Shaft Driven Extruder

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Shaft driven Extruder

Release status: Concept

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X-axis Shaft driven Extruder
CAD Models
External Link

Please note this is still being developed and I will add extra information soon Some of the ideas have been constructed and can be found in the table below.

Rough Example of a Spline Extruder

Pros and Cons

Design Possible Advantage Disadvantages
NO Stepper Motor on Extruder
  • Lower Weight
  • Lower Inertia experienced on extruder
  • Faster move speeds
  • Better Accuracy
  • As stepper is farther from drive gear
there may exist some unknown behaviors
Stepper Motor Placed on Right of X-axis
  • Balances Frame weight out
  • Frees space near hotend for other goodies
  • Possible better distribution of wear on
threads of z axis (hard to verify this claim)
Shaft Drive
  • Multiple heads can be driven by the same motor
  • Maintains high degree of control at extruder
  • Interchangeable Hotends become feasible
as the motor assembly is out of the way
  • Might get quickly bogged down if too many heads
  • Cost dependent on shaft profile
  • Increased complexity for single extruder

The Premise about this is to reduce the amount of weight on the extruder, a previous approach was to use Bowden cable extruders however some of the claims are that it is unresponsive and elastic in comparison to a traditional extruder. As such by having a shaft driven extruder you wold not have the same problems

Examples of different drive shaft profiles that are available

While there are a multitude of drive shafts out there these are just some of them.

Ball splines: though the most accurate and best for linear motion as well as rotation are ludicrous in price costing $100+ per 12inchs and the take off gear is about $80 One proposed method of creating them is via a router or dremel tool in a channel cutting groves into a shaft for a cheap replacement, This has not yet been attempted.

ReprapSplineExtruder OpenScad Code These are CAD files for the total OpenScad model. .scad, [[media:]] Dfk20012002 13:48, 17 November 2011 (UTC)
Remote Direct Extruder STL-FILES A shaft driven extruder with a worm gear drive built with public available parts. Instruction with Files User: Nikkitoshi June 2022

Considerations / Ideas

As I talk with people on the IRC there have been several ideas come up and any name mentions is just a general direction where the idea came from. (might not be a perfect quote)

From sparr, Replacing the lower support rod with the drive shaft so as to reduce parts needed, the potential problems with this is if the rotation binding on the carriage if there is any slack, but this could be solved with rollers in the filament drive gear or by using ball splines again but they would need to be homemade.

From peeps, make sure to keep the filament drive gear as small as possible in order to maintain mechanical advantage.

Possibly use the drive shaft as the filament drive gear itself, if the right shape and size. Possible problem of cutting into the filament and or gumming up the drive shaft.

Interchangeable hotends almost shaped like printer cartridges, having the power connections be press fit or nearby, this would be a good spot to connect the cartridge in at the top and pull it down to lock like a hinge.