Designing a Ready-To-Run Model - A / A1 / A1X Terrier

[Ian J.]

I see your points there. Once I get a chance to have a proper look at the prototype's frames then I will be better placed to see how a central block would interfere with between frame detailing, but your variation is worth bearing in mind.

 

As for doing the whole body in metal, I'd have to look into that once CAD is available, but potential loss of crispness of detail would worry me so for now I'm still inclined to stick to an injection plastic moulding.

[Ian J.]

I've been thinking about the idea for side extensions on the keeper plate - and why it isn't already done.

 

From looking over the models I have to hand (Bachmann's 8750 and 4575), it appears that current designs are based on workers assembling the wheelsets independently from the chassis. To be able to get them into the chassis during final model assembly, there can't be anything in the way of the axles. By putting a representation of the frame on the keeper plate that 'drop in' capability is lost. It might be possible to produce plastic frames independent of the keeper plate that fix to the central metal core, but we're starting to get to a complex assembly again.

 

So it then comes down to which of the complex assemblies is the best of the bunch? I'm more inclined to stick with my original idea of separate metal frame sides with substantial spacers between, with the pick ups attached to but insulated from the frames. I'd possibly use plunger pickups (which the Dapol Terrier used for four of the six wheels), and have no keeper plate.

[number6]

Ian

With regard to the frames. If you look at a side view there is a large cutout in the frames between the front two axles and there is a large void under the boiler where the 'knitting' goes.... and getting this effect would be really going a long way to the character - and something the existing model totally fails to do. It would preclude a solid chassis forward of the middle axle. Perhaps thinking of the rear two axles as a unit and the front end as free of a solid chassis would make a huge difference to the appearance.

 

Because of the space constraints I would look at other very small locos [possibly also just 0.4.0s] from any manufacturer and see how they do it. Even a Pannier is much bigger. I'm not sure you really need to do all the thinking behind the design work you just need to set the brief of what the design manufacturers can do for you!

[Ian J.]

Ian

With regard to the frames. If you look at a side view there is a large cutout in the frames between the front two axles and there is a large void under the boiler where the 'knitting' goes.... and getting this effect would be really going a long way to the character - and something the existing model totally fails to do. It would preclude a solid chassis forward of the middle axle. Perhaps thinking of the rear two axles as a unit and the front end as free of a solid chassis would make a huge difference to the appearance.

I'd like to put some detail in there, but I will probably find the costs associated with it impractically high. But my design will hopefully allow for it.

 

Because of the space constraints I would look at other very small locos [possibly also just 0.4.0s] from any manufacturer and see how they do it. Even a Pannier is much bigger. I'm not sure you really need to do all the thinking behind the design work you just need to set the brief of what the design manufacturers can do for you!

One of the things about looking into the design and thinking it through myself is I am unfettered by current factory processes. Companies like Dapol, Bachmann, Heljan and Hornby tend to consider their models in light of the production line arrangements they already have access to. If I left the thinking for the design work to them, they will continue to work within those set ups and won't push the fidelity of chassis design forward.

 

I must add though that I see why they do so. Their designers are 'forced' to take account of very commercial decisions so the companies can pay their shareholders. I am coming at this clean of existing processes, and if the project comes to fruition then the assembly line will need to change to suit the model, not the model to suit the assembly line.

[woodenhead]

I must add though that I see why they do so. Their designers are 'forced' to take account of very commercial decisions so the companies can pay their shareholders. I am coming at this clean of existing processes, and if the project comes to fruition then the assembly line will need to change to suit the model, not the model to suit the assembly line.

 

And they are not going to do that for one model line, you will have to commission from another source if you go down that route.

[Ian J.]

And they are not going to do that for one model line, you will have to commission from another source if you go down that route.

The thought had crossed my mind. I am wondering if I need to change the title of the thread accordingly. Perhaps 'Designing and Producing an RTR Loco - A1/A1X Terrier' would be more appropriate now?

 

Edit: Thread renamed to 'Designing a Ready-To-Run Model - A1/A1X Terrier'.

