Assignment 2 Technical Document Final

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Page No. List of Illustrations ---------------------------------------------------------------------- 2-3 Introduction Purpose --------------------------------------------------------------------------------------------- 4 Scope ------------------------------------------------------------------------------------------------ 4 Intended Users ------------------------------------------------------------------------------------ 4 Usage ------------------------------------------------------------------------------------------------ 4 Safety Information ---------------------------------------------------------------------------- 4-5 Process Description ----------------------------------------------------------------------- 6 Required Tools List ------------------------------------------------------------------------ 7 Materials List --------------------------------------------------------------------------- 8-11 Before You Begin ------------------------------------------------------------------------- 12 Directions Assembling the Air Chamber ----------------------------------------------------------- 13-16 Assembling the Barrel ------------------------------------------------------------------------- 17 Assembling the Trigger Valve ----------------------------------------------------------- 18-21 Assembling the Receiver --------------------------------------------------------------------- 22 Final Assembly ----------------------------------------------------------------------------- 23-24 Testing and Operation Air Chamber Pressure Test ------------------------------------------------------------------- 25 Trigger Valve Test ------------------------------------------------------------------------- 25-26 Operation ---------------------------------------------------------------------------- 26 Launching A T-Shirt ----------------------------------------------------------------- 26 Future Options ---------------------------------------------------------------------- 27

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Page No. Figure 1: Process Flow -------------------------------------------------------------------------- 6 Figure 2: Sch. 40 Example 1 ------------------------------------------------------------------- 8 Figure 3: Sch. 40 Example 2 ------------------------------------------------------------------- 8 Figure 4: PVC Primer -------------------------------------------------------------------------- 12 Figure 5: Heavy Duty PVC Cement --------------------------------------------------------- 12 Figure 6: PVC Bonding Directions ---------------------------------------------------------- 12 Figure 7: Air Chamber (Step 2) ------------------------------------------------------------- 13 Figure 8: Air Chamber Bushings (Dry-Fit) ------------------------------------------------ 13 Figure 9: Air Chamber Bushings (Bonded) ----------------------------------------------- 14 Figure 10: Drilling Air Chamber Inlet ------------------------------------------------------ 14 Figure 11: Thread Cutting Tool ------------------------------------------------------------- 14 Figure 12: Cutting Air Chamber Threads ------------------------------------------------- 14 Figure13: Applying Teflon Tape to Threads --------------------------------------------- 15 Figure 14: Air Chamber Inlet Nipple ------------------------------------------------------- 15 Figure 15: Pressure Gage and Schrader Valve Configuration ----------------------- 15 Figure 16: Assembled Air Chamber Inlet ------------------------------------------------- 15 Figure 17: Installed Air Chamber Inlet ---------------------------------------------------- 16 Figure 18: Drilling Air Chamber Cap ------------------------------------------------------- 16 Figure 19: Safety Pressure Valve ----------------------------------------------------------- 16 Figure 20: Completed Air Chamber ------------------------------------------------------- 16 Figure 21: Threaded Barrel Connector --------------------------------------------------- 17 Figure 22: Completed Barrel ---------------------------------------------------------------- 17 Figure 23: Unmodified Irrigation Valve --------------------------------------------------- 18 Figure 24: Electronic Actuator Removed ------------------------------------------------- 18 Figure 25: Removing Top Screws ---------------------------------------------------------- 19 Figure 26: Disassembled Irrigation Valve ------------------------------------------------ 19 Figure 27: Taping Valve Hole ---------------------------------------------------------------- 19 Figure 28: J-B WELD --------------------------------------------------------------------------- 19 Figure 29: Sealed Valve Cavity -------------------------------------------------------------- 20 Figure 30: Cutting Valve Body Threads --------------------------------------------------- 20
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List of Illustrations (continued)
Figure 31: Valve Nipple Installed ----------------------------------------------------------- 20 Figure 32: Reassembling Irrigation Valve ------------------------------------------------ 21 Figure 33: Reinstalling Valve Body Screws ----------------------------------------------- 21 Figure 34: Cutting Blow Gun Tube --------------------------------------------------------- 21 Figure 35: Assembled Receiver Adapter ------------------------------------------------- 22 Figure 36: Bonded Receiver Pipe ---------------------------------------------------------- 22 Figure 37: Attached Trigger Handle ------------------------------------------------------- 23 Figure 38: Air Chamber Threads ----------------------------------------------------------- 23 Figure 39: Air Chamber/Trigger Valve Assembly --------------------------------------- 23 Figure 40: Marking Receiver Pipe for Cutting ------------------------------------------- 24 Figure 41: Bonded Receiver Pipe ---------------------------------------------------------- 24 Figure 42: Attaching Zip Ties ---------------------------------------------------------------- 24 Figure 43: Completed Air Cannon --------------------------------------------------------- 25

