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).

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.

  1. 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

  1. web page: Amazing 3D printer in action: Watch a working wrench being made from powder, (2012). Available: http://www.dailymail.co.uk/sciencetech/article-2117570/Amazing-3D-printer-action-Watch-working-wrench-printed-powder.html
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