How Accurate is 'Scale'?

[MikeOxon]

Many years ago, I bought a plastic 'Keil Kraft' kit of a Fowler Ploughing Engine.  The box stated it was 1:72 scale and, at the time, I thought it might look ok on my 4mm (1:76) scale model railway.  After I'd built the thing, it looked huge, so I decided that the 'scale difference' did matter!

 

Then, recently, I found a scale drawing of one of these engines on the web at http://www.steamscenes.co.uk/blog/merl-engineering-drawings-workshop

Since the actual dimensions are marked on the drawing, it was fairly easy to print a copy to 4mm/foot scale and to compare the print-out to my model.

 

To my surprise the model 'fitted' the drawing perfectly in almost every respect, except the height of the chimney.  It seems that, although marked 1:72, this model is in fact to 1:76 scale! 

I wonder how often this happens and we discard a model because we think it is 'wrong'?

 

 

It seem that these engines really were huge.  In fact, most were exported to Australia, since they proved too large for British farmers.  One was demonstrated at a Gloucestershire show in the 19th century, so it might find its way onto my layout, probably as a stationary engine.

 

Mike

[Classsix T]

Those ploughing jobs ARE mahoosive, as you say. Bressingham have a pair and they always impressed when I visited.

 

Regards non railway kits, it has been mentioned on this website previously that the Airfix vehicles can vary despite stating 1:72 on the box.

 

C6T.

[Spitfire2865]

I bought a 1:72nd scale sopwith camel kit and its tiny. Though, the actual plane is tiny as well at less than 30' wingspan. I never did check its accuracy...

[Adrian Wintle]

Considering that 'Scale' consists of:

 

1. The scale marked on the box

2. The scale it was actually intended to be

3. The scale it was made at

4. The modelmakers interpretation of the size/shape/dimensions

5. The accuracy of the drawings etc. used by the modelmaker

6. The accuracy and dimensional stability of the model production technique and materials

 

it is not surprising that you can find some curious items.

 

It was quite interesting building model kits of Soviet jets (before the collapse of the USSR) as they tended to be based on whichever intelligence estimate was current when the manufacturer decided to make the kit. This led to some very interesting interpretations of size, shape, and detail....

 

Adrian

[Guest Centurion]

I think the problem sometimes lies in that you think something that's not in your usual scale but only a little bit out will be ok. I mean in your mind you could think that there is not much difference in :1:72 and 1:76, it's only apparently a difference of .4. The same mistake is made with people using HO figures mixed in with OO, with the thought of "It's ok they will be a bit shorter and not everyone is the same height".

 

The key thing, and my point, that the difference in scale exists in all 3 dimensions as X, Y & Z so in the example of people they are shorter, thinner, and have less depth so the difference is more marked than the in the brain difference of only.4.

 

Having said that.....things that are slightly out of scale I think can be mixed if you think about placement. Things slightly too small could be placed nearer the back, things slightly too big nearer the foreground in a sense of false perspective. HO and OO can be used as long as they are not too near each other. I have used, or rather kit bashed HO building kits in OO scene too, these have generally very little noticeable difference.

 

But to be honest, unless something is way out does it really matter? If someone feels the need to point out that your plough is a bit big that's down to them, there will always people you will never please and you would tear your hair trying. I have recently made a display of cakes and bread on a rack to go inside a bakers, it's only after I did them it turns out my iced fingers are about 12" long, who cares!

 

Oh, and before a pendant says it yes OO, HO are gauges not scales but they have a scale attached to them!

 

[DCB]

To be pedantic Centurion it would be a pedant not a pendant who complains...

[Chimer]

Pendant = someone who hangs about checking for spelling mistakes? 

[jbqfc]

yes they are huge engines 

 

 

 

 

[Jeff Smith]

The obvious example of mixing scales is using 1/87th track for 1/76th vehicles and scenery......sorry, a bit below the belt but I like P4 for the appearance.

 

I have been building some US laser cut wooden craftsman building kits in 1/48th scale.  Several buildings from one manufacturer all look good together and in proportion.  However a station building from another manufacturer looks huge and out of place - so much so that I queried the manufacturer, in particular on the door height which scales as 8 feet.  The response was that it was based on a real example which had 8 foot doors......perhaps the other buildings are on the small side but the doors scale as 7 foot.

[edcayton]

Do the real ones come in different sizes?  To me the ones in the photo's look different, but that could be the angles.

 

All the time I worked in engineering we were told "never scale from a drawing", indeed when I was in the Drawing Office our pre-printed drawing sheets had that on them. It was sometimes noticeable that prints were different from the original.

 

Ed

[34theletterbetweenB&D]

Do the real ones come in different sizes?  To me the ones in the photo's look different, but that could be the angles...

