Is the CSB Doctor in?

[jon price]

I'm aiming to use CSBs for the first time, and (surprise) I'm having difficulty working things out. I've used the basic spread sheet to produce what looks like a workable solution, but I'm not sure I've got it correct as the spring wire I need appears to be 35 or 6 SWG (.2mm/7.6thou) to give a deflection of .5 or .6mm, which seems very light, and also seems not to be available.

My 0-6-0 wheelbase is (p) 18.5, (q) 21.5
My plot is (a) 6mm, (b) 8mm, (c) 13mm and (d) 6mm
Weight is 150gms, at the moment assuming equal loading of 50gms per axle (though this will involve some weighting in the chassis, which I can't yet gauge for obvious reasons)

Eileen's Emporium has SWG 25, 26, 28, 29, 30 and 33. 33 SWG (.254mm/10thou) only gives a deflection of .2mm

[grovenor-2685]

Go for Guitar strings from a music shop, 8 thou is available, but I don't think I've seen 7.
That's a very small, very light loco. I would try for more weight if at all possible.
Regards

[Russ Elliott]

Jon - give yourself some decent room:

Try a = 12mm, b = 11mm, c = 13mm and d = 9mm, with 0.23mm (0.009") wire.

[jon price]

Thanks Keith and Ross. Being new to this I had no idea what to alter on the spreadsheet after my first guestimate. It is a small engine, not tiny, but not a lot of space: the body, with smokebox, saddle/boiler and bunker are filled with stacked lead sheet, (the firebox is where the motor sits, and the cab will just be a narrow curved sheet) but without chimney and safety valve it weighs 100 grammes . I think I might get it up to 180 if I use the L shaped chassis spacers to carry as much stacked lead sheet as will fit (inside motion would have been beyond me anyway). With Ross's suggested figures, and the increased weight I can use the SWG34 9thou wire which Keith says is available.

PB030717.JPG

[Alan Turner]

Here you go:

CSB.png

8.5 thou wire required.


regards

Alan

[grovenor-2685]

One source
http://www.stringbusters.com/Ko-Bespoke/productlist.asp?cat=1/SINGLE%20STRINGS/SINGLE%20STRINGS%20PLAIN%20STEEL/ERNIE%20BALL
regards

[Will L]

Jon - give yourself some decent room:

Try a = 12mm, b = 11mm, c = 13mm and d = 9mm, with 0.23mm (0.009") wire.

I'm with Russ on this one, his plot works and I think it is to be preferred. Being a very short, light and distinctly asymmetrical prototype, going with a relativity short overhang front and rear is taking you into a region where the results vary quite considerably for small changes in the fulcrum position. Given the uncertainty about the exact effective potion of the fulcrum point which itself has a significant width, we don't usually specify fulcrum points to any greater accuracy than the nearest half a millimetre. Generally the result are stable enough not to worry about this variability, but it doesn't seem to be true in this case with for and aft fulcrum point as close as 6mm. Increasing the overhang takes you to a region where the results seem much more stable and we can happily apply the normal tolerances. Also 9 thou wire is readily available.

[Phil O]

Using whitemetal loco crew would add valuable weight too it.

Phil

[David Knight]

Jon,

How many wagons are you hoping to pull/propel with this engine and on what sort of grades? I have a couple of 0-4-0Ts that weigh in at around 100 g that can handle 21 assorted wagons on the flat so your quest for more weight may not be necessary.

Cheers,

David

[jon price]

The answer David is flat and not a lot. The loco was primarily a yard shunter at Wrexham, but was used as a relief engine at other locations, hence my excuse for having it appear at Connah's Quay. Trains were severely limited in size on the Buckley section so it is unlikely to be dealing with much more than around a dozen wagons at a time. It might also get to pull a ballast train (a long way down the construction list) which was apparently made up of a goods brake, a four wheeled passenger brake, and ten ballast wagons.

[Will L]

Using whitemetal loco crew would add valuable weight too it.

Phil

...and need to be factored in when sorting out the loco's centre of gravity see here.