A little hand, big idea :-)
Description
is my first attempt at a printable prosthetic hand. I have yet to finish the forearm and servo mounts... it all takes time. I have uploaded a 60% scale model for two reasons. One it has to fit within the guidelines of a particular competition and secondly it demonstrates the unique ability of 3D printers to rapidly produce the right size part for end use. eg from a child's to a very large man's hand. It also gives the user ability to upgrade or repair at home for a mere fraction of what this type of prosthetic currently costs. If any company or individual is interested in this work feel free to contact me.
Instructions
After the print finishes you need to cut off the support pads some are circular others are rectangular. I needed them to help keep the print attached to my heated bed.
You will need some fishing line 0.5-0.8mm dia and 1.5-2mm dia self-tapping screws. not easy to get but available, go to a hobby store.
All fingers snap together, you will need a hammer. Rest one phalange on a bench and the other phalange held at 90deg (vertical to bench) line up the pin joint and give it a good wack! They are surprisingly strong if printed with high-density +50%
The wrist and thumb base parts I recommend screwing together for initial assembly, then when it all works well glue and screw it together.
The tips are a separate print because I printed them hollow, 0.3mm wall thickness with soft pliable PLA, any printable plastic will do though. If I get time I intend to design and print finger and palm pieces to give the entire palm a soft but firm grip! The tips should be glued on with super glue.
Once it’s together thread 5 lengths of fishing line through each finger and tie knots in the end to retain them (I'm working on the components to connect these lines to but for now just tie them to rings for your fingers to control the hand). Then you will need some very small rubber bands to set the knuckle tension correctly I used two orthodontic bands on each knuckle. One screw is installed below the thumb ball joint to hold a few rubber bands there also.
The hand should probably be put in a rubber glove to enhance its grip.
I'm working on a mod to include duel tendons that will enhance the movement.
Any questions please ask I'll try and answer ASAP but I can be away for long periods of time.
Updating files be patient
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Hi, I am a hand amputee looking for a new robotic hand, are you still working on this project? Regards
Would really like to see your concepts James when you get some time.
Updating files be patient no one is paying me to do this so progress is slow.
why there are no more associated files?? I was about to print one!!!
Perhaps some Sugru could enhance the grip and fill out a softer shape around the plastic.
hello again, I printed out your parts and this is Awesome Thanks. I have a problem I think, The Ball size for the knuckle seam to be Much smaller than the Ball socket in the wrist. I printed the fingers 2 times just in case I did the scale wrong but the same problem is still there. My coworker said he wants to automate it but I wana make sure The print is good before we move to the next level. I guess if I have another question it would be is there supposed to be a large cushion in the joint?
Thanks for the complement. The CAD model and assembly are rather complex and there could be an unrestrained parameter that caused it. But first I would like to know what material you printed it in? Thermal expansion contraction and warping can be a problem. Did the thumb and finger balls come out spherical? I had a small amount of warping that caused me minor problem with the thumb ball but it was oversize in its socket. Does your oversize condition exist on all fingers and thumb joints? Is your printer and profile well calibrated? Mine is generally good to +/-0.15mm. Do the metacarpals connecting ball joints snap together well? My later designs use thin soft felt in the ball joints for both ease of movement and shock absorption but this first iteration was not indented to be that way. If there is enough room you could do that. Or you could sand down the mating surfaces of the wrist parts to reduce the ball size (in one plane). If your business is interested in further development of this design I would be willing to work with you as I
âm currently seeking new employment having left my profession. Sorry you are having some problems. :-[
great work. beautiful how our bodies are created and are so intricate in their functioning
Take a look at my final year BSc Robotics video - features tendons, motors and fingertip sensors :) Made it in 2007 :D
Hi, this is a nice project. I'm printing the finger part on the moment! I seem to encounter a problem with the wrist STL file, everytime I slice it in different software, I always encounter a problem with faulty STL. I also tried to download it again, and export it into Blender and reexport. It would a shame to have only the fingers... :(
Thanks for an inspiring submission. I will try to make. I need to get my bot back in service.
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Hi. are you going to post a file for printing? Rich