This handy little downloadable program can help you with rescaling from any scale.
Ever have plans for a model that are at say 3/16"=1' scale but wanted to determine how to rescale them to 1/4"=1' scale?
With this program you simply enter both scales click enter and it gives you a multiplier that you apply against the original dimensions of your plans. This works on the same premise as in the "Scales and Conversion" article in the Resources section.
Maybe you would like to take your plans and blow them up on your photo copier. This same multiplier number can be input into your copier. Even if your photocopier has limitations on how big it wll rescan (i.e. the maximum blow up you can make is 100% of the original), using the Copier Scaler, input your copiers variables (min reduction and maximum blow up), your scaling variables and the Copier Scaler will tell you the steps you need to go through with your copier to get your plans to the appropriate size.
No installation required with this handy little tool either. Simply download it, unzip it and away you go. (you need a program like Winzip or WindowsXP compression tool to unzip it).
Click link to download Copier Scaling Program (64kb)
How to Use
Reducing
You want to reduce a document 6 times, using a copier with a 25%-400% zoom range. By inputting your scales you can see that this can be accomplished in two steps; first, reduce your document by 25%, then take the result and reduce it again by 67%. The program indicates that there will be a small amount of error, because the real zoom value should have been 66.666672% and not 67%, but copiers are not THAT smart.
Increasing
Another example, you have 1/72 plans, and want to enlarge then to 1/35 scale. This time, the copier you have access to has a limited 50%-200% zoom range. Two steps are necessary again, first enlarge by 200%, and then take the output result and enlarge it to 103%.