4-4-0 midland compound CSB's

[simonmoore]

Having read various posts on this forum & others regarding CSB,s & Highlevels new components i have decided that the 4 projects i am working on are going to be done using the Highlevel CSB system. I have read the various posts in Wills CSB thread & i want to ask a few simple questions regarding the set up. Whilst i have been going about my daily duties at work i have been in deep thought trying to get a picture in my head of the chassis & also work out a plan of action of how i am going to tackle the job. This way works for me & its helped me get results but i am also hitting the problems & obstacles that my chassis's are going to have. Firstly i have no idea where to place my handrail knobs & how many an 0-6-0 loco is going to need, secondly one of the locos is an 0-6-0 with a tender so again how many knobs & where to place them. The other thing i am concerned about is weight in the locos once built, one of the locos is a Barton Wright saddle tank which is going to be shunting a small amount of wagons at a time so i guess this isn't going to be a major factor but still questionable. I understand the fundamental basics of CSB's & how they work but after that i am in the dark. The other thing is wire choice there seems to be so many choices i only have 26 gauge nickel silver wire is this any good or am i barking up the wrong tree still??

Regards,

Simon

[David Knight]

Hi Simon,

Since you are going to be using the High Level blocks the High level jig for plotting CSB positions might be a good idea. Instructions can be found here; http://www.clag.org.uk/pics/beams/high- ... system.pdf
along with a lot of other useful stuff to be found on the CLAG site.

If you can get the frame length and wheel spacing of your engine and tender it is possible to calculate where the knobs need to be placed.

Spring wire is easy, go to your local musical instrument shop and all the wire you need can be found in the form of guitar strings in increments of .001" from about .008" up. ask for a top E string to get the clerk on the right path.

I'm sure others will be giving you more info soon.

HTH

David

[Russ Elliott]

Simon - any 3-axled thing (loco, tender, bogie) needs 4 frame fulcrum points on each side of the chassis:



The longitudinal positioning of the frame fulcrum points (handrail knobs) will depend on the wheelbase dimensions. I understand the Barton Wright saddle tank wheelbase is 15' overall, but I don't know the wheel spacings. (7'6" + 7'6"?)

I wouldn't worry about the overall weight at this stage - of more importance is the balance, and it shouldn't be too difficult to get that tank balanced reasonably about the middle of the wheelbase.

Nickel-silver wire won't make a particularly good spring - spring steel is the best, so guitar strings are ideal for us. You'll probably need 12, 13 or 14 thou springs for most locos.

[Dave K]

Nickel-silver wire won't make a particularly good spring - spring steel is the best, so guitar strings are ideal for us. You'll probably need 12, 13 or 14 thou springs for most locos.

Russ,

Not knowing to much about guitar strings but when on the packet it says "custom gauge 12" does this indicate that it is a 12 thou

[Trevor Grout]

The size on the packet is the size of the string.
These are the ones you are looking for.

earnie ball strings.JPG

earnie ball strings 1.JPG

Regards
Trevor

[simonmoore]

Thanks so far everyone for the help, Today i managed to get some elixer plain steel none rust strings from a friend at work who is a guitarist i got the 12,13 & 14 thou so hopefully that will do. My friend did say that there are so many strings to choose from he didnt know if they would be any good but i got them for the price of a pint so i guess it isnt a big loss if they are no good.

Simon.

[simonmoore]

One of the things i forgot to mention was the chassis i am tackling firstly is a comet chassis for a midland compound using the hornby body. The thing i am struggling with is where to place the handrail knobs & also how many i will need to make the chassis sprung. Just looking at the chassis i would think it would need 3 per side but how do i space the handrail knobs?? If i am doing a chassis like a compound with 3 knobs do i space the knobs equally apart so everything is evenly spaced out & with enough room for the spring to act as springs & not be to close so they make them to tight ??? Am i on the right path here with this kind of thinking??

Cheers

Simon

[Paul Townsend]

Am i on the right path here with this kind of thinking??

No!
The spacing required is unlikely to be symmetrical as you suggest.
You really must read all the stuff about csbs on the CLAG website as recommended by Dave on Thursday. You will also find some info re 4-4-0s there.
There is a spreadsheet there which helps design the positions for 6 coupled and an improved version by Will Lichfield in this Forum which does 4 coupled too.
There are also several other recent and helpful threads here in this Forum.

If you contact Russ directly he may even work out the positions for you if it isnt in the list of done ones.

I too am a csb virgin so wont advise on the technicalities, but I do advise that you start an 0-6-0 csb chassis before tackling the 4-4-0, partly because many fulchrum plots have been done for various locos, but also because the road to success will be smoother while you gain experience. There is enough information floating about to satisfy the curious and make it easy to have a go

[simonmoore]

Paul thanks for that, I do have a couple of 0-6-0 in the post right now both of l&y prototypes so hopefully i can start with one of those. The Barton wright saddle tank is going to be the first but i believe this is the same chassis as the class 25 barton wright which i am also building. If i have time tonight i shall have a read on the clag site & take it all in.

Simon

[Russ Elliott]

Simon - the 2-axle case is 'symmetrical', in as much as the middle fulcrum is usually centred between the axles, and with the 'front' and 'rear' parts being a mirror image, i.e. the two outer fulcrums are spaced from their axles by the same amount, i.e. x1 = x2 :

2axle-general-case.gif

The symmetry will equalise the sprung weights carried by the two axles. Departures from symmetricality can be made if desired to cater for unsprung gearbox/motor weight, but this is not recommended unless you know exactly what the unsprung and sprung weights are.

Typically, x1 and x2 , as well as being equal to each other, should be between 0.3 and 0.4 times the length of the coupled wheelbase. There is no point in making the beam longer or shorter. The optimum (peak deflection of the beam) setting is approximately 0.35 times the coupled wheelbase.

It perplexes me though why there seems to be a wish for the 3-fulcrum CSB for the 2-axle case. Maybe it's because CSBs happen to be flavour of the month. A springy equaliser is just as much 'continuous' as any other type of beam, and has the advantage of being immune to chassis horizontality. Springy equalisers will perforce be used on the bogie of a 4-4-0 because of beam length constraints, so why not use them on the drivers as well?:

fig77c-revised.png

[simonmoore]

Thank you Russell for the detailed reply you've given that explains the 4-4-0 perfectly for me. I'm about to start the working week on nights so as a rule i do not do any modeling when i am working on nights because my head is not completely with it due to lack of sleep so i shall pick it all back up during the weekend. I must admit that now i have basic understanding of how csb's work & the tools to do the job i am looking forward to the build with confidence in myself for once.

Thanks again Russell,

Simon