Acurit Brass Proportional Divider

How To Use A Proportional Divider:

First, choose the scale of your drawing. This means deciding how much smaller or larger you want your drawing to be. You can do this by loosening the dial and sliding the legs up or down to shrink or enlarge the scale. Once you have the scale set, you can measure any object.

If you're trying to enlarge a tree in a reference photo, position the tool so that the smaller end of the X is touching the top and bottom of the tree. Then use the wider opposite end of the divider to mark the tree's proportions on your paper.

To reduce the size of a large subject, reverse the process. Use the wide end of the tool to measure your object and the smaller end to make your marks on the paper. Once you have the tick marks in place, connect the dots with a freehand line.

You can also hold the proportional divider in front of you at arm's length while looking at something you're drawing from life. You'll get relatively accurate proportions as long as the length of your arm is consistent and doesn't change much as you draw.