A Workshop Air Filter, UK Edition

With the MVP Workshop up and running, one of my first priorities has been air filtration. I needed a portable filtration solution for sawing and sanding, to prevent everything getting coated in a fine layer of sawdust.

There are lots of videos on building Corsi–Rosenthal Box-style air filters for workshops. Two I found especially useful are The 3D Handyman, who has tested many variations to find the most effective design, and Simplifycnc’s clear step-by-step build video.

As these designs originated in the US, they rely on hardware that’s not common in the UK. Notably 20” air filters for US HVAC systems and square box fans designed for sash windows. Box fans in particular aren’t readily available at 240 volts, which is what attracted me to a drum fan design.

Here’s what I used:

• 4 x 20” MERV 13 filters: US-made filters, coarser than HEPA but suitable and affordable
• 16" Drum fan (240v): A refurbished model, with a cowling that allows it to sit flush atop the filter box.

Using Simplifycnc’s frame design, I built a housing for the filters and routed a circular hole for the fan. One of the key tweaks with this style is having the fan pull air in before pushing it through the filters. The 3D Handyman shows this in action in a workshop setting, and notes you can flip the fan if you need more general air circulation.

It’s early days, but I’ve already noticed a big improvement in air quality. Running the filter with the door open clears stale air faster, and my humidity sensor drops to more comfortable levels. I’ll still need to mask-up when generating lots of dust but this was a satisfying build that’s already making the workshop fresher and more pleasant to work in.