[JohnR]

• Minimum radius curve in OO (coarse) would be third radius. In OO (finescale), EM & P4 it would probably be at least three foot radius. Let me know if it needs to be a larger radius.
  

 

I suspect this will actually limit your market quite a bit. I appreciate that you want to move RTR on a bit, but you dont do it by cutting out most of your customers - its easier to buy another loco than it is to rip up all your trackwork and start again with a larger layout.

[Ian J.]

 

I suspect this will actually limit your market quite a bit. I appreciate that you want to move RTR on a bit, but you dont do it by cutting out most of your customers - its easier to buy another loco than it is to rip up all your trackwork and start again with a larger layout.

Are first and second radius that common in their usage? On the 'toy train' type layouts maybe, but how many use second or first for hidden curves on otherwise more 'to-scale' layouts?

 

However, my intention is not to design something for such layouts. Rather I'm aiming at the more serious modeller, hence the specification for being able to gauge-widen the chassis out to EM and P4. If it turned out to be easy to allow for second or even first radius within the OO (coarse) default, then I'm happy to let that be so. I'm working from the top down so to speak, giving importance to the finer tolerances first and formost and the sloppy tight radius OO commonly produced at the moment must bow to the finer scale.

[JohnR]

Ian,

I wouldnt say first radius, but the commonly accepted minimum radius for every model on the market at the moment is 2nd radius. If there is one designed for 3rd or greater, I'm not aware of it. The only models which run on 1st radius are the small wheelbase toy locos (smokey joe et al), and I would discount it.

 

In my view, it would be best to try and design for that standard (2nd radius) to encourage as many sales as possible.

 

Much as I laud your aims for the project, I think it would be commercially naive to design something for the much smaller EM/P4 market, and take the much, much larger OO market as of secondary importance.

[Ian J.]

As I've previously stated I'm not designing for EM or P4. I'm designing to allow the buyer to convert to OO(finescale), EM or P4 - that's a big difference. Any actual RTR loco would be to OO (coarse), but the question of how coarse will be one dictated to by the more important (in my eyes) capability for the conversion to finer tolerances.

[JohnR]

As I've previously stated I'm not designing for EM or P4. I'm designing to allow the buyer to convert to OO(finescale), EM or P4 - that's a big difference. Any actual RTR loco would be to OO (coarse), but the question of how coarse will be one dictated to by the more important (in my eyes) capability for the conversion to finer tolerances.

 

I know thats what you've said, but as I said, 2nd radius is the current "standard" (like much in OO, unofficially), and by designing something for greater than 3rd radius you will put off a large number of potential purchasers.

[Guest dilbert]

I must add though that I see why they do so. Their designers are 'forced' to take account of very commercial decisions so the companies can pay their shareholders. I am coming at this clean of existing processes, and if the project comes to fruition then the assembly line will need to change to suit the model, not the model to suit the assembly line.

 

Changing the assemby line approach in real terms will probably cost more than the R&D and the tooling combined. That doesn't mean it can't be done, especially if there are advantages

 

Reverse engineering a product is relatively simple, reverse engineering a process such as an assembly line is highly complex - changes in one sub-process will impact on one or multiple sub-processes - the more you drill down the bigger the headache becomes... dilbert

[Ian J.]

 

Changing the assemby line approach in real terms will probably cost more than the R&D and the tooling combined. That doesn't mean it can't be done, especially if there are advantages

 

Reverse engineering a product is relatively simple, reverse engineering a process such as an assembly line is highly complex - changes in one sub-process will impact on one or multiple sub-processes - the more you drill down the bigger the headache becomes... dilbert

Agreed. It makes me feel that setting up a new assembly line is probably the only way to get such a change through. Using existing factories is therefore out of the question.

 

(Did I mention earlier that I thought this was a million-to-one shot? )

[spamcan61]

In terms of manufacturer then given the 'million to one' status I don't see a need to stick with OO manufacturers, is there not someone somewhere who makes a HO 0-6-0 vaguely Terrier sized maybe?

[Oldddudders]

Does this go anywhere nearby?

 

http://www.rmweb.co.uk/community/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=140139

[34theletterbetweenB&D]

Ian,

I wouldnt say first radius, but the commonly accepted minimum radius for every model on the market at the moment is 2nd radius...

