At last a Fowler 7F 0-8-0 (Cotswold)

[Dave Holt]

You shouldn't scale from drawings Larry, especially ones that have been enlarged/reduced. When I worked in the drawing office at ICI every drawing had "do not scale" writ large. We worked on the assumption that machinists etc would use the dimensions.

 

Ed

 

Larry has already posted a response to this comment, but at the risk of hijacking Larry's thread, I'd just like to explore Ed's comment a bit further.

 

As a professional engineer, I agree with the principle stated, in particular in the manufacture of real life, functional equipment. However, here we are concerned with small scale models where we are aiming for realistic looking cosmetic representations of real items. So called "scale" drawings published for modelling purposes are frequently of dubious accuracy, whether or not they've been re-sized. Even when drawings of a high degree of accuracy are available to modellers, such as the excellent Wild Swan locomotive profile books (a growing, but relatively limited range of ex-LMS locomotives), which contain reproductions of the original engineering drawings, or where similar drawings are obtained from the York Museum, the drawings available are generally limited to general arrangements, pipe & rod and maybe some valve gear, bogie, pony truck drawings, etc. These are assembly drawings which show some key dimensions, such as axle spacings, cylinder centres, overall lengths, widths and heights, but they do not show every dimension or full details of component parts. So, even here, most dimensions can only be established by scaling the drawing from known dimensions. The exception may be where a full size example is available for detailed measurement, but that route is not open to many modellers and even full sized preserved examples may have been subject to modifications or replacement of parts by non-authentic items (just look at the injectors fitted to most preserved Bulleid pacifics).

So, in my view, if we stuck rigidly to Ed's principle, there would be virtually no models of railway items in existance. I'm not sure how serious Ed was, but perhaps he could indicate how many models he has made where no dimensions were assumed or scaled?

 

Happy modelling to all - and keep scaling!

 

Dave.

Edited January 12, 2012 by Dave Holt

[Michael Delamar]

The "Austin 7" was one of the new generation multi-depth etched kits from AG, I think - look out for footplate sections that are longer than they should be, e.g. this happened on the "Crab" and the "Std.5". Whilst the original artwork may have come out perfect, the actual etch did not in those two kits, with strange "stretching" errors! Means sawing off the excess, and losing rivet detail that should be there.

 

ive just got one of these and not only is the frame longer than the drawing supplied but so is the chassis, so even if i do cut the frame and chassis down the wheels wont be in the right place

 

Edited January 12, 2012 by michael delamar

[coachmann]

"ive just got one of these and not only is the frame longer than the drawing supplied but so is the chassis, so even if i do cut the frame and chassis down the wheels wont be in the right place "

 

I'm really sorry to read this as I wasn't aware.

[Michael Delamar]

whats strange is the smokebox firebox and cab match the drawing perfectly even though they are on the same etch as the frame, the boiler comes rolled and is longer than the drawing,

 

i didnt ask for any driving wheels with this by the way so need to know what size the wheels are, thats if i do decide to crack on with it.

[Michael Delamar]

also strange that the tender chassis is include on the nickel etch and thats perfect.

[Michael Delamar]

look at this beauty that was on the vectis auction site, says it was a gibson kit, if its a bit too long i dont think anyone will notice.

 

the kit looks good in itself, theres not that much too it. just puzzled by the drawing,

 

does anyone know what the correct length of the frame should be on the model in mm?

 

ps, sorry for hijacking your thread coachman

 

[mikemeg]

whats strange is the smokebox firebox and cab match the drawing perfectly even though they are on the same etch as the frame, the boiler comes rolled and is longer than the drawing,

 

i didnt ask for any driving wheels with this by the way so need to know what size the wheels are, thats if i do decide to crack on with it.

 

I managed to find a 4 mm drawing of the Austin 7's, which was published in the December 1987 edition of Railway Modeller. Some salient dimensions (not scaled from the drawing but explicitly stated) :-

 

Driving wheels are 4' 8 1/2" (19 mm) 15 spoke, with the crankpins between spokes.

 

The distance from the rear dragbeam to the centre of the rearmost set of driving wheels is 6' 0" i.e. 24 mm.

