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Hands-Free Crutch

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MOST Delta filament as guide.JPG This page was part of an MTU course MY4777/MY5777/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.


Preliminary Student Design Warning
Note that this page is a preliminary student design and has not been vetted.
Care should be taken to read critically and weigh the evidence.
Remember non-tested and vetted designs should not be relied on, especially in matters of health and safety. Recommendations to improve this project follow:


  • Current iteration unstable - move to multiple legs,wheels
  • weak points on velcro attach
  • too much materials in non-stress points -- not enough in others.
  • move to flex materials on all parts touching person

Hands-Free Crutch[edit]

Project developed by [[[User:JLaureto|JLaureto]] (talk) 07:27, 17 November 2016 (PST)], Tjmahan (talk) 18:53, 5 December 2016 (PST), Krcipriano (talk) 19:19, 5 December 2016 (PST),Shan Zhong (talk) 19:34, 5 December 2016 (PST)Snuchitp (talk) 19:57, 5 December 2016 (PST)
Status
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.

Abstract[edit]

This page is dedicated to the design and development of an open-source Hands-Free Crutch for the developing world. All components are designed with open-source software. OpenSCAD, FreeCAD and/or Blender have been utilized for digital file generation (STL). All components have been printed on a MOST - Athena Delta Printer. Standard crutches are produced between $10.00 and $120 ref. This Open Source Appropriate Technology (OSAT) aims to decrease the overall cost of a standard crutch and to enter the specialized market. This provides a 3D printed alternative by simultaneously allowing for customization based upon a user / patient's condition and size (height, weight, leg size, etc...).

Bill of Materials[edit]

All printed component files and design sources are available on YouMagine: LINK to files

  1. Printed Components
    1. 1x 60mm Threaded Rod Support Filename: Threaded Main Support Rod_58mmDiameter_Pitch5_Height190
    2. 1x 58mm Female-Threaded Height Adjustment Filename: Threaded Outer Support Rod.stl
    3. 1x Threaded Bottom Foot Filename: crutch foot-1.1.stl
    4. 1x Leg-Rest (Front - Knee) Filename: legrest_kneeside_Laureto_3
    5. 1x Leg-Rest (Rear - Ankle) Filename: legrest_ankleside.stl
    6. 2x 40mm Threaded Knee Rest Rod Filename: 40mmDiameter_Pitch5_Height100_Female
    7. 2x 38mm Threaded Knee Rest Height Adjustment Filename: Threaded Main Support Rod_38mmDiameter_Pitch5_Height100
    8. 1x Knee Rest Filename: 'Leg Brace.stl
    9. 1x C-Clamp Filename: 'C clamp.stl"
    10. 1x ea. Support Rods Filename: bottom_rod_version2.stl, connector_rod_version2.stl, top_rod_version2.stl
Part Gallery
60mm Threaded Rod Support  
58mm Female-Threaded Height Adjustment  
Threaded Bottom Foot  
Leg-Rest (Front - Knee) mated with Leg-Rest (Rear-Ankle)  
Secondary Support Rods with C-Clamp and 90mm M6  
40mm Threaded Knee Rest Rod  
38mm Threaded Knee Rest Height Adjustment  
Knee Rest  


  1. Secondary Components
    1. 2x M6 X20mm Socket Screws (LINK)
    2. 1x M6 X90mm Socket Screw (LINK)
    3. 4x ~6mm ID Washers (LINK)
    4. 3x Nylon Insert Locking Nut (LINK)
    5. 1x ~50mm diameter x 1mm thick of recycled bicycle tire (or some rubber equivalent)
    6. 8x 1mm x 12.7mm Wire Nails (LINK)
    7. 2x Side Release Buckle Straps (LINK)

Tools needed for fabrication of the OSAT[edit]

  1. MOST Delta RepRap or similar RepRap 3-D printer
  2. 6mm Hex Wrench (Application: Tightening M6 Bolts)
  3. 10mm Wrench (Application: To fixture nylon nut while tightening)
  4. A small hammer (Application: Tighten wire nails and fix the rubber on the crutch foot)

Skills and Knowledge Necessary to Make the OSAT[edit]

  • The significant design considerations that allow this part(s) to be printed with minimal support have already been accounted for in the provided files. Thus, any 3D printing operator with sufficient machine (~>3 months) experience should be able to successfully print these parts without trouble.
  • Useful tools that may help an inexperienced user:

Technical Specifications and Assembly Instructions[edit]

  1. Print all printable parts from Bill of Materials. Printing time will be approximately 71 hours 58 mins.
  2. Insert M6 nut into the hexagonal insert on the leg rest (Front-Knee)
  3. Insert the tongue on the leg rest (Front-Knee) into the groove of the leg rest (Rear-Ankle). Press firmly until the internal faces of the two parts are flush.
  4. Insert M6 Bolt into the hole of the leg rest (Rear-Ankle). Thread into M6 nut. Tighten with Alan Wrench until tight. Repeat on opposite side.
  5. Thread 40mm Threaded Knee Rest Rods into the threaded holes on leg-rest(Front-Knee). Continue to tighten until resistance is felt.
  6. Thread 38mm Threaded Knee Rest Height Adjustment onto 40mm Threaded Knee Rest Rod. Adjust to desired height.
  7. Slide Knee Rest onto 38mm Threaded Knee Rest Height Adjustment.
  8. Thread Threaded Bottom Foot onto 58mm Female Threaded Height Adjustment. Tighten until tension is felt.
  9. Thread assembled 58mm Female-Threaded Height Adjustment onto 60mm Threaded Rod Support. Adjust to desired height.
  10. Assemble Secondary Support Rods with C-Clamp and 90mm M6 as shown in part gallery.
  11. Slide C-Clamp onto assembled 58mm Female-Threaded Height Adjustment.
  12. Insert ends of Secondary Support Rods into bottom holes of Leg-Rest (Front-Knee)
  13. Tighten M6 nut on C-clamp until tensioned around 58mm Female-Threaded Height Adjustment, until tension is felt.
  14. Feed desired straps through slots provided on top of leg rest(Rear-Ankle)
  15. Assembly time will take approximately 10 minutes.

Common Problems and Solutions[edit]

  1. Ensure you do not apply excess force in tightening the bolts. These should tighten just until strain is felt on the wrench, no further.
  2. If threads do not fit correctly, an x-acto blade can be used to clean up any defects that are visible. Otherwise, the provided OpenSCAD includes parameter "tolerance", which can be increased or decreased s needed.

Cost savings[edit]

Estimate your costs Commercial equivalent link/Cost US$ Approximate Savings in US $ and % savings
$33.02 [1] [2] $149.99

or [3] $ 149

$ 115.98 and 77.83 %

Outreach[edit]