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Flexy-Hand

by Gyrobot, published

Flexy-Hand by Gyrobot Mar 4, 2014

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97600Views 31613Downloads Found in Robotics
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Summary

A proof of concept printable hand with "live hinge" flexible joints. Individually activated fingers using Filaflex filament as tendons.
Printed in Makerbot Translucent Red and Filaflex hinges.
Re-mix this idea into your own robotic or prosthetic project.

  • Fingers open automatically, no return tendons or springs needed.
  • "Frictionless" articulation - no rubbing parts.
  • Stretchable tendons offering adaptive grip on irregular objects (only one motor required to activate all fingers).
  • Fully printable solution, no vitamins required.
  • Tough and rugged.
  • Realistic form under a surgical glove (see images).

Video here : http://youtu.be/K8mtqPTJ-Ys
Video review here : http://youtu.be/Z70YWNuOB8E Thanks to 3DUniverse.org and jesimon
Here is an article about the Flexy-Hand on 3DPrint.com
My 1st printed Flexy-Hand (above) is now on display in the iMakr Store, London.
.
EDIT 19/03/2014 : Added an "Opposable Thumb" version of the body.
EDIT 24/09/2014 : Added "Ring Pull.stl" so you can attach to the tendons to make it easier to pull them, see one of the images.
EDIT 16/08.2014 : Added two mounting holes in the base of the Hand for attachment to rigs/arms/boxes etc.
EDIT 29/07/2014 : Increased the tendon hole diameters in the fingers from 2mm to 3mm when printed at full scale. To help printing at smaller scales.
EDIT 16/07/2014 : Put hole in base of finger hinge (7.stl) so that it can be inserted into hand body easier.
EDIT 07/07/2014 : Updated the profile of the base hinges for the fingers (7.stl). This new profile, requires less force to close the fingers, yet it is shaped to better aid finger return.
EDIT 19/05/2014 : Due to Janfigueroa request, added hands (LH/RH) with a more opposable thumb for better grip, print the same fingers for either hand body, The tendons exit the base in this version in a circular pattern instead of a line.
EDIT 06/05/2014 : Two part mould for hinges uploaded from my remix here.
EDIT 02/05/2014 : Right Hand uploaded along with it's fingers.
EDIT 12/03/2014 : After many requests, I have uploaded a STEP file of the hand body (6 - 45deg Thumb Step File.zip)
EDIT 09/03/2014: There has been some confusion regarding how much articulation the fingers have. I have uploaded 3 photos, which show the thumb touching the first two fingers and very close the the ring finger also. I have also uploaded a plate of fingers (yum yum) for anyone who wants to print them all off in one go.
.
http://www.gyrobot.co.uk
http://www.facebook.com/gyrobotuk

Instructions

Print hand body without support.
Print finger segments either vertically (as modelled) or horizontally with support.
Print Hinges segments without support.
Assemble according to PDF

Hinges :

I modelled for Filaflex which is more elastic than Ninjaflex and other flexible PLA atm. However Ninjaflex does work but it maybe a little harder to assemble hence the hinges that fit into the hand body may need a little extra persuading with a screwdriver etc, maybe with some lubrication that can be washed away, e.g. liquid soap. I printed hinges with no infill and 2 or 3 perimeters (depends on scale) using Slic3r, this makes them nice and "spongy" adjust this if you want stiffer or more flexible hinges. The hinges at the base of the fingers are assembled a certain way round to aid finger return, please see section image to show this. Any issues getting the base hinges in can also be helped by using a craft knife and trimming a little off either the hinge or the body of the hand, YMMV
You can also cast your own with silicon sealant using the Hinge Mould which I also include here for completeness.

For the tendons :

Pre-stretch a length of 1.75mm Filaflex filament till it wont elongate any more, this reduces it's thickness. This stuff is so strong, I have yet to snap it. Feed each end through the two filament holes in the end of the finger tip. Both ends of the filament should come out of the same hole in the base of the finger tip part (see section image plus photo). Tie off in a none slip knot (left over right then right over left) and snip off one of the excess strands. If tensioned correctly the knot should hide itself in the base hole of the finger tip. Thread the tendon down through the finger segments out of the base of the hand.

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Hey,I printed this flexy hand but it just printed a normal stuff and not flexible at all it is just a structure.
So,can you help me in making my structure flexible.

Did you print the hinges in flexible filament, eg Filaflex as per instructions?

I'm really excited to try this hand. I wanted to know what process you used to make the finish so smooth? I've been toying around the idea of building some type of vapor chamber to deploy chemical vapor to help smooth/melt the outer skin to enhance the smoothness. I especially like the more realistic look! I'm amazed at how people come up with ideas around special problems and the use if these elastomer joins is one great idea!
Thanks for sharing!
Scott

Thank you, but it's just printed, no finishing.

