The thumb is more complex than the fingers as it has an additional rotation at the base.
Thus it requires four tendons to control it with two passive elastics and one torsional link between the last two joints.
The stl files for a sample finger are here: :5384399
The WIP files for the whole hand and forearm are here: :5466653
The last two joints are torsionally linked to remove a degree of freedom i.e. both joints always move the same amount relative to each other so effectively operate as a single action.
This is achieved with a figure-eight loop of ligament secured front and back, and top and bottom of the last two joints.
The thumb is extended by elastic bands tensioned against a bolt that embeds in the knuckle cross and internally rotated by elastic bands between the top proximal end of the first phalange and a support attached to the first finger palm. This support also gives attachment for the upper thumb knuckle tendon.
Designed and tested for high speed printing using a diameter nozzle and layer thickness except for the tendon spools (three type of Tendon_Spool_01 supplied, ymmv) and tendon hanger which benefit from printing at layer thickness or better.
Test printed in CF nylon.
To finish 3d prints to a high standard requires a fine sandpaper or emery board.
Diamond coated steel nail files are a handy tool:
Additional components required are listed below. Please consider buying via the Amazon links to help me out.
2mm diameter steel pins - alternatively cut lengths from a wire coat hanger or in Europe order much cheaper from
10mm length:
- Amazon UK:
- Amazon FR:
- Amazon US:
16mm length:
- Amazon UK:
- Amazon FR:
- Amazon US:
M2 screws and washers also in Europe from
- Amazon UK:
- Amazon FR:
- Amazon US:
M2 brass threaded inserts M2 * 4mm long *
Note that the type required has a plain section between the knurled ends to allow attachment of the tendon in the fingertip.
- Amazon UK:
- Amazon FR:
- Amazon US:
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.
- Amazon UK:
- Amazon FR:
- Amazon US:
Ball Bearings 6*10*3 - Need 50, packs of 10 available
- Amazon UK:
- Amazon FR:
- Amazon US:
MicroServos like the Emax ES3302 23mm * - 19 needed
- Amazon UK:
Or search on AliExpress...
These are the servos used in the video of the test finger and have an excellent performance characteristic.
The next iteration of the hand will be able to fit SC90 servos which are considerably cheaper though not quite as small or punchy.
2 views
1521
440
4 days ago 00:29:28 1
🎥 Can you guess the Anime by the First 10 Seconds? 🔥 Anime Quiz
2 weeks ago 01:10:29 1
Поиграли в 8 пропущенных игр [РефАААнд?!]
3 weeks ago 00:17:21 1
Russian Video, the first orbital flight of Buran
3 weeks ago 00:02:02 12
DayZ Update Teaser
4 weeks ago 00:39:19 1
Historian Answers Witchcraft Questions | Tech Support | WIRED
4 weeks ago 00:04:40 1
Joint Special Operations Command(.) (GTAV PS4 MilSim on Discord)
4 weeks ago 00:35:59 1
JP’s Shocking MedBed Medical Treatment Here’s What Happened
4 weeks ago 00:08:58 1
Как же это Вкусно Отрывной Пирог 2 яйца кефир 3 ст. муки Рецепт Бомба Тесто для новичков Замес 3 мин
4 weeks ago 00:12:32 1
Arditi: The Insane Combat Techniques of Italy’s WW1 Assault Troops
4 weeks ago 00:21:14 1
Can You Beat Baldur’s Gate 3 While Locked In First Person PoV?
4 weeks ago 00:04:54 1
International Rugby League | England v Toa Samoa | Match Highlights | First Test
4 weeks ago 00:34:11 1
1. Foreword: Interview with John Robb
4 weeks ago 01:04:47 1
Steam Deck 100 GAMES TESTED!
4 weeks ago 00:04:26 1
Marc Anthony - Love is all
4 weeks ago 00:04:46 1
Half-Life 3 | All Trailers
4 weeks ago 00:03:35 1
Sigma 30mm f/1.4 DC DN Contemporary Lens 4K Video Test (Shot it with a6300)
4 weeks ago 00:10:14 1
Suzuki motorcycle ignition key - custom product!
4 weeks ago 00:10:58 1
“ALCOHOL IS DYNAMITE“ 1960s DRUNK DRIVING DRIVER’S ED SCARE FILM 13144
4 weeks ago 00:10:11 1
The World’s Quickest Cars: Lucid Air Sapphire v Bugatti Chiron v Tesla Plaid - Cammisa’s Drag Race
4 weeks ago 00:02:17 1
Celtic Training: Go Inside Lennoxtown as the Celts prepare to take on Motherwell (25/10/24)
4 weeks ago 00:04:23 1
Delta Force | PC Global Open Beta Cinematic Trailer: Genesis
4 weeks ago 00:08:05 1
New satellite pics reveal Israel struck Tehran nuke site ’crippling Iran’s missile production’
4 weeks ago 00:01:40 1
Testing The Smart Grid [Beginner] Bot! | Crypto Bot!
4 weeks ago 00:02:11 1
Осень в Нью-Йорке. Тест камеры iPhone 16 Pro Max, запись 1080 60 fps. Проспект парк, Бруклин.