious consideration.

As has been said, it would be an enormous aid to the finescale side of modelling in general, and definitely in line with the formal Aims of the Society. That said (and having seen from a distance the production of the AJ Book, St Merryn, and most recently the Civil Engineering CD), producing a book is no light task, and we would need one or two committed volunteers to help produce it. I'll leave that thought there for the moment, and let Will crack on with some more writing.

Cheers
Paul Willis
Deputy Chairman.
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Re: A CSB Source book

Postby dal-t » Sat Mar 01, 2014 11:12 am

Whilst I welcome the idea of a book, being of sufficient pre-new-media vintage to always appreciate something tangible in my hands compared to ephemeral links on a screen, I do wonder (and did when I first saw this topic) whether it would not be the ideal subject to kick-start/revive the concept of a 'Wiki' reincarnation for the Digest Sheets et al?
David L-T

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Re: A CSB Source book

Postby John McAleely » Sat Mar 01, 2014 12:40 pm

dal-t wrote:I do wonder (and did when I first saw this topic) whether it would not be the ideal subject to kick-start/revive the concept of a 'Wiki' reincarnation for the Digest Sheets et al?


I agree - I had similar thoughts. I think me and Paul need to reach out to Will, and share our progress so far. I think the wiki is technically ready to go, but we have some admin details to sort out, and we need some starter content...

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Re: A CSB Source book

Postby Russ Elliott » Sat Mar 01, 2014 1:28 pm

Two (or three?) years ago, Bob Bourne suggested to me that a further revision of Digest 41.0 might be a good thing because of the growing volume of material on CSBs. I wavered at that time, conscious of two main problems:

- 41.0 is a hefty Digest sheet, and extremely expensive to print and distribute in paper form, as we did when issues 1 (1984) and 2 (2003) were produced. Cost-wise, it was equivalent to at least one Snooze, and a further revision would be even larger.

- At the time of discussion with Bob Bourne, I felt that 'CSB-lore', for want of a better phrase, was still evolving and maturing, and a further revision of 41.0 was therefore premature at that stage.

On the printing aspect, Danny has subsequently clarified that paper versions of Digests are issued only a demand basis, and that the demand is extremely small, so that big cost hurdle has to all intents and purposes disappeared.

On the matter of a future 41.0 revision, I think events subsequent to my talk with Bob Bourne, viz the amount of material here on this forum, mostly authored by Will, and additions to the material on the CLAG site, have indicated we are still in a state of evolution and discovery, especially on specific implementation areas (Ian Penberth's drive bogies for example). CSBs might be 'old-hat' to some, but to many others in other gauges and scales they are still shrounded in mystery, mistrust (or even disbelief), and perceived hair-shirtism and over-complexity by those nutty finescale extremists. Having said that, there will be a further revision of 41.0 at some time in the future, but I'm still far from resolved as to what its scope and structure should be. I'm unwilling to throw out old compensation stuff because illustrating how things were done in the past (and in context, still perfectly valid) is just as important as illustrating how things can be done in a different way. Suspension should I feel remain and reflect a broad church. Btw, if I can muster the skills, a future revision of 41.0 will not be printable or pdf-able anyway because I want to put animation in the graphics.

Book production is expensive, reaches only a limited audience, and the material is not updatable. Furthermore, suspension is a dry subject, and does not fall into the attractive coffee-table treatments of something like the excellent St Merryn book. Pretty pictures sell, equations and arcane diagrams don't. It is I think interesting to note, despite excellent submissions by evangelist Dave Franks a few years ago, that MRJ has studiously avoided CSB treatments. Maybe the subject isn't sexy enough. Compare RMweb though (and a church doesn't get broader than that), and there are encouraging green shoots of CSB interest in 7mm scale, despite the congenital and comedic inability of many 0-gaugers to consider what their locos should or might actually weigh.

The beam pages on the CLAG site are popular, peaking at over 100k hits per annum, (rather less nowadays perhaps because of their familiarity), with the CSB-specific pages growing at around 13k hits p.a., and I do have extra material on the beam height axis area, arising out of some discussions here and RMweb, to be added in the near future. Page hits on the CSB threads in this forum look similarly healthy, and there's little doubt these forum pages attract a lot of non-member visitors.

I applaud this source consolidation thread of Will's. Long overdue perhaps! (And a good example of what a 'Wiki' should be.) But as he says, he's "not finished yet", and it perhaps proves we are in a state of flux in addressing CSBs. More power to his elbow. I think it also shows, at this stage of proceedings, our current pluralistic and wide-audience approach, i.e. web pages, and the forum(s), and the Digest, and of course not forgetting the flagship Snooze, is the correct one.

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Re: A CSB Source book

Postby Phil O » Sun Mar 02, 2014 8:20 am

Hi Will

Many thanks for your time and effort in putting the CSB threads into one place making it much easier to find. :thumb

If the committee are considering producing it in book form, could it be done in digital form IE. either on a disk like the Civil Engineering book or in a down loadable format like Kindle or other E books.

