In thinking about my new shop, I am planning on building a wood floor on top of the slab. 2×4 sleepers covered with 3/4″ plywood. I would like to run the dust collection in the floor. If I put the 2×4’s on edge, this would only be 3 1/2 high, smaller than even 4″ ducts. Unless I “squished” the ducts a bit, I would have to use 2×6’s on edge for 4″ or 5″ ducts.
Does anyone have an opinion on using the space between the floor, the 2×4’s, and the plywood as the actual space for the airflow (similar to the cold air returns between the floor joists in a house? Obviously it would have to be made air-tight. A hole cut in the plywood could then be fitted with a duct or dust collection hood to be connected to the tool or the collector. The inside could be painted or coated with polyurethane to decrease friction. I would think the increased friction of the wood and concrete surface would be more than offset by the increase in size.
Thanks for any comments.
Paul
Replies
Am I to understand that you want to utilize the space under the wood floor as part of the duct system instead of running pipe all the way through?
I think you'll have a problem with changing the geometry of the duct run from round to rectangular if I'm understanding you correctly. I think there would be a lot of turbulence at each end of the rectangular part of the run.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
I like the idea of getting DC ducting under the floor (God knows I'm tired of having to step over mine!! - lol), but I think that I would go to 2" x 6" joists and run circular ducting in the bays.
Using the joist bays as ducts will change the geometry and cross sectional area of your duct system from round to rectangular and back to round which will probably degrade the air flow and allow sawdust to accumulate in the bays. Getting an air-tight seal may also be difficult.
Whichever way you go, make the DC bays as accessible as possible. Sooner or later, you'll need to clean out a plugged duct - or modify the system.
You do not want ducts that are oversize for the expected airflow. If a duct is oversize, the air velocity is too low, and the larger chips fall out of the airstream. You will also get lots of turbulence--and further precipitation of chips--at every sharp corner.
-Steve
Steve,
Thanks. That makes sense.
Paul
This forum post is now archived. Commenting has been disabled