STUDIO 3 MACHINING & ELECTRONICS PROJECT ...singhose.marc.gatech.edu/courses/me2110 summer11/studios...Georgia Institute of Technology George W. Woodruff School of Mechanical Engineering

Georgia Institute of Technology

George W. Woodruff School of Mechanical Engineering

ME 2110 - Creative Decisions and Design

Summer 2011

STUDIO 3

MACHINING & ELECTRONICS PROJECT: PNEUMATIC LAUNCHER

In order to successfully design and build a product, you must understand the capabilities of the tools and

supplies at your disposal. For example, you must understand how motors and sensors work.

Furthermore, you must have knowledge of manufacturing processes, such as machining with milling

machines and laser cutters. This project will help you develop an understanding of the supplies and

manufacturing processes available to you in ME 2110.

Your goal is to build a pneumatic-powered launcher that shoots a Q-tip at a distant target. The launcher

will be controlled by the ME 2110 controller box. Since your team is sharing the mechatronics kit

amongst yourselves and there are a limited number of machine tools available in the lab, your section

will be split into two groups, Group A and Group B, where half of each project team is in each group.

This studio is pass/fail. You must complete the assigned tasks to pass the course.

Week 4 in Studio (6/6-6/10)

Group A:

In Week 4 of the semester, Group A will learn how to program the controller box, as well as use

the sensors and actuators in your mechatronics kit. You will have to connect and program the

electronics to complete the tasks found in Electronics Lab Tasks: Group A in the Electronics

Section of this document. You will have to demonstrate proper execution of the tasks to your

Studio Instructor or TA. They will sign your assignment sheet, indicating the tasks have been

completed.

Group B: In Week 4 of the semester, Group B will learn how to use the tools in the machine shop. A quick

instructional seminar will take place in the lab in which the TA will instruct the group on proper

lab safety, tool checkout procedures, and proper use of all of the lab tools. You will then begin

to construct a pneumatic launcher. To do this, you are provided a detailed process plan and

mechanical drawings for the device, located in the Manual Machining Section of this

document, and you will receive plastic (Delrin) workpieces from which you will machine your

launcher.

Week 5 in Studio (6/13-6/17)

Group A:

In Week 5 of the semester, Group A will move on to the machining section of the project. They

will undergo the same machining seminar as Group B and receive their own plastic workpieces.

Group B: In Week 5 of the semester, Group B will learn how to use the mechatronics kit. They will have to

complete the Electronics Lab Tasks: Group B found in the Electronics Section of this

document.

Week 6 in Studio (6/20-6/24)

By Week 6 of the semester, you will have completed your pneumatic-powered Q-tip launcher and

gained sufficient knowledge of the mechatronics kit to compete against other students in your studio to

determine who can shoot a Q-tip with the best combination of accuracy and distance. Figure 1 shows a

schematic diagram of the competition setup. You will get three attempts to shoot a Q-tip at a target

approximately 40 feet away. Landing a Q-tip in the middle ring of the target will earn 5 points, landing

in the outer ring of the target will earn 3 points, and shooting the Q-tip anywhere past the front of the

target will earn 1 point. You must secure your device using the provided vice with adjustable launch

angle. The vise is designed to fit into the channels on your launcher Baseblock. Note that you must share

your computer controller and the pneumatic supplies with the other members of your team.

Outside of Studio (6/6-6/20)

In addition to doing work inside your scheduled studio time, the lab will be open for other periods of

time throughout the week. These are known as “Open Lab.” Any ME 2110 student may work use either

of the ME 2110 rooms during Open Lab. The Open Lab schedule is posted on the ME 2110 website.

Due to limited time during scheduled studio, you will need to utilize Open Lab to complete your

deliverables. In addition to using Open Lab to complete the manual machining and electronics

assignments, you will also need to use the ME computer cluster to create a drawing for bracket for one

of your mechatronics components. This task is detailed in the Automated Machining Section of this

document.

Deliverables

Table 1 shows the deliverable schedule for this project.

Table 1 - Deliverables for each Individual for Next Three Weeks of Studio

Group A Group B

Deliverables due at the

Beginning of Studio in Week 5

(6/13-6/17)

- 3 completed and signed Electronics

Lab Tasks: Group A - 1 machined plastic component

Deliverables due at the

Beginning of studio in Week 6

(6/20-6/24)

- All 5 completed and signed

Electronics Lab Tasks: Group A - Both machined plastic components

- 1 Drawing for a mechatronics

bracket

- All 5 completed and signed

Electronics Lab Tasks: Group B - Both machined plastic components

- 1 Drawing for a mechatronics

Figure 1 - Pneumatic Launcher Competition Setup (not to scale)

Controller Box

Air Tank

Valve

40’

5 pt.

3 pt.

