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

[Guest dilbert]

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.

 

Have you fixed a market price range for the final product and also some volume sales predictions for example of the first initial three years.? That will give you a target indicator of what the total cost of getting the product to market.

 

One approach (that you may have already considered) is to ensure that the body is Dapol/Hornby chassis 'compatible'. One way of reducing the price/cost element could be to release fully painted bodies only that people can use to replace the original... dilbert

[Ian J.]

I can't even guesstimate any prices until I am much further into the process, so no, no market price range, or even volume sales predictions. When I have something more to show in the form of decent CAD, and have more idea of the number of separate parts, their cost to assemble, etc, then I'll be in a place to start gathering those figures.

 

I'm not intending to design in any compatibility with any existing model or chassis, be they the RTR Dapol/Hornby or kits. Doing so could compromise my design process. If by fluke of chance what I produce could potentially be comfortably put on a different chassis, then I may consider selling bodies only, but don't bet on it.

 

Personally I think the Dapol/Hornby chassis is very primitive. IMO there isn't a part of the model, either chassis or body, that has any redeemable features when compared to the kind of models that have been produced more recently. It's an old school design that owes more to toys than models.

[Ian J.]

I have received the first two drawings from the NRM

 

As they are General Arrangements, they are quite 'noisy' with information so I will need to set to work picking out various elements. Firstly will be the frames from the frame GA. I think it will be a fiddly process and may take quite a while, but I'm 'starting the journey', so to speak.

[Ian J.]

After the pause waiting to see what Bachmann were going to announce, and making sure the Terrier wasn't in their plans (for this year at least), I can now pick up from where I left off. I have a number of drawings to get from the NRM to fill out what I will need, but hopefully that won't take too long. First thing, as mentioned above, will be the chassis and picking out the frames from the drawings.

 

My current plan is to have what is in effect a split chassis, but I'm not sure whether to have it with one set of wheels insulated with pickups and solid axles, or in two distinct halves with split axles. My memory of the Mainline/Palitoy implementation of split axles is that they break down over time. I wonder if technology and materials science has moved on enough to produce a robust insulated axle centre that won't break at the first sign of a wheel turning? Any advice on the best way to implement split axles would be welcome, if it is indeed even worth considering.

[richbrummitt]

I would use 3D CAD for the designs. No point in converting to 3D later. Something like VIACad is cheap enough if you are serious and advertises all the capability you will need. Everyone will expect 3D data for the mould tooling further along in the process. The learning curve is steep but beyond basic sketching out and layout drawing you should want to work in 3D because it is a much better way of working.

 

I would guess that if I had all the dimenions laid out in sketches that it would not take too long to work out the design. Maybe a couple of weeks. Contract 3D CAD work is in the regiong of £30+/hr. The mould tool pricing depends heaviliy on what you want (quality/complexity/...) and how long you want it to last and how much of it you need. A suite of 20 mould tools (45 parts) for a recent project I did professionally was £250,000 plus extras (in China). They have lower complexity than a model locomotive, but are larger parts. I think these are your major costs if you get all the leg work for the design sketches together.

[Ian J.]

ViaCAD looks to be a reasonable option. According to the PunchCAD website the Pro version has additional advanced 3D modelling tools - how valuable would they be?

 

Also (not mentioned in their specs) what kind of file formats it can save as / export to? I would need something that can produce files that can be upscaled to Solidworks or similar if the project works out and I want to work on other models in the longer term.

 

Their forum seems to be predominantly private, suggesting only registered users get to see it - feels a bit like they're hiding something, but I am willing to be proven wrong.

[34theletterbetweenB&D]

... I wonder if technology and materials science has moved on enough to produce a robust insulated axle centre that won't break at the first sign of a wheel turning? Any advice on the best way to implement split axles would be welcome, if it is indeed even worth considering.

The Hornby diesel chassis with split axle collection (in my case I have examples of the chassis used under class 30 and 31) appear to work well; not seeing numerous complaints about this aspect of the models, 100% reliable for me over several years regular use. Don't the two new Dapol steam models use split axles too? Worth a purchase of the Beattie WT if it does: there's a recently developed model of a Terrier sized prototype that probably has much of the relevant technique embodied in it, worth using as a benchmark.

[Ian J.]

The Hornby diesel chassis with split axle collection (in my case I have examples of the chassis used under class 30 and 31) appear to work well; not seeing numerous complaints about this aspect of the models, 100% reliable for me over several years regular use. Don't the two new Dapol steam models use split axles too? Worth a purchase of the Beattie WT if it does: there's a recently developed model of a Terrier sized prototype that probably has much of the relevant technique embodied in it, worth using as a benchmark.

 

I did wonder if the BWT used a split axle, as I've not been able to see any contacts to the wheels at all. I will keep the split axle idea in mind as I go about the chassis design, it could save on contacts to the wheels which would reduce the overall fiddliness of the pickups.

 

On that note, I think I've managed to isolate the frame shape from the frame GA, with a bit of help from a photo I took of Fenchurch stripped back almost to the frames way back in 1999. It's a little later than the similar pics in Handel Kardas's book, and mine also happens to be in colour:

 

[Ian J.]

Well, I've opted to get the ViaCAD 2D/3D package to get me started (as after rich's post above seems more what I would need for starting off). It's on offer on Amazon's US site at just $56, which once postage was added came out to £45. What tax, if any, I'll have to pay on its arrival in the UK I'll have to wait and see. It wasn't directly in stock so I've a bit of a wait unfortunately with delivery expected sometime in the second half of April.

 

The wait will delay the work, obviously, but I've other things to keep me occupied in the meantime.

[Ian J.]

The ViaCAD software has arrived, somewhat earlier than I expected

 

Now I just have to get myself familiar with it

[Alex Thompson]

The terrier would make a good model to prouduce. I think there will by alot of willing buyers who want to buy it for they layouts. If you proudce them in a large enough numbers you could take the retail price down to an price which any can buy it.

[Joseph_Pestell]

I wish Ian well with this project even if I have no great desire for a Terrier.

 

I do think though that this thread should be compulsory reading for all those that grumble at the manufacturers for not producing their personal favourite locomotive. It sets out very well how difficult the R&D for a new model still is even with the benefits of modern technology.

[Ian J.]

A Spanner in the Works

 

Due to changes at home it looks likely that I'll not be able to get any work done on the Terrier CAD for quite a while. My landlord is going to sell the house this year but I'm not sure when, so I have to be ready to move as soon as possible. This means much tidying up of detritus and packing everything away, including the PC I use for design work. Also, I don't currently have any place to move to so it's quite likely that all my stuff will end up in storage of some kind and I'll be temporarily on someone's living room floor! Not a good environment to set up a computer in.

 

I want to move anyway, as I'm fed up to the back teeth with Stratford, Newham, and London. However I don't think I'll get much choice in where I move to. I can dream of a move 'back' to the West Country, but that's all I can do

 

If or when I have more concrete information on my circumstances such that they will allow me to continue the design work, I'll revive this thread. However, for the moment I think it will have to be left on ice