ME 2110: Creative Decisions and Design Prof J.Rhett Mayor 1 Introduction to Machining & Electronics and Pneumatics Lecture #5a.

ME 2110: Creative Decisions and Design Prof J.Rhett Mayor

1

Introduction to Machining&

Electronics and Pneumatics

Lecture #5a


2

Introduction to the ME2110 Kit• Controller Box• Electro Mechanical Actuators & Sensors• Pneumatics


3

Features of the Controller Box

• BASIC Stamp II-SX microcontroller• Interfaces with various external devices

– Stepper Motors– DC Motors– Pneumatic Valves– IR Distance Sensor– Flex Sensor– Microswitches– Solenoids

• RS-232 Communication Port


4

Layout of I/O Ports

Motor_1

Motor_2

BatteryCharger

On / OffSwitch

P1P8P6 P5 P4 P3

RS-232Connector

P7 - Start

P9 - Speaker

RF / RS-232Selector

P11 P12 P14 P13 P15

ResetID

Inputs

Outputs


5

Interfacing the BASIC Stamp• Connections

– P1: Flex Sensor– P3-P6: Microswitches– P7: Microswitch that will

be used to start competition

– P8: Distance Sensor– P9: Speaker– P11-P15: Solenoids, DC

Motors,Pneumatic Valve

– Large Plugs: Stepper Motors

Motor_1

Motor_2

BatteryChargerOn / OffSwitch

P1P8P6 P5 P4 P3

RS-232Connector

P7 - Start

P9 - Speaker

RF / RS-232Selector

P11P12 P14 P13P15

ResetID


6

Electro/Mechanical Supplies


7

Microswitches

• Lever arm closes circuit

• Status of IN register holds status of port– 0 = Open Circuit– 1 = Closed Circuit

• Same action is going to start competition


8

Solenoids

• Consists of a coil of wire – Electromagnet• When powered up, pulls in plunger.


9

DC Motors

• Speed is proportional to voltage

• Moves in one direction

• Gearbox to slow down shaft

• Very high torque• Requires time to

ramp up and down.


10

Stepper Motors

• Both motors are controlled through P10

• Speed is a value chosen between 2 and 240

• Can move both directions

• Negligible ramping time

• Low Power


11

Flex Sensor

• Detects deflection• Works like a strain gage

– Resistance changes with deflection– Voltage reading sent through A/D converter– 12-bit output (0 – 4095)


12

Infrared Distance Sensor

• 4” to 30” Range• Infrared beam is emitted• Beam reflects off object• Detected by receiver• Output voltage

proportional to distance• A/D Converter: Reading

between 0 and 255.


13

Best Way to Learn is to Do

• Read through the manual • Examine the sample programs and

program fragments• Studio assignment• Ask questions• Additional Information

– www.parallaxinc.com (BASIC Stamp)


14

Pneumatic Supplies


15

Pneumatic Actuator

• Pressurized Extension• Spring Return• 2.5 in Stroke


16

Pressure Vessel

• Pressurize with Bike Pump• Max 100 psi• Supplies 10-15 Actuator strokes


17

Pneumatic Valve


18

Machining Studio

• Learn to Respect Machine Tools• Learn to Cut• Gain Experience• Generate Design Ideas• Build Confidence• Preserve Digits

Goals:


19

The Coupler

0.500 0.650 1/32 0.750

1/2-20 UNF6-32 UNCTHRU

0.125 0.750 DP

0.900 0.500

0.250

All tolerances 0.010 unless otherwise specified

0.500+0.000-0.005


The Lathe


21

Process Plan for Coupler (1)

1) Chuck OD, face one side, turn 75% of shaft to 0.900 diameter

2) Turn 0.750 X 0.500 diameter segment

3) Drill 0.750 X 0.125 diameter hole using tail stock

4) Flip part in lathe and chuck on 0.900 diameter.


22

Process Plan for Coupler (2)

5) Turn 0.500 X 0.500 diameter segment

6) Thread 1/2-20 UNF segmentusing lathe tail stock to keep

the die straight

7) Mount the part in either a mill or drill press

8) Drill (using #35 drill) and tap 6-32 UNC threaduse the head from the drill

press or mill to keep the tap straight.


23

Important Notes

• Do not remove more than 0.020 inch per cut

• Cross slide readings are radius, not diameter– Removing 0.010 inches from

the part will result in the diameter being reduced in size by 0.020 inches

– Do not to hit the chuck with the cutting tool when machining.


24

The Bracket


25

The Mill


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Process Plan for Bracket (1)

1) Mill outside dimensions 2.30 X 0.950 X 0.950 part

2) Mark part off for operations 3 and 4 using a felt tip pen. Make sure to leave material for milling the final part.


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3) Drill 3/4 inch holes near 1/8 inch radius corners

Drill holes in material to be removed

You will use these holes for turning points during sawing.

4) Rough saw 0.700 X 1.500 inch grove

sawing from the top to the first 3/4 inch hole

rotating the part 90sawing to the next 3/4 inch hole

rotating the part 90sawing back to the top


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5) Mill the slot that was roughed in operation 41/4 diameter mills will yields

a 1/8 inch radius

6) Drill (using the #25 drill) and tap the 10-24 threadsuse the head from the drill

press or mill to keep the tap straight.


29

Bracket Important Notes

• Do not remove more than 0.020 inch per cut

• Do not to cut into the machine itself when end milling– elevate the part to provide some clearance

between the machine and the cutting tool.


30

Don’t Rush

Ask Questions


31

Franciscan friar William of Ockham

OCKHAM’S RAZOR –

entia non sunt multiplicanda praeter necessitatem

Translation:

entities should not be multiplied beyond necessity

OR:

All things being equal, the simplest solution tends to be the best one

Good guidance for DFM efforts

Simplest design/process is usually the most producible

ME 2110: Creative Decisions and Design Prof J.Rhett Mayor 1 Introduction to Machining & Electronics and Pneumatics Lecture #5a.

Documents

rhett mayor

design prof j

creative decisions

competition slide

stroke slide

pneumatic supplies slide

basic stamp slide

communication port slide