3D Printing for VEX Robotics: Redesigning the Clawbot

2. Project Overview • An introduction to 3D printing • Designing 3D printing parts • Redesigning the Clawbot • 3D printing new Claw components • Assembling & Testing 3D printed components • Open 3D printing design challenge

3. LESSON 03

4. Lesson 03 - Quick Starter Task:On your worksheet, look at the photos of the 3D printed VEX parts that others have designed and shared online to help VEX robotics builders like yourselves to achieve a better robot solution.For each, propose what you think…The problem was that the designer wanted to solve with the new partWhat you think the new part actually doesWhy the part is cleverWhat the part could be called Key words: CAD, Library, heat processes, acrylic, MDF, profile, forming.

5. Lesson 03 – Quick Starter The ball holder… The ping pong ball part is a clever use of an existing smooth standard component (the ball) that can be designed to interact with the VEX robotics kit in a useful way. The ball moves smoothly as you can see in the video, and provides free movement of the robot from this position. It is much more effective to use the existing ball than print out a ball, which would not have been as smooth or as accurate.The design is also clever as it has small aligned holes that match the metal frame hole spacing, so that it is easy to assemble. Key words: CAD, Library, heat processes, acrylic, MDF, profile, forming.

6. Lesson 03 – Quick Starter The battery holder… The battery holder is designed to replace the cable tie design of the current VEX robotics cable battery holder. The design is clever because:- it features a place to fit a VEX nut into the lock so that a standard screw can tighten ittogether- it features a hinge that uses the longest VEX screw and a lockingnut- The battery holder clampsthe battery once tightened- The holes inside the holder areset below the surface to help the battery fit! Key words: CAD, Library, heat processes, acrylic, MDF, profile, forming.

7. Lesson 03 – Quick Starter The spacers The spacers have been designed so that two bars can be fitted parallel to one another, and be tightened using screws and nuts. The central bar is hollow so that the VEX shaft fits through, and can revolve inside.The purpose of the part is to provide support all the way along the shaft so that it does not bend or bow as pressure or force is applied to the bar at the other end (this could be from a wheel turning or during a game when other robots bash into the bar) Key words: CAD, Library, heat processes, acrylic, MDF, profile, forming.

8. Lesson 03 - Starter Learning objective: Learnt how to build 3D printed parts onto a VEX metal frame, explore the issues associated with tolerance of 3D printed parts, and analysed opportunities for 3D printed parts to be introduced into the kit library. Task:Here is a 3D printed version of the claw from the VEX Clawbot kit. In pieces each part fits together to make a functioning product. Your quick starter is to sketch new parts (any part) to make the claw perform differently. How it performs and what it does is up to you… This claw design was 3D printed and modified to hold two craft knife blades, so that the claw could cut through wires. It was part of a robot designed for the British Army to disarm bombs. Key words: CAD, Library, heat processes, acrylic, MDF, profile, forming.

9. Redesigning the Clawbot Build yourself the clawbot with 3D printed/laser cut parts. If you are also laser cutting VEX parts, or have done the laser cutting unit already, now is your chance to either build the parts onto your existing clawbot or to build an entirely new robot from made parts.Considerations to make:1. Use screws instead of pop rivets for connections2. Or use nail varnish to bond the connections3. Explore the tolerance of parts to one another4. Tighten parts to the acrylic/metal frame as best you can5. Use locking nuts for the claw

10. Redesigning the Clawbot How do 3D printed parts compare? How do the strength of 3D printed parts compare to the injection moulded parts? How do the clawbot 3D printed parts appear different to injection moulded parts? How do the tolerance of 3D printed parts compare to the injection moulded parts? Are the any other performance characteristics that make 3D printed parts better or worse than injection moulded parts?

11. Redesigning the Clawbot Consider modifying the drive This gear is part of the gear chain that drives the wheels at the same time (as a set of three).What would happen if we removed two sections (half) of the teeth as shown in the diagram, and used the gear as the drive gear for the gear chain? (Motor) Task: Predict the change to the way the robot drives, then fit this 3D printed part onto the clawbot you have built and test to see if you were right.

12. Redesigning the Clawbot

13. Redesigning the Clawbot Consider modifying the function This claw finger has been modified so that it is much taller in both directions (above and below the original)Task: Predict what the purpose is of making the claw into this design?You are able to modify the parts of the claw in any way you see fit. The finger, being the part that “actions” the function, could be something you change. Similar to the earlier example with blades, the purpose is up to you to imagine.Task: Design in sketch form, three new designs of the claw, by focusing on the finger parts to change what it can do.

14. Redesigning the Clawbot Consider modifying the aesthetics This wheel guard is very typical of machines such as dirt bikes, in which the reduction of dirt and waste to the wheel will improve many aspects including; appearance; smooth running; grip and need for cleaning and maintenance. This guard also prevents any robots in a VEX “match” from preventing the wheel from turning. Four guards would protect each of the wheels of a clawbot during a Sack Attack game, and also prevent sacks getting stuck in the gap to the frame. Task: Sketch and design unique aesthetic changes to the clawbot, parts which you can add to the existing design which do not necessarily provide any functional benefit. If the parts offer any function, even better!

15. Redesigning the Clawbot How would you print these parts? Look over any of the 3D printing parts you have sketched so far, and complete the following quick task:Sketch the design as a small thumbnail sketch, onto a 3D printer bed. Plan where the part will be:- in contact with the bed- need a raft (where the part does not come into much contact with the bed)- need support (where the part needs to print in thin air)- where there might be any issues with printing the part

16. Lesson 03 – plenary As a class, let us consider the following questions?A. How do 3D printed parts compare to injection moulded plastic parts?B. Will 3D printing replace any of our consumer plastic products?C. Based on your experience, would you or would you not, buy a 3D printed phone case? Why?D. How could 3D printed parts improve VEX Robotics kits?

17. Summary Learning objective: Learnt how to build 3D printed parts onto a VEX metal frame, explore the issues associated with tolerance of 3D printed parts, and analysed opportunities for 3D printed parts to be introduced into the kit library. • Today you have: • Learnt how to build a VEX clawbot using 3D printed parts • Explored the issues associated with micron level tolerance of parts that are 3D printed • Discovered what opportunities 3D printing present to the VEX customer.