Gripper

In this step we will install the gripper arms to the rover main assembly.

IMPORTANT WARNING:

• When performing this step, you will work on the bottom side of the robot. Be careful you don't place unnecessary stress on the pan / tilt head assembly as you turn the robot upside down and work on the bottom side.

Required Parts:

• 1x Gripper Bushing Block

• 1x Primary Gripper Arm (the one with a cutout in it)

• 1x Secondary Gripper Arm (the one with a small drill hole)

• 1x Short Servo Horn (in the small bag with each servo)

• 1x Servo Horn Mounting Screw (the small screw in the small bag with each servo)

• 1x Servo Mounting Screw (one of the long screws in the small bag with each servo)

You may need to "clean up" the gripper arms from the machining operation. There may be some thin plastic bits hanging off the arms. These are easily removed by scraping with a finger or knife. Be careful to not damage the gear surfaces where the two arms meet. If there are some thin bits of plastic in this area it is okay.

Prepare the gripper primary arm by pressing the small servo horn into place. It is a tight fit, but it does fit. Press it all the way into the machined opening. The servo horn should then be flush with the surface of the gripper arm.

Install the bushing on the bottom of the gripper servo. It presses into place and is not screwed down.

Important Note:

• Make sure the smooth side of the bushing block is facing outward, as pictured above. This smooth surface will slide along the smooth surface of the gripper arms.

Once the primary gripper arm is mounted, this bushing block will be held in place, though it may still wiggle around some. The gripper will usually work fine like this, but if you want to get things more secure, you may wish to use some small dots of glue to hold the bushing in place. For this we recommend using a small dot of hot glue or similar at each of the four corners of the bushing while avoiding glue on the gripper servo mounting screws - this will glue the bushing to the bottom of the rover frame. Don't use too much glue in case you ever want to remove the bushing.

Mount the primary arm on the servo as shown. It should point almost straight forward, but still slightly leaning to the right - as if the gripper is slightly open. Don't install the mounting screw yet.

Add the secondary gripper arm. Use the screw pictured to screw the secondary arm into the bushing block. Mate up the gears with the primary arm so it looks like the image above. There should be a small opening in the arms. Don't tighten this screw all the way. It should almost tighten the secondary arm all the way, then back it off just slightly so the arm can move freely without the screw pinching it too tightly against the bushing block.

Double check that the smooth sides of the gripper arms and the smooth side of the bushing block match up so the movement will be smooth between them.

Secure the primary arm onto the servo with the small screw from the bag of parts with each servo.

You can carefully rotate the arms back to the stowed position. Note that the arms may feel like they are "binding" and not wanting to move. This is likely due to the gears inside the servo. This is okay. Just don't force the servo if it feels it is binding. Move slightly the opposite direction and it will clear the bind. If you move both arms at the same time they move fairly easy.