Motion unit development

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VDX
Re: Parallel-kinematics versus string-pod
December 04, 2007 09:51PM Admin
Registered: 12 years ago
Posts: 12,332
... by the way - by rethinking the wire-systems i realized, that this could be an extreme cheap'n'easy repstrap-basis ...

With some ball-gliders, magnets and a steel-plate (or a MDF-plate with an atached iron-sheet) above the wire-plane i can apply a toolhead, which is fixed through the magnets upside-down at the plate, glides freely around with the ball-gliders and is positioned by the wire-tripod.

With good magnets it's no problem to hold some kilograms upside-down, so the toolhead, the extruder/syringe and the support should be manageable ...

With a second wire-setup there could be a hoovering plate under the construction, which could be elevated in Z up and down, to complete the 3-dimensional repstrap.

Imagine a wire-tripod-repstrap fixed under the ceiling, which lowers the bottom-plate with the fabbing-process, so the ready parts comes down automatically and in idle-mode the aparatus is 'vanished' to a thin plate under the ceiling - maybe with some keen paintings on the bottom winking smiley

I estimate an extreme low count of mechanical parts and assembly-working:
- 4 driving motors: 3 for the wire-tripod, 1 for the elevator
- some meters of thin steel-wire
- basis-plate with iron-sheet (for the magnetic fixing)
- bottom-/elevator-plate
- 3 ball-rollers
- 3 strong NdFeB-magnets
- upside-down-tool-head with extruder and feeding
- rolls for wire-feeding
- some scrap for assembly ...

The electronic is the same (with 4 motors) and the software has an additive converter from X,Y- to {La,Lb,Lc},Z-paths, as mentioned in the post above ...

Viktor

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atmark
The idea with the ball-gliders was something I didn't get completely. Did you mean ball bearings for routing the wires?

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Atmark
... the Hangprinter concept ...

cable driven site:forums.reprap.org

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atmark
Couple of interesting photos before the end of year! The mail-man dropped at last the dyneema line I've been waiting for.
Check especially the video! It reveals a distinctive pattern on two sides and perpendicular to that pattern a second pattern, that repeats itself every 5 mm.
Those patterns are formed by two reflective yarns that go through the braid in opposite directions.

The line is a 1 mm line with UHMWPE (dyneema) core and a polyester jacket.
It should be able to withstand at least 40 kg of drag. And it is, as advertised, stiff and round with a smooth surface, although the reflective yarn makes little bit wavy on the side. That might cause a pattern, similar to Z-wobble. But anyway, I bought this line for testing purpose. If the sensor readout works with this line flawlessly, I might tend to invest a bit more for a heavy duty dyneema rope 2-3 mm. Those are rated between 200-400 kg of drag.

I'm pretty convinced by this so far! Next year, I get back to business. Happy New Year!!

Close-up video