CNC budmen face shield

Getting started

The Budmen mask was the first popular face shield that we became aware of. The main issue was that initially it was a 3d printed design. The print took ~5 hours to complete. We wanted to investigate faster ways to make compatible shield holders. Angela sliced up the model and laser cut parts. These were a couple minutes per mask, but required glue to assemble, and since they were laser cut acrylic, they were quite brittle, and not alcohol resistant.

CNC

I modified the design just enough to retain the same barb geometry, while allowing an endmill (1/16th”) to get into the recess, but still maintain the same length of flat on the internal barb face. After some tool-path tweaking, i got the machine time down to about 2 minutes per mask. That was not the limit of what was possible, but it was quite enough. From sheets of 1/2” HDPE stock, i could get 99 masks, and they required little to no cleanup. Importantly, the HDPE is immune to alcohol (a powerful disinfectant against covid), and were significantly tougher than the 3d printed or laser cut versions.

Stock usage was not particularly efficient though, which has a negative environmental effect.

Compatibility

It was important to retain cross compatibility between the original 3d printed design, and the laser cuter version. This simply means that the barb geometry and spacing needed to be consistent. This allowed the clear plastic shield itself to use used all three variants of the holder.

Scaling

After proving out the process and sharing the files, we contracted local machine shops to produce these masks for us. In a few months, we were directly responsible for 25,000 masks.

With contacts at Boston Scientific, through a zoom call, we inspired them to make over a million masks based on these designs.

https://www.somethinglabs.org/blog/1000000-face-shields-by-boston-scientific