Q: Major bucket collapse: When I used my Fein vacuum without any power tools I didn’t have any problems. I tried to use the Dustopper with a DeWalt palm sander and was sad to see my bucket collapsing. What is a good way to prevent this?

A: First, some simple “physics.” Vacuums suck! It’s that simple. Some more than others!  If one looks at the performance specifications of the European vacuums, they will notice they can lift a column of water as high at 90” or more. In US terms, this specification is called “Inches of water lift”. In other words, if you had a clear hose with one end immersed into a bucket of water, and a typical European vacuum connected to the other end at a height of 100 inches, the suction power of the vacuum is enough pull the water almost all the way up! This distance is measured and recorded as the vacuum’s suction specification. Your Fein vacuum has a water lift specification of between 90 and 99”.  This is NOT a measure of how much air flows. More on that in a minute. Bosch, Fein, and Festool vacuums all have suction specifications that exceed 90” of water lift. US-made vacuums range from about 40-60” of water lift.

From Fein’s website: Vacuums having strong suction along and good flow, or cubic feet per minute (CFM), can easily lift very dense debris like screws and nails. Both flow (CFM) and suction (inches of water lift), are necessary for good overall performance in a shop setting. Manufactures of all vacuums know they must make the dust compartments of their vacuums strong enough to withstand maximum pressure should the end of the pickup hose be closed off or plugged, otherwise the dust compartment would collapse. Since a bucket with a dust separator was not a part of their original design consideration, vacuum design engineers had no concern about what could happen when a standard 5-gallon bucket was included in the air pathway. Vacuums with high suction are great at pulling debris away from cutting tools like routers, drills, CNCs, etc. Vacuums with high flow are better for planing, cutting dados, or any other operations where large volumes of debris are made very quickly. There’s no such thing as a “best” vacuum; it largely depends on how you use one.

Here’s what is happening with your bucket:

When you attach a palm sander to the end of the hose, the pressure differential between the outside and inside of the hose is very high. If there is a bucket and a separator in that air pathway, the surface most impacted by the pressure differential will be the inside of the bucket.  That means the walls of the bucket are quickly drawn inward, causing the bucket to collapse. Buckets, incidentally, are designed to work with pressure from the inside-out, not from the outside-in.

Below are some photos of modifications I’ve made to hose adapters that will usually eliminate the problem. The holes in the reducer allow air to continue flowing thereby keeping the internal pressure from causing the bucket to implode. These images are with the original Dustopper, but the concept is the same with the Dustopper PRO.