User:Powdermetal

Cycloidal Extruder Drive

Release status: Concept

Description	Gearbox for direct drive extruders, based on a cycloidal drive
License	GPL
Author	User:powdermetal
Contributors
Based-on
Categories	Extruders Cold End
CAD Models
External Link

Intro

Running a delta printer with a Bowden-style type extruder, many people have been looking into alternatives for a more direct filament feed response (especially when using flexible materials) while still keeping the dynamics of a lightweight effector system. There are a bunch of options out there and each one has it's specific strengths...

Project Target

• Use a small, lightweight and powerful NEMA8/NEMA11-stepper to drive a filament drive gear (like MK8 or others)
• Minimize gearbox package through choosing a cycloidal drive system (gearbox ratio probably between 36:1 and 10:1)
• Setup a potential alternative to the outphased NMB PG35L-048

v0.1

Objective

Quickly check general feasibility using some existing components:

• StepperOnline Nema 8 Bipolar 0.6A 4Ncm(5.7oz.in) mini stepper motor 8HS15-0604S
• MK8 Drive Gear
• E3D v6 HotEnd - 3mm Direct (12v)

Design

• Gearbox ratio: Some simple engineering calculations based on required feed-forces for 3mm filament and comparisons with existing extruder solutions propose for the 4Ncm stepper a gearbox ratio of approx. 20:1. Having an existing CAD model of a small cycloidal gearbox with a ratio of 36:1, this one was simply adopted.
• STEP-files of the assembly with detailed components, simplified geometry for the core parts (for simplifying mods) and some tools/jigs which help you to assemble this thing: Media:CycloExtruder v01.zip

BOM

• Printed parts
• 1 x StepperOnline Nema 8 Bipolar 0.6A 4Ncm(5.7oz.in) mini stepper motor 8HS15-0604S
• 1 x MK8 Drive Gear
• 1 x E3D v6 HotEnd - 3mm Direct (12v)
• 3 x MR105-ZZ (5x10x4mm) Ball Bearing
• 2 x MR128-ZZ (8x12x3.5mm) Ball Bearing
• 1 x 5mm Stainless Steel Precision Shaft (or a 5mm aluminium shaft from your local hardware store - make sure you go shopping with your caliper: 4.97..4.99mm is sufficient if you are on a hurry)
• 4 x DIN912 M2x4 Hex Socket Head Cap Screws (for fixing the stepper)
• 2 x Springs
• A bunch of DIN912 M3 Hex Socket Head Cap Screws

Make & Assemble

Validate & Test

Results

Todo

v0.2

Objective

xxx

Links

• Wikipedia: Cycloidal drive
• Design of a Planetary-Cyclo-Drive Speed Reducer Cycloid Stage, Geometry, Element Analyses
• Building a Cycloidal Drive with SOLIDWORKS