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Purpose
Air cannons are used to launch various projectiles in such a way which surpasses the throwing range of an ordinary human being. You may have witnessed them in use at sporting events where individuals on the field launch t-shirts, footballs or other promotional items to fans in the nosebleed section of a stadium, or on a less powerful scale, at carnivals where a participant would shoot foam or other soft balls at targets in order to win a prize. Structural engineers use air cannons to launch two by fours at walls, doors and windows to evaluate safety while developing tornado resistant building materials, while still others use air cannons for pure recreational use and entertainment to launch potatoes, pumpkins or other various produce items distances from 100 yards and up to nearly a mile. The air cannon you will be building in this project will have a range of 50-200 yards, depending on the size, shape and weight of the projectile and is also designed with versatility in mind due to the option for interchangeable barrel sizes in the future.

Scope
This instructional document will direct you through the entire building process from selecting proper materials to final assembly, testing and operation.

Intended Users
The individual who will utilizing this instructional document will have a working knowledge of the tools and their uses required for this project, but not necessarily have experience when working with plumbing materials. The user will have safety as a top priority at all times.

Usage
The instructions in this document are intended to be completed in sequence. Failure to follow the sequence as set forth herein may cause unintended operation and potentially imminent danger.

Safety Information
 It is the user’s responsibility to research, observe and comply with all local, state and federal laws and statutes which may govern, regulate of restrict the use or possession air cannons. Read and abide by ALL directions and safety precautions within this document.



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Safety Information (continued)
 NEVER point the air cannon at any person whether or not the barrel is loaded or the air chamber pressurized. ALWAYS point the air cannon in a safe direction when using or loading. ALWAYS treat this unit with the same duty of care as if it were a firearm. Do not place your hand or fingers on the firing mechanism unless the gun is pointed at the intended target. ALWAYS launch the air cannon in a safe direction. This means NEVER point or fire at anything that you cannot clearly and identify easily as a target. Air cannons can be dangerous and even deadly when improperly handled. Never store or transport a loaded air cannon. Do not load the air cannon unless you intend to shoot it immediately. NEVER attempt to pressurize the air chamber above 100 psi. The pressure safety valve it set to open if the pressure rises above 115 psi. DO NOT attempt to circumvent the pressure safety valve. It is installed for your safety and protection. DO NOT use or pressurize the air cannon if it is become broken, damaged or if you have dropped it on a hard surface until a full inspection is performed on the components and joints. ALWAYS perform an inspection on the air cannon before and after use to check for damage or leaks. Always remember to discharge the air chamber pressure when not in use by gently opening the safety pop-off valve. The user of this document assumes ALL liability and risk associated with ANY actions taken pursuant to the information contained herein. This instructional document is for educational and instructional purposes only. The author of this instructional document is not responsible for the use or misuse of the plans or any device created from the plans.

