Robot hand design in Solidworks for 3dprinting

Progress continues on the V2 #DexHand - next stage is making sure that it's actually physically possible to assemble in the real world.


The V1 robot hand is freely published and needs under $300 USD of components to build, assuming you have a 3d printer, a few handtools and a place to work.

!!!!!----------- Scroll down for links to the stl files and to purchase components ---------------!!!!!

The stl files to print the hand and forearm are on github: https://github.com/TheRobotStudio/Dex...

Press the green button at the top right labelled code, then at the bottom of the menu Download Zip.

Read the readme document!

The #cad for the arm and hand is available as a parasolid at:

https://cad.onshape.com/documents/16c...

The forearm and hand can operate as a stand-alone unit allowing unlimited axial rotation for rotational tasks like scrubbing.

Some notes on printing:

Designed and tested for high speed printing using a 0.6mm diameter nozzle and 0.4mm layer thickness except for the tendon spools and split parts of the palm sections which benefit from printing at 0.3mm layer thickness or better.

Tested in PLA, PETG and CF nylon. ABS is not recommended for the large pieces.

To finish 3d prints to a high standard requires a fine sandpaper or emery board.

Diamond coated steel nail files are a handy tool: https://amzn.to/3VBBsOX

Though my favourite diamond file is actually intended for maintaining whetstones, just a nice big expanse of diamond dust to use :-)

- Amazon UK: https://amzn.to/3gj1ExD
- Amazon FR: https://amzn.to/3EU3pM2
- Amazon US: https://amzn.to/3eN3bvo

Additional components required are listed below.

Please consider buying via the Amazon links where available to help fund the robot development.

The biggest cost item are the servos, order direct or from Ali:

16 slim microservos like the Emax ES3301 (approx $6.6) are needed for a total of approx 100 - 200 bucks.

The hand in the video uses Emax ES3302 but any slim micro servo that fits inside the envelope of 23.2*9.2*24.1 will do.

Emax themselves make four variants at this size with plastic or metal gears and using either digital or analog control technology.

ES3301 (approx $6.6)
ES3302 (approx $9.2)
ES3351 (approx $8.5)
ES3352 (approx $12)

Official website: https://emaxmodel.com

2 micro servos needed for wrist flexion and extension (required).

Feetech SCS2332 - https://feetechrc.com/product-name_55... are recommended.

These are serial bus driven servos over allowing a greater range of controlled rotation.

They cost around 35 bucks each plus delivery obvs.

If you prefer to use a traditional servo for simplicity they can be substituted by any servo that fits inside the envelope 23.2*12.1*28.5mm.

The trade off is the reduction of the powered range of motion of the wrist to about half.

1 standard servo needed for axial wrist rotation (optional)
Feetech SCS15 - https://feetechrc.com/6v-15kg-digital... or any servo that fits inside the envelope 40*20*40.5mm. Reduces powered range of motion to about half and the loss of a continuous rotation option.

The rest of the components are relatively inexpensive:

2mm diameter steel pins - alternatively cut lengths from a wire coat hanger or in Europe order direct from https://www.visseriefixations.fr/goup...

Otherwise kits are available on Amazon:
UK: https://amzn.to/3SfoC5Q
FR: https://amzn.to/3D9QkwI
US: https://amzn.to/3VYrnfh

M2 screw and washer kits, or also in Europe from https://www.visseriefixations.fr
UK: https://amzn.to/3gk2MB6
FR: https://amzn.to/3VPF9AK
US: https://amzn.to/3sf4NkE

M2 brass threaded inserts M2 * 4mm long * 3.5mm
Note that the type required has a plain section between the knurled ends to allow attachment of the tendon in the fingertip.
UK: https://amzn.to/3D9mTeb
FR: https://amzn.to/3giNcFY
US: https://amzn.to/3yYl1lY

Kite or fishing line for tendons and ligaments - Sufix 832 is the best I know of for longevity, the 80lbs breaking strength is stiff enough to thread easily and most readily available in the US.
UK: https://amzn.to/3VCbs5T
FR: https://amzn.to/3TsDsHa
US: https://amzn.to/3DgjNoF

Ball Bearings 6*10*3 - Need 50 for a hand, packs of 10 available which are enough for the sample finger.
UK: https://amzn.to/3CMa7Ry
FR: https://amzn.to/3Tw9x0P
US: https://amzn.to/3Dj7cBn

Ball Bearings 2*6*3 or 2*6*2.5 - Need 6 for a wrist.

UK: https://amzn.to/3gggdBU
FR: https://amzn.to/3TDgTQj
US: https://amzn.to/3yYlTHg

Ball Bearings 15*21*4 - Need 4 for a wrist.

UK: https://amzn.to/3skHiXj
FR: https://amzn.to/3Dh9sJf
US: https://amzn.to/3TsMSTO

Get involved at patreon.com/therobotstudio