- 1 Article Updates
- 2 Design
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
Bill of Materials
Note: This BOM is very incomplete, please help improve it! For a complete BOM, see this Google Sheets spreadsheet.
|12V 7.5A (or 10A) power supply||Power supply||1|
|15-lead (or more) ribbon wire||Connection electronics - effector||~5m|
|Arduino Mega 2560||Mainboard||1|
|NEMA 17 stepper motors||motion||5|
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.
- 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.
Things that will produce rotational forces
- Dragging filament around
- Dragging power cable around
- Accelerating motors
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?
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:
-- Florian Festi
<videoflash type="vimeo" align="center">114817782</videoflash>
Motors are working. (Tobben, 17 dec 2014)
Forum thread: