Parallel-axis syringe pump concept design

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About this device
Parallel-axix syringe pump.JPG
Keywords lab equipment
Variant of syringe pump
Authors Tuomas T. Hämäläinen
License data
Hardware CC BY-SA 4.0
Instructions data
Translation data

Concept design for syringe pump; non-functional

Project[edit | edit source]

This one doesn't work; for a working, tested design see Open-source syringe pump.

Motorized syringe pumps are commercially available for eg. laboratory work but they are often expensive. Thus, an open-source version has been developed (see link above).

This project aimed at improving the OS syringe pump design. While the conceptual idea was sound, the mechanical functionality was not met due to a lack of knowledge of those parts. The concept improvement ideas are found below.

Concept[edit | edit source]

The idea of a syringe pump is to convert the stepper motor's rotation to linear movement. The threaded rod, when rotating, moves the screw or a similar part alongside its axis. The concept in this is to move the end of the syringe plunger above the stepper motor so that the length of the product is shortened to a lenght little more than the length of the sum of the syringe cylinder and plunger. This is achieved by moving the plunger head above the stepper motor.

Design[edit | edit source]

Bill of Materials[edit | edit source]

  • 1x NEMA 17 stepper motor
  • 1x 5 mm - 5 mm shaft coupling (threader rod diameter - stepper shaft diameter. Both can change, but small steppers have 5 mm shaft)
  • 1x M5 threaded rod, 10 cm
  • 1x ball bearing for the above
  • 1x lead screw or bolt
  • 2x M5 threaded rod, 15 cm
  • 8x M5 bolts
  • 2x 5mm metal rods, lenght 20 cm
  • 4x linear bearings for the rods
  • 1x 6 cm of thin metal wire or 2x sowing pins
  • Stepper driver chip, Arduino or similar, etc.

3D printed parts:

  • Syringe holder
  • Syringe side wall
  • middle part 1
  • middle part 2
  • stepper wall

Estimated Cost[edit | edit source]

The estimated cost for the project in this state exceeds the previous superior design with 3d printed parts being rather big; the design needs work. The lowest cost is 10–20 € if parts can be ordered with a longer shipping time.

Conclusions and improvement ideas[edit | edit source]

The project did not yield a finished product, it gave a great number of improvement ideas and tips:

Cons:

  • The upper part rods cannot even with structure extending, be without connections at the other end
  • The rod lengths vary and may not be standard lengths
  • The middle part (slider) may need rods through it, stabilizing the whole thing considerably
  • The structural (outer) rods must have exceedingly sturdy connections to the parts, or a hull structure must be printed

Pros:

  • Middle part is actually very sturdy and works
  • Plunger attachment with (copper) wires/needles/pins through small holes seem to be holding the plunger tight
  • The concept for a separate plunger holder that attaches to the whole structure may be good for slightly differing pump sizes

Files[edit | edit source]

stl and freely modifiable openscad source file can be found at concept design: parallel-axis syringe pump

Designer Tuomas T. Hämäläinen, a student at Aalto University, as part of the course 3D Printing of Open Source Hardware for Science