Chassis kits for CSB

wakefield
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Re: Chassis kits for CSB

Postby wakefield » Sat Aug 10, 2019 4:56 pm

I operate a fairly large P4 layout based on the East Coast main line circa 1950's. Long heavy trains and some high speed were the order of the day. To get the maximum hauling capacity from my loco's independently adjustable springs for each wheel is the only practical method.
This enables the maximum adhesion to be obtained in relation to the distribution of the weight of the loco. Carrying wheels must take some loco weight and be sprung. This includes Cartazi arrangements on the large loco's. If this is all set up correctly, and it is not difficult, quiet smooth running ensues. To my mind if it is necessary to move the actual weight within a CSB sprung loco as opposed to adjusting individual springs then the opportunity is lost for adding maximum weight.
Mike Wakefield.

Philip Hall
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Re: Chassis kits for CSB

Postby Philip Hall » Sat Aug 10, 2019 6:42 pm

Will L wrote:
Philip Hall wrote:I think what Guy meant was picking up from the running surface of the tyre, as it tends be the part of the tyre that picks up the most muck.

Is that as a valid objection Phil? I'm with Ted, If the wheel surface is dirty enough to stop the rubbing contact pickup working it will be quite dirty enough to prevent rolling pick up from the rail. So your wheel cleaning requirement are no different and top wipers are hidden where you are less likely to accidental adjust them while your doing the clean.


I guess you have a point there, Will. I have never had much luck with those kind of wipers though, and have always found it easier to arrange 'edge of flange' ones. I actually don't like 'back of tyre wipers' either really (and they do get dirty), but have sort of been forced into their use on the many RTR conversions I've done, not wanting to go into a major rebuild of the underpinnings when they run so well. Extra pickup (tender, leading or trailing wheelsets) helps as well of course, which I always try to arrange if it's not provided.

Philip

Julian Roberts
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Re: Chassis kits for CSB

Postby Julian Roberts » Sun Aug 11, 2019 4:46 am

Hi Jol, Chris, Bob - I posted the question partly as a way of answering the OP Jol. I didn't expect you Chris to answer but thanks for the good news! Bob I'm grateful for your suggestions. In fact I intend to try CSB with this chassis as it's designed in with no compensation option. Everything I've made of Chris' products works properly straight off so I'm sure this will too. It's where there are carrying wheels I want to be able to adjust how much weight each wheel bears after my Crab experience.

Could I just point out that with compensation you don't necessarily have to have one axle in fixed bearings except (as far as I can see) an 0-4-0. With an 0-6-0 two axles can have twin beams and one axle a central rocking point. The ride I would suggest is hard to discern as being inferior to full springing.

4479
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Re: Chassis kits for CSB

Postby 4479 » Sun Aug 11, 2019 9:22 am

Well Julian, you appear to have retreated somewhat from the statement you made after visiting Chris P's layout, where you advocated being able to individually adjust the weight bearing on all wheels. I've no doubt at all that the J50 will work using the CSBs which come with the kit. Just be careful how much weight you put in and where you put it.

As for your contention that there is nothing to choose between compensation and springing as regards ride quality - really? Then why are we doing it? I'll believe you when you can demonstrate this using similar locos with the different arrangements on the same layout.

Regards,
BobH

davebradwell
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Re: Chassis kits for CSB

Postby davebradwell » Sun Aug 11, 2019 8:56 pm

You've missed the point, Julian. Springing gives vital sound insulation by decoupling the mass of the body from the track so a sprung loco will always be quieter than a compensated one - unless the beams are bendy or the springing is one of those strange systems where they run bottomed out. Difficult to appreciate in a vast hall but very pronounced on a home layout. It's why a Penberth diesel is streets ahead of its more basic origin. Of course your twin beams won't quite give the great crash you get when a rigid axle on a heavy loco goes over a baseboard joint at speed but you still get the rumble from the unsprung mass. A sprung train gives a satisfying whoosh as it storms past on it's way north whereas rigid/compensated stock tends to grind its way along.

