3.1/2″ or 5″

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3.1/2″ or 5″

This topic has 11 replies, 9 voices, and was last updated 7 June 2014 at 14:06 by Clive Haynes.

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5 June 2014 at 17:30 #154527
Clive Haynes
Participant
@clivehaynes74488
Hi, I am just setting up my workshop after many years of planning and I am considering building a britannia class loco. I have no intentions of public steaming it. My question is that the drawings from Blackgates have 11 sheets for the 3.1/2" and 24 sheets for the 5". The 5" would I feel be to big and heavy for display so I will be bulding the 3.1/2" but I like the idea of the 5" drawings, so can I scale down from the 5" drawings or are the 3.1/2" drawing adequate. Another option would be to buy both sets.

Hope there is someone out there in cyber space that can help.

Clive
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5 June 2014 at 17:30 #7189
Clive Haynes
Participant
@clivehaynes74488
Britannia loco
5 June 2014 at 22:29 #154552
stan pearson 1
Participant
@stanpearson1
Hi Clive

if you want to build it just for fun and keep the cost down then go for the 3,5" but if you want a good working model then 5" there are more scale parts for the 5" but the cost is higher.

Regards

Stan
6 June 2014 at 00:49 #154556
julian atkins
Participant
@julianatkins58923
hi clive,

if you have considered the LBSC 3.5"g BRIT then there is a big issue re the throatplate design on the boiler.

not sure why you would want to build a loco but not run it – that's the end game and 'fun' in my book!

Stan's advice is excellent.

cheers,

julian
6 June 2014 at 14:04 #154589
Clive Haynes
Participant
@clivehaynes74488
Thanks Stan & Julian for your replies which are helpful but still does'nt answer my main question of wether the 3.1/2" drawings are good or just adequate or would it be a good idea to scale from the 5" drawings or even buy both sets?

My enjoyment is in the building and I think the 'brit' is a thing of beauty but the 5" will not fit on my mantlepeice (if I could lift it). I have built a house which took me 16 yrs to complete and a Jaguar replica kit car which I sold. I am still living in the house.

Clive
6 June 2014 at 14:30 #154590
RRMBK
Participant
@rrmbk
Hi Clive.

Have you looked at Doug Hewsons website? This might help you in your choice. If you are building for acuracy rather than for running, have you considered getting the full size drawings from the NRM in York and scaling from those?

Kind regards

Brian
6 June 2014 at 15:11 #154591
old Al
Participant
@oldal
Hi Clive

you open up a massive can of worms if you play the 'scaleing' game. It can be done and I see it regularly in 2 1/2" gauge, but be prepared to make everything and not rely on someone checking casting stock to check a dimension for you.

I would get a set of 3 1/2" drawings that have a reasonable amount of detail and get some/loads of photos of your prototype loco. LBSCs would not be a choice of mine in this case.

Alan
6 June 2014 at 16:43 #154598
Neil Wyatt
Moderator
@neilwyatt
Clive,

I'm assuming you want a 'fine scale' model, not a working one? It may not be worth as much as one built to a working design if you ever sell it.

If it was me (who has never built a loco from plans) I would get the 3 1/2" plans, as scaling down from 5" will mean that you either can't use stock sizes or you have to modify every dimension affected by the choice of stock. That's either a massive amount of extra work (imagine thinning or thickening the frames…) or risking many errors.

I would then get the most useful plans from the NRM, such as backhead details, and use them to aid with detailing. Doug Hewson's recent series in ME may be of help too, even though for 5" gauge.

If others have convinced you to go for 5" gauge, you could always knock the house down and build a scaled up version with a bigger mantlepiece.

Neil
6 June 2014 at 17:22 #154604
Another JohnS
Participant
@anotherjohns
Hi Clive;

I've got a locomotive in the living room; wife did not think it should sit outside in a shed in a box. So she's now got a book case with "glass" display case on top of it! I have a 3-1/2" gauge 2-8-2 in it.

Ok – to me, 3-1/2" gauge is great. Fairly easily managed, and the smaller the locomotive, the less detail you need to put on it to make it look fantastic.

The LBSC Britannia; have looked at these plans for a while, and, if you look at stationroadsteam, in their archive section, you can see some really nice 3-1/2" gauge pictures.

A couple of weeks ago I had a look at a lost-wax details site we all know and love, at the 5" gauge britannia. I was glad I was sitting down when I saw the complete price of all the bits; fantastic as they are, (and they are) they are outside of my price range.

If you do follow plans, as Neil has said, get plans from the NRM. The museum over here has "modellers packages" of plans for CPR locomotives; they know that modellers care about outlines, and not so much the internal details.

I've been doing a bit of cab remodelling with my 3-1/2" gauge "Ivatt", hopefully when all the plate work and boiler cladding is complete, it will look more like the real ones than the plans would give, but the details (the working bits) are all to plan.

If I remember correctly, the full size Brittanias had the horn blocks centred on the frame plates, not riveted to one side, as in most models. I think the 3-1/2" Brittania is not correct here, but I doubt if it is noticeable. Any Brits care to comment?

Good luck with your project – John.
6 June 2014 at 17:32 #154605
Nigel Bennett
Participant
@nigelbennett69913
Clive

I'm doing exactly this but with a 9F. LBSC's design for the 9F is pretty lacking both in detail and in adherence to prototype (e.g. his horns are inside the frames as per his usual arrangement – but the real 9Fs had the horns outside). I started building it to the LBSC design (a long time ago!) but when Les Warnett's 5"G version came out I scrapped the frames I had cut out and made new ones. I then started to scale everything down from Les' design, but using the LBSC design castings.

The LBSC Britannia design is better than his 9F for fidelity to prototype, but still lacking.

So if it's accuracy to prototype you want, use the 5"G drawings and scale it down.

You will need to take great care when laying out your valve gear and motion. Clearances are tight, and plate thicknesses, wheel standards and everything else all conspire to make everything hit everything else! If you have access to 3D CAD, I'd use that before cutting metal to check clearances and alignments.
6 June 2014 at 21:40 #154626
Ben Cannell
Participant
@bencannell37023
Hi Clive,

3.5" is a nice size for the mantelpiece! 5" gauge is getting somewhat heavy…

If and when I have the time and the money I'd like a 7.25" gauge one and a nice big line to run it on, fell in love with the one I saw at Hemsby Parklands Railway.

PS: You have a message in your forum Inbox regards King's Lynn club and Tuesday's evening meeting times…!
7 June 2014 at 14:06 #154655
Clive Haynes
Participant
@clivehaynes74488
Hi all, thanks for all your info which has been very helpful. I do intend to build a working model for display only. My heart is telling me to build the 5" but my head is saying 3.1/2" so I will (I think) be buying the 3.1/2" drawings and see how I get on, there will be a plan B if it all goes wrong.

Regards

Clive
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