Introduction: Paste Extruder Add-on for 3D Printers

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About: Media artist, maker at <3, studying at Bauhaus University.

3D printing is such a cool thing, right? All the many useful things you can print, right?

Have you ever stood in a pile of 3D printed gadgets and plastic waste and wondered what else to do with your printer? Have you ever wished you could go beyond plastics and work with natural material like clay or even experiment with edible materials?

This paste extruder is for everyone who wants to explore and go beyond plastics. It's an easy and low-cost solution for anyone with a 3D printer who wants to try printing with dough, clay, chocolate, silicone or other pasty material. It has a large volume container and is compatible with most 3D printers.

This instructable consists of only seven steps. Each one contains an image showing what the step is about and a second image giving a visual list of materials needed and how everything is put together.

The design for the extruder including the explosion graphics were created in Fusion 360. The Drawing fuction of Fusion 360 was used to get the outlines of

Supplies

The files for the 3D printed parts can be found in STEP 8!

Additional supplies

  • 1x acrylic tube outer diameter 50mm/ inner diameter 44mm, length 300mm
  • 3x linear shafts, 8x700mm with threaded holes on the ends
  • 1x threaded rod, 8x300mm (T8, 2mm pitch, often sold with a suitable nut)
  • 1x NEMA 17 stepper motor with planetary gearbox (27:1, but other transmission is possible)
  • 1x ball bearing, 6201 2RS
  • 3x sintered metal bearing, 8x12x15 mm
  • 1x hose/ flexible tube, outer diameter 8 mm
  • 1x hose clamp, ~22 mm
  • 2x rubber band, rubber rings
  • Superglue
  • Marker

Screws

  • 6x M4, 10mm
  • 7x M4, 16mm
  • 3x M4, 25mm
  • 4x M3, 10mm
  • 8x M3, 15mm

Nuts

  • 7x M4
  • 8x M3
  • 2x brass nut for threaded rod

Step 1: Preparing the Paste Reservior

Slip the upper lid and the lower cap onto the acrylic tube and mark the holes. Use a 4 mm drill to drill holes into the acrylic tube.

Step 2: Motor Mount Assembly

  1. Use four 10 mm M3 screws to mount the stepper motor to the 3D printed mount.
  2. Use some glue or double sided tape to make sure the bearings stay in place. Clip the sintered bearings into the slots on the 3D printed mount.

Step 3: The Motor Coupling

The coupling transmits the rotary motion of the motor shaft to the threaded rod. It has to withstand high forces and should be made out of a strong material. Depending on the viscosity of the paste having it printed in metal might be necessary.

Step 4: Installing the Brass Nut on the Upper Cap

Use four 15mm screws (M3) to install the brass nut into upper cap. Clip four M4 nuts into the holes on the inside of the cap.

Step 5: Plunger

  1. Screw the upper cap onto the threaded rod.
  2. The plunger consists of three separate parts. By glueing the three parts together two grooves will form in which rubber bands can be placed. The rubber band seals the gap between the plunger and the inner wall of the acrylic tube.
  3. Clip the ball bearing into the plunger and the clamp into the ball bearing.

Step 6: Frame Assembly

Assemble the frame as shown in the picture.

  1. Guide the linear shafts through the sintered bearings of the motor mount.
  2. Place the upper ring onto the linear shafts and fasten it with three 10 mm screws. Use washers to protect the printed part.
  3. Move the stabilizing ring roughly to the middle of the frame and use three 25 mm screws and nuts to fasten it. It's only function is to stabilize the frame.

Step 7: Installing the Material Container

Install the material container as shown in the picture.

  1. Slide the acrylic tube over the plunger and into the upper cap. Use four 16 mm screws (M4) to lock the upper cap in place.
  2. Push the lower cap into the acrylic tube and use three 16 mm screws to lock it in place.
  3. Push the lower ring onto the linear shafts and the tube and use three 10 mm screws to lock it in place.
  4. Push the hose into the lower cap and use a hose clamp on the lower cap to lock it in place.

Step 8: Print Files

In this step you can find all stl files for the 3D printed parts. The files were created with Fusion 360.

Attachments

Step 9: Final Notes

The extruder uses a regular NEMA 17 motor and can therefore be connected to the slot which is used for the filament extruder. To increase the torque of the motor a planetary gearbox is used which means that the revolution of the motor will be much slower. To make the extruder work on a 3D printer the flow rate and print speed need to be adjusted.

By using a flexible hose the extruder can be placed next to the 3D printer. Only the end of the hose needs to be attached to the print carriage.