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----------------------------------- IMPORTANT ----------------------------------REVIEW ALL OF THE ABOVE SAFETY INFORMATION BEFORE BEGINNING THIS PROJECT ---------------------------------------------------------------------------------------------

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Read Entire Manual
It is IMPERATIVE that the user read and understand the entire instructional guide before starting any processed described herein. Gather Tools and Materials Gather all of the tools and materials necessary to perform each step of every process as instructed by this guide. Assemble the Air Chamber In this process you build the air chamber to the air cannon, which will be filled with and hold the pressurized air until released with the trigger valve. Assemble the Barrel The barrel of the air cannon will consist of a 3” diameter barrel, 24” long with a threaded connector which attached to the receiver. Assemble the Trigger Valve Trigger valve is an irrigation sprinkler valve which will be modified for use in this application. The trigger valve effects a rapid release of air pressure from the air chamber during operation. Assemble the Receiver The receiver is the pipe and adapters which connect from the outlet of the trigger valve to the inlet of the barrel. Final Assembly The final assembly is possible once all of the individual components to the air cannon are assembled. Testing and Operation After final assembly the air chamber will be pressure tested and the trigger valve will be tested for functionality. A brief on the operation will also take place.

START
Read Gather Tools & Materials

Air Chamber

Barrel

Trigger Valve

Receiver

Final Assembly

Testing and Operation
Figure 1: Process Flow

6

The tools required for this project are common and easy to find in hardware stores if not in the garages an average hobbyist. The only tool which may be more difficult to find is the Pipe Thread Tapping Tool, which may need to be sourced from a plumbing or specialty tool supplier. Be absolutely certain about the type of PVC cement you purchase as further described in the warning below.

Required Tools
PVC Primer (Purple or Clear) PVC Cement (Heavy Duty) - SEE WARNING Power Drill or Drill Press 15/32" Drill Bit 1/4" Pipe Thread Tapping (cutting) Tool Adjustable (Crescent) Wrench 1 Roll Teflon Thread Seal Tape Bench Vise or Other Stationary Clamping Device #2 Phillips Screwdriver Flat Head Screwdriver Heavy Duty Box Tape (2-3" Piece) J-B WELD Epoxy & Sealant Popsicle Stick (For Mixing J-B WELD) Hacksaw Rasp (file) Measuring Tape Utility Knife Permanent Marker 4 10-12" Heavy-Duty Zip Ties (Or A Single 3' Tie) Air Compressor Safety Goggles or Glasses DANGER: ALWAYS remember to wear safety glasses, goggles or other appropriate eye protection when working with tools and when building, testing and operating the air cannon DANGER: Do NOT substitute PVC cement with multi-purpose plumbing cement, which is labeled for use on PVC, CPVC and ABS plastic materials. This type of cement does not create as strong of a bond as single-purpose PVC cement. Doing so in this application may cause joint leaks or possible bursting or explosion resulting in severe injury or death.

7

The materials list for the air cannon is extensive, but nearly all of the plumbing parts can be purchased at your local hardware or plumbing store. Gather all of the materials necessary for each component prior to beginning building each phase of the air cannon. Danger: ALL PVC used in this project should be “Schedule 40” rated PVC, generally indicated with a “Sch. 40” marking on each part, as shown in the figures below. Schedule 40 PVC is pressure rated (generally up to 200 psi) and able to withstand the pressure which will be utilized in this application. Failure to use Schedule 40 PVC will cause a risk of bursting or explosion of the air cannon during use which may result in severe injury or death.

Figure 2: Sch. 40 Example 1

Figure 3: Sch. 40 Example 2

Component

Description
4" Sch. 40 PVC Pipe - 16" in Length

Picture

Source

Air Chamber

The Home Depot

Air Chamber

4" Sch. 40 PVC Coupling

The Home Depot

Air Chamber

4" to 3" Sch. 40 PVC Reducer Bushing

The Home Depot

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Component

Description
3" to 2" Sch. 40 PVC Reducer Bushing

Picture

Source

Air Chamber

The Home Depot

Air Chamber

2" to 1" Sch. 40 PVC Reducer Bushing

The Home Depot

Air Chamber

1" Sch. 40 PVC Pipe - Approx 2" in Length

The Home Depot

Air Chamber

1" Sch. 40 PVC Female to Male Threaded Adapter

The Home Depot

Air Chamber

1/4" Brass Hex Nipple

The Home Depot

Air Chamber

1/4" Brass Pipe Tee

The Home Depot

Air Chamber

1/4" Brass Schrader Valve

Locke (plumbing) Supply

Air Chamber

Pressure Guage - 1/8" Male Pipe Fitting (Capable of up to 120 psi)

