Our two finger gripper was printed late last week and works without any complications, fitting all of our screw holes, pivot points, etc. The renderings of the two fingered gripper posted on May 6, 2014 do not include all of the features that are described below. These additional features are the cut-out for servo mount hardware/mounting flange and the depressions for mounting hardware, both are described below. Dimensions were also altered.
Figure P5.1: Two Finger Mobile Gripper Mounted on Servo
Figure P5.2: Annotated Image of Printed Gripper
The annotated features are described below
The top of this bracket will be fastened directly to the servo disk, but the bottom will be mounted to a ball bearing secured to the standard servo bracket.
A single rib along each finger adds strength allowing the fingers to be thinner (3mm) and reduce weight.
The 1mm depressions around the mounting holes allow for the use of short screws that was provided with the servos, keep waste and cost down. There appears to be no loss of strength due to these depressions.
The tips of the fingers are rounded, this is intended to reduce the snagging of the edges on objects in the gripper and also the third finger.
Figure P5.2: Annotated Image of Printed Gripper and Servo
This image displays the considerations that allow for the gripper to close fully around the servo's mounting flange. Not pictures in this photo is he bolt or push rivet head that would project above the top of the upper surface of the mounting flange. This consideration was made, rather than ending the figures further away from the servo, to reduce the gap between the servo and the gripper when it is closed. In this design the fingers are ended so that they just clear the corner of the servo. The "C" brackets that this gripper was based off of ended where the vertical bar is in the gripper, far away from the gripper. This left a large gap for objects to pass through, greatly reducing the effectiveness of the gripper.
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