Cheers Phil

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Re: A CSB Source book

Postby jayell » Sun Mar 02, 2014 8:37 am

John McAleely wrote:I agree - I had similar thoughts. I think me and Paul need to reach out to Will, and share our progress so far. I think the wiki is technically ready to go, but we have some admin details to sort out, and we need some starter content...


You will need to consider who will have editorial access to a wiki to ensure it isn't spammed/hacked/whatever. When I was a member of HantsLUG (Hampshire Linux User Group) the wiki had to be changed from freely editable like Wikipedia to password only access.

Apart from that proviso, putting technical material (like the CSB data) on a wiki has much to commend it.

John Lewis

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Re: A CSB Source book

Postby Terry Bendall » Sun Mar 02, 2014 9:04 am

Paul and John have already made something of an "official" response but as a committee member I also think the idea of collecting together the collective wisdom on CSBs is A Good Thing. Russ identifies some of the problems of a book that cannot be updated which is important to remember in the context of a developing technology so an electronic format may be the way to go, as we have done with the Civil Engineering book.

There is a committee meeting on March 19th and I am sure that this can be discussed then.

Terry Bendall

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Re: A CSB Source book

Postby billbedford » Sun Mar 02, 2014 9:42 am

Russ Elliott wrote:Two (or three?) years ago, Bob Bourne suggested to me that a further revision of Digest 41.0 might be a good thing because of the growing volume of material on CSBs. I wavered at that time, conscious of two main problems:

- 41.0 is a hefty Digest sheet, and extremely expensive to print and distribute in paper form, as we did when issues 1 (1984) and 2 (2003) were produced. Cost-wise, it was equivalent to at least one Snooze, and a further revision would be even larger.


I would suggest that 41.0 is not updated, but a completely new digest is written to cover CSBs. This would clearly distinguish newer from older thinking.
Bill Bedford
Mousa Models
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Re: A CSB Source book

Postby Noel » Sun Mar 02, 2014 9:55 am

Russ Elliott wrote: Btw, if I can muster the skills, a future revision of 41.0 will not be printable or pdf-able anyway because I want to put animation in the graphics.


This might present problems for those who prefer a printed page or pages for reference whilst working, rather than a screen. Apart from readability issues, computers and workbenches are not very compatible.

Noel
Noel

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Will L
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Re: A CSB Source book

Postby Will L » Sun Mar 02, 2014 11:53 am

While I'm very gratified by the reception given the Case Books, I would like to point out a few things
  • Much as I'm fascinated by the prospect of Russ animating a follow up to Digest 41. I for one have littered the internet with reference to the original, the prospect of it disappearing produces symptoms reminiscent of panic.
  • While I'm pleased my rambling have proved popular, they are, I regret to say, inclined to ramble. I think the definitive guide to CSB has yet to be written.
  • When it is written, what I think is required is the "fools guide" predicated on demonstrating a simple and practical system and consigning the fascinating detail (I find it fascinating) to, say, were its is now.
  • I have the literary equivalent to the unbuilt kit pile, and just for moment I'm trying to making a dent in the kit pile. Quite why the Case Book chose this moment to appear I'm not sure, I wrote most of it months ago. Probable a displacement activity to avoid doing a job on a Buckjumper I wasn't entirely sure about.
I'm back to the modelling bench now, new summary sections of the Case Book will appear in due course, hopefully.

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Re: A CSB Source book

Postby Russ Elliott » Sun Mar 02, 2014 12:39 pm

Noel wrote:This might present problems for those who prefer a printed page or pages for reference whilst working, rather than a screen. Apart from readability issues, computers and workbenches are not very compatible.

In general, Noel, I would agree, but in the particular case of 41.0, whose primary purpose is to try and get ideas and principles across ('digest'), I find it difficult to imagine anyone having that on their workbench as an adjunct in actual construction. It's not like a set of kit instructions, is it?

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Russ Elliott
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Re: A CSB Source book

Postby Russ Elliott » Sun Mar 02, 2014 12:53 pm

billbedford wrote:I would suggest that 41.0 is not updated, but a completely new digest is written to cover CSBs. This would clearly distinguish newer from older thinking.

It's a difficult editorial conundrum. It depends whether one imagines a reader is thinking "I've got an 0-6-0 and insist on using a CSB" or is thinking "I've got an 0-6-0 and want to know what the options might be." There's a spectrum of comparison to juggle with.

Is this 'old' or 'new' thinking, and does anyone care whether it is 'old' or 'new' thinking?:

new-or-old.gif
new-or-old.gif (1.58 KiB) Viewed 12532 times

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Re: A CSB Source book

Postby billbedford » Mon Mar 03, 2014 12:31 pm

Russ Elliott wrote:Is this 'old' or 'new' thinking, and does anyone care whether it is 'old' or 'new' thinking?:

new-or-old.gif


That is the sort of woolly thinking that confuses the hell out out people coming fresh to loco building. What is needed are succinct, easy to follow 'How-To' booklets that can lead people through the process of building working loco frames. If need be there could be a discussion in the text about why a particular approach, to the suspension system being described, has been adopted but in general the tone of the booklet should be that with a little effort anyone can successfully build a set of working frames.