NOSHOK, Inc. www.noshok.com

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Component

Description
1/4" to 1/8" Brass Reducer Bushing

Picture

Source

Air Chamber

The Home Depot

Air Chamber

4" Sch. 40 PVC End Cap

The Home Depot

Air Chamber

1/4" 115 psi Safety Valve (Pop-Off Valve)

Lowe's

Barrel

2" Female to 2" Male Threaded Adapter

The Home Depot

Barrel

2" Pipe - 2.5" in Length

The Home Depot

Barrel

3" to 2" Reducer Bushing

The Home Depot

Barrel

3" Coupling

The Home Depot

Barrel

3" Pipe - 24" in Length

The Home Depot

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Component

Description
Irrigation Sprinkler Valve 1" Female Threaded

Picture

Source

Trigger Valve

The Home Depot

Trigger Valve

1/4" Brass Hex Nipple

The Home Depot

Trigger Valve

Air Compressor Blow Gun

The Home Depot

Receiver

1" Female to Male Threaded Elbow

The Home Depot

Receiver

1" Pipe - Approx 6" in Length

The Home Depot

Receiver

1" Street Elbow

The Home Depot

Receiver

2" to 1" Reducer Bushing

The Home Depot

Receiver

2" Female to 2" Female Threaded Adapter

The Home Depot

11

Before you begin assembling the air cannon, you must bear in mind how critical the strength and integrity of each cemented PVC bond on the unit is to your own personal safety and the safety of others around you. Review the information below describing Proper PVC Bonding Technique BEFORE continuing. Step 1: Apply PVC primer to the hub of the pipe fitting, spreading with the applicator to coat the entire surface to be bonded.

Figure 4: PVC Primer

Step 2: Apply PVC primer to end of the pipe and let primer dry for about 1 minute before applying cement.

Step 3: When primer is dry, apply clear PVC cement to the hub and pipe end of the fitting spreading to coat the entire primed surface.

Figure 5: Heavy Duty PVC Cement

Danger: Avoid contact of PVC chemicals with skin, eyes or any body part. Avoid breathing of vapors and use in well ventilated area. Follow all product label directions, precautions and warnings during use.

Step 4: Without delay, push the pipe into the hub of the fitting WHILE turning the pipe about one-quarter turn. This removes any air bubbles which may have formed in the cement. Hold for 1 minute. Step 5: Wipe off excess glue with a cloth or towel.

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Figure 6: PVC Bonding Directions

Assembling the Air Chamber
The strength and integrity of the air chamber is one of the most important factors to safety and desired operation of the air cannon. The air chamber is constructed using 4” pipe and will hold the air pressure until released by the trigger valve. Attached to the chamber will be a cap on one end with the safety pressure valve, the pressure gage, the air inlet valve (Schrader valve) and the reducer bushings so that the air chamber may be threaded onto the trigger valve. Warning: Make sure you have studied proper PVC bonding techniques as previously discussed in this guide before proceeding.

1.

Gather the listed materials required to build the air chamber

2.

Bond the 4” x 16” long pipe to the 4” coupling using the aforementioned proper PVC bonding technique. See Figure 7
Figure 7: Air Chamber (Step 2)

3.

Prepare a “dry-fit” of the reducing bushings and threaded adapter to verify compatibility prior to bonding. These items include:      4” to 3” reducer bushing 3” to 2” reducer bushing 2 to 1” reducer bushing 1” pipe – 2” in length 1” female to 1” male threaded adapter

Figure 8: Air Chamber Bushings (Dry-Fit)

See Figure 8 Caution: Be sure to NOT press the pieces so firmly together leaving them difficult to separate by hand prior to permanent bonding. 13

4.

Separate the “dry-fit” components from the previous step and bond them permanently with PVC primer and cement using proper PVC bonding technique. See Figure 9

5.

Drill a 15/32” hole through the coupling and pipe wall approximately 1” from the inside edge of the coupling. Deburr and clean the edges of the hole, if necessary. See Figure 10

Figure 9: Air Chamber Bushings (Bonded)

Figure 10: Drilling Air Chamber Inlet

6.