0 pt. 1 pt. 20’’

Vice (provided)

Individual

Launcher

Electronics Section This lab will provide experience with integrating electrical, mechanical, and pneumatic systems. The lab

is broken down into two weeks. During the first week, Group A of your team will complete part of the

lab; the second part will be completed by Group B during the second week. Although the programming

style will not be graded, the code written during these two labs should be helpful in developing the code

for the final project. Therefore, it is important to program using a standard structure and adequately

comment the code so the program will be easy to follow when referred to later on. The suggested format

for your code is:

• Constants Table

• Program Variables

• Main Program

• Subroutines

Before attempting to perform these programming tasks, it is helpful to read through the Mechatronics

Kit Manual and Pneumatics Manual which are available on the website. These should provide a good

background to the layout of the controller box and how to implement the electro-mechanical-pneumatic

components in a design.

This project has two checkpoints: at the beginnings of Week 5 and Week 6. At that time, each student is

responsible for showing appropriate progress through the assignment as indicated by a signed task

checklist. The task checklists for Group A and Group B are provided in the subsequent pages. After each

task is completed, have the professor or TA initial the checklist to verify that the program works.

Remember that each individual needs separately signed checklist. Feel free to ask the professor, TA, or

peers for help in completion of this assignment.

Electronics Lab Tasks: Group A, Name:__________________________________________

1. Have the DC Motor run for 2 seconds, stop for 2 seconds, run for 2 seconds, etc.

2. Connect a microswitch to P0 (START) and have the DC motor run at full speed when the switch is

held down and turn off when the lever is released.

Hint: Connect the microswitch to P0, read in the value of P0 when the lever is pressed and the

value of P0 when the lever is released. The variable name corresponding to P0 is IN0 (it does not

have to be defined).

Note: This is what will happen during the competition. The machines will begin when the circuit

on P0 is shorted (lever is pressed) and will stop when the circuit is opened (lever is released).

These couple lines of code will be very important in your final design project.

3. Connect two microswitches and the pneumatics. The program starts with the cylinder retracted. When

one switch is pressed, the cylinder should extend and remain extended after the switch is released. When

the other switch is pressed, the cylinder should retract and remain retracted. This process should run

indefinitely.

4. Connect two solenoids and two microswitches. When one microswitch is pressed, one solenoid is

activated for 2 seconds and then release. When the other microswitch is pressed, the other solenoid is

activated for 500 ms and then release. When one actuator is active the other cannot be activated.

5. Same as #4, only now the other actuator can be activated when the other is active.

Hint: Put a short pause in the program loop and assume that the time through the loop is equal to

the length of the pause. You’ll know when to turn off the actuator by counting the number of

times through the loop.

Checklist for Group A:

1. __________

2. __________

3. __________

4. __________

5. __________

Electronics Lab Tasks: Group B, Name:__________________________________________

1. Connect the stepper motor and the DC motor. Make them run clockwise for five seconds, stop for 2.5

seconds, run counter-clockwise for five seconds, and then stop for 2.5 seconds. Repeat this sequence

five times.

2. Perform the same act as #1, but always have the stepper motor and the DC motor rotating in opposite

directions.

3. Connect the IR distance sensor and one stepper motor. Have the motor run if the reading > 128 and

have the motor stop if the reading <127. Put a two-second pause between distance sensor readings.

4. Connect the encoder and have the DC motor run at full speed when the encoder is being rotated and

stopped when it is not being rotated.

5. Connect the encoder and the pneumatics. When the encoder is rotated 5 complete revolutions, the

actuator should extend and remain extended until the encoder is rotated 3 complete revolutions. The

cylinder should only extend 4 times and then remain retracted regardless of how many times the encoder

is rotated.

Checklist for Group B:

1. __________

2. __________

3. __________

4. __________

5. __________

Manual Machining Section

Pneumatic Cotton Swab (Q-Tip®) Launcher

In the machining section of this project, you will build the components for your pneumatic launcher. A

sketch of the launcher assembly is shown in Figure 2. Detailed step-by-step directions along with

mechanical drawings for the components are given on the last few pages of this handout. It is suggested

that you use both to correctly machine your parts.

Figure 2 – Isometric Exploded and Assembled Views of Pneumatic Launcher

Fitting from

Pneumatic

Actuator

Barrel

Baseblock

Barrel

screws into

Baseblock

Adapter

screws into

Baseblock

Channel in

Baseblock

for Vise

Arm

Suggested Process Plan for Pneumatic Launcher Barrel: 1. Obtain nominal 2.5” length of round 1” diameter Delrin stock

2. Face one end on the lathe to make it perpendicular to the axis of rotation.

3. Flip the piece over and face the other end, leaving the final length of 2.00”.

4. Now turn down 0.40” length of the stock on one end to a diameter of 0.50”. Use multiple axial paths

with approximately 0.05” radial depths of cut per pass.

5. Mount the tailstock onto the lathe. Chuck the small center drill into the tailstock Jacobs chuck. Use

the center drill to start a centered hole in the end of the workpiece.

6. Replace the center drill in the tailstock chuck with the #36 drill bit. Use the tailstock and drill bit top

drill a 0.1065” diameter hole through the entire workpiece. The drill may need to be advanced and

retracted multiple times to clear machining chips from drill flutes.

7. Remove the workpiece from the lathe headstock chuck and place it into either the mill vice or clamp

vise on the drillpress table.

