# Scaling Guide

Discussion in 'Scratchin' & Bashin'' started by RonP, Jan 11, 2008.

1. ### RonPMember of the WMRC

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Is there a scaling guide somewhere where i can figure this resizing thing out ?

I am taking drawings like nazgul with realworld measurements and taking them down to HO

I know i can get a ruler with HO on it but that takes the fun out of it and my son likes to steal them meaning i already have 3 that are out of site for me.

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2. ### MasonJarIt's not rocket surgery

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That's a great plan! :thumb: :thumb:

You can use a calculator (or long division ) to change real world measurements to HO scale by dividing by 87. E.g. something that is 20 feet long in the real world is now 20/87 = 0.2299 feet long (or 2 3/4 inches).

If you haven't yet, you might want to consider getting a digital caliper that displays either fraction or decimal inches, so you can dial up the size you need directly from your calculation.

Andrew
3. ### doctorwayneActive Member

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I think that a set of proportional dividers will do the rescaling for you, although I'm not sure where you'll find them. I think too that they're fairly expensive.
If you're looking to re-size the plans to HO on a copier, you need to know the scale of your plans and the percentage of that in regards to HO. Even so, I'd check at least a couple of dimensions on the re-sized plan to ensure that they are indeed the scale that you want.

Wayne
4. ### RonPMember of the WMRC

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Thank nazgul for the plan i found it from his post.

ok for the slower ones hows the best way to find this out on a calculator ? Or would it be better to do a chart with easy conversions. This would be a great sticky for the scratchin and bashin forum.

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6. ### MasonJarIt's not rocket surgery

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The calculation goes like this:

Dimension is 20 feet (read off the plan)

Scale factor is 1/87th for HO scale (160th for N, etc).

So divide 20 feet by 87 = 0.2299 feet (remember that the units stay the same, and the "87" has no units).

To find inches, multiply 0.2299 feet by 12 inches/foot (foot units cancel, leaving you with inches)

Answer = 2.7588 inches or ~ 2 3/4 inches.

If you have a digital caliper set to decimal inches, simply dial up 2.7588 and that's your reference.

Andrew
7. ### doctorwayneActive Member

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Ron, if you want the plans in HO scale, simply re-draw them using an HO scale ruler: if your plan shows a dimension as 20'6", simply mark off that distance using the HO scale on the ruler. Personally, I can't see any purpose in re-sizing the drawings, as you'll need to mark out every measurement again, on the material, when you build the model.
If you absolutely have to have the drawing in HO scale and don't want to do any calculations, measure one marked dimension on the drawing with your HO scale ruler: for example, if a dimension on the drawing is stated to be 20'6", but your HO scale rule measures it as 9'9'', try making a copy at 200%. Then, measure the same dimension again with your HO scale ruler and see how close it comes to 20'6". Simply adjust the copy size up or down as required until that dimension is correct. When it is, all other parts of the drawing, whether dimensioned or not, should measure out correctly when checked with the scale ruler. You should already be aware, though, that things like door and window trim on elevation drawings are not necessarily drawn to exact scale, as the plans will specify the type and size of material required. Perhaps you could enlighten us as to why you require the plans to be in HO scale?

Wayne
8. ### RonPMember of the WMRC

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Thank you mason jar

Doc i have historical drawings with 1:1 measurements and only want the HO measurements for the piece i am cutting
9. ### MasonJarIt's not rocket surgery

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Ron,

I think we may be misunderstanding your request, but tou do not need to make the drawings HO scale to build from them, unless you intend to use them as a template of sorts. HO scale plans are provided sometimes for scratchbuilding, for example: trestle bents, but is not necessary for structures like the grain elevator.

You can simply read the measurement, and use your HO scale ruler (as doctorwayne suggests) or make the calculation, and use a caliper or regular ruler to measure and cut the model parts.

Andrew
10. ### doctorwayneActive Member

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Andrew is correct, Ron: if the dimension on the drawing says 20', it's 20' in whatever scale you're working. That's why the scale ruler is so useful and the reason why many how-to articles give the prototype dimensions. Drawings published in modelling magazines may be printed to a specific modelling scale, but invariably, the dimensions on the drawing are for the full-size prototype. You could redo the drawing in HO scale, but unless you're using it as a template, there's no reason to do so.
Or are Andrew and I both missing something here? :-D

Wayne

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To avoid doing double the math, multiply feet by .138 and you'll get the result in inches. So a 20 foot dimension would scale to 2.76 inches (round off to the nearest "sensible" dimension...). To convert real inches to scale inches, multiply by .0115. So 8 real inches would be .092 real inches. This of course only applies to HO....
12. ### RonPMember of the WMRC

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Thanks guys i found some callipers in the shed and im all set...
13. ### 60103Pooh Bah

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Ron: one nit-pick: HO scale is closer to 87.1:1 but it makes the results messier.
The real scale is 3.5mm to the foot. You need the other side of your calipers.
This is nasty because while complete feet end up at the .0 or .5mm, inches come out somewhere else. (Can we convert you to OO where the mm markings are 3"?)
You may have to coat your scale rules with tabasco sauce to keep them away from your son.

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