If others want to indulge themselves producing a treatise on all the possible suspension systems then so be it, but the two sorts of documents shouldn't be confused.
Bill Bedford
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Russ Elliott
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Re: A CSB Source book

Postby Russ Elliott » Mon Mar 03, 2014 4:30 pm

billbedford wrote:What is needed are succinct, easy to follow 'How-To' booklets that can lead people through the process of building working loco frames.

There's lots of 'how to' in many of Will's threads. (And in Mike Smith's recent Pannier article in the Snooze and Ozzyo's 7mm 517 thread on RMweb for example.) 90% of these builds however is concerned with conventional chassis challenges (choice of blocks, rod construction, axle and block alignment and setting, wheels, brakes, pickups, etc) and the CSB aspect is comparatively minor and straightforward - the answer to the question "What's different about building a CSB chassis?" seems to be "very little, apart from some forward planning in making room for the beam".

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Re: A CSB Source book

Postby David B » Mon Mar 03, 2014 6:03 pm

The 'How to . . . ' I could do with concerns working out where the pivot points are meant to go. The rest is straightforward.

The spreadsheets are completely beyond me and I know this puts other people off CSB. How necessary are they? If I were to put a pivot half way between wheels with one at each end to match, would that be 'wrong' or mean it won't work? Can the placing of pivot points be simplified?

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Russ Elliott
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Re: A CSB Source book

Postby Russ Elliott » Mon Mar 03, 2014 7:09 pm

David, a spreadsheet (or equivalent software) is a necessary starter in CSB 'territory'. Putting fulcrum points half-way between the axles of an 0-6-0 would work, but with a fairly disastrous weight distribution, and since good weight distribution is one of the prime objectives of doing a CSB in the first place, it's not exactly going to do you any favours.

I realised spreadsheets would not be everyone's cup of tea, which is why suggested plots have been published, to build up a sort of 'library'. If you want a bespoke plot for a wheelbase, just ask me or Will or anyone else - a plot is usually only a few minutes' work.

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David B
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Re: A CSB Source book

Postby David B » Mon Mar 03, 2014 7:41 pm

Thank you, Russ.

However, I know the spreadsheet is a real stumbling block to people. Is there any way it can be simplified in both language and presentation? The practicalities of building a CSB chassis I think are quite straightforward, in fact easier than building a compensated one. It is that initial stage that can be the stumbling block - get over that and I am sure more people would take to CSB chassis building.

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Will L
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Re: A CSB Source book

Postby Will L » Mon Mar 03, 2014 8:36 pm

davidb wrote:The 'How to . . . ' I could do with concerns working out where the pivot points are meant to go. The rest is straightforward.

The spreadsheets are completely beyond me and I know this puts other people off CSB. How necessary are they? If I were to put a pivot half way between wheels with one at each end to match, would that be 'wrong' or mean it won't work? Can the placing of pivot points be simplified?


Yes you can put the fulcrum points mid way between the wheels, but the location of the end ones aren't where you might expect, if you scan through this post you will find near the end a paper and pencil method which produces a "good enough" result based on this basic approach, so long as it wheel base isn't outrageously asymmetrical. Russ would argue the result is a little stiffer than a more refined plot but I would reply that this just means you need to fit a slightly finer wire.

Russ is also correct in saying that many of the common prototypes have already been published here. Alternative posting the wheel base and asking for a solution here will probably produce an answerer in no time. Once you have mastered the spreadsheets they give answerers very quickly, typing the reply is what takes the time.

To the world I would suggest that knowing your facing a spreadsheet is half the problem. Only the original Roger Wyatt item is raw unadulterated spread sheet that requires some (not a lot but some) spread sheet knowledge. If we hadn't told you the other two were spread sheets you might not realise, as both have their mathematical works hidden and you have to do little more than is fill in the wheelbase in the indicated boxes.
  • Mine can look a little complicated because I provide the facilities to adjust the answers to suit your own fancy, but it will also produce a "good enough" answer automatically. It has "traffic light" indicators which are green for a good plot and red for one that need more work. It also fills in a diagram which tells you all the chassis key dimensions for a given set of fulcrum points which is supposed to help you mark out the chassis once you've got your fulcrum points, and the Notes tab brings up copious instructions.
  • Alan's spread sheet again has all the works hidden and you just need you to enter the key dimensions, there are less introduction and some may find his display a bit more intuitive. Click on the up and down arrows to adjust the fulcrum potions and watch the display with the green diamond and red triangle. When you have these aligned you have a working solution.


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