Using the 1/4” male pipe thread tapping tool, carefully begin to hand-thread the tool into the hole. Try to keep the tool as perpendicular to the pipe as possible. See Figure 11

Figure 11: Thread Cutting Tool

7.

Once the tapping tool becomes too difficult to turn by hand, continue to thread the tool into the hole using an adjustable wrench and cut the threads until approximately 1” of the tapping tool has been inserted into the hole. See Figure 12
Figure 12: Cutting Air Chamber Threads

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8.

Wrap one end of the 1/4" brass hex nipple approximately 3-4 layers of Teflon thread seal tape. See Figure 13

Figure 13: Applying Teflon Tape to Threads

9.

Thread the nipple into the pipe and tighten with the wrench until flush with the surface. See Figure 14

Figure 14: Air Chamber Inlet Nipple

This brass nipple will connect to a pipe tee which will provide ports for the fill valve (Schrader valve) and for the air pressure gage. 10. Prepare the 1/4” brass pipe tee, air pressure gage, 1/4” to 1/8” brass reducer bushing and brass Schrader valve for connection by wrapping the threads with 3-4 layers of Teflon thread seal tape similar to step 8 above. See Figure 15

Figure 15: Pressure Gage and Schrader Valve Configuration

11.

Connect the components in the configuration shown in step 10 and tighten them firmly with a wrench. The bench vise will be very helpful in this step by holding the brass tee in place while tightening the connecting components. See Figure 16

Figure 16: Assembled Air Chamber Inlet

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12.

Prepare the brass nipple on the air chamber for connection with thread seal tape and connect the assembled tee to the chamber. Tighten firmly and position the tee as shown in Figure 17.

13.

Drill a 15/32” hole in the center of the 4” end cap. See Figure 18

Figure 17: Installed Air Chamber Inlet

14.

Using the same technique in steps 6-7, cut pipe threads into the hole then remove all debris created from the drilling and thread cutting process.
Figure 18: Drilling Air Chamber Cap

15.

Prepare the 1/4" brass safety pop-off valve for connection by applying Teflon thread seal tape, thread into the 4” end cap and tighten firmly with a wrench. See Figure 19

Figure 19: Safety Pressure Valve

You will now prepare the 4” end cap for connection to the air chamber. In performing steps 5-7, debris such as PVC shavings and curls has fallen into and collected in the air chamber. Now is the time to clean all debris from inside the air chamber before sealing it with the end cap because you will not have access to this area after step. 16. Bond the 4” end cap to the air chamber using proper PVC bonding technique. Figure 20 shows the completed air chamber. Set aside until the air cannon final assembly.

Figure 20: Completed Air Chamber

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Assembling the Barrel
The barrel of the air cannon will hold the projectile prior to launching. Just like the air chamber, the barrel must be capable of withstanding a significant amount of air pressure. The difference between the barrel and the air chamber, however is that the barrel will be subject to instantaneous pressure spikes when the air is released from the chamber, therefore the integrity of the barrel connections is crucial to the safety of the individual using the air cannon. The air chamber is constructed of 3” pipe which will be reduced to 2” pipe and connected to a 2” male threaded adapter which will attach to the air cannon via the barrel receiver.

1.

Prepare a “dry-fit” of the barrel coupling, reducer bushings and threaded adapter to verify compatibility prior to bonding. These items include:     3” coupling 3” to 2” reducer bushing 2” pipe – 2.5” in length 2” female to 2” male threaded adapter

2.

Separate the “dry-fit” components from the previous step and bond them together using proper PVC bonding technique. The assembled barrel connector is shown in Figure 21.

Figure 21: Threaded Barrel Connector

3.

Bond the 3” x 24” barrel to the barrel connector coupling using proper PVC cementing technique. Figure 22 shows the completed barrel. Set the barrel aside until the air cannon final assembly.

