The Bootstrap Mill is designed to be created from forms that can be cut on a PrintNC or similar router. It uses commodity Ultra-High-Performance-Concrete (UHPC) or similar mixes to create the main forms of the machine frame. Precision surfaces are meant to be optimized using epoxy transfer method and features are built into the frame to facilitate this more easily. Table is 400x300mm with around 150mm of z clearance, and there is some over-travel so the spindle can reach all the way around the outside. The box section off the the side is so that the spindle can travel over to access an ATC changer, and it also serves as a moutning point for the X motor to keep the frame mold as simple as possible. The frame is abidextrous so the toolchanger could be mounted on either side with minimal modifications.

While the main CAD is drawn from scratch, the design obviously derives inspiration from the excellent frames and machines that are produced by https://www.cnc-technik-mueller.de/ as well as by other UHPC projects that have been posted across various websites. By posting detailed CAD for both the machine and the molds it is our hope to create a project that anyone can reproduce, even if they are in a remote rural area without access to large machine tools that are commonly used to create the precision faces for frames like this.

Note that this model uses components sourced from 3rd parties via GrabCAD.

Trinic UHPC premix

Bottom base volume: Volume = 27.75 liters 66.6 KG cubic feet 0.979982

Arch volume: Volume = 30.12 liters 72.30 KG 1.0636778

Total is < 2.1 cubic feet.

138.3 lbs dry material = 1 cf. of wet mix 290.43 lbs of dry material total = 6.5 bags

16mm ballscrews (1605) 20mm rails (HGR or RGR)

X axis ballscrew is 850mm X Rails are 800mm HGH

Y axis ballscrew is 650mm Y Rails are 600mm HGH

Z axis ballscrew is 350mm Z Rails are 400mm HGW-CC