How to build a V1.0 DexHand Part 4: Knuckle and palm prep

Описание: Lightly edited footage of the preparation process for the knuckle joints and the palm sections in the V1.0 DexHand.

The DexHand is part of the Open Humanoid Robot Project - an #open #alternative to the commercial #humanoid #robots being developed by tech giants like #Tesla #Optimus

If you’ve always dreamt of having your own humanoid robot that dream is within reach and right now can be made with under 20k USD of components - all you need is a place to work, some hand tools and a 3d printer.

If you can't wait to get started the V1.0 #DexHand is now freely published and available for download at https://github.com/TheRobotStudio/Dex... with more instructions for code at dexhand.org.

Video instructions to assemble the V1.0 are in production and being added to this playlist:    • V1.0 Dexhand assembly details #dexhand #v1...  

The parts can be printed on any extrusion printer and the hand uses less than 300 USD of components.

The parasolid CAD model can also be viewed and downloaded for free on the cloud platform Onshape: https://cad.onshape.com/documents/16c...

Designed and tested for high speed printing using a 0.6mm diameter nozzle and 0.4mm layer thickness except for the tendon spools 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 due to warping.

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 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 16 slim micro-servos that drive the fingers and thumb.

The discount code ROBOTSERVOS will take off 10% from the official Emax webstore: https://emaxmodel.com

There are 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)

2 standard micro servos are needed for wrist flexion and extension.

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.

If you prefer to use a standard PWM 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:

Lee Tippi Micro-Gel Finger Tips, Clear, Size 5: https://amzn.to/3upO02S

2mm diameter steel pins - if you have a dremel cut down from shelf pins: https://amzn.to/3TaO7t9

Otherwise kits are available on Amazon US: https://amzn.to/3VYrnfh

Alternatively cut lengths from a wire coat hanger they are all roughly 2mm so YMMV.

In Europe order direct from https://www.visseriefixations.fr/goup...

M2 screw and washer kits: https://amzn.to/3sf4NkE

Europe from https://www.visseriefixations.fr

M2 brass threaded inserts M2 * 4mm long * 3.5mm like this are used throughout: https://amzn.to/3TwXhRg

You also need a kit for other sizes and the M2 inserts in the finger tips which have a plain section between the knurled ends: https://amzn.to/41KfAVb

Kite or fishing line for finger tendons - Sufix 832 is the best for longevity, the 80lbs breaking strength is stiff enough to thread easily and most readily available on: https://amzn.to/3DgjNoF

Slightly thicker 0.8mm kiteline for the finger ligaments and wrist tendons: https://amzn.to/3GMKQJL

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

Ball Bearings 2*6*3 or 2*6*2.5 - Need 6 for the wrist: https://amzn.to/3yYlTHg

Ball Bearings 15*21*4 - Need 4 for the wrist: https://amzn.to/3TsMSTO

Ball Bearings 3*8*4 - Need 6 for the wrist: https://amzn.to/3VyE28O

M3 * 70mm caphead bolt (grade 12.9 ideally)
Need 2 (1 is cut down to 60mm): https://amzn.to/3HM0Rjx

McMaster US: https://www.mcmaster.com/product/9129...

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