CSBs for outside framed locos

[Phil O]

Hi All,

Has anyone used CSB suspension on an outside framed loco? I have the Martin Finney kits for Aberdare and I have thought about using the CSB system, but the kits uses the outside frames for the hornblocks which means drilling them for the pivot points and also the trailing axle is fixed, which would mean fitting High Level hornblocks and guides.

Any guidance would be welcome. Within this link are links to the destructions and the etches. http://www.brassmasters.co.uk/gwr_aberdare_2-6-0.htm

Thanks

Phil

[garethashenden]

I believe all GWR outside framed locomotives are actually double framed, with the wheels in between the inside and outside frames. The kit appears to be designed in this way. I would fit the CSBs to the inside frames as normal, the outside frames are just cosmetic. The kit says to open the outside hornblocks to a loose fit. They’re just along for the ride, not doing actual work.

[davebradwell]

Well that's the standard way of doing it but if you were feeling brave you'd have the potential for a better running chassis with the working hornblocks in the outside frames. I did it on a narrow gauge engine years ago and it probably had less slogger than anything I've built since. Using the inside frames, the cranks are cantilevered well out and any small amount of play in axleboxes and hornguides will be amplified. Finney chassis are rather stone-age now and well rooted in Flexichas - there's significant room for modernisation however you build it, particularly with the tiny width of hornguide offered by a single plate.

DaveB

[davebradwell]

If following the traditional approach, it would be useful to look at how the late John Hayes used the Finney axleboxes and guide plates in his description of a Hall build way back in MRJ 55. He subsequently used this method with springs in the A3 in #66/67. Briefly, he added angles bearing on the sides of the axlebox to increase area of slide and also reduce clearance. This was done before jig setting the axle centres.

DaveB

[andrewnummelin]

No comments on the specific kit in question, just some observations on my own experiences.

Is the aim to getting all things right?
- this would almost certainly mean bearings in the outside frames for all driving wheels and also in the inside frames for the driven axle. (That sounds like a "fun" CSB calculation! I don't intend to try...)
- inside frames will often need to be extended above the footplate level so need to be at prototype spacing to look visually correct (I doubt if many do this but this is also relevant if there is gap between smokebox and buffer beam so that the chassis frames are visible from above.)

Look at the prototype carefully:
- the outside faces of the outside frames need to be at the prototype spacing for good visual appearance of footplate & buffer beam overhangs
- some prototypes have horn blocks & bearings that extend outside the frames, some do not (large effect on spacing between the frames)

0-6-0T 26.jpg

DSC01114.JPG

Be careful with thicknesses/clearances:
- wheel (boss) thickness may need to be reduced
- crankpins nuts may need to be very thin
- bearing thickness (length along axle) may need to be limited
I got this wrong on one model that cheerfully demolished ground signals.

Think about chassis construction (scratch building - a kit may have solved these)
- frame spacers between inside frames and separate ones between inside and outside frames (prototypical but fiddly especially as one needs to allow space for CSB spring wire)
- frame spacers between outside frames and bits of inside frames between spacers only for visual effect and added last of all. (I'm trying this at present.)
- inside frames probably did not extend backwards beyond the front of the firebox. Do you make the firebox & ashpan part of the body or part of the chassis?
- with axleboxes and CSB supports in the outside frames one has more room between frames for gearboxes etc.
- access (for tweezers) for threading CSB spring wire between the frames.

DSC01851.JPG

As I have a couple of (odd) outside framed locos on my to-build list I be grateful for other people's experiences.

[petermeyer]

For what it's worth, I currently have two Finney outside frame locos on the go: a City and a Duke. I also have an Aberdare in the to do pile. The outside frames, although etched in nickel, are very flimsy almost overlays and would not withstand working hornblocks. These kits are designed to use hornblocks on the inside frames. The view that Finney kits are from the dark ages is also worth challenging. I have built a High Level Dean Goods chassis, in theory state-of-the-art, and that owes a lot to the Finney Dean Goods design. Anything that isn't sprung on here is often dismissed as archaic but there are many that swear by flexichas chassis. In tandem, following threads on here, I am building another City in tandem using the Lycett-Smith 4-4-0 fixed axle approach and it will be interesting to compare the performance with the twin beamed Finney City.

