Byteborg's Direct Drive Extruder (3mm)

This is my version of a direct drive extruder.

You will need to strengthen the part with the spring-loaded lever, if you want to use it

Sources are included - please, send me your modifications.

It is optimized for the following aspects:

• dead simple, no unnecessary parts
• low profile, maximising effective print height on my prusa
• easy operation, spring-loaded mechanism for easy load/unload
• easy to build

The source lives at https://github.com/byteborg/mendelparts/tree/master/parts/direct-drive-extruder and you are welcome to play with it.

Update version 0.2:

Added a part to hold the bearing in place (bearing_clip.stl)

Update version 0.3:

Sturdier extruder body

Public Service Announcement:

Print the roller lever in ABS, and print it twice :)

PLA is too brittle andwill break after mangling a few kilograms of material. You want to have one of these in spare.

Perhaps I'll redesign the lever shape a bit, in case it troubles me too much.

Public Service Announcement #2:

Do use DRV8825 stepper driver for added torque ;-)

Instructions

BOM

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• plastic parts as in STL
• NEMA17 stepper, as much torque as possible
• pulley 5mm bore x 8mm outer dia
• 4x M3x30 screw
• M3x40 screw
• spring, fitting said M3 bolt, needs to be strong
• M3 nylock nut
• M3 nut
• 2x M4 nylock nut
• 9x M3 washer
• 625ZZ ball bearing
• 608ZZ ball bearing
• M8x20mm threaded rod, or 8mm x 20mm smooth rod
• reprapsource-style hotend (or customize the OpenSCAD file)
• 2x M3x30 bolts for hotend mount ridges

Assembly

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1. print the parts

   • I made mine from PLA
   • layer 0.3mm thickness, 2 perimeters, 2 solid top/bottom layers, 40% infill

2. roller-lever spring assembly:

   • M3x40 bolt > washer > spring > washer > lever > nylock nut
   • the nylock nut is just threaded flush at the end

3. roller-lever roller assembly

   • put 20mm long piece of 8mm rod through lever and 608ZZ bearing

4. put M4 nylock nuts in nut traps for later mounting on x-carriage

5. attach pulley to motor

   • don't tighten too much, need to adjust later

6. attach NEMA17 motor

   • M3x30 bolt > washer > extruder body > washer > motor
   • put bolts through extruder body, add washers, attach motor

7. attach spring-loaded lever

   • secure with M3 bolt

8. adjust pulley to fit ridge over feed hole

9. press in 625ZZ bearing to side of extruder body

10. install extruder body on x-carriage

11. install hotend to extruder body and secure with bolts

Configure firmware. I use 420 steps/mm in Marlin for a RAMPS board with DRV8825 driver in 1/32th microstepping mode.

Commissioning

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1. load filament by pressing down hinged lever
2. adjust spring tension, you'll need lots of it, trust me ;-)
3. print
4. be happy.

Category: 3D Printer Extruders