Robotics Unit 4: Hardware and Safety

Robotics Unit 4: Hardware and Safety

Different parts of robots are assembled along mobile or immobile joints.

What are examples of immobile joints?

Immobile Hardware or Fasteners

hex bolt, hex socket head screw, slotted scre, square slot screw, nut with self locking nylon insert and washer

Multiple Choice

What should you consider when selecting a fastener? Write the answer in your notes.

• Material of construction (stainless steel, carbon steel, or alloy steel).

• Weight restrictions.

• Re-usability.

• All of the above.

When choosing hardware, look closely at the shape of the screw head.

Discuss the photo with your shoulder partner. Identify the name and intended use for each.

Bolt vs. Screw

Bolts are used to assemble to unthreaded objects, typically with the use of a nut. In comparison, screws are used to assemble objects with threads.

Washers

• Teflon Washers are the thinnest of the washers/spacers available and have a low coefficient of friction.

• Steel Washers are very durable and are a good all-purpose washer.

• Plastic Spacers are the smallest diameter, ideal for a shaft between a wheel and a piece of structural metal.

Multiple Choice

What would you expect to happen here?

• rotation

• stick together

What kind of hole would you use to attach a gear to an axle so the gear would spin with the axle?

Write your answer in your engineering notebook.

Why do bearing flats and pillow blocks have round holes?

Write your answer in your engineering notebook.

Example of mounting a gear with spacers to a piece of structural metal

Example of a spacer being used to reduce friction.

Spacers

One purpose is, spacers can be used to keep space between two components. For example, placing spacers between Intake Rollers on a shaft may provide a more efficient intake.

Spacers

• Nylon Spacers when more support is needed from a larger contact surface, such as filling in the space on a shaft between a tower and an arm of a robot.

• High Strength Spacers are designed specifically for the High Strength Shafts and have a center hole which is shaped to fit the High Strength Shaft and they will not free spin on the shaft.

Multiple Choice

Which of following hardware is typically used along with the nut and bolt assembly?

• shaft

• bearing

• washer

• spacer

What's the difference between

a bearing and a bushing?

write or draw your answer in your engineering notebook

Ball Bearings vs Bushings

Bronze bushing are going to have more friction and steel ball bearing are going to be able to deal with minor misalignments better.

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Go online to https://www.vexrobotics.com/

and with a partner search for the following items:

bushing, bearing, bearing block and a D-shaft

Be prepared to share your findings with the class.

Multiple Choice

Axles must be supported by two bearings.

• True

• False

What are shafts used for?

These are available to support the ⅛” square shafts.

Multiple Choice

__________ allows shafts to spin smoothly through the square holes in a structural metal component.

• Bearing Flats

• Pillow Block Bearings

• 1-Post Hex Nut Retainer w/ Bearing Flats

Multiple Choice

__________are plastic pillow blocks which allows a shaft to be offset either above, below, or to the side of the structural metal piece the bearing is mounted on. Pillow Block Bearings are not sold separately.

• Bearing Flats

• Pillow Block Bearings

• 1-Post Hex Nut Retainer w/ Bearing Flats

Multiple Choice

__________ are plastic parts with a series of threes holes which will support a shaft in 1 hole and allows Screws and Nuts or Attachment Rivets to be used for mounting in the remaining holes.

• Bearing Flats

• Pillow Block Bearings

• 1-Post Hex Nut Retainer w/ Bearing Flats

Free Spinning Assembly - 3D model by VEX Robotics (@robomatter) [5eeff63] - Sketchfab

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High Strength Shaft

These shafts are ¼” square bar. The shafts can be cut to custom lengths and can withstand high stress, and weigh more than the standard Shafts.

Using V5 Shafts

These shafts are ⅛” square bar. The shafts can be cut to custom lengths, however they can twist, bend, or shear off when subjected to extreme stress.

The parts available to support the ⅛” square shafts include:

Bearing Flats, Pillow Block Bearings, 1-Post Hex Nut Retainers and High Strength Shaft Bearings

General Safety

When assembling, programming, and competing with robots there are certain precautions which need to be observed. There are safety guidelines which will help you safely work with your robot.

Pinch points

Pinch points occur wherever a moving object comes in contact with another object. Pinch points can occur near gears, the turntable, and on the moving arm. Three out of the many possible pinch points on the Workcell are shown in this image below.

In the lab, can you identify a pinch point?

Be prepared to share your pinch points observations with the class.

Multiple Choice

Which of the following best describes when to use an E-stop?

• If the machine's functioning becomes a hazard to individuals, other machinery, or itself.

• When you need to charge the V5 Battery.

• To download and run a VEXcode V5 project.

• To measure the angle in degrees that the motors turn.

Safety - Introduction Video | VEX EducationVisit the VEX Robotics Facebook PageVisit the VEX Robotics Twitter PageVisit the VEX Robotics Instagram PageVisit the VEX Robotics YouTube Page

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