Lightweight Wrenches

Project developed by Jackie Mayrose

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Abstract

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).

  1. Paragraph description of the OSAT - why is it Appropriate? What need does it fulfil? Are there case studies you have found of a technology being used successfully?
  2. Picture of completed print using
    File:Name-of-your-image.png

Bill of Materials

1. Your choice of filament

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

2. [broken Thingiverse OpenSCAD files]

    • Editable OpenSCAD file for making different size wrenches
    • Common sizes of wrench also in STL

Tools needed for fabrication of the OSAT

  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

  • If you used special skill – link to relevant wikipedia or wikiversity articles/courses

Technical Specifications and Assembly Instructions

  1. Provide directions for print/assembly - be detailed enough in your “how to” to ensure that someone could construct the device from your description. Consider the elegance of IKEA like instructions.

Time Estimates

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

Printing

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

Slicing app.PNG

Finishing

  • Remove support on box end with knife/pliers/etc.
  • Smooth underside of wrench if necessary
  1. Including drawings or pictures of the device at stage of assembly at minimum. (http://www.appropedia.org/Special:Upload)

Common Problems and Solutions

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 (PLA) or solvent mix (ABS)
Support hard to remove
Pliers useful for ripping off support
Should not negatively affect usability
Clean up with sharp knife

Cost savings

  • Commercial 22-piece combination wrench set: 28.99 USD
    • ~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

References

  • The sources of information (e.g. engineering handbooks, journal articles, government documents, webpages, books, magazine articles etc.). References should use the <ref> </ref> and <references/> tags and can be in any format but should include all the information necessary for someone else to find the same information you did. For example: [1]
  1. web page: Department of Energy (DOE) Landscaping and Energy Efficiency, DOE/GO-10095 (1995) Available: http://www.eren.doe.gov/erec/factsheets/landscape.html

Based on the developmental needs addressed (e.g. food, heat, electricity, clean water, health care, etc.) be sure to label your device in the proper categories e.g. use [[Category:Water]]. Be sure to categorize your device so that it will be easy to find – for example “Low voltage connection basics” is categorized in

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