Extended shaft extruder

Hi guys,
as a spinoff from my dog-box extruder development, I want to show you another way to reduce x-carrier weight.
We all know Bowden extruders, with their pros and cons. Also the flex3drive is a way to reduce mass for the x-carrier.

Now I want to introduce you to my extended shaft extruder. [see attachment]
The extruder stepper is mounted on the right x-end and drives a square shaft that is also supported at the left x-end with a ball bearing.

The hobbed gear has 4 grub screws that are fixed with Loctite in a way, that they allow the x-carrier to move along the square shaft.
But at the same time make the hobbed gear turn by the extruder stepper.

The way of mounting the hobbed gear to the shaft can be done in a better way. I just want to point out the idea behind it and start a discussion about pros and cons, too.
Also I left out additional bushings to mount the hobbed gear and the all_metall MK8 extruder to the x-carrier, but that´s a no brainer, I´d say.
-Olaf

Changed the title to be more accurate

Edited 2 time(s). Last edit at 07/11/2015 02:11AM by o_lampe.

That things going to screech like nothing else when moving along the X axis. Really good idea if you can solve the friction issue. What might work is coupling a square bearing to a hobbed gear somehow.

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Thanks,
I think the same. Wouldn´t need to be a ball bearing, but two short igus-style bearings for a square rod will do.
I ordered a 4x4 CFK bar and will make some bushings/brackets a.s.o. I want to design it to be an aftermarket addon, everyone can install on his Prusa i3.
The problem with the hobbed gear is the max. diameter of the inner hole. I´m not sure, if a 4x4 bar has too much torsion, but going bigger is difficult then. Maybe 6x6 at most. ( 8.5mm hole )

-Olaf

PS:I also thought about replacing the upper smooth rod of the x-carrier with my square rod assembly.
The pimped hobbed gear would then act as linear bearing for the whole x-carrier, too. But that wouldn´t be an addon anymore, but a complete new x-axis...