Top strengthener: This component further secures the system in
place, particularly the syringe. It is secured onto the frame using the
same M3 x 35 mm screws used for attaching the bearing holders onto the
frame. The top strengthener protects the syringe from moving, once
secured into place for printing (Fig. 8b).
Mounting bracket: The mounting bracket is used to secure the
fully assembled extruder onto the aluminum frames of the bioprinter
(using M4 x 15 mm screws and T-nuts) (Fig. 8b).
Drive gear and driven gears: These components are used together
with the NEMA17 stepper motor to rotate the threaded bars and therefore
move the drive block (Fig. 8b). The drive gear mounts onto the NEMA17
motor shaft and is designed to be self-centering on the motor shaft. The
driven gears are mounted onto adjacent corners of the motor face
(meshing with the drive gear in the center) using two M2 nuts. The M5 x
95 mm threaded bars are secured in the center of the driven gears using
two M5 nuts (Fig. 8b).
Frame: This is the main component of the extruder. The NEMA17
motor is secured onto the main printer frame along with the bearing
holders and drive block. The design allows for a syringe to be secured
in place whilst the plunger side is secured to the drive block (Fig.
8b).
Drive block: This component is secured to the end of the
syringe plunger and is responsible for enabling actuation of the syringe
plunger (extrusion and retraction). Two M5 x 95 mm threaded bars are
used (one on either side of the drive block) which control the movement.
These are secured into place using M5 nuts (Fig. 8b).
Bearing holders: The bearing holders are attached to the
extruder frame and included to allow the rotation of the threaded bars
which move the drive block (Fig. 8b). They are secured into place using
623 bearings, M3 nuts and M3 washers.
Luer lock effector plate adaptor: This component completes the
extruder by connecting the mounted syringe extruder to the effector
plate and nozzle (Fig. 8b,c). The design incorporates a male Luer-lock
connection fitting and a Bowden tube connection fitting (Fig. 8c). It
was secured onto the standard effector plate using four M3 x 8 mm screws
and M3 nuts (Fig. 8c).