Chapter 6 – Extruder
At the moment it seems to be a trend to use very expensive commercial extruders. Why seems not quite understandable, since we have already achieved outstanding results with simple, self-printed extruders for years.
Commercial extruders are out of the question to keep costs down.
Even if there are already very good open-source extruders, a new design was needed. The extruder should fit seamlessly into the appearance of the Tantillus, be free of third-party licenses and also fit into the very limited space available.
The new extruder should also work without pushfits/connectors.
Thousands of hours of printing have taught us that the biggest weakness in a Bowden system is always the pushfit/connector.
These will eventually wear out or cut themselves further and further into the bowden tube. In the end, the backlash becomes bigger and bigger. The printing results are slowly getting worse and worse until you wonder why you need larger values for a retract, for example.
The original Tantillus uses an extruder with gear wheels (2.7:1) for 3mm filament.
Here are some calculated data:
Output data: 1.8° stepper, 8mm hobbed bolt with 7mm effective diameter, 3mm filament
approx. 24.56 full steps/mm (392.89 at 1/16 microstep)
approx. 3.47 full steps/mm³ (55.57 with 1/16 microstep)
Meanwhile filament with 1.75mm diameter has become the standard on the market. We decided to use a MK7 drive gear because we are convinced of the fine but quite sharp toothing.
Here again some calculated data:
Output data: 1.8° stepper, MK7 drive gear with 10.6 mm effective diameter, 1.75mm filament
approx. 6.00 full steps/mm (96.1 with 1/16 microstep)
approx. 2.49 full steps/mm³ (39.96 at 1/16 microstep)
The resolution of the new extruder is therefore sufficiently high even for fine prints due to the direct drive of the 1.75mm filament. Fast retracts are possible.
Since „only“ an 8-bit processor is used, the available steps must be used economically. A generous gear reduction, e.g. in a Wade or Titan extruder, can negatively influence the maximum speed of the XY kinematics.
The newly designed extruder compresses all necessary functions to a minimum of space.
The two printed halves of the extruder housing are screwed together to form a single unit. This unit is attached to the printer using a lasered cover plate and 2 screws. The extruder gear can be made accessible or cleaned without disassembling the extruder itself.
For housings made of coloured acrylic or other materials it is advisable to laser the cover plate made of clear acrylic. The extruder can therefore always be inspected. Anyone who trusts their extruder can manufacture the printing plates from the material of their choice for the benefit of the optics.
- Chapter 0 – Introduction
- Chapter 1 – Housing
- Chapter 2 – Z axis
- Chapter 3 – XY axis system
- Chapter 4 – Heated Bed
- Chapter 5 – Cooling
- Chapter 6 – Extruder
- Chapter 7 – Hotend
- Chapter 8 – Electronics
- Chapter 9 – Spool Roller
- Chapter 10 – Silicone parts
- Chapter 11 – Option: Belt drive cover
- Chapter 12 – Option: Rasberry Pi Zero
- Chapter 13 – Option: UPS for the pi
- Chapter 14 – BOM / Downloads
- Chapter 15 – FAQ
- Chapter 16 – Samples
- Chapter 17 – Concluding remarks