Turns out there’s more than one way to thread a screw. Chris talks to Jon about the upsides and challenges of crafting multi lead threads for his pens, and why you should use metric—not imperial—measures.

• Jessica Edwards The Producer of the documentary film, Design Canada & founder of Film First Co.

• Timely Tees Jon recently released a co-axial version of the Escape Tee

• Multi Lead Threading One of Chris’ most popular blog posts

• The Machinery's Handbook A quintessential reference in any machine shop

• The Sheaffer Snorkel A stupendously over-engineered fountain pen design

• Fischer Space Pen A pen engineered for use in zero gravity

• David Oscarson Pens

• Dykem Layout Fluid A surface masking solution that makes it easier to see where the tool you're using has come into contact with the material you are working on

• Taig Lathe One of the first lathes in Chris’ n+1 collection of lathes

• The Perfectionists A book, by Simon Winchester, that details the history of precision manufacturing

• Archimedes Screw

• Logan Lathe The lathe Chris upgraded to from the Taig

• Higbee Thread

• Breech Thread

• Follower Thread Cutting A video demonstrating how threads are cut using a follow rest

• Hello internet A podcast hosted by CGP Grey & Brady Haran

• Demise of the Kilogram A video produced by Hello Internet co-star, Brady Haran, that explores how the way we define various units of measurement is changing

• Veritasium Derek Muller goes hands-on with the world's roundest object, a sphere of silicon used as the definitive standard of a kilogram

• Veritasium Redux A follow up to the previous video, Derek Muller ventures deep into the National Institute of Standards & Technology to discover how science is redefining the kilogram & rendering that perfect sphere of silicon effectively obsolete