Feb 1, 2016 - Modified Feb 1, 2016

Hello, I am beggining to experience with 3D printers, I recently made a Robohand, but want to try with the flexy hand. What are the directions for scaling it properly? Can I use PLA? Are there other alternative materials I can use for the moulding?

Nov 26, 2015 - Modified Nov 30, 2015

hi,

I'm a grade 11 robotics student and i was thinking of making this hand motorized and i was wondering if you know how much torque my servos should have to move the fingers and still have some good grip. Thanks

Hello Bmax

This one works for me: http://www.amazon.com/Futaba-S3305-Standard-Servo-Gears/dp/B0015H4C24/ref=sr_1_5?ie=UTF8&qid=1448998936&sr=8-5&keywords=Futaba+servo

keep in mind that there are fake Futaba servos available, make sure you buy directly from the Futaba Store.

Regards

AJ

i have a small print area and i was wondering if I could print this and it will function if scaled. I am able to print to a scale up to 0.8 on the hand body with a 45 degree thumb. Thanks for any more information.

Hi,

I have a makerbot mini and I believe it does not support filaflex filament... Can you give me a solution? or an alternative that I can use as I printed it all but the finger hinge

Cheers
Luis

hello Luis

Check this file Mould.stl under thing files. You can cast the tendons by using silicone.

best regards

AJ

One more question... Have you done a motion study on the Flexy Hand

Hey! Thing Info said that on 12/03/14 you uploaded a step file for the Flexy Hand but I can't seem to find it under thing files

All done, re-uploaded, sorry for the confusion.

THANK YOU!! Any updates on a step file for the Flexy Hand 2?

This comment has been deleted.

Hello, I woudl like to print this hand, but I haven´t got nijaflex or flexible materials, so I tried the mould, which was a complete disaster.
What can I do?
I´m 13, and I´m new at 3d printing .Help me please

Maybe try 3Dhubs.com to find a local printer of flexible filament.

after very thanks and grateful Sir i would like to say you the second generation of flexy hand is really great and one question please .
how many kilo gram this hand can carry ?

Hi,

Is it possible to get the full New-grip Hand assembly into one single Stl file?
I would like to print it in one peace with a fexible filament, and the very exact positioning of all the pieces should not be hasardous...
Thank you for the best hand's design to be found in open source : ) !

En que software de diseño fue realizado el modelo??????????????

Fue modelado en Meshmixer .

Hey, awesome work!
But we are struggeling with the hinges, as our printer does not provide ninjaflex support :/
So we tried to print the hinge moulds and fill them with silicon, which also did not work somehow, maybe we used the wrong silicon.
My question is now, which silicon did you use?
Best Regards Richard

Hi,
As mentioned I printed the hinges in Filaflex so I have not used Ninjaflex or the Silicon casting process. However I believe others have used Dragon Skin 30, Silcoflex and Latex with success, although it is not as strong as printed Filaflex. This is due to the fact that a printed hinge has lot of little crack arrestors within the grain of the print, whereas with the cast version, a crack/split once started can quickly propagate through the hinge, causing it to fail.

Hi, Can we print this in normal PLA?

Absolutely, except for the hinges, they need to be flexible.

I'm a cartoonist/graphic designer, and I've been going nuts trying to find a poseable hand model to use as a reference for drawing. The wooden ones they sell in craft stores are useless, with little to no poseability. I want one that can make a tightly clenched fist, splay the fingers, and do all the normal stuff a human hand can do.
Is there a version of this hand that can be used in such an aspect? I don't need an actual prosthetic, just a really nice hand model...

Has anyone successfully printed this without support? I think everything would work except the fingers. The palmar surface where the hinges attach is 1.0 to 1.2mm off of the plate.

its sometimes very difficult, when the parts of the fingers fall down few seconds before both parts start getting attached by the bridge. i think that very much hairs spray is needed for them to stick to the hot bed, also a little pressure with the finger on the initial tiny layers would help.

Also print with a raft for better bed adhesion, although I use a good hairspray (Nelly) so a raft is not required.

Thanks a looooooot for the modifications!!! will print right away!!!!

Hi to all Flexi hand followers!!!
I printed this hand with a Rep 2. It came out perfect!!! ... almost no fixing necessary. For the joints i used Nylon 645 at 0% infill, works Great!!!! But i have two small changes i wish someone can make to this hand.
First, the idea of individual channels for each finger is great!!!. I think it will be better if those channels exits the palm as a circle instead of the actual lined-up configuration. Having those exits centered make the hand closer the the real hand (Carpal Tunnel) and makes it easier to make a wrist with movement for attaching it to a forearm.
Second, in another comment a guy asked for splitting the palm in parts to let the thumb one more degree of movement. I settle for fixing the thumb in a position that when flexed, it comes opposite of the index or middle finger, like a claw. That way keeps the hand close to the original design but enables to grasp round things like soda cans and glasses.
Thanks to gyrobot for this thing and to anyone that implements my suggestions.

