Building Boaz: An Engineering Guide to the Effective DIY 3D Printer ibook

Boaz: One CoreXY 3D Printer, Built Twice

There is a particular disappointment that belongs to the person who builds their own 3D printer. You spend a year sourcing parts a hundred dollars at a time, you assemble something that looks like the CAD render, you press Print, and the part that comes off the bed is worse than what a $300 factory machine produces on its first attempt.

This book argues that the disappointment is not a case against building. It is a case against building the way the hobby builds. Printed structural parts, idlers on M5 screws, rails aligned by eye: these conventions were inherited from a project whose goal was self-replication from the cheapest parts, not precision. Machine-tool builders solved the precision problem decades ago, with exact-constraint design, kinematic couplings, interference fits, and measurement as a construction step rather than an inspection step. Boaz is the record of applying those answers to one machine.

Boaz was designed in 2023, built through 2024, and put to work: two hundred toys for a charity drive, a thousand pet-medicine boxes for a medical organisation in Iraq. Then it was taken apart. The first build had failed in almost every subsystem, and the failures were specific enough to teach: a dowel pin in a hole reamed too large, a PCB heatbed whose stiffness fought the rack meant to flatten it, a grease correctly specified by the rail maker and wrong for the job. The rebuild is where most of the engineering lives.

Twenty-nine chapters take you from first principles to firmware. Why a frame must be stiff before it can be square. Why CoreXY, why belted Z, why a toolhead's centre of mass matters more than its weight. How to press a pin, tram a bed, read a resonance sweep as a report card on your assembly. Eight success criteria were fixed before construction and the rebuilt machine is scored against them in the open: seven met, one missed, and the production contract lost outright to a $300 commercial printer. Those numbers are in the book because published build logs are success narratives, and success narratives leave out what a builder most needs.

The book is not a parts list. Boaz is a one-off, and some of its components need services not every reader has. What transfers is the method, compressed into eleven rules and a set of measurement procedures that will improve any machine you build, on any frame, with any kinematics. The most useful pages describe what did not work.