Scaling plans to 1/700

[Trevor A]

Hello all,

I am trying to expand my skills into the realm of scratchbuilding and I was looking at some ship plans online many of which are in 1/192 scale and I was curious as to how people go about scaling plans down to 1/700. Does anyone have any advice on this matter? I also hope to do similar scaling to 1/350. Thanks, and sorry if this topic has been covered elsewhere in previous threads

Trevor

[Cliffy B]

I've been scaling plans down to 1/700 from 1/96 lately so I'll share what I'm doing. There really aren't that many ways to do it but here goes.

I first take a measurement of a long flat area (I use centimeters). Take it and multiply it by 96. That will give you the measurement in 1/1 scale. Then take the quotient and divide by your target scale (this case, 700). The answer will be the measurement in 1/700 scale. Substitute any scales in you the need.

After I find the measurement I go into Photoshop and open a scan of the plans. I make two guides, one at zero, and one at the measurement I found. I then scale the plans until they fit within the guides. Print and enjoy!

Hope that helps.

[HMAS]

Hi
Scales are ratios of measures in similar units: 1/72 is 1 inch on the model = 72 inches on the full-sized original (or 1 centimeter, furlong, or parsec on model to 72 of same at full size).
The desired scale is then the existing scale times some unknown percentage or fraction, i.e. the conversion factor (either enlargement or reduction):
DesiredScale = ExistingScale * ConversionFactor


Therefore, to find the conversion factor, we regroup and divide to get the universal scale conversion formula:
ConversionFactor = DesiredScale / ExistingScale

Example: to convert 1/72 to 1/48

ConversionFactor = 1/48 / 1/72 = 72 / 48 = 1.5 = 150%
1/700 / 1/192= 700/192 =.27 now as a % 27%
in your case the answer is 27% ( as it is less than 100% it is a reduction)
I think the slide rule is correct

[Timmy C]

I wrote a short guide on the math for scaling here:
viewtopic.php?f=5&t=33867

[DrPR]

Trevor,

Some commercial printing places, like Kinkos, have scanner/plotters. They can scan large sheets, like the 1:192 plans, into a digital file. The "units" in this file are the distances on the original paper plans. So one inch in the file represents 192 inches on the original ship. Have them save the file for you in a format you can use, like PDF or JPEG (PSD if you have Photoshop).

Then you can print the plans at a different scale. For 1:700 you want one inch on the paper to represent 700 inches on the original ship. So you need to scale the print from 1"=192" in the file to 1"=700" on the paper. To do this have the printer scale the print to 27.43% (192/700 = 0.27429).

CAUTION: some printers do not actually print at the defined scale! I have a 2400 dpi HP color LaserJET printer that does not print accurately. Given the printer's dot pitch it should be able to print accurately to 0.0004". However, a 10" line (drawn in a CAD program) prints 9.959" long - an error 10 times the printer's resolution! In order to get this piece of HP junk to print correctly I have to use a print scale multiplier of 1.0041!

This amount of error on an 8" model is 0.032". On a 24" long model the HP printer error is 0.1"! These errors are easily visible to the unaided eye.

Other better quality printers do print accurately. I have a black and white laser printer that prints correctly to within 1/600 of an inch, or 0.0017" (the printer's best print resolution is 600 dpi). A test print of a 10" ruler on this printer comes out to about 10.0008" (I use a magnifier and an accurate caliper and I still can't measure the error clearly), vastly superior to the HP junk. Run a test print of a drawing of known dimensions and measure it to see how much error the printer introduces.

Phil