Figure 22: Completed Barrel

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Assembling the Trigger Valve
The trigger valve is a unique component in this model of air cannon due to the fact that it is not a typical PVC or brass pipe fitting. The trigger valve is actually an electronically actuated sprinkler valve used residential and commercial lawn irrigation systems which will be modified for use in this application. The purpose for using this type of valve as a trigger in the air cannon, as opposed to using a standard brass or PVC ball valve, is that valve can open and release the pressure from the air chamber much more rapidly, near instantaneous, which can have a dramatic effect on the power and speed in which the projectile is launched from the barrel. The modification of the valve as described in the steps below removes the electronic actuation motor and essentially turns it into a manually operated combo valve, whereby opening the outer valve via the trigger handle effects the opening of the main pressure release valve, thereby releasing the pressure from the air chamber and allowing rapid flow into the receiver and barrel of the air cannon.

Caution: Pay attention to this process carefully because performing the steps incorrectly may render the valve permanently inoperable.

1.

The trigger comes from the box with the electronic actuator motor attached. The actuator is the black cylinder with two wire leads attached. See Figure 23

Figure 23: Unmodified Irrigation Valve

2.

Remove the electronic actuator by unscrewing it from the valve body. Discard, if desired. See Figure 24

Figure 24: Electronic Actuator Removed

18

3.

Using a screwdriver, remove 8 screws from the circumference of the valve body and set aside. These screws will be used again when reassembling the valve. See Figure 25

Figure 25: Removing Top Screws

4.

Separate the top half from the bottom half of the valve body. You may need to use a flat head screwdriver along the seam to pry apart the pieces. Be careful not to cut the rubber seal just inside the outer edge of the seam. Set the base and spring aside. See Figure 26

5.

Apply a small piece of heavy duty box tape covering the small square-shaped hole along the inside edge of the valve body. This will prevent leakage of the sealant into the inner valve. See Figure 27

Figure 26: Disassembled Irrigation Valve

Figure 27: Taping Valve Hole

6.

Prepare a mixture of equal parts J-B WELD (steel + hardener) sealant to be applied to the cavity where the electronic actuator was located. Mix the two components together thoroughly with a popsicle stick on a thick piece of paper or cardboard. You will need approximately 15cc, or a half-dollar size amount of prepared sealant.

Figure 28: J-B Weld

19

Danger: Avoid contact of J-B WELD with skin, eyes or any other body part. Use in a well ventilated area to avoid breathing of vapors. Follow all directions, safety precautions and warnings included on the product packaging.

7.

Transfer the prepared J-B WELD sealant mixture with the popsicle stick to the threaded cavity on top of the valve body covering the air ports inside completely. Transfer the entire mixture to the cavity. Place the valve body on a flat, even surface to cure and this process will allow the J-B WELD to settle into a smooth, even seal inside the hole as shown in Figure 29.

Figure 29: Sealed Valve Cavity

Caution: You must allow the sealant to cure 10-12 hours before proceeding.

8.

Now that the sealant is fully cured, remove the heavy duty tape which was applied previously in step 5. Drill another 15/32” hole in the center of the valve body and cut 1/4" pipe threads with the thread cutting tool. Be sure to center the hole as closely as possible within the circle. See Figure 30

Figure 30: Cutting Valve Body Threads

9.

Prepare the other 1/4" brass nipple with Teflon thread seal tape and thread into the hole in the valve body as shown in Figure 31. Tighten thoroughly with a wrench. The trigger handle will attach to this brass nipple which will allow the valve to be opened manually.

Figure 31: Valve Nipple Installed

20

The modifications to the sprinkler valve are now complete and it is time to reassemble the unit and prepare the trigger valve for assembly. 10. Re-attach the top of the valve body to the base of the valve body while carefully centering and aligning the internal spring and the screw holes along the outer diameter. See Figure 32

Figure 32: Reassembling Irrigation Valve

11.

Reinstall the screws which seal and hold the valve together and thread the screws in by hand until they are about halfway inserted as shown in Figure 33. Tighten the screws with a Phillips screwdriver and set the unit aside until final assembly.

