The Big Boy

Learn about our Flagship Project

Quick Facts


  • Print Area of 330mm x 475mm x 500mm

    Suitable for printing most large objects and prototypes for our team to continue learning with!

  • Overall Size: 700mm x 700mm x 900mm

    Our requirement was for the printer to fit through a standard door. We were able to meet that requirement.

  • Weight: Approximately 250 lbs

    Since this is steel construction through and through, the printer weighs a fair bit. This weight and rigidity make it easy to add a spindle.

  • Reliable 80mm/s Print Speed

    The 7 NEMA 23 steppers provide more than enough speed and force to move the X,Y, and Z axes.

  • Polycarbonate Enclosure and Heated Bed

    The polycarbonate enclosure is useful for temperature control. The silicone mat heater keeps the bed nice and warm. In the future we hope to heat the chamber to print more exotic materials.

  • Custom Designed Tool Changer

    Our custom milled dovetail magnetic tool changer is a completely novel design, we even had to buy a special insert for manufacturing it!

Notable Design Choices

Generative Design Tool Mount

Metal 3D Printed Generative Design Part

Generative Design is a new trend in Computer Aided Design where simulated loads are put on a structure and the computer determines the most optimized design for the stresses put on the part. In this case, we designed our tool mount to be able to withstand the forces of both a spindle as well as a 3d print head. Our part was Printed with the Markforged Metal X in Stainless Steel. Unfortunately one of our prints failed due to a filament break (Pictured above)

The benefits of generative design are as follows:


  • Optimized parts for load 
  • Less material used
  • Ability to be additively or subtractively manufactured

Milled Steel Frame with Laser Cut Gussets

Strength and Rigidity, to spec.

Steel is an incredibly versatile material. Thanks to the generosity of the donors to the Bechtel Center, we were able to utilize community steel stock to make the frame of our printer. Due to us wanting a precise platform, we needed to take the irregularities out of the cold rolled steel tube stock that was available. Therefore we face milled each side, as well as tapped, drilled, and bored all of the features we needed into the individual pieces. Since our goal was to use the frame we have built to support a mill head, the steel here added for incredible rigidity to mill harder materials.

We were also able to use the Fablight Metal Laser Cutter to manufacture the gusset plates needed for the design. This was cut from 1/4 in sheet stock.

Custom Couplers

Learning Active Tooling

The parts shown were all manufactured on the ST-20 Lathe utilizing Active tooling. These parts are the couplings that lead from the stepper motors to the ball screws. Making these on the lathe allowed us to work with an unfamiliar CAM and manufacturing style. These parts are stainless steel. 

Custom Dovetail Tool Changer

Creative Solution to a Common Problem

Our custom aluminum tool changer design uses magnetism and gravity to keep the tools aligned properly. The dovetail slots are cut to allow the female piece to grasp onto the male bracket and lock in place using magnets. Due to the steppers having more than enough torque to break out of the magnetic force and pick up the next tool. These parts were milled on the 4 axis mill. 


Project Inception: August 2018

Design Completed: May 2019

Materials Procurement: August 2020

Manufacturing: November 2020 – November 2021

Assembly: November 2021

First Prints: January 2022

Machines Used

  • Waterjet
  • 5 Axis mill
  • 3 Axis Mill
  • FDM PLA 3D Printer
  • FDM Nylon/Carbon Fiber 3d Printer
  • FDM Stainless Steel 3d Printer
  • Metal Laser Cutter
  • Wood/Plastic Laser Cutter