A few months back, I released a 3D printed robotic gripper that used hard plastic and soft silicone in order to act like a human finger and grip objects. However, I did have many people tell me that either: A. They don't have access to a 3D printer or B. They don't want to mold silicone. As a result of this, I built a new gripper. It uses the same concept to actuate the fingers, but uses no 3D printed parts, no silicone parts, and only easily available parts.
- Hot glue gun (with glue)
- Small vice (Optional)
- Spade bit (You want a spade bit that is about the same diameter of your tubing)
- Drill bit (You want a spade bit that is about the same diameter of your paracord)
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Step 1: Prepping the Bucket
You are going to want to start by going to start by using the spade bit to make holes in the plastic bucket. Make the holes in a triangular configuration on the sides of the bucket towards the narrow end of the bucket. Then take the handle off of the bucket.
Step 2: Starting on the Tubing
Take your plastic tubing, and cut three, 12" long pieces. Use a pen to mark each piece of tubing at every inch. Then, take the hacksaw and starting at the second marking on either side, saw the tubing almost all the way through. You only want to leave ~5 mm of tubing left at the cut. Continue this at all the marked points and on all three pieces of tubing.
Step 3: Gluing the Tubing Pieces
If the tubing you are using is not pre-cut down the middle, you can skip this step. Since most electrical tubing is pre-cut down the middle, we need to fix this. With each cut segment of the tubing, push one side over the other and apply hot glue generously. You may want to use a small vice to hold the tubing in place. Make sure you don't accidentally glue any segments together. Do this for all three pieces of tubing.
Step 4: Finishing the Tubing
Now take the scissors and cut every other segment. It may be helpful to bend the tubing as you are doing this. After that, use the drill bit to drill a hole through the middle of the 2" long segment on each tubing piece. The second picture on this page shows what each piece of tubing should look like by the end on this step.
Step 5: Installing the Paracord
Take the paracord and cut it into three, 2' long pieces. Take one side of each piece of paracord and melt the tip with a lighter. Then run the melted end of the each paracord through the tubing until it reaches the hole that was drilled in the last step. Push the tip through the hole and pull about an inch through. Put a knot in it and pull it taught from the other end. Do this for each finger.
Step 6: Glue on the Fingers
Take the end of the tubing that is 1" long and squeeze it so it fits in the hole we drilled in Step #1. Once it is in, hot glue it into place. Do this for all the fingers.
Step 7: Finish the Paracord
Pinch the other ends of the paracord together and melt them with the lighter. You may want to use a zip tie to hold the ends together. Tie the now-joined paracord pieces on itself and position the knot to be about 5" below the melted tip. You're done!
Step 8: Try Out Your Gripper!
Congratulations if you made it to this step, because that means you probably have a cool gripper. Experiment around and see what it can grab!
There are a few modifications that I may add in the future, such as electronics, handles, more robust actuators, etc, so stay tuned for those. Anyways, thank you for taking the time to read this Instructable and I would really appreciate it if you voted for this project in the Summer Fun Contest!
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