Figure 33: Reinstalling Valve Body Screws

Caution: The valve body is made of softer plastic material. When tightening the valve body screws with the screwdriver, be as careful as possible not to over-torque the screws causing them to strip the threads of the valve body. This will cause the valve to leak under pressure and result in undesired operation of the air cannon. The air compressor blow gun which will connect to the irrigation valve consists of a plastic body, plastic trigger, brass threaded receiver and a metal tube approximately 4-5” long. The metal tube will not be need in this project and will need to be cut from the blow gun. The blow gun will be attached to the modified irrigation valve during final assembly. 12. Using the bench vise to hold the blow gun firmly, use a hack saw to cut the metal tube off as close to the blow gun handle as possible. Set aside until the air cannon final assembly. See Figure 34
Figure 34: Cutting Blow Gun Tube

21

Assembling the Receiver
The receiver of the air cannon consists of the pipe and adapters which connect the trigger valve to the barrel. The receiving end which attaches to the barrel has a 2” threaded female adapter which would allow multiple sizes and types of barrels should you wish to build them. 1. Prepare a “dry-fit” of the receiving adapter components to verify compatibility prior to bonding. These items include:    2. 2” female pipe to 2” female threaded adapter 2” to 1” reducer bushing 1” street elbow
Figure 35: Assembled Receiver Adapter

Separate the “dry-fit” components from the previous step and bond them together using proper PVC bonding technique. The assembled receiving adapter is shown in Figure 35.

The second part of the receiver is the 1” male threaded elbow and the 1” PVC connecting pipe. The second part will not be bonded to the receiving adapter above until the final assembly process.

3.

Bond the 1” x 6” PVC pipe to the 1” male threaded elbow as shown in Figure 36. Be sure to remember proper PVC bonding technique.

Figure 36: Bonded Receiver Pipe

22

Final Assembly
Now that all of the individual components of the air cannon are assembled and all adhesive is fully cured, it is time to assemble the components into one unit. You may want to refer to the picture of the fully assembled air cannon on the cover page for reference. Caution: The trigger valve is directional and air flows only one way through the 1” female threaded ends of the trigger valve, or the inlet and outlet. The body of the valve will have arrows ( ) indicating the flow direction of the valve. Steps 1, 2 and 4 below involve connecting components to the trigger valve and ensuring these connections are made on the appropriate side of the valve is critical.

1.

Wrap the 1/4" brass nipple on the trigger valve with 3-4 layers of Teflon thread seal tape and attach the air compressor blow gun. Turn the handle until almost completely tight and then point the trigger lever towards the inlet end of the valve body. See Figure 37
Figure 37: Attached Trigger Handle

2.

Wrap the threads on the 1” male threaded adapter located on the end of the air chamber with 3-4 layers of Teflon thread seal tape and attach to the trigger valve on the inlet side. Turn until the valve is firmly attached and continue turning until air pressure gage is at the 10 o’clock position and the valve handle is in the 6 o’clock position. See Figures 38 and 39

Figure 38: Air Chamber Threads

Figure 39: Air Chamber/Trigger Valve Assembly

23

3.

Insert the 2” male threaded barrel connector into the 2” female threaded receiving adapter and turn until hand tight. Do not over-tighten and do not apply Teflon thread seal tape when connecting these components. Wrap the 1” threads on the male threaded elbow from the lower half of the receiver with 3-4 layers of Teflon thread seal tape and insert into the outlet end of the trigger valve. Continue turning until the connection is tight and the 1” pipe is in the 12 o’clock position in comparison to the pressure gage and trigger handle. Lay the barrel and other components side by side where the barrel touches the air chamber and make a cutting line with a marker on the 1” receiver pipe to allow enough material to be bonded into the receiving adapter. See Figure 40

4.

5.

Figure 40: Marking Receiver Pipe for Cutting

6.

Remove the 1” receiver pipe from the trigger valve and make a cut with a hacksaw at the cutting line. The bench vise may come in handy one more time to hold the pipe steady while making the cut. File the cutting debris left on the edge of the pipe with the rasp. Re-attach the receiver to the trigger valve in preparation for the next step. Using proper PVC bonding technique, bond the receiving pipe to the receiving adapter with the barrel attached as shown in Figure 41. This is a one-time shot at aligning the barrel and air chamber correctly. As soon as you press the pieces together with the cement applied rotate the barrel to come into alignment with the air chamber.

