If you’ve ever wanted to improve dust collection at the tablesaw, knowing how to measure its current efficiency is a great place to start. Obviously, the dust collector unit itself plays a large role in the overall performance of the system. For instance, a 2-3 hp cyclone will outperform a 1 hp single-stage unit over time. Likewise, the diameter and layout of your ducting has an impact as well. But how do we quantify the collection efficiency?
As it turns out, it’s a pretty simple process, and all you need is a digital scale and your candy bowl from last Halloween. Put your anemometers and airflow sensors away, and get out your postage scale! Believe me, its hard to put the technical toys away, and I will use the anemometer to test performance of the dust collector unit itself. However, when testing the system as a whole, ie: the tablesaw, shrounds, deflectors, ports, ducting and collector… simple weight measurements are often best. Plus, these tests are accurate and highly repeatable.
Start by selecting two boards about 3-4’ long. One should be hardwood, and the other should be plywood. This will make it a “real-world” test that produces a meaningful number, since most shops use a variety of solid and veneer products. Using a digital scale, obtain a starting weight of the wood you’ll be cutting. Weigh it twice to confirm the precision of your measurements, and record it in a journal. Empty your dust collection bin, and clean the tablesaw inside and out. Next, proceed to rip the boards into ¼” strips until you’ve made 7-10 cuts with the hardwood board, and 7-10 cuts with the piece of plywood. The number of cuts isn’t critical, but you want to have a large enough dust sample for a valid test. Be sure to set the blade ‘half a tooth’ higher than the material being cut for optimal dust collection. Also, avoid ‘skimming cuts’ where one side of the blade is exposed during the cut. Make each rip cut at ¼” for consistency between tests.
Next, carefully empty the dust collection bin into a bucket. Sweep up any dust you spill, and transfer it to a container on a digital postage scale. Make sure to zero out the container on the scale before slowly dumping the sawdust to be weighed. I used a large plastic bowl, the Halloween candy bowl in fact, and that worked just fine to contain the dust, which typically weighed in around 1 lb.
Now weigh the remainder of the wood from your tests. Subtract that number from the initial weight of the wood to find the difference in wood weight. This represents the total weight of wood lost during cutting, and we’ll calculate what percentage was recovered. The formula looks like this: Initial Wood Weight – Final Wood Weight = Total Weight Lost
Dust Weight / Total Weight Lost x 100 = Percentage Efficiency
So, for instance, if your dust weighed 17oz. and the total weight lost was 18.2oz
17 divided by 18.2 x 100 = 93.4% efficiency
All this helps to establish a baseline measurement. Then, as you proceed to make modifications to your tablesaw dust collection, you can re-test to see if the mod helped or hurt the systems performance. Just like ‘jetting out the carbs’ on your old motorcycle… it may or may not help overall performance until you swap the exhaust to match. The only way we know for sure is to test the overall system. Limit yourself to one change at a time, then re-test to see how you did.
My wife and high-school sweetheart helped me throughout this process, and we found it was a fun experiment. We both felt like we were back in science lab! In the end, her ideas vastly improved tablesaw dust collection. Our dog Trooper doesn’t have as much sawdust to roll in, but he’s still happy to be in the shop. Stay tuned for a video of dust collection mods on the Laguna Fusion F2 tablesaw!