Rotary 3D Printer?

[Jay Raxter]

Anyone else seen the new 'turntable' rotary 3D Printer?

Here's one but there's a couple of others...

http://www.amazon.com/Polar-3D-Printer/dp/B00M48BLRW/ref=sr_1_77?s=industrial&ie=UTF8&qid=1407880756&sr=1-77&keywords=3d+printer

Anyone know anything about these?? 

Thanks

Jay

[Ryan Carlyle]

Odd. Can't decide whether that's clever or stupid.

The fact that the build resolution isn't constant strikes me as an issue, but you can say the same about Deltas, and they make it work.

[Joe Soap]

My immediate concern would be that the coordinate system would be based
upon providing an angle and a distance - and the further away from the
centre you go accuracy would diminish.

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[Ryan Carlyle]

Yeah, and presumably the rotary actuator has some backlash due to gearing down a stepper. Although it could use a belt reduction drive or something. Dunno.

[3duser]

I always thought these would be neat if the extruder came in from the side.

[Michael Carter]

This is a derivative of the Pi maker kickstarter for 2012. (https://www.kickstarter.com/projects/wjsteele/ultra-bot-3d-printer/comments)

I personally had a great deal of difficulty with Mr. Steele and the Pi maker printer the version ultra-maker that he shipped. The printer had problems in both its physical structure and firmware. The machine had significant wobbling problems and could not support the mass the mrk9 extruder Mr. Steele recommended. The structure eventual failed under its own weight and was never able to print.

The firmware and software did not implement the polar movement correctly and as a result the edge of the disk under extruded while the inner edge over extruded. Further the polar converter he supplied functioned by slitting every ling segment in to 12 parts regardless of the length of the individual lines resulting in positional errors for larger objects. The code had several unhandeled exceptions such as a dead spot when line segment crossed the 0,0 point. This created a whole center of the build platform where no object could cross.  

When myself and others tried to address these issue Mr. Steele became evasive and non-communicative. After several months Mr. Steele acquired a new partner and created the Pixel Printer (https://www.facebook.com/PixiePrinter) using components and equipment purchased for the Ultra-bot kickstarter. After crossing state lines to prevent lawsuits and an attempt to start more crowd sourcing for PixiePrinter which were terminated by the crowd sourcing websites Mr Steele attempted to seeks protection against litigation by kick-starter backers by claiming  that he had declared bankruptcy. He never actually did however. After waiting several months and writing several letters to kickstarter, several judges, the FBI, attorneys general in three different states and meeting with a Federal prosecuter, we received an email from Mr. Steeles newest business Polar Printers notifying us that we would receive refunds. I received a refund for my printer a few weeks ago.

I do not have access to the Polar Printer machine but looking at polar printer design it appears that they have addressed many of the problems with the initial printer design and replicatorwarehouse.com's R-360 has a working version of marlin for the polar format. I would not that the use of their firmware is not credited anywhere on the polar printers website. In short caveat emptor, I had great difficulty with Mr. Steele and through his actions has demonstrated his character and that of his partners and as such I cannot recommend any of projects.

[Robert Nee]

Are there any universally agreed upon advantages to this design over Cartesian bots?  What does it do better?  It seems like the claimed advantages with regards to hardware simplicity and size are offset with the need to more complex firmware, no?  

[3duser]

The obvious advantage would seem to be round prints.

[Dan Newman]

On 13/08/2014, 10:35 PM, 3duser wrote:
> The obvious advantage would seem to be round prints.

Excepting the fact that our slicers and CAD models first
reduce everything to straight line segments. To get any
real benefit, one needs models and a slicer which will work
directly in cylindrical coordinates. Does their toolchain
do that?

Dan

[Michael Carter]

Mr. Steele has closed the work flow and removed the open source files from the the project. However the latest version of the software I used accepted gcode produced by skinforge. Each point from the gcode was then converted into a polar format using the equations r=(x^2+y^2) and theta=arctan(y/x) and exported back to gcode. The resulting gcode now had the X coordinate as movement of the extruder on the carriage (r) and the Y coordinate as movement of the plate(theta). This code was then loaded back into repG so it could be sent to the gen3 motherboard for printing.

[Ryan Carlyle]

Well, that's straightforward. The outputted arcs will definitely be just as segmented as the input gcode. 

The center dead zone is pretty comical. Divide by zero error, lol.

[DonadJ]

Plenty of stuff on polar variations at the RepRap forum: http://forums.reprap.org/list.php?185

[Dan Newman]

> The center dead zone is pretty comical. Divide by zero error, lol.

No, Stephen King novel territory ;)

Dan

[Michael Carter]

> No, Stephen King novel territory ;)
>
>Dan

The dead center zone problem = Roald Dahl

The fact that path between two points in polar systems is longer than the path between to points in the linear system. = R. L. Stine

The fact that the impact of the polar path on the rate of linear travel (extrusion rate) has no close form solution. (ie the solution can not be expressed in terms of elementary functions) =  Stephen King