I will add some qualifiers to this to avoid falling foul of the scrutineers but stop short of the full legalise. An rtr coach with clipped in P4 wheels has enough resilience in the plastic bogies to run silently, I'm talking of all metal vehicles. We're running at speed here, scale 80 say and large layouts, particularly those in lofts, which require expansion gaps at board joints. Yes the gearbox carries the sound from the drive directly to the track however you suspend the loco.

DaveB

Julian Roberts
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Re: Chassis kits for CSB

Postby Julian Roberts » Mon Aug 12, 2019 4:21 am

I completely see that Dave.

I hadn't clicked Bob who you were and that we met each other recently. I hope Kings Cross is nearer having a new home? I think to reconvene the party with Dave too at the Queens Arms for another delicious pint is called for sometime! Meanwhile here is a quite inspirational 14 year old talking about how the way we say something can change the meaning of what we are saying... :P


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Noel
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Re: Chassis kits for CSB

Postby Noel » Mon Aug 12, 2019 10:51 am

davebradwell wrote:Of course your twin beams won't quite give the great crash you get when a rigid axle on a heavy loco goes over a baseboard joint at speed ...... We're running at speed here, scale 80 say and large layouts, particularly those in lofts, which require expansion gaps at board joints.


In steam days, trains which were scheduled to achieve 80mph, even in the 'Streamliner' era, were a vanishingly small proportion of the overall total, and could only achieve such speeds on favourable track lengths [one of the problems the LNER had with its streamliners was the number of speed restrictions between London and Newcastle]. For at least some parts of the steam era there were no trains scheduled to achieve that speed at all. If you reduce the figure to 60mph, it's still quite a small proportion of trains. Semi-fasts and some express freights might come close to that figure sometimes, but the great majority of trains would be unlikely to be scheduled at more than 40mph anywhere.

I'm puzzled by your comment about baseboard joints; wood is generally far more stable with variations in temperature than metal, so the baseboard gaps shouldn't change much over the normal range [and how many loft layouts would be in areas less well insulated than the rest of he house, these days?] Even assuming a layout which is removable, there is no obvious need to limit the allowance for rail expansion solely to baseboard joints, which seems to be the implication of your comment.

Assuming that such layouts are a small proportion of P4 layouts, and not all of those will be running at a scale 80mph anyway, and discounting exaggeration for effect, how strong an argument for springing is this really?

{Note that I'm questioning this argument specifically, not springing as a concept.}
Regards
Noel

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Will L
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Re: Chassis kits for CSB

Postby Will L » Mon Aug 12, 2019 11:30 am

davebradwell wrote:I note the unnecessary swipe at the mature design of springing which I use and which might threaten my commercial arm. You prefer a non-adjustable design, WillL, whereas I won't build a model without adjustments on the springs. Both are perfectly valid design approaches largely based on how we choose to build the rest of the model and what it has to do to justify its existence. It boils down merely to personal preference.

I agree personal preferences come into this, and given the overall quality and excellent reputation of your kits, I rather doubt any reservations I may have about the individual adjustable springs approach represents any real threat to your sales. After all, we do agree that proper springing is the right way to go, and at the very least, of the springing systems which have commercial support, only your system and CSBs can ensure that the model is properly suspended at the midpoint of their springs. None the less, I can't let your suggestion that CSB are "non-adjustable" go unchallenged. The whole concept is based around ensuring, at the design stage, that the springs achieve the desired weight distribution given a specified location for the Centre of Gravity. On a completed loco you can adjust the weight distribution to meet the design by ballasting the loco appropriately, and replace the spring wires to ensure they match the final model weight. No other adjustment is necessary.

I agree it may seem mildly perverse to adjust the locos Centre of Gravity(CofG) to suit the springs, rather than adjusting the springs to suit the weight distribution of the loco. Given how easy it is to find the CofG, and how difficult people have found it to produce a practical weigh bridge capable, with any degree of accuracy, of determining the weight carried by an individual wheel on a 4mm loco, perhaps coming at it from the CofG direction makes sense.
I feel a discussion coming on, about whether fixing the location of the CofG unduly limits our ability to ballast up a loco to pull the maximum possible load, but I think perhaps that response would be better in reply to another post I have already seen.

davebradwell
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Re: Chassis kits for CSB

Postby davebradwell » Tue Aug 13, 2019 12:32 pm

I think you'll find that wood moves far more than metal, Noel, particularly with humidity and temperature, too. See Google. I have vague memories of an American article which was circulating a while ago and which pointed this out. Anyway, it was just an excuse for having gaps at baseboard joints which can be a source of an irritating noise even at speeds below 80.

