Available at: 1.2 – Build the Tumbler Build the Tumbler

Available at: www.etcurr.com Lesson 1.2 – Build the Tumbler

Build the Tumbler


Build the Tumbler Performance Objective: Given a VEX robotics system, build the Tumbler

to the specifications in the Guide for Building the Protobot and Tumbler. Enabling Objectives: identify the following VEX parts: angle (chassis bumper), rail, plate,

standoff, shaft, nut, 6-32 x ¼ motor screw, spacer, 8-32 x ¼ screw, 8-32 x 3/8 screw, 8-32 x ½ screw, delrin bearing flat (bushing), plastic rivets, motor, motor clutch, battery tie on or battery strap, large 5” wheels, micro controller, collar

identify the following tools: Hex wrench (Allen wrench), open end wrench, nut driver

explain how metal VEX structure components are described or named explain the advantages and disadvantages of KEPS versus Nylock nuts

and VEX rivets versus screws


VEX parts

The majority of the components used as structure components are made from sheetmetal

These pieces (either steel or aluminum) come in a variety of shapes and sizes and are suited to different functions


Required parts

A) Standoff used to offset one structure from another Standoffs come in varying lengths

B) Shaft used as an axle for a wheel, gear, sprocket, etc shafts come in varying lengths

A

B


Required parts

A) Plate B) Bar C)Rail D) C-Channel E) Angle (chassis bumper)

A B C ED


Describing structure components

VEX structure components are describe by their shape and the number of holes they have

The piece to the left is describe as a C-Channel 1x2x1x35


Required parts There are two types of screws that are part of the VEX Robotics

Design System Size 8-32 screws are the primary screws used to build robot

structure Size 6-32 screws are smaller screws which are used for specialty

applications like mounting the VEX Motors and Servos

6-32 x 1/4 motor screw

8-32 x 1/4screw

8-32 x 3/8screw

8-32 x ½screw

The 8 and 6 refer to the nominal diameter of the screw The 32 refers to the number of threads per inch of the screw The fraction (e.g. 1/4, 1/2) refers to the length of the screw


Required parts

Nylock nuts have a plastic nylon insert in them which will prevent them from unscrewing

These are harder to install, but will not come off due to vibration or movement

Nylock nut KEPS nut

KEPS nuts have a ring of “teeth” on one side of them, These teeth will grip the piece they are being installed on

These nuts are installed with the teeth facing the structure

These nuts are easily installed, but can loosen up over time

When using screws to attach things together, there are two types of nuts which can be used


Required parts

Spacers Collar

Spacers come in varying sizes Spacers are used to add or fill

a gap where needed

Collars are placed on shafts (axle)

The set screw (8-32) can be tightened to prevent the shaft from sliding


Required parts

Delrin bearing flat Plastic rivet

Bearing flats are used when placing a shaft through a square metal hole

The bearing flat supports the axle while providing a round hole for the axel to rotate

These are really bushings

Plastic rivets are used to attach bearing flats to metal structure (screws are recommended over rivets, because screws hold tighter and are more secure)


Required parts

Motor with clutch Wheel Battery with battery tie on

Motors are used to turn axles

The green clutch is used to prevent the motor from becoming over loaded, and stripping the plastic gears inside

Wheels come in various sizes, the large 5” knobby wheel is used on the Tumbler

The battery tie on straps can be screwed onto a metal structure and can hold the battery in place

VEX straps are a good substitute


Required parts

VEX Cortex micro controller

The micro controller is the brain of the robot

The micro controller receives the program from the computer which will allow you to control the robot

Motors and sensors are wired to (plugged into) the micro controller


Required tools

Hex wrenches Open end wrench Nut driver

Hex wrenches are used to tighten screws

A 5/64” hex is used for 6-32 motor screws and collar set screws

A 3/32” hex is used for 8-32 screws

Open end wrenches are used to tighten nuts or prevent nuts from spinning while tightening screws

Nut drivers are also used to tighten nuts or prevent nuts from spinning while tightening screws

Nut drivers tend to be more efficient


Build the Tumbler

To build the Tumbler you will need the Guide for Building the Protobot and Tumbler

Follow the steps to build the Tumbler beginning on page 29

Stop after step 11 on page 38 Once you have completed step 11, continue

onto the next slide of the PowerPoint


Adding the micro controller

Position the Cortex Micro Controller on the top of the Tumbler chassis as shown below


Adding the micro controller

Add four (4) screws and nuts in the four corners of the micro controller


Add the battery tie ons

Add two battery tie ons to the bottom of the Tumbler, using two (2) screws and nuts for each tie on


Insert the battery

Using the battery tie ons, attach a 7.2 V battery pack to the Tumbler


Plug the motors into the micro controller

Take notice of the white, black and red wires, be sure the white wire is toward the inside of the micro controller

Insert the left side motors into ports 2 and 3

Insert the right side motors into ports 4 and 5


Almost there

You are done building the Tumbler, and are about ready to drive it!

Show the completed Tumbler to the instructor before continuing onto lesson 1.3 – Operate the Tumbler using a jumper pin

Documents

Available at: 1.2 – Build the Tumbler Build the Tumbler