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Lightweight Wrenches

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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.

Lightweight Wrenches[edit]

Project developed by Jackie Mayrose
This OSAT has been designed but not yet tested - use at own risk.
This OSAT has been prototyped.

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


Lightweight combination wrenches are simple enough to guarantee a usable print with at least one end of the wrench. The OpenSCAD script can easily be modified to generate custom sizes in metric and add additional features if the user wishes. These wrenches are easy to carry, relatively durable, and much cheaper than conventional options. They can be made with locally available materials in PLA, ABS, or other filaments, and could be used to service the printer itself.

Someone may need only one or two particular wrenches to work on a vehicle, and individual wrenches are more affordable than an entire set (but the entire plastic wrench set is also much cheaper and lighter than a conventional wrench set). Although this wrench does generate a small amount of waste resulting from the support for the angled box end, ideally this plastic could be saved and recycled using a Recyclebot. (This design choice was also made because non-angled 3D printable combination wrenches already exist.)

Adjustable wrenches have been used as tests to show abilities of 3D printers [1], however data is not available on field usage of plastic wrenches and their usefulness.

Wrench 012.jpg

Bill of Materials[edit]

1. Your choice of filament

    • Based on printer capabilities, cost, availability.
    • Parts shown printed in PLA. ABS is probably best.

2. Thingiverse Page with OpenSCAD/STL files

Tools needed for fabrication of the OSAT[edit]

  1. MOST Delta RepRap or similar RepRap 3-D printer
  2. Utility/hobby knife or similar (small saw)
  3. Pliers optional but helpful

Skills and Knowledge Necessary to Make the OSAT[edit]

Technical Specifications and Assembly Instructions[edit]

Time Estimates[edit]

  • Varies based on wrench size
  • 13mm wrench ~1.5 hours printing plus ~20 minutes assembly
  • 3mm wrench 10 minutes printing plus ~15 minutes assembly


  • Slicing program - load model, lay flat
  • With support, touching buildplate
  • Wall thickness, top/bottom thickness ~1mm
  • Fill at least 10%
Slicing app.PNG


  • Remove support on box end with knife/pliers/etc. (can be saved and used with Recyclebot_v2.3)
  • Smooth underside of wrench if necessary

Common Problems and Solutions[edit]

Box end not proper size (ie round inside, not hexagonal)
Increase print quality
Thinner layers
Slower print speed
Change extrusion rate
Not sticking to print bed
Clean bed and reapply glue/solvent
Support hard to remove
Pliers useful for ripping off support
Should not negatively affect usability
Clean up with sharp knife

Cost savings[edit]

  • Commercial 22-piece combination wrench set: 28.99 USD [2]
    • ~1.30 USD per wrench
  • 13mm PLA wrench ~8g
  • 3mm PLA wrench ~2g
  • PLA ~30 USD/kg
    • ~0.30 USD per wrench (depending on size)
  • 1 USD per wrench saved on average
  • 77% cost savings in PLA
  • Same approximate savings in ABS given ~35 USD/kg


  1. web page: Amazing 3D printer in action: Watch a working wrench being made from powder, (2012). Available:
  2. Amazon product page, (2014). Available: