You do not need your own slide rule because this Instructable will make use of a virtual Pickett N600-ES slide rule available for anyone to use at this link. It is the slide rule shown in the graphics. With the mouse cursor on your computer and your left mouse button, you can work the moving parts on this virtual slide rule just as if you were holding an actual slide rule in your hands. Just click and drag the moving parts at the link above. You can also drag the entire slide rule across your screen for a better view. Clicking and dragging will not work on the graphics in this Instructable. It is highly recommended that you open a second browser window and bring up the virtual slide rule so you can practice each new thing you learn in this Instructable.
The graphic shows the left end of the virtual slide rule with the various scales. From the top down you can see the LL1 or log-log 1 + and - scales; the A and B scales; the ST, T, and S scales; the C and D scales; the D1 scale, and the K scale. Different makers of slide rules arranged the scales slightly differently according to what each maker thought would make its rules more user friendly. If you go to this virtual slide rule on the Internet, you will see a radio button on which you can click to display the scales on the back side of this virtual slide rule. Do not worry about that for now. Just be aware that this rule has two sides with additional scales on the backside. Because of all of its scales and features, a slide rule really is a full scientific calculator for all types of multiplication and division problems.
Some, but not all graphics in this Instructable do utilize text boxes. They are not always easy to see because the N600-ES slide rule used an eye saver (ES) yellow and black color scheme. Sweep your computer's cursor over key areas of the graphics to find any text boxes if you do not see them.
(Note: In my experience, some browsers may introduce some inaccuracies when using this virtual slide rule. If a reading is not quite accurate, try a different browser and see if that solves the problem. I will explain how to check for accuracy in a later step.)
Step 1: A first check for accuracy
To adjust a slide rule, loosen the screwhead just to the left of the LL1 scale about a quarter turn. There is an identical screwhead at the right end of the rule. Loosen it a quarter turn, too. The top member of the slide rule's frame can now be moved a little to the left or right until the lines for "1" on all of the scales are directly inline with one another. Use a magnifying glass to be as accurate as possible. When all is in order, gently tighten the two screwheads again. The Pickett virtual rule shown is properly aligned.*
If you are using a plastic slide rule, it is permanently glued in place and (hopefully) is set accurately.
*Loosening these screws allows two adjustments. Already mentioned is aligning the top member of the frame so the 1 on the left side of each scale aligns with the 1 on the others. These screws also are used to adjust how much drag or tension there is on the movement of the slide rule parts when they are worked back and forth. If the slide rule is adjusted to be too loose, the center sliding portion can fall out and become damaged or lost. If the slide rule is adjusted to be too tight, using it for calculations becomes a lot of hard work.