01.Printing - reivaxy/kinetix GitHub Wiki

Printing the Kinetix hand

Do not scale any of the parts. The tolerances are pretty adjusted. The different knuckle sizes, for instance, are not obtained by scaling but by recomputing.

Supports may help but are not mandatory. Use your experience and knowledge of your printer to adjust.

Beware, the STL files (at least for now) may not place the parts in the printing position, you'll need to adjust this in your slicer.

I printed all parts using PLA, except for the "cover" printed in TPU.

The knuckles

You should start by printing the knuckles, because they are the most sensitive part and depending on filament and printer settings they might print all right or not.

This is why they come in different flavors. The defaults ones from the "3D/common" directory have a 0.15mm tolerance, but in "3D/common/easierKnuckles" you will find looser ones with 0.2 and 0.25mm tolerances.

Many thanks to Connie Marchek who suggested printing them partly folded, rather than straight, which makes folding them much easier with small tolerance.

The tolerance is the space shown in this picture:

The wider the easier to print but there will be a little wiggling in the larger tolerance knuckles.

They should be printed with 0.1 to 0.15 layer heights.

Three different sizes are provided, with their sizes engraved on top to easily match them to finger parts.

You need to print 4 knuckles size 1.1, 4 knuckles size 1 and 1 knuckle size 0.9.

Since precision is required, if your filament is stringing, you should try printing them only one at a time, or use sequential print (complete one object before starting the next on the bed) if your slicer handles it (requires appropriate spacing of course).

Once printed, they may not fold right away, and may need to be "broken". I have found out the best way to do that is to insert them into their target slots in the fingers and the palm, and then fold the finger. It should snap and become mobile :)

You will also need to make them rotate a few times manually, until there is no effort required to open and close the fingers.

In case they do not fold you may want to try the easier version, with a less tight tolerance:

https://github.com/reivaxy/kinetix/tree/main/3D/common/easierKnuckles

The fingers

They are numbered from 1 to 5, starting from the thumb, so all parts related to one finger bear the finger number (except the knuckles, which are used in more than one finger).

The thumb is only one part, other fingers are two parts, and each part should be printed standing on one of their flat faces.

For the top finger parts, you will probably get better results with the finger tip facing the cooling fan of your extruder.

The phalanx should be printed with the engraving on top for better results:

The finger parts will likely be reworked to accept better silicon inserts insuring some good grip.

The wire blockers

These small pieces are inserted in the top phalanx of each finger to block the wires. They are very basic for now and do not allow any adjustment.

I would like to rework them to make adjustments possible after the wires have been blocked.

The first design had top holes a little to big, and may not block the beads well enough. The new design has smaller top holes that might need a little cleanup after printing.

The palm

Nothing difficult here, should be printed standing, with at least 20% infill. Using 0.2 is okay, but 0.15 will look smoother of course.

The servo platform

To be printed flat, 0.2 is totally fine.

The double grove pulleys

Better print them at 0.15 for finer results, 30% infill, and also one at a time if your filament is stringing.

Of course, keep the narrower halves on top (number engraving facing up).

Make sure to clean up the central hole after printing, so that no filament debris will be in the way of the screw.

The servo covers

Print them flat, which means with number engraving facing down except for the thumb servo cover (engraved "1")

Printing a left hand

Disclaimer: I have completed this yet.

Use the files from the "left" folder to print a left hand. This is a work in progress, I haven't fully assembled a left hand yet.

They are obtained by symmetry from the right hand files, which is why the engraved numbers are reversed too.

(except the knuckles and the servo pulleys which do not need this)