Copier Reductions and Enlargements Done Right

Getting the right size of reduction or enlargement on a copier the first time should not be difficult in principle, but secretaries always ask me to do it for them.

The challenge for this Instructable is to enlarge the Christmas Pageant graphic near to the black pen cap to fit the box at the left of the photo. It would be possible to make a series of copies at different sizes and hope for the best. It is better to calculate the enlargement or reduction needed and get it right the first time.

Step 1 Measure the original

You will need to use a calculator, and they do not handle fractions without first converting to decimals. Save yourself some trouble and measure the graphic in millimeters. Leave a little margin on each side of the original. With a margin, the long measurement of the graphic is 72 mm.

Comments

[kill-a-watt]

Way back when I used to do paste-up like this, we had a wheel style "slide rule" calculator. This saved a lot of effort with fractional inches.

I see you are using millimeters, that's a good way to get around it. We also had rulers in decimal inches, rather than fractions.

I use to do the calculations like this: say a 2.5 inches to 6 inches enlargement:

2.5            100%
----     =     -----
6                 x%

Solve for x. Take 100 * 6 and divide by 2.5 = 240% enlargement.

This is basically the same thing you are doing. Someone might recognize this method from first year algebra and remember.

[Phil B]

You are correct. Our methods of calculating are very similar. It basically involves the product of the means equals the product of the extremes. I believe that is how they put it in algebra when we studied proportions. Folks in our office tended to keep making copies of different sizes until they finally got one that was close enough. It totally amazed some of them when I would make a couple of measurements, punch a couple of buttons on a calculator, and then get it right the first time. I assumed some other folks might have the same difficulties with this process people I know have had with it I chose to use millimeters because the measurements are base 10, which means no mental gymnastics when feeding numbers into the calculator. But, that is about the only time I use metric measurements, otherwise. Thanks for looking and for commenting.