7.

Figure 41: Bonded Receiver Pipe

8.

In order to hold the air chamber and barrel securely, attach a series of zip ties around the air chamber and barrel along the inside edge of the air chamber end cap as shown in Figure 42.

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Figure 42: Attaching Zip Ties

Figure 43: Completed Air Cannon

Air Chamber Pressure Test
The pressure test of the air chamber is the first in a series of steps which will test the functionality of the air cannon. Make sure you wear safety goggles! 1. Begin this test by pressurizing the air chamber with an air compressor to 20 psi and wait 3-5 minutes. Observe the pressure gage and note if the chamber holds the pressure for the entire period. Slight pressure drops (0-5 psi) are normal the first few times the chamber is pressurized. Release the pressure by manually opening the pressure safety valve. Repeat the process in Step 1 at 40 psi, 80 psi and finally at the maximum 100 psi. If pressure leaks are found, determine the source of the leak and take the appropriate steps necessary to remedy the leak. This may be as simply as applying more Teflon thread seal tape to leaking joints.

2. 3.

Trigger Valve Test
1. Pressurize the air chamber to 40 psi and, while pointing the air cannon in a safe direction, release the pressure using the trigger valve. NOTE: Squeeze the trigger valve quickly and completely. (Squeezing the trigger valve slowly does not work well) 25

2.

Repeat the process in Step 1 at 60 psi, 80 psi, and 100 psi. Be prepared because the air cannon will become increasingly LOUD as the pressures increases.

Operation
----------------------------------- IMPORTANT ----------------------------------REVIEW ALL SAFETY INFORMATION ON PAGES 5-6 OF THIS DOCUMENT PRIOR TO USE PERFORM ALL OPERATIONAL TESTS DESCRIBED ABOVE PRIOR TO USE ------------------------------------------------------------------------------------------During the testing process, you should now be familiar with the general functionality and mechanism of the air cannon and you are ready to start launching projectiles, but first you must understand how to load the barrel. In order for the air pressure released from the air chamber to have the greatest effect on desired projectile, the projectile must seal as tightly as possible in the barrel. If there is any airspace between the walls of the barrel and the projectile, the majority of the air pressure will simply bypass the projectile and will not propel the projectile with any substantial force. Choose a projectile that can be slightly compressed when loaded into the barrel to achieve the most effective seal. For smaller projectiles, change to a smaller barrel, which will be discussed below. For the purposes of this document, the air cannon will be used for launching t-shirts as discussed in the introduction.

Launching A T-Shirt
1. Fold the t-shirt lengthwise 2-3 times and then tightly roll the shirt into cylindrical shape, ensuring the rolled shirt will be slightly larger than the internal diameter of the barrel. Wrap the shirt with 2-3 strips of heavy duty box tape to maintain shape. Insert the shirt into the barrel while slightly compressing the shirt to create a good seal. Push the shirt down to the base of the barrel. Pressurize the air chamber. 50 psi is the initial recommended air pressure until you become more comfortable with the air cannon. CAREFULLY pick up the air cannon WITHOUT placing you hand on the trigger handle. Aim at the intended target and firmly squeeze the trigger handle to launch. 26

2. 3. 4. 5. 6. 7.

Future Options
The air cannon built in this instructional document was engineered with the capability to have interchangeable barrels in order to launch a variety of sizes and types of different projectiles. A 2” diameter barrel is the optimum size for launching potatoes and a 2.5” size is the optimum size for launching slightly larger projectiles such as tennis balls. Smaller diameter barrels such as 1” to 1.5” also have their uses and size of the barrel is determined by the size of the desired projectile. By building this air cannon you have now gained enough knowledge and experience to select appropriate materials and build different barrel sizes. Whatever size (diameter) barrel you choose, simply install a bushing to increase the size to 2” and attach a 2” male threaded adapter. Then you can simply detach the 3” barrel, attach the new barrel and operate as normal. Have fun and ALWAYS remember to practice safe launching.

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