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Holliger Documentation
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Release status: working

A Huxley variant that can represent a much higher proportion of itself and is stiff enough to support limited milling.
CAD Models
External Link
Holliger milling a brace for itself.

The Holliger was designed by three students at the University of Bristol as a submission for their Masters Degree. Capable of both milling and Fused Filament Fabrication (FFF), the Holliger offers more capability than the Huxley on which it is based. The Holliger also makes use of a new 'wedge-together' printed frame system, allowing it to be assembled faster than the Huxley. As the frame is made from PLA, the Holliger is also capable of producing approximately 50% of its own components including nuts and bolts.

PAGE UNDER CONSTRUCTION More information will be put up over the coming weeks (posted 10/05/14)


Specification Value
Self-replicable parts 75
Non Printed Parts approx. 150
Cost £300-400
Controller Electronics Any controller compatible with RepRap Interface Standard RIS 1.
Printing Size 140 x 140 x 100
Milling Size 120 x 120 x Tool length
Motors 5 x NEMA 17 Stepper
Frame Material PLA
Frame Manufacture Fused Filament Fabrication (FFF)

Wedge-together Frame

Assembling the Huxley's frame and making it square is a time consuming process due to the large number of nuts that need to be finely adjusted. To avoid this, the Holliger uses a slot together frame, secured by wedges, for easy assembly. The frame members are also thicker, and therefore sturdier than the Huxley's. This, combined with the cross bracing, makes the Holliger's frame twice as stiff as the Huxley's, giving it the ability to support some milling operations.

How the system works

Cross section and exploded view of the joint system.

The joints have arrow-shaped 'slugs' on them which fit into corresponding grooves in the beam pieces. As far as possible the frame is comprised of similar repeating units, but there are specialised pieces for attaching motors and other fixings. When the frame is loosely assembled, it can be adjusted so it square by sliding the slugs along the grooves. When the frame is aligned, it is secured by wedges.

How long does it take to assemble

The prototype shown in the figures on this page was constructed using pieces salvaged from a Huxley (the Holliger is designed to be backwards-compatible). As such, when it was constructed, assemblies such as the X-axis and heated bed could be transferred across without assembly. Assembling the Holliger in this manner took just over an hour.

If the Holliger were being built from scratch, a loose estimate for construction time based upon that required for a Huxley would be seven hours; obviously this is dependent on how fast one can solder etc.


The frame system is very adaptable; as it is modular, individual parts can be replaced or modified to improve the design. For example, there is currently no attachment point for the extruder motor; a beam section could be easily modified to accommodate this. Additionally, cable troughs built into the beam sections would be useful.

Details of how to design compatible components will be posted shortly (posted 12/05/2014)


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To Professor B. Hicks for his guidance on this project.

To Dr D. Boa and Dr C. Snider for their suggestions and support.

Finally a thank you to the University of Bristol.