An old tool

I started working in the early days of CAD and these were still in common use. They were left from the old days of manual drafting. It is a bolt calculator. It is kind of like another old tool the slide rule.

It is used to determine the dimensions relevant to the size screw or bolt you have selected. To use it you pull the slider until the size you are interested in shows up in the SCREW SIZE window. The other windows then show all the relevant dimensions for a screw/bolt of that size.

You want to know the dimensions for a socket head cap screw, a hex head bolt, or a pan head for example - it is all there.

I actually find this tool more useful than handbooks or CAD libraries. Handbooks and CAD libraries have their place but the interface on the calculator is hard to beat.

The good news is they are still available. You can still order them from Media Marketing Associates. They are available in Inch and Metric versions.