This is a robotic gripper controlled using two inexpensive servos (SG90 or MG90).
The Nails of the clamps have been designed to catch object of small to medium size
The NAILS when printed will be fixed one to the other. As a measure of printing accuracy: if you can not SNAP and separate the two nails, that means you have printed the Gripper without the required accuracy and the gears will not work as intended. Reduce the layer height and printing speed to increase the printing precision
any PLA or PETG will work PETG or PLA
NOTE:This Gripper has been designed to be 3D printed. It is easy to print, but as every 3D printer-made object it has it disadvantages. If you tighten up the screws too much, you can break the pieces or increase the friction unnecessary. If you notice that the nails of the clamp are not moving freely or there is too much friction, loosen the screws just a little bit.
NOTE:After printing clean the parts of any plastic burr or the friction will reduce the gripper performance
This 3D printer-made actuator can be controlled with two inexpensive servos (MG90 or SG90)
The Robotic Gripper
The problem with the servos is that they tend to get hot (even get damaged) when you force then to apply force continuously . So we are using the same solution LEGO uses: letting a rubber band to close the clamps.
Assembly guide with more info, images an videos here: https://www.jjrobots.com/robotic-arm-gripper-2-degrees-of-freedom/
This clamp have been created after many iterations. It will serve as the official actuator for the SCARA Robotic arm
Strong enough to lift medium size objects
Most of the bolts and screws used to create the gripper are the ones included with the servos.
EVA FOAM is recommended if you want to increase the grip of the nails. But you can use any other material you have around for the same purpose (rubber?)
Pay attention to this step, otherwise, the claw will not close nor open properly.
First, you will have to find the rotation limit of the servo turning the horn anticlockwise (photo 1).
Once you have found it, take the horn out of the gear and place it back but as indicated in the photo number 1: completely horizontal.
Then, rotate it 90º clockwise, now it is ready to receive the NAIL. Cut the ends as indicated in the photo 2.
More info: here
The robotic gripper has been designed to close around the main Z axis. So the “wrist servo” gear will be the X,Y zero coordinate system. Basically: You will grab an object that is located just below the "Wrist" servo gear.
The Robotic gripper in action mounted on two SCARA Robotic arms. More info at: jjrobots.com