Thank you for your comments, a more opposable thumb and carpal tunnel style tendons exit uploaded, see file section.

After lots of difficulties printing the phalanges, I have settled on the following settings in Slic3r:

  1. Support material > CHECK "generate support material" with all the defaults.
  2. UNCHECK "detect bridging perimeters" in "layers and perimeters"
  3. Bed temperature (for PLA) is 110 for the first layer, then 60 for subsequent layers
  4. Extruder temperature (for PLA) is 210 for all layers.

tarek : )

not 1 problem on a replicator2

I think adding rubber finger pads and palms could improve the grip substantially

Print the whole thing in Filaflex.

Great design! Do you think you could use Nylon rather than Flex PLA and get the same results?

i used ninja flex for the joints and it works great. i heard filaflex is changing their name because fila shoes got mad.. if any1 needs help with the settings for printing with ninjaflex i know the sweet spots.

I have Taulman Nylon and you cannot tie this in a knot like the flexible filament, and stretch it to make it thinner. However Nylon fishing line with a high breaking strength would be perfect. You wouldn't get such an adaptive grip but you could get a more resistive grip.

I'm not too familiar
with printing nylon, but I have found out that Nylon is flexible and also
really strong. Do you think you would be
able to print the hinges in nylon (at a lower infill) and achieve the same dexterity
with added tensile strength? Thanks for your help.

Sorry, I thought you meant use Nylon for the tendons.
With regards to the hinges, I would not print this in Nylon, Nylon is just too rigid and not flexible enough. Although my experience is with the Taulman 618 variety. Please check out the review video, but to re-iterate from this and my experience, you cannot break Filaflex printed parts, they are just so tough.

have you thought of running a second line only past the first joint to be able to get more variety of motion

only thing needed at this point i think is 6.stl could be cut into a couple pieces so the thumb could possibly have some sort of gyrating mechanism within to convert thumb into a true opposable thumb. or maybe the thumb section of 6.stl could connect like a joystick on a game controller perhaps, thats what i wanted to do to it but i'm not that advanced at design. I did mirror all pcs for a right hand as well. also wanted to make a back scratcher out of it too haha

can you share the right hand? i can't mirror it i'm using SolidWorks 2013.Thanks

You can use Meshmixer to mirror stl files.

Thanks you, I'm going to try, you did an excellent design.

Hmm, printed with Makerbot replicator 2 and having trouble with the hinges, they seem a little big. If I hammer them I can get them in but doubt they'll flex at all :-/

Wgray - in reply to fat

Same here, however when I imported the .stl file to the maker software it said the hand was to big would you like to scale to fit. I allowed this however it never told me how much it scaled it down. I will scour the site for hand dimensions and hopefully go from there. But I think this is what happened to you. I printed the hand model as a whole.

The hand model as a "whole" is quite tall at Z200.39mm, so I understand why Makerware would want to scale to suit. The largest individual part which is the hand body (6.stl) is 50mm x 113mm x 115mm. The diameters of the lobes of the flexible hinge parts are 5mm and 7mm (base hinge) so if you measure your hand model, find out what the slot diameters are for the fingers and scale the hinges to suit.

Hope this helps,
Steve.

Gyrobot - in reply to fat

There are two sizes of hinge, the larger ones (item 7) are for the finger base and the smaller ones (Item 8) are for the finger joints. Which ones are you having trouble with? You could scale the hinges a tad smaller if your flow rate is too high. Have you cut away all the support in the finger's hinge slots? You can reduce the infill percentage to make the hinges more flexible too, depending on what filament you are printing with.

Hope some of these ideas help you.
Steve.

@ Gyrobot - has anyone taken up the remix challenge?

Everyone's probably busy as bees remodelling as we speak (hopefully)

I challenge someone to remix this and Robo hand to make an awesome prosthetic hand.

What a beautiful design. Using flexible filament for the joints is a stroke of genius
I've been playing around with the Robohand variations out there and this design solves a bunch of issues like a separate elastic band required to bring the fingers back
I cant wait to print this out and see how strong the joints are
Have a stupid question though. I own a Replicator 2 with acrylic bed. I'm waiting for a glass replacement (un heated)
Do I need to consider some modifications to the Rep2 in order to be able to print Filaflex or Ninjaflex? Any guidance would be helpful

Hi, thank you for your questions, I guess acrylic is ok, although I am not sure, unheated glass definitely works though.

