Circular linkage Free 3D print model

Circular linkage with no fixed center. This particular mechanism can be expanded and contracted as it shows in the video demonstration. It is a model that can be easily printed on all 3D printers.

Print settings (PLA):

• For all the files use 2mm layer and no supports. 100% infill recommended.
• The stl files Circular_link_lock and Circular_link_pin may be printed at low speeds (around 20mm/s) to make sure that them don't unstick from the hotbed during printing time. It's also recommended to enable the option Z hop when retracted (betwen 0.4 and 1mm) to make sure that the hot end don't rubs the print and unstick it (because those two files dont't have much contact area to the hot bed.
  -The stl file Circular_link_arm can be printed at higher speeds (up to 50mm/s).

Assembly:

-You'll need x24Circular_link_arm, x36 Circular_link_pin and x36 Circular_link_lock. (Circular_link_lock is not necessary to print, but is a safe way to make sure that the mechanism stays in place and don't get loose.

To assembly the mechanism is really simple. Take x2 Circular_link_arm . Just make sure that the flat parts (in contact with the hot bed) are facing out. Join them as shown in the fifth picture using x1Circular_link_pin".

To fit the pin into the arm, you need to bend the pin as sown in the seventh and eighth pictures. It makes the pin to fit in the holes of the arms. Later you have to insert a 2mm allen key or similar into the pin as shown in ninth and tenth pictures to prevent the pins to fall off. You may also put one Circular_link_lock in each side of the pin to lock the pins in place.

I recommend to make x12 units made by x2 arms, x1 pin and x2 locks (in cross shape, like the ninth picture). Join the x12 units toegether to make the Circular linkage.