The key set track component that sets 2nd radius 'in stone' from the perspective of a mass produced RTR model is not the plain track curves. It's the standard points, which for a very long time were the only set track points. These devices are, like it or not, embedded in a great many layouts and not coming out any time soon if I am any judge (They actually go slightly under 2nd radius, but on a short wheelbase model like a Terrier that's unlikely to change matters significantly.)

 

For a model for the UK OO market, it is easy enough to predict what the most common next largest point radius installed on the nation's layouts are likely to be: Peco's 24" job. My opinion would be that if striking out for more closely toleranced territory, that's the next 'logical' radius as an aiming point.

[Ian J.]

Well, we'll see. The Terrier has a very 'simple' chassis compared to an outside cylinder loco, so it may be possible to get away with a tighter radius, but I need to do designs and tests before I will know.

 

I have DoubleCAD installed, it's going to be a bit of a new experience for me as while I did technical drawing at school, that was in the days of pencils and paper! I hope to get along to the National Archives tomorrow to renew my Reader's Ticket, and see if there are any technical drawings there. I've emailed the NRM and Bluebell, but as it's been the weekend I've had no responses as yet.

[number6]

All this talk of minimum radii for a loco with one of the shortest wheelbases! I have a pair of kitbuilt terriers with very little side play and they both went through a set track point and around a ferocious curve on Southerham.

[John B]

I'm what you might call a Terrier fan. I've built several, and have a few more "on the go". I wish you every success, Ian. And if this venture gets anywhere past the ruminating stage, I'd be keen to support you by way of committing to purchase.

 

The major problem I see (other than those already alluded to above - like "daylight" in frames & under boiler, etc) is that the choice of prototype, charming and much needed as it might be, is fraught with detail differences. One size won't fit all for the A1 and A1X - other than the basic chassis. With Terriers (and apologies if I'm indulging in egg-sucking lessons here) you really have to pick one - at a given point in time - and model from that. Very few (if any) got through their entire working lives without some significant changes - whether it was conversion from A1 to A1X, Isle of Wight specific alterations, sandbox shifts, Drummond boilers, stovepipe chimneys, brake blocks changing from original wooden to iron, etc etc. Even the preserved locos vary pretty wildly from one to another. It's a good job you've got plenty of time for research...

 

I'm 2,600 miles away from my refernece library right now, but if I can be of help in suggesting books / photo & drawing sources, etc, feel free to PM me and I'll see what I can dig out at the weekend..

[Ian J.]

I am something of a Terrier nut myself, which is one of the reasons why getting a good one in RTR is important to me. That there has only ever been the one hybrid RTR model, which was never even close to correct for most of the liveries, and technically not correct for any when all details are taken into account, is to me a 'sin'.

 

Just the obvious visual differences are as you say 'fraught':

• Bunkers
  
• Bunker railings
  
• Front wheel splashers
  
• Boiler length
  
• Smokebox type
  
• Under frame sandboxes
  
• Chimneys a plenty (due to the various owners over the years)
  
• Domes and consequently safety valves
  
• Air brake equipment
  
• Spectacle plate guards
  
• Lamp irons
  
• Condenser pipes (or not, as the case may be)
  
• Locations of various pipework and other such sundry items
  

I can't just pick one, as to make any tooling cost effective, it needs to be capable of handling all the major arrangements, from the original A1 like Boxhill, through the A1X variants both in LB&SCR/SR/BR and private ownership, right up to the preservation conversion of Fenchurch to be like an A1. This is one reason why I need to do lots of the R in R&D, starting with (if I can find them) the original LB&SCR plans. I was at the National Archives in Kew today and while I found some small basic GA blueprints in amongst some Southern Railway IoW material, there was nothing else obvious from the descriptions in their catalogues which leads me think they have the full technical drawings. To do justice to the model I need the frame drawings to a good, accurate measurable size. No replies yet from NRM or Bluebell, but it's early days.

