A project log for Dual-Disc Polar Printer

alpha and beta instead of x and y

heinzheinz 03/26/2021 at 12:255 Comments

I added another gear with a hollow shaft in the middle to route the z-axis through.        
Had a look at nema17 motors with a hollow shaft, but they unreasonably expensive, at least with a hole >10mm.

Z-axis in the middle of the assembly makes the overall footprint smaller, but limits your bed size if you want to be able turn around the whole pole.
For a multiple hotend setup a small bed would be okay, since this way parts on the bed can't collide with the other nozzles, 
because individual build areas don't cross eachother.

After the rebuild the testprint came out skewed, not sure what caused this.
The gear ratios shouldn't have changed. Maybe the pen/bed was slipping, have to investigate further..


Ahron Wayne wrote 04/19/2021 at 02:43 point

when are you going to mount a laser to it? 

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heinz wrote 04/19/2021 at 07:39 point

FDM printing ist planned first. :)

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Paul McClay wrote 03/31/2021 at 06:48 point

Hello Heinz. Thanks for the  skull/follow over at #A Cheap Compact Linear Slide !

I'm not sure I get how Z will work. Will it be a solid rod through the hollow shaft that is driven up/down to raise/lower something in place of the yellow pen holder in the video? If so, I wonder if fixing the center of the top disk (i.e. make it the only disk) and adding rotation as a second d.o.f. to Z could reduce the total footprint?

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heinz wrote 04/01/2021 at 06:05 point

Do you mean like Tyler Anderson's Theta printer or the sculpto2 polar printer? Swinging arm over rotating bed?

Definitely possible, but smaller footprint is not the ultimate goal here, only when coupled with being able to rotate to different stationary extruders. Stationary only because I plan to make the Extruders quite heavy, think direct drive diamond hotend on each arm. Having them move only in Z should be easier.

Probably will try a simple leadscrew/rod assembly first for the Z-axis
and test how rigid they are without a frame to mount to. 
Single Z-axis is common in crane printers like prusa mini, but I don't want to make the middle bearing too big to fit an aluminium profile for support..
and screw..and all the cables for multiple direct-drive extruders..

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Paul McClay wrote 04/18/2021 at 17:43 point

Oh. Now I get it. The next log, "toolchanger alignment test", solved my confusion.

It is as you described, I just wasn't ready to think what you were thinking.

Neat. Now I can see this using different _kinds_ of tools more effectively than some other attempts.

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