J. Phil Thien's Projects

I was discussing the baffle design today with another woodworker, and there are some interesting things to try.

One problem with Dust Collection in general is the tradeoff between velocity and volume. For chips, you want velocity. For fine dust, you want volume. With the smaller DCs like the one from Harbor Freight, 4" is about optimal. A 6" pipe would be better for the fine dust, but the chips would get stuck. This could be used to an advantage on the trash can separator, by making the inlet 4" but the outlet 5" (or even 6" - whatever fits on your DC). Since we have a sealed system, increasing the pipe size will cause a drop in velocity, which is exactly what we want to further reduce scrubbing.

Again, this is a tradeoff. Even though the fine dust is very light, you still need some velocity. So don't reduce your trash can lid to just the rim  :)

An outlet of 5" precludes the use of PVC, but 5" metal fittings are readily available at the local home center. 5" hose is not as common as 4", but not too difficult to find on Amazon or Grizzly.

Increasing the outlet size may not make too much of a difference on the smaller systems. And for the average woodworker, it's irrelevant whether the baffle efficiency is 97.2% or 98.5%. But, with larger impellers and motors, this could be important.

Bas.

I built my own trash can separator, using particle board for the lid. It's a 40 gallon can, metal, with the hoses attached to the lid via PVC fittings. The dust collector I'm using is the Harbor Freight "2HP" model, with a Wynn cannister. My shop is pretty small, the longest run I have is ~25 feet.



The results of the separator (without modification) were so-so. At first, I still had to empty the bag as often as the can, the "scrubbing" was awful. By tweaking the size of the pipe inside the trashcan, I was able to improve this slightly, and now I could fill up the trash can twice before having to empty the bag. Better, but not great.

I built the baffle from your design out of some particle board (5/8"). Probably overkill, but it made it easier to seat the dowel spacers, and I also happened to have some left over from a previous project. Construction was very simple using the pictures posted on your web site. A router, a Forstner bit, glue and screws: DONE!



The results are nothing short of spectacular! I haven't done any formal testing, but 95% (if not more) of the dust now stays in the trash can. Only the very fine dust ends up in the bag. And it is MUCH easier to empty the trashcan than emptying (or replacing) the bag. Getting the metal buckle around the bag can be a tricky job, only having to empty the bag once a blue moon is a real lifesaver! In the pictures below, the trash can is about 2/3 full. The dust in the bag is minimal, maybe 2 cups (if not less).




I can't believe what a tremendous difference this modification has made. The two hours I spent making it (including cleanup and shopping for the materials) will be recouped within a couple of weeks simply by not having to hang a new bag. Thanks for sharing the design! You should definitely pursue your patents, or at least recover some of your investment by selling plans on building a better separator.

Bas.