Hangprinter

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Hangprinter

Release status: working

800px-Hangprinter v3 printing 01.jpg
Description
A RepRap using walls and ceiling as its frame
License
Author
Contributors
Based-on
Categories
CAD Models
OpenSCAD
External Link


The Hangprinter is an original RepRap design created by Torbjörn Ludvigsen (user:tobben that is installed in a given space using the room itself as the frame. The design can also be adapted to use a table rather than an entire room. The printer has an effector that is suspended from the ceiling and moves using stationary stepper motors with pulleys and fishing line.

Full bill of materials (BOM), STL files for printed parts, and build manual can be found here

Article Updates

March 2017: This page has not been updated since the very early days of Hangprinter development. Until someone gives this wiki-page an overhaul, use refer to dev blog (https://vitana.se/opr3d/tbear/) and Gitlab repo (https://gitlab.com/tobben/hangprinter). See also the old Github repo (https://github.com/tobbelobb/hangprinter) instead. -tobben

November 2018: This page is in the process of being overhauled by myself as it is in serious need of it, especially for such a great design. I have never built a Hangprinter, much less seen a Hangprinter in real life so any help with this process would be greatly appreciated! -NinthDimension

Design

Specifications

Printed Parts (Proteins) Non-printed parts (Vitamins)
Excluding hardware, wires, and cables 93 ~44
Including hardware, wires, and cables 93 ~153

Advantages Over Traditional Designs

  • Low part count
  • Easy to print, assemble, install and distribute
  • Huge build volume (especially height).
  • When printer is idle, one could retract all the strings. Hanging it in the z-achor point (the ceiling) with no dangeling strings might be elegant storage solution. Could make it popular in big cities, where indoor area is scarce.

Issues

  • Special geometry-compensating firmware
  • Keeping strings tight
  • Keeping rotation at zero
  • Finding a reasonable home position
  • Convincing people to put anchor points (screws) in walls...

Geometry compensating firmware

Converting from Cartesian coordinates to the four wire lengths we need is just a matter of using Pythagoras' Theorem. The maths needed to regulate the velocities properly has not been worked out.

String Tension

We need to know if springs are wanted/needed. Some work on this has been done, check out SkyDelta [1], [2] and the forum thread for details.

Mitigating Rotation

Things that will produce rotational forces

  • Dragging filament around
  • Dragging power cable around
  • Accelerating motors

Misc. Comments

Rotation around z-axis might be considered less harmful since one could place the hotend in the rotational midpoint. All motors probably need to be downshifted heavily, and accelerations kept minimal. It might have to be a very slow printer. Will it help to keep all motor shafts in parallel with the z-direction in order to avoid induced xy-torque? Will it need a very thought out extruder?

Homing

Procedure Based on Known Positions

This has being worked on in the RigTig community. Basic idea is that instead of measuring the anchor points you drive the print head manually to a set of known point and determine the geometry of the printer from the differences in cable lengths needed to get from one point to another. We got a first grip on the mathematics involved:

https://hackaday.io/project/13420-rigtigs-big-3d-printer/discussion-79916

-- Florian Festi

Helpful Links

Helpful Videos

General Information