DaveB

davebradwell
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Re: Chassis kits for CSB

Postby davebradwell » Tue Aug 13, 2019 2:42 pm

Indeed it's all about adjustment, WillL and I don't think it perverse to adjust the c of g. Some find it easier to turn a screw, others apparently not.

An approximate balance point can be predicted before building a loco, even with weight bearing carrying wheels. What I often find impossible is getting it there while achieving enough adhesion. You wondered about this.

My first B1 4-6-0, built to check the artwork for the original kit, has a Portescap in the firebox and I was very pleased with the sprung bogie. Lightly weighted it ran occasionally with any vehicles to hand - normal usage, probably. It was when we turned to formal operations and King's Cross opened just down the road that it was required to haul 10 coaches round corners and uphill like the prototype. Lead was stuffed everywhere until it eventually did its job but at the expense of balance and it needed 2 springs on the front axle to level it up. There's no law that says all axle weights have to be the same but care is required or you end up with something that will derail when going astern. I should say that a later B1 with motor in the tender turned out much better but probably still outside the scope of a csb.

Take the humble J72, a standard NE region shunter. Mine can end up with 30+ wagons in tow during a shunt. Once again weight is stuffed everywhere, leaving space for decoder and speaker of course, but the bunker is larger than the smokebox and it inevitably ended up tail heavy which I could adjust more normally this time by turning little screws (actually 10BA is quite large by our standards).

So you see you can't move weight from one end to the other when the loco is built for maximum haulage. I don't doubt that the csb is a perfectly satisfactory solution on many models but it would rarely suit the type of loco that I build.

Balance is less of an issue with Pacifics, although with the long rear overhang any lean will upset the rear drawbar or fallplate and the tender will likely throw a tantrum. We find load bearing bogies and Cartazzis essential, both for safety at speed and, in particular, when backing out of platform 1 at The Cross where even the prototype has a kink next to a K crossing and I believe was notorious in steam days. Getting the right balance between these and adhesion isn't something that can be dreamt up in a chair and takes considerable testing, perhaps even some movement of lead because turning a screw doesn't create weight from thin air, it just alters the distribution. Further, a Pacific on a curve with a heavy train will yaw significantly at the front and this can bring the bogie off so further fiddling. I know examples of Pacifics and an Atlantic where the haulage has been almost doubled after making these adjustments.

So why didn't I try csb on my 2-6-2T, a perfect example of balance? Well, life rarely goes to plan and experience has taught me not to design myself into a corner. Do you put lead in the smokebox or not? Well I did and remainder of boiler was filled behind it then the tanks and, oh dear, it's very nose heavy. By the time I had filled the bits of the bunker that didn't contain other stuff I achieved an almost balance but it weighs 200 tons. Yes, a csb might almost cope with such a disaster but I knew I could survive even if things had turned out worse. There's still final adjustments to make.

I like having the springs underneath where possible enabling our flimsy frames to be well stayed. My 9F kit is really a model of the prototype's frame stays so although it appears a good potential target for csbs, you wouldn't have much left. Anyway, it already has perfectly adequate springs.

Finally a passing thought: I'm suspicious of the concept of extending the csb to carrying axles. Surely the work involved in transferring the force to the bogie/pony without stiction or backlash is greater than just springing these items normally and you lose the ability to adjust the relative weight distribution. Your 2-4-2T might pass here as it's probably a radial tank but I think you'd be searching for a little screw if it had to pull 10 coaches. The jury's out.