Flexible filament buckles when you push it, especially 1.75mm and especially Filaflex. You therefore need to have FULL filament support after the hobbed shaft and the hot end. a PTFE liner all the way down is what I use. Here is my modification : http://www.thingiverse.com/make:54389http://www.thingiverse.com/mak...

The Recreus hotend for Filaflex has an M6 thread so it is interchangeable on a Rep2 I believe. This is stainless steel with a PTFE liner :
http://www.thingiverse.com/thing:263143http://www.thingiverse.com/thi...
Then there is the extruder with filament support if you intend to print with Filaflex
http://www.thingiverse.com/thing:263133http://www.thingiverse.com/thi...
Cheers
Steve.

RECREUS HOTEND
by Recreus
Recreus direct drive
by Recreus
ORCA 0.43 Extruderderivate
by Gyrobot

I am attempting to make one of these. I want to know how you connect the tendons. Could you post a vid or just tell me? Also how to you keep from falling off. Another thing is my printer is printing 3mm filament right now and I dont want to get the adapter(A Lulzbot Taz). In your instructions you said to use 1.75 for the tendons. Should I just use fishing line like sTeAkNuggeT did or will 3mm work? Thanks in advance.

3mm would be far to big for the tendons, therefore nylon fishing wire is the way to go. There are images + a section view which show how the tendons are threaded at the end finger tips + instructions in the instruction tab too. I will attempt a video if I get time. Support will stop the fingers falling over + you can print them on their side too, again, its in the instruction tab.

Thanks for making.
Steve

i'll post a picture soon, its all gizmo black with white ninjaflex joints(hinges). I also mirrored the left hand and all the fingers in blender. Printed the right hand when i was sleeping and now to finnish the fingers. this hand is sick!! props

Oooooooooo. I await impatiently.

i used ninjaflex on the hinges works great, but need to order some fishing line..

Your model looks amazing, but what is filaflex? Their web page is terrible! There's an image of an angry little man with the title "How to print with filaflex?" that leads nowhere. I'm curious as all get-out, but all I can find is this tiny little entry over and the bild3r wiki: http://www.bld3r.com/w/filaflexhttp://www.bld3r.com/w/filafle... and this poorly spell-checked video over at youtube: http://www.youtube.com/watch?v=Vmb9iwFpaOshttp://www.youtube.com/watch?v...
Please tell me more!

Filaflex is currently the most flexible filament for 3D printing, available in 1.75mm and 3mm diameters.
It is made by Recreus which is a Spanish company so that will be the reason for not so great English.
You can find it for sale here : http://www.recreus.com/en/http://www.recreus.com/en/

For this design, other flexible filaments can be bought, i.e. NinjaFlex, Arnitel, and Makerbot also sell a flexible filament too plus others no doubt. Their properties will vary across the manufacturing range so you may have to adjust the infill density to get teh flexibility you desire.

Hope this helps,
Steve.

is there any way for you to upload a .STEP file for this

Unfortunately I used Meshmixer to create this, if you want step files then you can download FreeCAD and follow this easy "step" by "step" (I'm here all week) post.
http://northernhope.blogspot.co.uk/2013/05/stl-to-step-with-freecad.html?m=1http://northernhope.blogspot.c...

Oh and one more thing....since it would be easier for you to do, would you mind posting a plate or two for us? This way we can print a whole finger, or more than one finger at a time.

This is the coolest thing I've seen so far. I wonder how it would work if adapted to the InMoov robot.

Filaflex now exists in 1.75mm

What printer are you using to print with Filaflex since it's only a 3mm filament?

Hi, I print with an Orca 0.43 but with a modified JackT extruder design (http://www.thingiverse.com/make:54389)http://www.thingiverse.com/mak... using a PTFE hot end liner. You can now buy 1.75mm Filaflex.

ORCA 0.43 Extruderderivate
by Gyrobot

Well, next Halloween decorations are going to grabby with one motor. Excellent....

Yes this going to be turned into a zombie crawling hand soon.

You know, before the modern day prosthetic, people walked on wood pegs and used hooks.. LOL. This is really the best "entry" into a new era of assistance devices I think I've seen out here. And it's without a doubt an awesome reflexing of what a maker-movement can represent. The Gyrobot rocks! Ha!

Thank you for your kind words.

strangers not recommended.

Very pretty, and i love the idea of the flex-hinges. Should be featured.

Great Job! This is awesome. Add a motor to wind and tighten each line and some programming, you are set. To the Future! Salute!

Thank you. I believe for the simple task of just gripping objects, you could use a single higher-torque motor/servo, winding all tendons together. The tendons will stretch according the irregularity of the object gripped. However, if you wanted to do gesturing then individual finger activation is necessary.

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