Workbench

Thread rule for printing

A rule with a millimetre scale and a calibration mark. Print it at 100 per cent, check the red line against a folding rule for 100 mm, then read off the thread diameter and the pitch.

ELDI THREAD RULE · PRINT 1:1 (scaling 100 %) · calibration mark below = 100 mm 0102030405060708090100110120130140150160170180190 100 mm CALIBRATION
To the thread finder

How to measure with it

  1. Check the print: the red line has to be exactly 100 mm long. If it is not, set the scaling in the print dialogue to 100 per cent, not "fit to page".

  2. Diameter: lay the bolt across the rule and read outer edge to outer edge over the thread crests. 21.8 mm is M22.

  3. Pitch: count ten thread turns, read off the length, divide by ten. 15 mm for ten turns is a pitch of 1.5 mm.

  4. Enter the result in the thread finder.

Accuracy

A paper rule is no substitute for a vernier caliper. For flywheel threads it is enough to tell M22, M26 and M27 apart.