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2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.

Posted by mmiscool 
2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
December 30, 2015 09:41AM
Hello,
I started kicking around a concept for a supper cheap 3d printer last night.

It works with a rotating bed that when it dose a complete rotation it can move the vertical access.

I am not too familiar with all the firmware out there but this looked like it could be tweaked to be compatible.
[reprap.org]

I am attaching a few pictures of the concept.



Let me know what you think

Edited 1 time(s). Last edit at 12/30/2015 09:47AM by mmiscool.
Re: 2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
February 08, 2016 12:40PM
Have fun with the kinematics! And the slicer! And the non-planar layers! And the anisotropy!

It's really not worth it.
Re: 2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
February 10, 2016 03:17PM
I think I see where the idea is going, the reason the plate is oddly coupled to the bed. He's relying on the z-carriage to stay in position via friction with the threaded rod while the bed goes through its printing movements, presumably uncoupled from the rod. Theoretically, it gets rid of the non-planar layer and anistropy problems, though it causes the printer to be locked into a layer height equal to the thread pitch. And as mentioned, the kinematics and slicing exist for polar printers already.

Meanwhile, in reality, any affordable thread pitch is huge compared to any kind of good layer height, spinning the bed 360o for each layer is time consuming, and friction isn't going to hold up the z-axis while there is vibration up there.
Re: 2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
February 24, 2016 02:17AM
rotating bed has been done a few times...

[reprap.org]
[reprap.org]

Edited 2 time(s). Last edit at 02/24/2016 02:20AM by Dust.
Re: 2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
February 24, 2016 07:26PM
FWIW

X Axis, Y Axis, Z Axis (Act sis)
Plural Axes (Act sees)
rsc
Re: 2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
February 25, 2016 01:43PM
with some modifications sounds very interesting
continue your developing grinning smiley
Re: 2 MOTOR 3D PRINTER. 2 MOTORS FOR 3 ACCESSES.
February 26, 2016 05:58PM
Hey, that's a pretty clever idea, mmiscool.

I see that other people have talked about 3D printing with only 2 positioning motors (plus the extruder motor) at "3D printing with only 2 motors" ( [reprap.org] ).

But if I understand your concept, unlike those previous ideas that have the Z threaded rod rigidly attached to the rotating print bed, your initial design has a range of over 180 degrees of rotation that one motor can turn the print bed without affecting the Z threaded rod.

If I understand the concept:

One motor rotates the print bed.
During printing of one layer, normally the tooth on the print bed is nowhere near the tooth on the Z threaded rod, and we depend on the anti-backdrive-properties of the worm-gear to hold the Z threaded rod in position.
At the end of that layer, that motor rotates the print bed to exactly the position it was in the last time the tooth engaged with the Z threaded rod, turns the print bed *another* quarter turn, which causes the tooth on the print bed to push the tooth on the Z threaded rod enough to rotate that rod *another* quarter turn, which (with a standard "fine pitch" 8 mm threaded rod, which has 1 mm thread pitch) raises the print nozzle 0.25 mm, which is a standard layer height used by many people with a 0.5 mm nozzle.
(Alternatively, it could turn the print bed a half-turn every time, which with the same threaded rod raises the print nozzle 0.5 mm, which is a standard layer height used by many people with a 1.0 mm nozzle).
Then the motor rotates the print bed the opposite direction, which disengages the tooth,
turning far enough to return the part currently being printed to directly under the print nozzle.

Clever, I like it.

Does picking a layer height that tells it to turn the print bed exactly a quarter-turn between each layer restrict the build volume for a single part to a sector slightly less than 90 degrees of the print bed?

Because of symmetry, I'd be tempted to make 2 teeth a half-turn apart (or 3 teeth a third-turn apart, or 4 teeth a quarter-turn apart) (rather than just 1 tooth),
offset at various heights so the #1 tooth on the build plate only hits the #1 tooth on the Z threaded rod, and passes over or under the #2 and #3 teeth on the Z threaded rod.
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