Every manufacturer free to do their thing, so of course they can be. It's only railways and canals with gauge considerations that have a fixed envelope for vehicle size.

 

...All the time I worked in engineering we were told "never scale from a drawing", indeed when I was in the Drawing Office our pre-printed drawing sheets had that on them. It was sometimes noticeable that prints were different from the original...

And when you saw the reprographics processes of years gone by, it was an absolute necessity because there was no dimensional stability in the process. The drawing showed you how the parts were arranged, the dimensions were only to be taken from the numbers on the page, with interpretation of standards by the drawing office standards book cross referenced to the drawing.

 

Wasn't it fun when the drawing standard moved from imperial to metric, and some inattentive draughtsman put the old imperial reference book on the drawing, which was dimensioned metric? I cannot have been the only person here who has seen a rapid effort using the apprentices to mock up the new part from such a drawing; then with much hilarity it was conveyed to the D.O. to ask how this monster part was intended to fit in the end product? In the case I saw a pushrod forty feet long, intended for the secure locking mechanism in a roughly metre high cupboard...

[Pacific231G]

I think the problem sometimes lies in that you think something that's not in your usual scale but only a little bit out will be ok. I mean in your mind you could think that there is not much difference in :1:72 and 1:76, it's only apparently a difference of .4. The same mistake is made with people using HO figures mixed in with OO, with the thought of "It's ok they will be a bit shorter and not everyone is the same height".

 

The key thing, and my point, that the difference in scale exists in all 3 dimensions as X, Y & Z so in the example of people they are shorter, thinner, and have less depth so the difference is more marked than the in the brain difference of only.4.

 

Having said that.....things that are slightly out of scale I think can be mixed if you think about placement. Things slightly too small could be placed nearer the back, things slightly too big nearer the foreground in a sense of false perspective. HO and OO can be used as long as they are not too near each other. I have used, or rather kit bashed HO building kits in OO scene too, these have generally very little noticeable difference.

 

Oh, and before a pendant says it yes OO, HO are gauges not scales but they have a scale attached to them!

 

I'd say that OO was originally a gauge but it's come more to represent a specific compromised scale/gauge combination just as did TT-3 and "British N scale" For H0 though, the scale definitely seems to lead the charge but as 16.5mm is exactly 1/87 of standard gauge (to within 0.006 of a millimetre)  it can equally define both a scale and a gauge* .

For narrow gauge, H0 definitely defines the scale so you can have H0m, H0e and H0i all using the same scale but with different gauges.

 

When they established standards for British modellers during and soon after WW 2, the members of the BRMSB do though seem to have seen OO as a scale rather than a gauge. In their original standards "Standard OO" used a gauge of 16.5mm but "Scale OO"  was to use 18mm. Since relatively few people took up Scale OO they rechristened it EM in the late 1940s and  I've always wondered whether it was really pressure from the trade who didn't want to be denied use of the word scale that led to that. You could argue that OOn3 and OO9 also demonstrate that OO is still a scale rather than a gauge but as there is (fortunately IMHO) no central governing body for the hobby in Britain,  pedantry is meaningless and it's up to you how you see it. 

 

I've found to my cost that many European "H0 scale"  building kits are more like 1:00 than 1:87. For background buildings I've been OK with that as a little forced pespective can be useful but when I built an Artitec corrner Café for my French layout I realised that it was to the correct scale and towered over the station building in front of it. It is a very nice model but it just looked wrong so  I replaced it with a couple of underscale industrial buildings. They look fine but now my passengers and shippers now have nowhere for a beer or a glass of wine and they don't like that at all. 

 

*For the real pedants H0 and HO are actually different scales. European H0 is defined by MOROP as 1:87 scale but American HO is defined by the NMRA as 1:87.1 which is almost exactly 3.5mm/ft but makes 16.5mm ever so slightly over gauge (by 0.0235mm !!) Does this mean though that in the USA ,where imperial measurements are stil the norm, modellers reduce prototypes dimensions in feet and inches to millimetres for scale modelling ?  

[Jeff Smith]

In my experience millimetres are not used much in US modelling however my US modelling is restricted to 1/48th which is an Imperial scale anyway.  I believe most HO modellers are likely to use a scale rule and not worry about doing sums......

[Pacific231G]

In my experience millimetres are not used much in US modelling however my US modelling is restricted to 1/48th which is an Imperial scale anyway.  I believe most HO modellers are likely to use a scale rule and not worry about doing sums......

Thanks Jeff.

That does sort of make me wonder why the NMRA didn't keep it simple and define HO as a simple numerical ratio as MOROP did but I guess that's lost in the mists of time  (before scale rules were widely used?)

[davefrk]

Yes, ploughing engines are huge. I used to help out on a number of traction engines and rollers but standing next to a Fowler ploughing engine one felt the size of the thing. They weren't just used for ploughing either - a pair were used with a grading bucket on the first part of the M1 motorway, digging out some of the cuttings, circa 59-60.