It's been a lengthy explanation of my views and experience in an attempt to be fair. There is nothing wrong with the csb concept and the time put into writing a guide makes it's application to a kit not designed for springing relatively straightforward as long as you can predict certain things about the finished model. Nothing can ever be a total solution, however, and I believe I have shown that there are situations where its application would fail and also its questionable ability to cope with a typical cock-up. Separate springs are not difficult to apply or adjust, however, where these are preferred and it's possible to adopt a more suck-it-and-see approach because of the increased adjustability. Csbs appear to be a safe option for small layouts and low speeds but this does raise the question of whether you build for the layout you have or the one you aspire to.

DaveB

4479
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Re: Chassis kits for CSB

Postby 4479 » Tue Aug 13, 2019 5:44 pm

Julian Roberts wrote:I completely see that Dave.

I hadn't clicked Bob who you were and that we met each other recently. I hope Kings Cross is nearer having a new home? I think to reconvene the party with Dave too at the Queens Arms for another delicious pint is called for sometime! Meanwhile here is a quite inspirational 14 year old talking about how the way we say something can change the meaning of what we are saying... :P




Julian, Dave B has expanded rather well on the brief point I was trying to make, and now you know why I was making it. My J50 will likely have to haul ECS up to 10 corridors up my gradients and around my curves. Maximum weight will be essential and with decoder and speakers to house, I won't have a lot of choice over where it goes, hence I will probably use individually adjustable springs. You may of course not feel you need to go that far (at this stage) and can follow whatever Chris G suggests. As Dave says, it's horses for courses.

However, that's all for the future. The way things are going, Kings Cross will not have a home until the housing market picks up and there is something suitable to buy. The other bad news is that the Queen has closed so your good idea to reconvene will have to take place elsewhere. Umi Garrett is an incredible talent, but I'm not sure what message you are sending me....!

Bob

Dave Franks
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Re: Chassis kits for CSB

Postby Dave Franks » Wed Aug 14, 2019 9:09 am

Well, so far I've kept shtume about CSB vs anything else. Probably because I'm a bit biased towards CSB having manufactured CSB replacement chassis for various tenders. I've been playing about with CSB for years since the late Mike Gilgannon showed me how his Caledonian coaches ran and boy did they run beautifully. My first attempt was the dreadful DJH WD tender which clattered and bumped even over seemingly good track, I tried compensation and it was okay but next with an early form of CSB it was transformed. For me the rest is history. Dave B. mentioned a 2-6-2 and that is the latest chassis to be built with CSB, this was to be a test bed for motors actually, the gearbox was a modified Highlevel one but with various holes enlarged to accept different motors. The tanks of the Bachmann Ivatt 2mt were filled with lead sheet, nothing in the smokebox or bunker so it was nicely balanced, pony trucks loose so they don't count yet. The loco with a tiny square motor trotted round Wharfeside nicely with 10 Mk1s, the motor got very hot if you crawled it but okay at a good speed, it could take 15 Mk1s just. The various motors were tested but the CSB chassis performed very well and will eventually be finished as a layout loco with the trucks having side control fitted in my usual way.
Yes I do have compensated locos too and they work well but once you understand how CSB works it is easier to build a CSB chassis.
I've got another of Dave Bs J39 chassis on the bench and it will be built with his independent suspension just because the kit is designed that way and my first J39 works very well once I adjusted the suspension to the right ride height.
Just my take on the subject.

Dave Franks

Website:- www.lanarkshiremodels.com

Julian Roberts
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Re: Chassis kits for CSB

Postby Julian Roberts » Fri Aug 16, 2019 2:26 pm

Bob what I didn't want to provoke was another of those useless arguments that people can waste their time with on this Forum, by saying anything more ill-considered or that could be construed in the wrong way. What I meant by putting up that Ted Talk was in a way addressed to myself, as well as for some beautifully played music. "Out of the mouths of babes and sucklings comes wisdom" - her point that the same notes played in different ways can change what they are saying. I didn't have anything to add and writing more was likely to be counterproductive. I've made fewer than 10 locos so hardly think I've anything profound to offer. Dave has done the subject proud and taken the discussion to a level where I for one now see issues far beyond my hitherto quite primitive and undemanding level, so thank you Dave for being inspirational too.

Tragic that the Queens is no more. Another pub gone and more of our social fabric unravelling. Both Daves have much to offer us Dave F having given me plenty of help too over the years.


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