Dust Collection for Small Shops

DUST COLLECTION FOR THE

SMALL SHOP

It seems that are more articles written about dust collection than those that discuss “how to build a router table”.  We installed a system about 3 years ago and it has proven to be the very best investment that we have made.   One of the amazing things that happened is that it reduced the amount of colds that we get every year and our general health seems to be better.  We work in our shop every day and for the weekend user you may not notice this type of change.  The most important thing is, the shop is cleaner, not dusty and I am sure that we must be healthier with the system.

 There are five things that you need to consider before planning the size of your system.  How much to spend, type of collector, piping, location of the machines and sound levels.

Today there are many manufactures of systems and we will provide a list of them at the end of this article.  Before we start let me discuss the advantages of plastic pipe verse steel.  Drain and ABS plastic pipe is inexpensive, easy to work with and many people use it.  One thing that happens is that static electricity builds up and can suddenly discharge and spark a fire or even worst an explosion.  Losing your shop or your home to a fire because plastic pipe, is too high a price to pay for saving time and a couple of bucks on the system.

Static electricity occurs in steel pipe, but the difference is that grounded steel pipe discharges the electrical charge. Galvanized sheet metal piping is strong and light an only takes a pair of tin snips, a pop riveter and a crimping tool to install an entire system.  You will find that 24-ga.or 26-ga. HVAC pipe is available at most home supply centers.

The following are suggestions on sizing the branch ducting for your machines. (CFM cubic feet per minute)

We have found that the three highest producing machines, are the planner, shaper and the table saw.  The planner and shaper for the bulk and the heavy chips and the table saw for the continuous amount of material produced. If you put these machines at the end of the system you may find that the large chips from the planner will build up in the pipe.  Source the largest producers as close to the beginning of the system as possible.

Our system is 2 hp and has an estimated cfm of 1450.  Our main line from the collector is 6” stepped to 5” for the line runs and 4” to the machines.  Each machine has a separate blast gate and there are no hard 90-degree turns in the system.  We used the large radius elbows and it really helps the material negotiate the turns.  When we merged the ducts we used 45-degree wye connectors whenever we could.

The continuous noise level that the collector generates can be annoying after a long day in the shop.  If you surround the collector with a rolling 2x4 panel with drywall and some insulation it will reduce the level quite a bit. We have wired the collector to turn on with a hand held remote that works very well.

Sandor Nagyszalanczy has written one of the very best books on dust collection and if you are considering adding a system you should spend the time reviewing it. We carry the revised edition AFD325 and it retails for $18.95

HOW TO DESIGN THE SYSTEM

Shop Layout

You need to consider the limitations of your workspace.  Most shops today are 2 or more garage areas. As discussed earlier, place the machines requiring the largest cfm of airflow closest to the collector.  Our suggested cfm chart will help in locating your machines.

Shop Drawing

Using grid paper, make a scale drawing of your shop and the exact location and diameter of each dust port. 

Determine the CFM requirement for your shop

Add up all the cfm requirements for all the machines dust needs.  The cfm for the entire shop may exceed the capacity for the dust collector.  It that is the case, blast gates will allow machines not in use to be isolated from the dust system by closing off those machines.  There are some blast gate manufactures that have systems that sense the electrical use of the machine when it is turned on to automatically open the blast gate. 

Locate the position of the main duct line.

Be sure to run the ducting so that it ends directly above each dust port. 

Determine the necessary duct size.

On your drawing begin at the machine farthest away from the collector and work back towards it.  Determine the appropriate diameter of the pipe from the CFM needs at the first machine. Continue on to the next machine. Size your branch from the chart above for pipe size.  Continue on to the remaining machines, adding blast gates as necessary until the main line is equivalent to the size of the collector inlet. 

Turn on the system and check for leaks as there will be many.  GE silicon sealant works very good and in some areas you may wish to use duct tape as it may be necessary to remove a section of pipe when a large piece gets stuck.  The main culprit for this is the table saw, as very small narrow cut offs about 6” long end up in the system and can get caught side ways in the pipe. 

Enjoy the good health, clean shop and all the other benefits you will find after you have installed your new system.

Brian Murphy
American Furniture Design Co