The fac­tory’s prod­ucts

The Shed - - Twist drills -

The Ka­iapoi fac­tory makes 280 types of drill. They dif­fer in their di­am­e­ter, length, shank type, coat­ing, and tip. The shank can be straight, re­duced, or ta­pered.

There are three se­ries of di­am­e­ter: met­ric, im­pe­rial, and ‘num­ber’. The met­ric di­am­e­ters in­crease from 1mm to 3.5mm in 0.05mm in­cre­ments, and from 4mm to 13mm in 0.5mm in­cre­ments. Im­pe­rial drill bits in­crease in size by 1∕64 inch. Num­ber drills have di­am­e­ters from 68 (1.25mm) to 1 (5.76mm). The tip can have different an­gles and be chisel point or split point. Split-point drills are more ex­pen­sive be­cause they re­quire an ad­di­tional grind­ing oper­a­tion to add an­other facet to the tip, re­duc­ing the size of the chisel point. They aren’t as durable in more sta­ble drilling en­vi­ron­ments such as drill presses, but they can drill a hole with­out a punch-mark with­out wan­der­ing. This makes them pop­u­lar for the DIY mar­ket and they are the most pop­u­lar type of twist drill sold in the US.

An oil press un­der con­struc­tion

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