Largest Engine Made By a Model Engineer?

[RedsetterParticipant @redsetter]

Posted by Chuck Taper on 15/12/2022 11:04:02:

Naive question.

If building a "x-inch" model that means the scale of the model is x inch = 1 foot. Is that correct?
Whereas a x inch gauge refers to the spacing between rails. Is that correct?

Is there a (simple) relationship between these two selectors or are they incompatible.

I have (briefly) poked around on the web – 'nuff said.
Could someone here could point me towards a decent reference (preferably the old fashioned kind – a book)

When deciding which scale to use what factors might go into that decision. It looks to me that the gauge scale will mandate the (finished) size of any rail based model whereas the x inch per foot allows more leeway with non rail related models.

There is a table in Tubal Cains Model Engineers Handbook concerning track and wheel standards but not enough.

Thanks in advance.

Frank C.

Frank, You are broadly correct. You can model in any scale you want to – normally determined by the capacity of your workshop or the cost of the materials- but in the case of railway models it is best to build to one of the accepted rail gauges so that you can run on existing tracks. The scale you use will then depend on your prototype, and this is where it gets complicated, because prototype rail gauges are not always nice round numbers. Often some compromise is involved.

For example, standard gauge is 4ft 8 1/2 ins, and for 5 inch gauge models the usual scale is a slightly awkward 1 1/16 inches to 1ft. If you want to model a 2ft 6 inch gauge prototype to run on 5 inch gauge you would use 2 inch scale, which would result in quite a large model. Then again, 1 inch scale is sometimes used for 5 inch gauge but is more accurate for 4 3/4" gauge, which is commonly used in North America.

Again, historically 2 1/2 inch gauge used a scale of 1/2 inch to the foot, but nowadays 17/32 inch to the foot is used which is more accurate and produces a usefully larger and more powerful model.

Hope that helps, but it is the tip of the iceberg.

[DiodeDickParticipant @diodedick]

It's a bit off topic, but the comment that "Wikipedia is not definitive" is an understatement.

Check the Wikipedia Commons entry for "Decauville locomotive Lilliput" Most readers here will spot that in the engraving in the middle, the loco has outside cylinders, whilst in the two photographs, which are believed to be the Corpet works photos, there are inside cylinders, actually a V-twin with longitudinal cylinders on a common crank and slip eccentric valve gear reversible from the footplate.

When this was brought to Wikipedia's attention, through their community of experts, they removed the work's photos and kept the engraving. The photos were reinstated some time later. The loco in the engraving is a later one, probably built by Couillet, bearing the same name but definitely not Decauville 0001.

Dick

[Alan CharlestonParticipant @alancharleston78882]

Hi,

I've seen the Newcomen engine running and it's truly a sight to behold. There's a video on YouTube.

I suspect it doesn't qualify as "The Largest Engine Made By A Model Engineer" because there were more than one involved.

Regards,

Alan

[SillyOldDufferModerator @sillyoldduffer]

Posted by Chuck Taper on 15/12/2022 11:04:02:

Naive question.

If building a "x-inch" model that means the scale of the model is x inch = 1 foot. Is that correct?
Whereas a x inch gauge refers to the spacing between rails. Is that correct?

Is there a (simple) relationship between these two selectors or are they incompatible.

…

A broad question rather! Admittedly not my area of interest, but I read the articles and am still uncertain. The big picture is an unholy mess, but individual examples make sense when drilled into.

Scale is expressed as a ratio, and one way of doing that is in inches per foot. It's a heritage system, quite handy if working in Imperial aka English Measure, otherwise daft as a box of frogs. Equally common in the day, and almost universal now, is for the scale ratio to be dimensionless. 3:1 or whatever, which works in feet, inches, metres and parsecs. As many models are based on a prototype built in feet and inches, inches per foot is still in currency. Anyone not familiar has to engage brain until the puzzle comes together.

But beware, builders aren't constrained to build exactly to any scale! Instead designs are mostly proportioned that way, but detailed dimensions are often changed to suit the technical needs of the model or the track it runs on.

Gauges are even worse than scales. Gauging means 'sized by comparison', a method popular before weights and measures were standardised. There were once hundreds of gauge systems because every trade, company and region made their own up. Mostly consigned to history, but there are several survivals. One has to sort out Z, N, O, OO, Gauge 1,2,3 etc, plus the bigger than garden gauge sizes supported by clubs. Traction engines and boats are different again. I don't know of a single source that lays out all the possibilities.

Is the model scaled down from a size, or is it sized to run on a particular track gauge? Ship models are usually the first, 'our' sized steam locos are usually the latter – they have to run on a track.

Probably best to ask specifically to find out exactly what the gauge of interest means. My experience is miniscule, but I've dealt with gauges by translating them into standard measure, usually Metric because that suits me, and work to that. If you buy a set of plans for a 5" locomotive, the designer should have sorted out the build dimensions for you. though mistakes and omissions aren't unusual. Converting the same plans to 3½" Gauge isn't quite as easy as applying a scale ratio, doubly so if Imperial is switched to metric as part of the process.

The subject would make a good magazine article. Perhaps it's been done?

Dave

[John MCParticipant @johnmc39344]

This topic got me thinking. Does building something bigger than fullsize make the model the biggest?

I friend of my grandfather was a keen horologist, he made number of clocks but the one that has stayed in my memory was a pocket watch. His "model" was about 9" in diameter, that is to say 4 times full size. I recall him saying that the size was determined by two copper cooking pans that formed the case.

I wish I could remember more about the watch (clock?), often wondered what happened to it.

John

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