Mini dust collector 2 (a different approach to dust collection)
An update on my mini dust collectorWhen I built my mini dust collector, it was partly an experiment. It wasn't very powerful, but just enough to suck up the dust from my strip sander.
This made dust collection on the strip sander super convenient. No separate dust collector to turn on, no blast gates to open. I ended up using the strip sander a lot because I'd only have to turn it on and it was ready.
When sanding straight on the table, my Dylos particle counter hardly registered increases in airborne dust levels even standing right next to the sander.
I vacuumed off some of the dust using my small dust collector, then pulled out the first filter. The second filter behind it didn't have any noticeable dust on it. So maybe one filter is all that is necessary.
Building another mini dust collectorMy first mini dust collector had a 16x25" filter, but I had the idea of using a 20x25" (50x60 cm) filter, folded in half, to get more filter area in a smaller box. I cut part of the cardboard frame of this filter to allow it to fold better.
I cut the exhaust nozzle off the blower to allow for more air flow. The front of the housing had pieces missing, so I broke more off to fully expose the squirrel cage.
With the blower front missing, the squirrel cage is recessed by about 9 mm from the blower surface. I added a ring of plywood around the hole to extend it closer to the squirrel cage. This cuts down on how much air recirculates around the front of the squirrel cage, which should make the blower more efficient.
This made for a very snug fit. This way, I don't have to use any sort of sealant material to keep it tight. When I built my first dust collector I experimented with using felt for the seal, but shavings really stick to the felt, and it absorbs dust. Flat on flat wood is much more convenient, and tight enough as long as it's precise.
I cut off the 4" part on the bandsaw, leaving the 3" part and a 1/2" wide flange.
Then testing it with my belt sander. You can really see the dust getting pulled into the sander, though on a photo it's much less apparent than in the video.
And here it is put in place, to the left my other mini dust collector and hooked up to my belt sander and connected to that sander's switch so it turns on whenever I turn on the sander. Very convenient!
I also made one to attach directly to the back of the table saw, no hoses required. I added a small "dam" to the inside of the saw cabinet to keep the coarse dust in the saw. I will have to vacuum that out periodically.
The air flow for this dust collector was almost as much as at the end of the duct to my big dust collector, but checking how much dust ended up in the shop air with my Dylos, the air became much dustier than when using my big dust collector.
I did more experiments and made more measurements and eventually concluded that these fancy 3M filters ($19 each) are not nearly as effective than the cheap Garrison filter I used for my first one (two for $10). So I replaced the expensive filters with cheap ones to improve the performance. That said, I'm not using these filters in a way they were meant to be used, so maybe, as a furnace filter, the 3M filter isn't as bad.
With the mini dust collectors working well, my thinking is that instead of trying to build something with automated blast gates and automated power control for the dust collector, it's much easier to just build a small dust collector to be stationed at every machine, wired to the tool's own on/off switch. The goal isn't so much to suck the chips through ductwork, but to clean the air from inside the machine, leaving the chips in or at the machine to be cleaned out later.
Measuring dust with a
Dylos air quality monitor
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