glassblowing.tools

Glossary / Color Tools

Pi dividers

Calipers that turn the width of a laid-out row of cane into the right size collar for picking it up.

What it is

A pi divider is a caliper with straight arms at one end and curved arms at the other.⁠⁠[1] Cutting Edge’s is cut by CNC water jet from aluminum,⁠⁠[2] and Carlo Donà makes them in sizes from 110 to 315 mm.⁠⁠[3]

How it’s used

For cane pick-ups and roll-ups, the canes laid out on the plate have to wrap exactly around a collar, which means pi × diameter = circumference.⁠⁠[2] You measure the row of cane with the straight arms, and the curved end gives the size of collar needed.⁠⁠[1]

Sources

  1. Jim Moore Glass Tools — Other Cool Stuff
  2. Cutting Edge Products — Pi Divider
  3. Carlo Donà — Compass

Pi dividers in the archive 3

Photo Tool Maker Sellers
Pi DividerA divider for spacing cane or stripes evenly around a circumference, in five sizes. Carlo Donà 2
Pi DividerA layout tool for cane pick-ups and roll-ups. It divides a circumference evenly, so you don't have to do the pi math. Cutting Edge Products (Red Hot Metal) 2
Pi DividerMeasures a layout of cane with its straight arms and gives the collar size needed with its curved end. Jim Moore Glass Tools 4