From what I remember, the Finney Aberdare is actually designed to have a fixed axle and built like an 0-6-0 with one beam. That's how I intend to build it.

[Phil O]

From what I remember, the Finney Aberdare is actually designed to have a fixed axle and built like an 0-6-0 with one beam. That's how I intend to build it.

Yes that's what the instructions say, the difference to the 4-4-0s is that the working hornblocks are on the outside frames, the inner frames appear to have large cutouts.

Many thanks for all the replies, the jury is out on whether to build it as per the instructions or bite the bullet and try the CSB option.

[petermeyer]

OK. Having gone in with my size 9's before checking I thought I'd have a look at the Aberdare instructions. The instructions do say to fix the Flexichas hornblocks to the frames not the outside frames. There is one confusing picture that shows an axle bush going into the outside frames but all other components are shown attaching inside the frames including the fixed axle.

I'd previously come to the conclusion that I would use High Level hornblocks in this loco - so it might need extra surgery but should be workable.

[petermeyer]

Yes that's what the instructions say, the difference to the 4-4-0s is that the working hornblocks are on the outside frames, the inner frames appear to have large cutouts.

Having stuck my oar in here more than once, I thought I'd better complete the circle and actually have a look at the kit.

IMG_0900.jpg

My kit from the Brassmasters era has the chassis etched in brass. The hornblocks' cutouts are a standard 6mm so High Level are an easy fit. The outside frames are half etched and too flimsy for hornblocks without amending.

IMG_0899.jpg

Upon opening I see that my kit has the components for dummy inside motion. The central compensation beam might get in the way of these so, if I decide to use it, a rethink might be needed.

[Will L]

...Upon opening I see that my kit has the components for dummy inside motion. The central compensation beam might get in the way of these so, if I decide to use it, a rethink might be needed.

Of course CSBs could leave the way clear to fit the inside motion! I've seen you work and I'm confident your perfectly capable of fitting them. You only have to ask, you know where to find me Peter

[davebradwell]

People are, of course, free to build their models any way they want without fear of abuse, discrimination or intimidation. Finney kits build into a highly detailed model that has probably never been equalled in terms of appearance. However, in the years since they were introduced we have new components and techniques so hornblocks can be improved (Roy Jackson saw the point contact provided by the Flexichas bearings as the Achilles heel of P4), a single rigid axle gives a bumpier ride than other options and there are better designs of bogie and pony that are less prone to derailment. Further, why wouldn't you want to at least consider making a model that ran more quietly and smoother than as originally designed. As most kits were designed around this era these comments apply widely. Progress happens and you may choose to ignore it but it's still out there.

Someone asked a question on a public forum and I raised these matters so that they might stimulate some thought. I will continue to campaign for better running chassis in the hope that someone may, one day, just take note. Weren't we being accused of stagnation on another thread?

To be more practical, the Finney axleboxes may well fit the High Level hornguides to save you a few pence - perhaps someone will check. They're good deep frames so springs should fit easily but check around the firebox. Viability of using outside frames could only really come from a GA so that widths and clearances could be determined.

DaveB

[petermeyer]

Of course CSBs could leave the way clear to fit the inside motion! I've seen you work and I'm confident your perfectly capable of fitting them. You only have to ask, you know where to find me Peter

Thanks Will, I might just take you up on that and build a CSB Finney Aberdare. Peter

[Phil O]

An update, having spent the weekend at Missenden Abbey and got to grips with the actual build, I have bitten the bullet and I am building with CBS's.

So far I have hit only one minor snag and that was how the pony truck centering spring fitted through the frame spacer. The answer came from Gareth, who is building a Churchward 45xx, his pony trucks have the same system, there's a small hole through the spacer, a close inspection of the etch reveals a half etched dimple that needed to be drilled, I could find no reference to it in the destructions.

The spring wire has since been fitted, with a large amount of profanity, which may have made a fishwife blush.

Thanks Gareth for the assistance. Ditto for Paul for joining in the head scratching.

Cheers

Phil.