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Here is the other printed gripper. Everything was printed in PLA with the exception of the pads on the fingers. I printed these out of a flexible rubber material so they would have better grip. It uses some 4-40 and 2-56 screws for assembly and a 1/8" stainless steel rod for the gripper shaft.
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The gripper shaft has a flat spot ground in it for the 4-40 set screw on the worm gear.
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This smaller shaft of the gripper will mount to the motor shaft though a coupler. This will allow the grippers to be easily changed out when needed.
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I next cut a 6" long piece of 1/2" PVC pipe to use as the arm of the manipulator. Using the gripper assembly I mark the location of the mounting holes for the gripper. The first mark is for the mounting screw and the second mark will be the access hole for the coupler set screw.
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After drilling several holes through the arm on both the top and bottom the arm is glued to the motor housing portion of the manipulator. (some of the holes are for drainage because the arm portion of the manipulator is not water tight.)
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A quick test fit of the gripper is next to make sure the set screw access hole is in the correct position.
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I am using a piece of 3/16" stainless steel rod for the motor shaft. Again a flat section is ground into the shaft for the shaft slip clutch coupler set screw.
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Next the bushing is placed on the shaft and the shaft is inserted into the housing and through the seal.
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I then mark the center location of the set screw in relation to the motor shaft.
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I made a coupler out of aluminum to join the smaller gripper shaft to the larger motor shaft. I then mark the location where the motor shaft needs to be cut as well as how far in inserts into the coupler.
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After cutting the shaft to size and grinding another flat on that end (not shown) the shaft is reinserted into the motor housing. I temporarily attach the coupler to a scrap piece of the gripper rod so I can insert it into the arm and affix it to the motor shaft.
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I secure the set screw in the coupler to the motor shaft through one of the holes in the bottom of the arm.
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With the motor shaft and coupler in place I can go back and trim down the gripper shaft to length and grind the set screw flat on the end. (this is done with the shaft removed from the gripper)
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Then is just a matter of sliding the gripper in place, securing it with a 4-40 flat head screw, and tighten the gripper shaft to the coupler.
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Next it's on to mounting the motor. I first have to print a new motor slip clutch coupler first as this motor shaft is a different size.
I just noticed I grabbed the wrong motor off my bench while designing this... (too many projects going at once) I grabbed a 10RPM motor instead of a 30RPM. (I think this is a 30rpm anyway. 
) At only 10 RPM's the fingers would take like 1-2 minutes to fully close. The 30 might be a bit too slow too but it's all I have at the moment so that's what I'm using. The only problem is it larger so it just barely fits in the main housing so now I have to go back and redo the motor housing. At least everything else should still work.
)