 

The wheel base, reading from the front set of drivers, is 6' 9" (27 mm), 5' 9" (23 mm), 5' 9" (23 mm) i.e. a total coupled wheelbase of 18' 3" (73 mm). Yes, the distance between driver sets one and two is 1' 0" (4 mm) larger than between 2 & 3 and 3 & 4.

 

The distance from the front driving wheel centres to the front buffer heads is given as 8' 9 1/4".

 

The overall length of the frames is not shown but the dimension from the drag beam to the front buffer heads is shown as 33' 0 1/4" (132 mm). So subtracting the 1' 9" (7 mm) of the LMS buffer, plus a small (1" or .33 mm) allowance for the plate of the front buffer beam, would give an approximate frame length of :-

 

132 - 7 - 0.33 = 124.66 mm or 31' 2".

 

The drawing was attributed to Ian Beattie and, in view of the above drawing scaling dichotomy, there is no indication where these actual dimensions were taken from.

 

Hope this helps.

 

Cheers

 

Mike

Edited January 13, 2012 by mikemeg

[coachmann]

Michael Delamar, I have sent you two PM's concerning the Austin Seven. The etched Alan Gibson footplate is spot on according the my drawings.

 

Larry

[buffalo]

ive just got one of these and not only is the frame longer than the drawing supplied but so is the chassis, so even if i do cut the frame and chassis down the wheels wont be in the right place

From the picture in your post, you appear to be comparing the etch with the 'drawing' on the box label! On another Gibson kit that I have in front of me, the box label 'drawing' is almost correct for 3mm scale. It's only a picture on a box and is not intended to be a scale drawing...

 

Nick

[Michael Delamar]

yes, quite correct, there is also a drawing included in the instructions but is the same as the box drawing,

 

the kit is correct but the 2 drawings included isnt which is a relief

[Dave Holt]

Picking up from Mike's dimensions, according to the LMS Derby GA drawing, 29-11170, the distance from the front coupled axle to the inside of the visible part of the front buffer beam is 7' 0" with the buffer beam 1" thick. The 6' 0" dimension to the rear drag beam is to the outside. Again the beam is 1" thick.

At the front, the frames actually stop short at 6' 6" from the front axle, as the buffer beam was actually a 6" thick (outside) hollow section (possibly with wood between the front and back plates?).

 

Hope this helps solve the "how long are the frames?" question.

 

Anyway, whatever the precise dimensions, I think both Larry's Cotswold Models based model and the Gibson version posted above look the part and capture the look and character of the prototype loco.

 

Cheers,

 

Dave.

Edited January 13, 2012 by Dave Holt

[Michael Delamar]

im probably making this harder than it should be, but just wondering as there is a big gap under the boiler and the inside of the chassis visible, where is best to place the frame spacers? ive got about a dozen photos of these but all 3 quater views and nothing of whats between the frames,

Edited January 13, 2012 by michael delamar

[Michael Delamar]

I managed to find a 4 mm drawing of the Austin 7's, which was published in the December 1987 edition of Railway Modeller. Mike

 

ill have a look in the club library tomorrow night to see if we've got that one, if not can still get them on ebay and the like.

 

will try and get hold of some other drawings but not sure where to look.

 

probably making a mountain out of a molehill but ive wanted one of these for a long time and want to get it right

[Michael Delamar]

managed to get hold of a copy of the december 87 railway modeller

 

first one ive bought in years

[45157]

Larry has already posted a response to this comment, but at the risk of hijacking Larry's thread, I'd just like to explore Ed's comment a bit further.

 

As a professional engineer, I agree with the principle stated, in particular in the manufacture of real life, functional equipment. However, here we are concerned with small scale models where we are aiming for realistic looking cosmetic representations of real items. So called "scale" drawings published for modelling purposes are frequently of dubious accuracy, whether or not they've been re-sized. Even when drawings of a high degree of accuracy are available to modellers, such as the excellent Wild Swan locomotive profile books (a growing, but relatively limited range of ex-LMS locomotives), which contain reproductions of the original engineering drawings, or where similar drawings are obtained from the York Museum, the drawings available are generally limited to general arrangements, pipe & rod and maybe some valve gear, bogie, pony truck drawings, etc. These are assembly drawings which show some key dimensions, such as axle spacings, cylinder centres, overall lengths, widths and heights, but they do not show every dimension or full details of component parts. So, even here, most dimensions can only be established by scaling the drawing from known dimensions. The exception may be where a full size example is available for detailed measurement, but that route is not open to many modellers and even full sized preserved examples may have been subject to modifications or replacement of parts by non-authentic items (just look at the injectors fitted to most preserved Bulleid pacifics).