 

Dave Franks.

[Black Sheep]

Yes, ploughing engines are huge. I used to help out on a number of traction engines and rollers but standing next to a Fowler ploughing engine one felt the size of the thing. They weren't just used for ploughing either - a pair were used with a grading bucket on the first part of the M1 motorway, digging out some of the cuttings, circa 59-60.

 

Dave Franks.

They do make for a nice bit of brute force

[Jeff Smith]

Makes you wonder why British railway modelling didn't adopt 1/72nd - a nice imperial scale - track gauge of 0.785" or near as damn it 20mm. 4mm scale is great if you work entirely in metric but all the old railway drawings are in feet and inches.....

[Andy Reichert]

Back in the 60's I was rather bothered by having bought packs of Airfix 00/HO scale people, none of whom could be put across my 00 track with their feet on one rail and their head on the other.

 

I didn't think the average UK person was only 4ft 6 in tall.

 

Andy

[Pacific231G]

Makes you wonder why British railway modelling didn't adopt 1/72nd - a nice imperial scale - track gauge of 0.785" or near as damn it 20mm. 4mm scale is great if you work entirely in metric but all the old railway drawings are in feet and inches.....

In two words Jeff-  Henry Greenly. In many ways he was a founder of railway modelling, as opposed to railways in model engineering, but he developed his own "standards"  very early on and defended them vigorously when scale modellers were looking for something better. Juding by his letters in Model Railway News he simply didn't see why people were worrying about a few millimetres here and there. He was very much a miniature railway engineer and thought railway modelling was far more about running  a railway in miniature than scale modelling which he rather dismissed. 

 

I don't know whether 1/72 (2 inches to the foot) was an establlished general modelling scale back in the early years of the 20th Century but suspect that if it was and had been adopted by for railway modelling it might well be what the whole world would now be using. For Standard Gauge 20mm gauge at 1:72 is less than a tenth of a millimetre wide of gauge but given the well known British loco clearance problems suspect it would have been dropped to 19mm but that would probably have been close enough for everyone and with enough lattitude for all except toy trains.

[Adrian Wintle]

Back in the 60's I was rather bothered by having bought packs of Airfix 00/HO scale people, none of whom could be put across my 00 track with their feet on one rail and their head on the other.

 

I didn't think the average UK person was only 4ft 6 in tall.

 

Andy

 

However, by the '70s some of the packs were definitely OO or even 1/72 (e.g US Paratroops), while others were still closer to 1/87. There has always been something of a variability in the Airfix figure packs.

 

Adrian

[Jeff Smith]

David - I thought the clearance problems were associated with the smaller British loading gauge which meant that electric motors at the time used for 1/87th would not fit into the British outline loco bodies - hence the bodies were scaled up to 1/76th but the gauge (chassis/motor) kept the same?

[Spitfire2865]

I personally use Metric in my modeling as I find it easier. My physics teachings also have drilled metric into my head.

[jbqfc]

Do the real ones come in different sizes?  To me the ones in the photo's look different, but that could be the angles.

 

Ed

 

yes the bottom is a bit smaller 

[Jeff Smith]

I personally use Metric in my modeling as I find it easier. My physics teachings also have drilled metric into my head.

 

In my engineering career I have found mm are easier for estimating smallish things like material thicknesses etc but inches and feet win out for me when it comes to anything bigger.  When I took my final exams at college (1971) the physics paper had duplicated questions in Imperial and Metric and luckily we could choose whichever system we wanted for each question....I passed, just....

 

Some of you may know this but even in Metric designs Imperial threads are often used as thought to be superior to metric ones.  I remember years ago dealing with a Swiss engineering company and finding they used BSP (British Standard Pipe thread).

[Clive Mortimore]

In two words Jeff-  Henry Greenly. In many ways he was a founder of railway modelling, as opposed to railways in model engineering, but he developed his own "standards"  very early on and defended them vigorously when scale modellers were looking for something better. Juding by his letters in Model Railway News he simply didn't see why people were worrying about a few millimetres here and there. He was very much a miniature railway engineer and thought railway modelling was far more about running  a railway in miniature than scale modelling which he rather dismissed. 

 

I don't know whether 1/72 (2 inches to the foot) was an establlished general modelling scale back in the early years of the 20th Century but suspect that if it was and had been adopted by for railway modelling it might well be what the whole world would now be using. For Standard Gauge 20mm gauge at 1:72 is less than a tenth of a millimetre wide of gauge but given the well known British loco clearance problems suspect it would have been dropped to 19mm but that would probably have been close enough for everyone and with enough lattitude for all except toy trains.

Hi David

 

The ratio is one inch to 6 feet.