Tip #9
Dust Collector (continued)
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Pg. 1-4, Pg. 5-8, Pg. 9-11

Permanent Piping System

For some workshops, it may be more convenient to install permanent piping rather than to move the Dust Collector to various locations throughout the shop.

The optional 4" inlet assembly is the link to a permanent installation. It replaces the 3-way inlet of the Dust Coliector to connect to a permanent piping system along the walls of your workshop. With a permanent setup using PVC (polyvinyl chloride) pipes and 2-1/2" diameter flexible hoses, you can conveniently work with as many as three machines in succession without moving the Dust Collector or changing hose connections.

Inlet Installation

Warning: Turn off and unplug the Dust Collector. Remove the cover plate and 3-way inlet from the Dust Collector. Attach the 4" inlet assembly with the four screws that attach the 3-way inlet.

The elbow of the inlet assembly can be set at four positions 90-degrees apart. If necessary to change the position of the elbow, take out its two attaching screws. Turn the elbow to the desired position, making sure that the mounting holes of the elbow and inlet line up. Reinstall the two screws securely.

System Requirements
In planning a permanent system, keep in mind that long lengths of flexible hose will reduce airflow. Also, smooth piping causes much less resistance to airflow and is strongly recommended for the main collection line of your system. Rigid PVC pipe and various fittings are available at most home centers or plumbing supply distributors, and are best suited for permanent systems.

Figure 25-6. Suggested permanent piping system (overhead view). Click on image for larger view.

Figure 25-6 illustrates a suggested permanent piping system.The following requirements should be met in building an efficient dust removal system:

• Make your system simple, compact and efficient. Avoid long runs, sharp turns and restrictions.
• The overall length of the PVC piping should not exceed 25 feet. This length permits use of:
  - Two 90-degree elbows (including the 4" inlet assembly). Elbows reduce airflow. So, for each additional elbow used, you should reduce the overall length of your system. Refer to the chart below to determine the amount of piping reduction recommended for the addition of certain fittings.
  

  Resistance of Fitting s to Airflow
  Pipe Diameter	4"	3"	2"	Equivalent Lengths of Pipe of Specific Diameters
  Long Sweep 90-degree Elbow	7'	5'	3-1/2'
  Medium Sweep 90-degree Elbow	9'	7'	4-1/2'
  Standard 90-degree Elbow	11'	8'	5-1/2'
  45-degree Elbow or Y-Fitting	5'	3-3/4'	2-1/2'
  Sudden Enlargement	2-1/4'	1-3/4'	1-1/8'

  
  - One 4" dia. x 8' long flexible hose from Dust Collector (not available through Shopsmith). This will make it more convenient when changing bags or moving the Dust Coilector. However, it will reduce airflow slightly.
  - Three 2-1/2" dia. x 8' long flexible hoses to connect to machinery. If you're planning a system that will connect more than three machines, have provisions for plugging or switching the hoses. Only connect three hoses at a time. Failure to do this would cause the machine at the end of the line to have insufficient airflow, with too little suction to remove sawdust from the machine.
• Use Schedule 10 (thin wall) PVC pipe and fittings. If Schedule 10 plumbing is not available, thicker walled pipe and fittings (higher Schedule number such as 40 or 60) may be used. However, because of the resulting differences in diameters, the flexible hose and piping connections will have to be taped securely with duct tape to prevent reduced airflow due to leakage.

• Figure 25-7. How to make a “doughnut” reducer: 1. Make a 4" diameter wooden disc on a bandsaw (see illustration for the range of thicknesses). 2. Drill a hole 2-1/4" through the center of the disc. 3. Disc sand the outer circumference of the wooden disc to get a slight taper.

  If multiple-size “Y” fittings are not available, 4" x 4" x 4" “Y”, fittings may be used. Wooden “doughnut” reducers can then be made to adapt the 4'' I. D. branch of each “Y” to accept the 2-1/4" (outer diameter) male fitting of the 2-1/2" diameter flexible hoses. (See Figure 25-7.)
• 90-degree elbows should be used only where absolutely necessary. Long sweep elbows are recommended. Do not use 90-degree tees in place of the “Y” fittings.
• Mount the PVC piping on your shop walls at the same height as the inlet of the Dust Collector. Use nylon straps and screws, wire and screws, or L-brackets, screws and wire to support the pipe. Place supports at each fitting or every 4 feet, whichever is closer.
• Avoid vertical lines.
• Limit the length of flexible hoses.
• Locate equipment which produces high volumes of chips and sawdust closest to the Dust Collector.
• Plug or cap unused openings, but keep at least two 2-1/2" openings in use at all times to ensure sufficient airflow in 4" pipe sections.
• Use duct tape, PVC cement or silicone around all permanent joints to prevent air leakage.

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