So, in my view, if we stuck rigidly to Ed's principle, there would be virtually no models of railway items in existance. I'm not sure how serious Ed was, but perhaps he could indicate how many models he has made where no dimensions were assumed or scaled?

 

Happy modelling to all - and keep scaling!

 

Dave.

 

As Dave said "apologies for the slight hijack"

 

As a lifetime engineering draughtsman who retires in 10 Months (can't wait) I have to agree with Daves comments, it often makes me smile the faith modellers put in a drawing only.

When assembly drawings are "issued" for production they represent only the design principles and thoughts at the date of issue.

Changes and modifications for numerous reasons are often made during production, BUT, will only be included on revised/as built/as installed final drawings if the engineering office has been informed of them, and I am afraid to say that it is quite common for such information not to be communicated from production to engineering, so official drawings although generally correct may well contain numerous errors in certain detail areas.

Unless you know the history and the print you have is "as built" the drawing should only be used as a starting point, and get as many photos as possible.

 

Scaling from a print is common enough and fine for non-critical use, as long as you have a known dimension to work from, as paper prints tend to stretch a bit from the original and any marked scales are only appropriate to one particular print size, but it is officially frowned upon, and most engineering drawings will have a note advising against it.

One thing that was drummed into me from apprentice days was to Assume Nothing.

 

All this aside, the model looks the part, and if runs as well as it looks then it is spot on.

 

regards

Stewart

[kwallace6]

Wonder if there is a record for the revival of a thread? At just over 9 years I would like to submit this entry.

 

One for Coachman. In trying to get a working 0-8-0 I bought two; the first one was a nicely made and finished motorless 'Shelf Queen', and the other was 'working', with a DS10, although the gears didn't always mesh. 

 

Assessing the two as part of my Lockdown programme, the motorless one had a better, more freely-running chassis, and I have remotored it, although as I type, it is still on the work bench.

 

I had always fancied your Bachmann upgrade, having seen the thread originally. High Level are currently unable to supply gearboxes, and then a lower priced SDJR 2-8-0 turning up on eBay last week decided the matter.

 

The only bit I am not sure about is how you replaced the extended crankpin on the third driving wheel set. To allow trial running to take place I have used a top-hat bearing as a bush, but this is a terrible (although effective) bodge, and I would much appreciate guidance on how to fit a regular Bachmann crankpin bolt.

 

Cheers,

 

Keith

 

PS As I have been able to use the existing tender and drawbar, I felt this was good value for the £90 paid for the Bachmann, with the prospect of being able to sell on the SDJR loco body, whilst considering the cylinders and valve gear for a possible upgrade for my long-suffering Hornby Dublo ex-3-rail re-motored and re-wheeled 8F! I did consider the other options, which included one of my Mashimas being re-boxed with a High Level unit (£16 when available again) or an RG4 (c. £70 on eBay), and concluded the Bachmann was an attractive ready-to-run option, particularly as the tender has pick-ups and the socket for the chip, so I could add more weight in the loco if required.

 

 

[Blandford1969]

On 13/01/2012 at 19:32, Dave Holt said:

according to the LMS Derby GA drawing, 29-11170,

 

Cheers,

 

Dave.

Appologies on picking up on an old thread, I'm now working on a Gibson version. Does the GA lay out what each of the frame stretchers looked like? From photos at odd angles I can see bits but would like to make my model a little better

 

Thanks in advance

[Dave Holt]

Sorry to disappoint you, Blanford1969, but the part drawings I have only show side on view on C.L. and plan views. There are no end views or cross-sections showing the profile of the frame stretchers.

Dave.

[Blandford1969]

22 hours ago, Dave Holt said:

Sorry to disappoint you, Blanford1969, but the part drawings I have only show side on view on C.L. and plan views. There are no end views or cross-sections showing the profile of the frame stretchers.

Dave.

Thanks, far from it that's really helpful. I have found a frames drawing so am going to take punt on that and see if that helps. It was worth understanding if the GA had something . 

Duncan