8. Use the ½-20 UNF die to cut external threads on the 0.5” cylinder of the workpiece.

Suggested Process Plan for Pneumatic Launcher Baseblock:

1. Obtain the nominal 2.5” piece of rectangular 0.85” x 1” Delrin stock.

2. Using the mill, endmill one end of the workpiece to make its face perpendicular to the longitudinal

axis of the block.

3. Then endmill the other end of the block to a total length of 2.00”.

4. Next, facemill a channel on each of shorter sides of the block. The channels should be centered

along the length of the block, should be 0.125” deep, and should be 1.00” wide.

5. Now clamp the workpiece on end. Use a center drill to start a hole in the center of one end face of

the block.

6. Next, use a 8.50mm drill bit to drill a centered hole the full length through the block. Use a backing

material under the block in the vise to avoid drilling into the vise itself.

7. Next, use a 29/64” drill bit to drill a centered hole 0.70” deep into one end of the block.

8. Using the large tap wrench and ½-20 UNF plug tap, cut internal threads on the inside of the 29/64”

hole.

9. On the other end of the block, use the large tap wrench and M10x1 plug tap to cut internal threads

on the inside of the 8.50 mm hole.

Automated Machining Section

Mechatronics Kit Brackets

In addition to machining the plastic parts for your pneumatic launcher, you will also create a drawing for

a bracket for one of your mechatronic kit actuators. The TA will use this drawing on a computer-

controlled OMAX Waterjet Machining Center to cut your bracket out of ¼” aluminum plate. Your

bracket can then be used to mount certain mechatronic actuators in your final project device. There are

three separate brackets to choose from: Small DC Motor Bracket, Large Solenoid Bracket, and a

Pneumatic Actuator Bracket. Drawings are provided in this document for reference. You may choose

any 1 of the 3 to draw for machining. However, it is suggested that you strategically coordinate with

your teammates to draw different brackets so that you will have the ability to mount a variety of

actuators. In addition, here are some tips and suggestions on constructing your drawing:

Drawing a Cutting Path for the Waterjet:

Using a Standard CAD Software:

1. Create a solid model of the part by extruding the drawing profile to any nominal thickness.

2. Create a drawing from the solid model. Only draw the profile features and do not include any

dimensions or annotations. Make sure that your drawing is at a 1:1 scale. Also, do not include

any drawing sheet background information.

3. Save the drawing as a .dxf file. Make sure that the filename has your name in it.

4. Email the .dxf file to your TA when it is completed.

Using a OMAX Layout:

1. Open OMAX Layout.

2. Draw the part in OMAX Layout using the drawing tools provided in this software. Tip: Create

extra lines that can be used as construction lines in order to get feature lines to line up properly.

3. Make sure to delete any construction lines that will not be cut by the water-jet machine.

4. On the “Special” tool bar on the right side of the screen, click “Clean”. Keep all default options

and additionally select the “Remove unnecessary dots” option.

5. Use the “Measure” tool at the bottom of the screen to make sure your part is the correct size. If

needed, the entire drawing can be scaled: select all lines and click on the “Size” icon on the left

side of the screen to apply the appropriate scale factor.

6. Save the drawing and make sure that the filename has your name in it.

7. Email the drawing file to your TA when it is completed.

MACHINE SHOP SAFETY

ALWAYS WEAR SAFETY GLASSES

• Even when you are not working on a machine, you must wear safety glasses. A chip from a

machine someone else is working on could fly into your eye.

MACHINING

• Follow directions. If you don’t know how to do something, ask.

• Before you start the machine:

• Study the machine. Know which parts move, which are stationary, and which are sharp.

• Double check that your workpiece is securely held.

• Remove chuck keys and wrenches.

• Do not leave machines running unattended.

• Clean up machines after you use them: a dirty machine is unsafe and uncomfortable to work

on.

• Do not use compressed air to blow machines clean. This endangers people's eyes and can force

dirt into machine bearings.

• Report all broken or non-working machines.

CLOTHING, JEWELRY, AND HAIR

• Wear long pants (to your shoes).

• Wear short sleeves or roll up sleeves.

• Wear closed toe shoes and socks.

• Remove all jewelry - watches, bracelets, rings, necklaces, dangling earrings.

• Long hair or beards must be tied back.

• If your hair is caught in spinning machinery, it will be pulled out if you're lucky. If you are

unlucky, you will be pulled into the machine.

• No ties, scarves, and dangling clothes.

SAFE CONDUCT IN THE MACHINE SHOP

• Be aware of what's going on around you.

• For example, be careful not to bump into someone while they're cutting with the bandsaw (they

could lose a finger!).

• Concentrate on what you're doing. If you get tired, leave.

• Don't hurry. If you catch yourself rushing, slow down.

• Don't rush speeds and feeds. You'll end up damaging your part, the tools, and maybe the

machine itself.

• Listen to the machine. If something doesn't sound right, turn the machine off.

• Don't let someone else talk you into doing something dangerous.

• Don't attempt to measure a part that's moving.

• No fooling around.

VIOLATIONS OF THESE RULES WILL RESULT IN IMMEDIATE EJECTION FROM

THE MACHINE SHOP.