rostock

hi all - have been looking at the rostock printer - wow thats a groovy looking machine - thinking War of the Worlds
i know that the arms and stuff allow the print head to stay flat to the surface as it moves
but
could that be turned off so that it could print on a slight curve/concave (just thorectically - have no need or it).
ie. to print a friuit bowl effect.

(gosh the logic to push those arms around must be scary)

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

yes, it can be done Helical interpolation moves are supported in all reprap firmware. you could use cura to get the effect. [github.com]


you will want to check the Joris feature. it works best with single wall features.

The logic isn't really all that complicated if I'm not mistaken. Just basic triangulation. Calculate a straight line from the desired point to each of the three pillars, calculate a circle with that as the radius. The circle will intersect the pillar at two points, throw away the lower one and you have the position for that pillar.


rogerw Wrote:
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> hi all - have been looking at the rostock printer
> - wow thats a groovy looking machine - thinking
> War of the Worlds
> i know that the arms and stuff allow the print
> head to stay flat to the surface as it moves
> but
> could that be turned off so that it could print on
> a slight curve/concave (just thorectically - have
> no need or it).
> ie. to print a friuit bowl effect.
>
> (gosh the logic to push those arms around must be
> scary)

The Rostock geometry makes it impossible to tilt the platform, it will always be parallel with the bed.
With 3 motors you only ever have 3 degrees of freedom, you could construct variations on the Rostock that allow the platform to tilt, there are delta robots used for milling and othe tasks that don't have the restriction,, to get complete freedom there would need to be 6 motors.

polygonhell,
if one side goes up and the other two go down wont that tilt the whole platform so that you are printing a little bit sideways.
not saying that the rostock can do that now but if the firmware (???) or whatever was changed couldn't you still do it with 3 motors?
(talking out my arse here by the way).
roger.

---

Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

rogerw Wrote:
-------------------------------------------------------
> polygonhell,
> if one side goes up and the other two go down wont
> that tilt the whole platform so that you are
> printing a little bit sideways.
> not saying that the rostock can do that now but if
> the firmware (???) or whatever was changed
> couldn't you still do it with 3 motors?
> (talking out my arse here by the way).
> roger.


No you have 3 PAIRS of arms placed at 120 degree intervals the pairs move together, so it can't rotate.
In the case of the motion you describe the platform would simple move in a line, away from the single moving axis, possibly combined with vertical motion depending on the relative speeds of motion.

3 motors means 3 degrees of freedom, that's pretty taken up with XY and Z if you added more degrees of freedom without additional drivers to constrain it then the platform would not be stable, i.e. there would be multiple possible orientations for any driver position.

Now with 6 drivers you can do this

[www.youtube.com]