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MOST Delta filament as guide.JPG This page was part of an MTU course MSE4777 OA and MSE4777 OB/MSE5777/EE4777/EE5777: Open-source 3-D printing

Please leave comments using the discussion tab. The course runs in the Fall semester. It is not open edit.

AutoInjector for Medicine[edit]

Project developed by [Natalie McGrath]
This OSAT has been designed but not yet tested - use at own risk.

You can help Appropedia by contributing to the next step in this OSAT's status.


AutoInjectors are a spring-loaded device that aides in delivering the proper dosages of certain medicines. The have built-in adjusters to ensure the medicine is delivered at the proper depth in the body. They are useful for those that have trouble using a simple needle for injections, possibly children, the elderly, or those with needle-phobias. They are also useful for injecting pets with their medication. The AutoInjector keeps the needle covered until injection time to prevent injury, and some have a built-in safe measure of requiring the injector to be pushed against the skin before the trigger button can be pushed to prevent accidental discharge.

Bill of Materials[edit]

  1. 3.5" by .5" Spring
  2. 3" by .25" Spring
  3. 1.5" by .5" Spring
  • Optional Clear Plane to use as Window; leaving open works fine as well
  • Glue, like a hot glue gun
  • all colors are notional and used to specify which piece is being referred to

Glue Spring holder Top and Bottom pieces together Use hot glue to create small cushion on end of plunger rod, if desired, for comfort and to aid in stabilizing rod Place the 1st spring onto the plunger rod. Insert the spring holder with the smaller top into the spring with the plunger rod through the middle Place the 3rd spring onto the plunger rod, so that it falls into the spring holder. Place "yellow" indicator piece onto groves inside "blue" plunger and trigger button piece, with indicator marks facing the viewing hole in the "blue" piece Place small end of plunger rod through small hole at the top of the "blue" plunger and trigger button piece Place wide end of plunger rod into "yellow" indicator piece. You will have to compress the springs to do this Insert #2 spring followed by assembled pieces into Injector body. You will have to push down the trigger button in order to slide the pieces into the body

Thread long depth adapter into syringe housing Insert primer/depth guide into long depth adapter

Use syringe housing unit to set springs by inserting it into injector body, as far as it will go Remove from injector body once springs are set Twist syringe housing unit on assemble pieces

Tools needed for fabrication of the OSAT[edit]

  1. MOST Delta RepRap or similar RepRap 3-D printer

Technical Specifications and Assembly Instructions[edit]

The Injector Body needs supports generated when printed for the Trigger Button window; these will be snapped off after printing

About 4 hours to print all of the parts 5-10 min for final assembly

Common Problems and Solutions[edit]

  • Make sure the springs are loaded properly. Spring positions are not interchangeable*

This project was way beyond my CAD abilities, so not all of the pieces are optimized for printing; Hopefully a someone can improve upon my design

Cost savings[edit]

  1. $1 for plastic, $5 for springs, $6 in total
  2. $27.99 Owen Mumford Autoject EI [1]
  3. $22 total savings or a 78% price reduction.

Benefited Internet Communities[edit]

Owners of Dogs with Diabetes

People with Allergies

Parents of Kids with Allergies

People with needle-phobias



[[Category:Medicine]] [1] [2] [3]

  1. DallasMTBR, director. About the Autoject 2. Youtube - About the Autoject 2, Youtube, 18 June 2017, www.youtube.com/watch?v=fndalvwKF4s&t=222s.
  2. Owen Mumford. Autoject-Brochure. Autoject-Brochure, www.owenmumford.com/us/wp-content/uploads/sites/3/2014/12/Autoject-brochure.pdf.
  3. Rawlings, Kelly. “Injection Helpers.” Main.Diabities.org, 2015, main.diabetes.org/dforg/pdfs/2015/2015-cg-injection-aids.pdf.

External links[edit]

All scad files can be found on my YouMagine page.