 

One interesting titbit from my research today is that in the locomotive register for the LB&SCR covering from 1860 odd up to 1918-ish, the Terriers as introduced are given class 'A', not 'A1'. Only after Marsh's rebuild of boiler and smokebox around 1911-12 did the '1' come in with the 'X' to make A1X. However in not finding any of the original documents regarding their ordering, I can't know what their original intended designation was.

[Ian J.]

Update

 

I've just had a reply to my query to the NRM regarding drawings for the Terriers, and it looks like they've got pretty much the whole lot. I've scanned through their drawings lists for Brighton Works, and picked out the major items that would be good to start off with. Now I've just got to organise a visit so I can eyeball them and choose which to get copies of.

 

What is interesting in looking at the descriptions is that the majority of the ones for the Terriers (as they were originally were) are given just the 'A' classification, not 'A1'. So it looks like using 'A1' might be a tad incorrect, and they, or at least 'Boxhill', should really be referred to as just 'A'.

[Ian J.]

Update

 

I'm currently waiting on the NRM for the GA and frame drawings for the A/A1. Due to some issues they're having with scanning some stuff it'll be a while before I have the A1X drawings.

 

Good to see that Hornby aren't doing a new-tooling Terrier for 2012, gives me some breathing room!

[bbishop]

Update

 

What is interesting in looking at the descriptions is that the majority of the ones for the Terriers (as they were originally were) are given just the 'A' classification, not 'A1'. So it looks like using 'A1' might be a tad incorrect, and they, or at least 'Boxhill', should really be referred to as just 'A'.

When Stroudley took over the mess that was Brighton works, he planned to build a range of standard classes. He designated them A = suburban; B = express passenger; C = goods; D = local passenger; E = shunting / local goods; etc. He didn't distinguish between tank and tender classes so originally the D1 class was referred to as the "D tanks". For those of an LNER disposition, the wheel arrangement was an irrelevance.

 

Over time, and with the appointment of the elder Billington, there was a proliferation of classes. It became impossible to file the G.A. drawings properly so there was a numeric addition to the class designation. As there was only ever one suburban class, the Terriers could have been left as A, but they followed the trend and became A1; and, as most were rebuilt, were further revised to A1X.

 

Hope this helps and apologies for errors from a LSWR / DB modeller.

 

Bill

[Ian J.]

OK, while waiting for the A / A1 scans, I've been reading up a bit and checking out some photos and have come up with a list of the variations that I can ascertain so far that are likely to affect the design work.

 

This shouldn't be seen as a final list though. I'm sure other minor variations will come to light as my research continues.

 

Brakes

A/A1 - Wooden blocks with light iron fittings, later fitted with iron blocks and heavier iron fittings.

A1X - Iron blocks and fittings.

 

Footplate

Some IoW examples, notably the preserved 'Newington' had steps fitted below the footplate towards the front.

 

Couplings

A/A1 - Three link very early on, replaced with Screw link relatively quickly.

A1X - Screw link only.

 

Pipework

A/A1 - Tank condensing pipe linking the two tanks immediately in front of the cab early on, seems to have been removed quite early after introduction.

A/A1/A1X - the characteristic condensing pipes from tank front to smokebox at original build were variously removed and refitted throughout the locomotives' pre-nationalisation lifetimes. Photos for timing of such changes must be used to check authenticity.

A1X - At some point in later life (seemingly during late SR period), injectors were fitted with the associated pipework that extended forward from near the cab and wrapped down around the boiler in front of the tank fronts.

A1X - A vacuum ejector exhaust pipe began to be fitted between cab and smokebox from late LB&SCR days.

 

NOTE: Clack valves seem to have varied while in BR ownership, being different from the LB&SCR originals.

 

Chimneys

Four types as best can be ascertained:-

A/A1 - Stroudley copper capped.

A1 - Marsh cast.

A1/A1X - Wheeler & Hurst on IoW examples.

A1X - Drummond on some SR locos but not apparently on the two LSWR ones.

 

NOTE 1: 'Waddon', the SECR owned example, seems to have retained its Stroudley chimney up until it received a Drummond.

 

NOTE 2: On Hayling Island operations in later years, smoke arrestors fitted.

 

Boilers

A/A1 - Stroudley original boiler.

A1X - Marsh reboilered examples.

