Unified Prusa i3 Extruder for Mk8 drive gear, e3d v6 hotend, and BLTouch sensor. by inornate

Last crawled date: 3 years ago

I remixed the great extruder design by coricoco (thing #755164) and applied some design improvement from Marck80's remix (thing #932386).
This design has numerous advantages.
The solid and unified design requires minimal assembly.
No Bowden.
Minimal footprint, so it does not cannibalize printing volume.
The center of weight is on the X axis.
Capable of Flexible filaments.
This design is backward compatible. You might able to use various accessories from the previous designs (#755164 and #932386).
This extruder is for Mk8 drive gear (effective diameter 7mm) and an E3Dv6 nozzle.
Also, it equips BLTouch auto leveling sensor mount ( https://www.indiegogo.com/projects/bltouch-auto-leveling-sensor-for-3d-printers ).
Required additional parts and gears
PTFE tube (o.d 4mm / i.d 2mm)
M3*7mm countersunk bolts (x4)
M3*5mm bolts (x2)
M3*20mm bolt (x2)
M3*25mm bolt (x1)
M3*50mm bolts (x2)
M4*40mm bolts (x4)
M3 & M4 Nyloc nuts
Washers
Springs x2 (about 15mm)
3mm&4mm drills
M3 Tap
623 or 624 bearing 1ea
Mk8 drive gear
E3Dv6 hotend (or lite ver.)
NEMA17 & 31mm stepper motor.
(Optional) BLTouch sensor
Printing Instruction
I recommend using high infill rate (above 40%) and 3 perimeters. I used ABS but PLA probably works fine. Reorient parts if required.
Print [Extruder_mk8]. It's designed to be printed without raft and supports, however, choose decent bed adhesion option if needed.
Print [Extruder_fixer]. If you want to use BLTouch sensor, print the _BLTouch ver. Otherwise, print the _normal version.
Print [Extruder_tensioner] for your bearing size.
Print [Spacer] and [TubeClamp].
Assembly Instruction
For better vibration resistance. use Nyloc nuts for every possible place.
Remove the pre-designed supports.
Clean the holes using drills.
Tap two M3 threads at the center of the extruder.
Test mount an E3D nozzle. Cut the PTFE tube to be placed just below the drive gear.
Mount a stepper motor using M3*7mm countersunk bolts
Mount a bearing to the [Extruder_tensioner]. For 623 bearing, use M3x20mm bolt. For 624 bearing, use M4x25mm bolt. If you're using 624 bearing, place the bolt head toward the stepper.
Mount the [Extruder_tensioner] assembly to the extruder body. Use M3*25mm bolt and add some washers for clearance. Tightening the bolt is tricky here. Use a long-nose plier to fix a nut. Make sure the tensioner is moving freely.
Mount the Mk8 drive gear to the stepper.
Using two M3*50mm bolts, springs, and nut, push the bearing against the drive gear. Refer the picture.
Place four M4 Nyloc nuts to the extruder body. Apply a drop of super glue to avoid falloff during assembly.
Using [Extruder_fixer] and two M3x20mm bolts, mount the E3Dv6 hotend.
If your hotend has PTFE tube clamp, just go to next step. Otherwise, clamp the PTFE tube using TubeClamp part & two M3*5mm bolts.
(Optional) Mount the BLTouch sensor. The X-offset between the nozzle and sensor probe is 23mm. Y-offset is zero. Z-offset is required to be calibrated for your parts.
Mount the extruder assembly to the carriage using four M4*40mm bolts. Sandwich [Spacer] between them.
If you have some rubbery material, place it between the stepper motor and carriage. This will greatly reduce the vibration during print.