Solder fumes can be dangerous to breathe, especially over a long period. That’s why, here at the OMC factory, we’ve spent a lot of time using and developing solutions for extracting nasty solder fumes while we work.
Months ago, when we began developing wiring harnesses and the board assemblies that make every Othermill run smoothly, we invested in a benchtop fume extractor. We quickly added an LED bar to the top of the extractor to improve the soldering experience. It worked great, as long as the soldering happened close to the extractor, but if we wanted to solder a batch of boards in one go, we quickly moved out of its range, rendering it useless.
In order to improve the range, we tried building a connection between the soldering iron and the extractor with some tubing. This worked well for extracting fumes no matter where we were working, but the tube was obstructive and often got in the way.
Finally, a member of our hardware team, Joachim Pedersen, decided to build a downdraft table. The concept is similar to the desktop fume extractor — to remove all harmful fumes from an area — but accomplished by pulling the fumes down through the table instead of up and away through a smaller device. Extracting fumes over an entire work area also opens the possibility of using our extractor for non-soldering tasks where fume extraction is still necessary — for example, when applying nasty adhesives or cleaning parts.
We’ve really enjoyed using our downdraft table and are happy to share our build details with you.
Build Your Own Downdraft Table
A DXF file of the parts is available for download here, and a 3D model (courtesy of Autodesk’s A360) is at the bottom of this post and at this link. We waterjet-cut some cheap, 0.2"-thick plywood to build the table. You can cut material this thin with many laser cutters. If you do use the DXF file, make sure you adjust the fingers and finger cutouts to fit your material thickness.
We used three big cooling fans attached to the inside of the back piece (number 5) to do the extraction. On the outside of the same piece, we protected our fingers from the fans with grates. We used a daisy chain cable to connect and power all the fans together.
Our work surface acts as the main filter for the downdraft table, using a high-efficiency MERV 13 air filter. In order to raise the objects we’re working with off the filter itself, but still allow air to pass through, we cut and bent some hexagonal perforated sheet to cover the filter. This removable work surface makes it easy for us to replace the filter when we need to.
As an additional stop-gap to ensure the air coming out of the back of the table is odor- and residue-free, we placed two odor-removing felt sheets between the work surface and the base, along with more of the perforated sheet.
In order to test the pull strength of the new table, we used a smoke-generating pen. We’ve had one for a while now and find that it’s useful to visualize fluid flow in any situation (including how air moves around inside the Othermill).
And that’s it! I’d love to see this sort of downdraft table built right into an electronics workbench at some point. Please let us know if you use the files or modify them in any interesting ways! Reach us at firstname.lastname@example.org.