Flexy-Hand 2 – Filaflex Remix

Author: Gyrobot, published on 2015-01-23

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Summary

My most advanced Flexy-Hand to date.

This was designed for Jack via e-NABLE. The result of a collaboration between myself and Jeff Erenstone, Prosthetist and CPO of Performance Orthopedic Design.

Optimised to be printed with flexible filaments. This version was printed with Skin I Filaflex, Skin II also available.

Key Features :

  • Thermoformed Gauntlet, dual material, lower layers PLA, upper layers Filaflex, great strength.
  • Palm socket integral to hand. Can also be filled with mouldable medium, eg, Oogoo, Sugru, Silicone, Latex or foam etc.
  • Each finger and thumb printed in one piece. Using CraftWare customisable supports.
  • Silent articulation.
  • Recipient’s scanned limb printed with internal “bone” and wrist articulation. Using variable density “Modifier Meshes” in Slic3r.

Video here : http://youtu.be/dEQs-HXZj60
Video of the fitting to Jack on location at Mountain Orthotic and Prosthetic Services, I was privileged to be able to watch the live fitting via Google Hangouts : http://youtu.be/9EocIKpdPyw

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Instructions

Gauntlet

Print fully in PLA or pause partway to change filaments to the same skin tone Filaflex that you printed the hand with. Once printed in flat mode, gently heat either in boiling water or with lighter/blowtorch, hot air gun etc. to soften, then bend over the gauntlet’s arms to 90 deg. A good idea is to place a towel/cloth over the recipients arm before forming the gauntlet to suit. In this case, I printed off a scan of the recipients arm first. Match the hinge pitch to the printed hand width. Obviously be careful when using heat.

Hand Body

This can be printed without support, but I have found a little under the 45 thumb angle can give better surface finish to the surface quality when printed with flexible filaments. YMMV.

Fingers

You can either print them on their side with support as orientated in the original Flexy-Fingers thing. However I would recommend to print them as orientated (45 deg) in this collection with support. The fingers have much better surface quality and the nail areas look great. CraftWare is again perfect in this regard, because you can place the supports exactly where you want them, at the same time, keeping them out of those tendon channels.

Tensioner

Print 5 off.
I did try and print this in Filaflex too but there is too much stretch in the tendon for my liking, so it is best to print in rigid filament.

Hinge

Print 2 off in Filalfex filament.

Scanned Arm

I offset the outer scanned surface mesh in Meshmixer by about 6mm and then waisted in the offset mesh to create a thinner zone in the wrist area. The inner zone was printed at 45% infill and the outer zone was printed at 10%, this allowed a soft feel initially and then the feeling of bone if pressed firmer. The internal thinner zone near the wrist created a hinge which help the arm articulate in the correct place. See images and video for this example.

I see great potential printing “bones” internally inside the model.

Whilst this model is not actually part of this thing it is an interesting concept to show. There has been a lot of talk of about multi-material flexible parts, I think an easier workflow and less technical is this type of variable infill parts. No need to dual extrude, purge material from mixing nozzles, ooze problems. It maybe an option for you.

Assembly

Please follow the original instructions where applicable.

License: Attribution – Non-Commercial – Share Alike

Tags: amputee, cyborg_beast, e-NABLE, Flexy-Hand, Hand_Amputee, prosthetic, Prosthetic_hand, Raptor, robohand