'Clapham' and 'Newington' (the two LSWR examples) received Drummond boiler with Drummond domes and safety valves, the boiler was 1 and a half inches narrower than the LB&SCR ones, possibly within tolerance to not bother tooling a variation.

'Waddon' received a Wainwright SECR boiler until getting an A1X boiler, but notably never received an A1X smokebox, not sure about boiler diameter as at time of writing.

 

Domes

On Stroudley boiler the dome was in line with the tank filler caps.

On Marsh boiler the dome of same apparent design was moved forward slightly.

'Waddon' with SECR boiler had very different dome.

'Clapham' and 'Newington' (the two LSWR examples) received Drummond boiler with Drummond domes and safety valves.

 

Smokeboxes

A/A1 - Stroudley original with straight sides to mount directly on footplate, with wing plate.

A1X - Marsh tubular smokebox without wingplate with saddle.

Waddon never received the A1X smokebox.

Fenchurch has had A/A1 smokebox fitted in preservation, making it a hybrid like Waddon.

Rivets on both A/A1 and A1X smokeboxes seem to vary in application and by date.

 

Front Sandboxes

A/A1 - Above footplate, combined with front splasher and wingplate/smokebox.

A1X (Brighton examples) - below footplate and splashers refashioned accordingly.

A1X (non-Brighton examples) - sandbox retained above footplate as part of splasher but disconnected from smokebox.

 

Bunkers

A/A1 and Fenchurch - Original small bunker, open-framed extension railings fitted later to some members but not Fenchurch.

A1X (non-IoW, not Fenchurch) - original small bunker with open and later closed framed extension railings fitted.

A1X (IoW) - Toolboxes removed and bunkers extended back to rear edge of footplate.

A1X (IoW examples after return to mainland) - a small extension railing fitted to slightly increase capacity.

'Bodiam' only - a single variation to the bunker where the depth remained as per original, but the height was increased slightly, and different rivet arrangement and pattern of sheeting to make up the height at the back.

 

NOTE 1: Extension rails fitted to KE&SR examples appear to be a different pattern of similar dimensions.

 

NOTE 2: S&MR 'Dido'/'Millwall' had a higher bunker of different pattern to 'Bodiam', but is not relevant to this project as it's too off the beaten track to bother with.

 

2-4-0T

The motor train experiment would require a new or significantly modified chassis - probably skiing too far off piste to bother with.

 

Tanks

The exhaust steam domes at the front ends of the tanks seem to have been hapharzardly retained or removed. Photo evidence to support choices for suitable dates required.

 

Buffers

A1X had extended lamp holders for main line examples in some cases.

2-4-0T experiment had buffers raised higher from footplate, but reduced again for Boxhill on reversion to 0-6-0T but not for Beulah apparently.

 

Wheels

IoW examples appear to have had balance weight extensions when in IoW service.

 

Handrails

'Gipsyhill'/'Portishead' only - when in GWR ownership after WC&PR acquisition, the smokebox/boiler handrails were lowered slightly.

'Brighton' (and possibly other IoW examples) had additional handrail fitted to front of tanks while in IoW service and retained after return to the mainland.

[Ian J.]

At the risk of coming across as annoying, I'm making another post in a fairly short time.

 

I've been working through the possible parts needed for the RTR Terrier. Not including the variations, but including the optional components, I have worked out nearly 200 separate parts for assembly. This doesn't include the constituent parts of the single part for the main body which I'm hoping can be acheived via slides in the injection tooling. It does include all the bitty bits like all the screws, handrail knobs, lamp irons, and the like, plus all the multi-part components like the buffers (with at least four parts each) and the plunger pickups (again, four parts each).

 

I'm not going to list them all here, that would be just too tedious to read through, but suffice it to say that I'm going to be looking to see how much I can reduce that count, and still have an authentic, high fidelity design.

 

It does make me wonder though just how many parts there are in a current high fidelity standard Bachmann/Hornby/Dapol steam loco, and how long it takes the workers to assemble them. Obviously the labour cost of the assembly is a significant factor in the production of a model, so keeping that time to a minimum is a crucial part of keeping the final price tag down.