What is Good Dust Collection Air Flow?


Woodwork hobbyists know of the mess they create in their woodshops, those piles of chips and shavings that collect beneath your table saw or planer.  For many, dust collection probably means a dustpan and brush at the end of the day, which is fine for the larger particles and shavings that you can see.

But, what of the finer particles that float in the air?  Your dustpan and brush aren’t going to collect them.  Safety glasses will keep it out of your eyes, but unless you wear a mask that covers your mouth and nose, you’ve likely inhaled some of that dust, too. 

There are serious health risks to prolonged exposure to and inhalation of workshop dust.  These risks are real, and protective measures must be taken by woodworking enthusiasts regularly exposed. 

A good dust collection plan is essential to any shop. There are some excellent resources online with the calculations already done based upon the size of the shop, amount, and frequency of work done, to measure both the exposure and the means necessary to protect yourself from it.  We’ll touch on just the basics here.

Dust Collection Systems For Woodworking Shops

To make a meaningful and informed decision on what type of dust collection system(s) your home woodworking shop needs, it’s important to understand a few terms that apply.

  • Cubic Foot – picture a box, one foot tall, one foot wide, and one foot deep. It would hold a cubic foot of air.
  • CFM – cubic feet per minute and refers to the volume of air a dust collection system is capable of moving.

Measuring the CFM a dust collection system can move is a factor of its engine size and fan blade size.  The blades turn, sucking in air from one direction and pushing it in the opposite direction (through a tube), and either depositing the larger debris into a collection container or filtering out small particles and releasing the air back into room circulation.  Good airflow through these systems is crucial to keeping filtered air circulating well throughout the room.

Both of these actions, moving larger debris and filtering air, are important in the woodworking shop.  It is the amount to be moved/filtered that determines the dust collection system your shop needs, and the size of the operation and the number of tools generating that debris determine that volume.

How is Dust Collector Size Determined?

The dust collector size, then, is a factor of these considerations.  With a high number of power tools – table saw, band saw, planer, table sander, hand sanders, chop saw – a high volume of dust and debris is created and needs to be moved and filtered.

Generally speaking, a power tool from that list with a lower dust and debris creation during use and generating chips and shavings and large particles will call for a CFM of about 300; and for a tool generating a large volume of wood shavings (like a planer, for instance), would require 900 CFM and up.

Although there are ¾ hp dust collectors at 650 CFM, and while that would be fine for the single tool generating a small amount of larger chips, shavings, and large particles, they would be inadequate for a larger tool needing 900 CFM and beyond to clear away its debris.  They might be okay for a shop with a single table saw and the occasional use of hand sanders, but a serious hobbyist is likely to have more than that going on in his or her shop.

Is a 1.5 hp Dust Collector Enough?

How about doubling that size, then, and moving up to 1.5 hp?  Most serious woodworking enthusiasts would recommend this, as it will have a larger impeller (it makes the air/debris move) and better airflow.  You’ll have a better chance at moving large chips.

Some, though, recommend even more power, especially if you operate more than one tool at a time.  A 2 hp or 3 hp dust collector can move more volume faster and handle larger debris easier.  You’ll know the number of machines likely to be used simultaneously and how much debris they will generate, so plan accordingly.

How Much CFM Do I Need For Dust Collection?

Let’s briefly touch on dust in particular and how much CFM you will need for dust collection and filtering.  Safety goggles and masks that cover your mouth and nose are an essential part of workshop safety.

The health risks of prolonged inhalation of shop dust are very real and dangerous. 

A small shop with few tools and a small amount of dust and debris to be moved/filtered is not such an inconvenience to move a length of hose from one tool to another for collection.  But, in a larger shop and with more tools generating debris and dust, the more convenient system will rely upon a collection of ducts throughout. 

This would mean you can hook up a connection pipe to each tool and collect the debris and dust to be whisked away to its collection container.

The air speed through such a system is critical to its effectiveness, too.  Engineers recommend a speed of 4,000 feet per minute to move woodshop dust and debris or a wind speed of about 45 miles per hour.  Velocity depends on duct size, so the design of your system must include these calculations.

When choosing the engine size for your system, 2 hp, and 900 CFM, 3 hp and greater than 900 CFM, the amount of debris to be moved (based upon the number of tools being used), the air speed needed to move it through the duct system, and the duct size required to handle that velocity, all factor into your decision.

Where To Get Help

Online resources will get you started, of course.  So will the better salespeople at the large DIY stores.  Perhaps, for the larger shops, an engineer should be consulted.

And, for the true DIYers who want to build everything for themselves, you can even start with a simple and inexpensive shop vac and assemble your own dust collection system.

Here’s a video to show you how:

The point, though, is that no matter the size of your shop, a dust collection system is smart, healthy, and essential.  That’s not to say you won’t still need a dustpan and broom, but it will cut down on their use.