Saw dust extractor

I built a small dust/chip separator today. I combined an old 10 gallon shop vac with a Home Depot bucket. Again, I looked at many Youtube videos and put this unit together. I still need to add some silicone to where the bucket fits into the the hole I cut out in the clamping top of the shop vac and around the inlet tube. I did at test run on it to see if it was even going to work. Did a good job but didn't have the shop vac perfectly clean before I sucked up some debris. When I check the shop vac after pulling saw dust and chips out of my other Vac, I did find more dust on the bottom than I though I would. I took a lot of photos of the build today but won't put you all to sleep by posting them all! If you are interested I'll try linking my Shutterfly account.

If you are familiar with the Thien-Baffle disk and have any ideas about fine tuning it, I would love to hear from you. CIMG0004.jpgCIMG0024.jpgCIMG0025.jpgCIMG0028.jpgCIMG0064.jpgCIMG0065.jpgCIMG0050.jpgCIMG0051.jpgCIMG0072.jpgCIMG0073.jpg
 
Interesting mod, makes for a nice compact unit :thumb:

Strongest piece of advice I can give is a thinner baffle. Separation efficiency appears to be almost directly proportional to baffle thickness up until where the baffle starts to wobble from the airflow.

I suspect if you moved the baffle up a fair bit closer to the inlet it would also work better, you want it to swirl and drop out before the outlet has a chance to suck it up... if the baffle is to far below the inlet you loose a lot of the swirling action. The baffle shouldn't probably me more than one diameter of the inlet below the inlet and likely closer than that even.

You might also want to start with a narrower slot for this setup. The narrower the slot the better the separation as well, up until it clogs.. at which point you need to make it wider (I had a rather long series of iterations on that getting the baffle I built for my HF collector to work with my planer :D)

Not sure how much you reckon you're capturing at this point? Mine is "tuned down" to accommodate the planer without clogging up and I kind of messed up the baffle by making it a bit to thick and having to shave down the underside with a router.. but it still takes out at least 98+% of the dust and pretty much 100% of the chips of any measurable size (except when I overflow it :eek:).
 
Looks like that will make for a smaller footprint which is always a plus. Just so I'm clear on what I'm seeing, this is just the separator/container right? There is a vac upstream somewhere pulling the air from the top, yes?
 
Looks good Royall...nice compact footprint. I'll echo Ryan's commend on the baffle thickness and proximity to the inlet. I added a Thien baffle to the separator of my Harbor Freight DC and put the baffle right below the inlet.
 
At Glen: Yes, there is a Sears shop vac pulling the air.

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Ryan, I base this unit largely from Matthias Wandel design. His is a hybrid of a Thien baffle and a cyclone, thus the greater distance between the lid and the baffle. How thin and how did you support a thin baffle? I went with the 3/4" so that the screws would have enough meat to support the baffle in place. The width of the opening I went with is 1 1/4". It is less that what Thien, called for in a PDF file I found. He stated the baffle can be scaled to what ever size but the gap size of 1 1/2" is a constant.

I'm not going to tune this unit for the planner or jointer. I have an old Grizzly 1hp with 4" hose for those. I feel the important machines to tune to are the ones that make the finest dust, IE my sanding machines, router table, and band saw (if I can figure a way to get my bs closed up enough)....

I will try moving the existing baffle up closer to the inlet and see what happens. I need to caulk around the bottom of the bucket too so there are less air leaks. Another "work in progress"!!

 
Ryan, I base this unit largely from Matthias Wandel design. His is a hybrid of a Thien baffle and a cyclone, thus the greater distance between the lid and the baffle. How thin and how did you support a thin baffle? I went with the 3/4" so that the screws would have enough meat to support the baffle in place.

My design is substantially different and my baffle is actually supported by the separator body pretty well (I built the "top hat" design so the supporting area of the baffle is inset into the walls of the separator) so it won't translate directly to your build but I ended up about 1/4" thick with the edges feathered a bit thinner (mine is actually sheet metal topped plywood routed to thickness - I don't advocate going that route in anyway shape or form :rolleyes:). I know some have managed to use as thin as 1/8" hardboard but that can get a bit wobbly although it might work in as small of a space as you have here. Most common seems to be 1/4" tempered hardboard (smooth side up). Soaking the edges in a bit of glue and then buffing them smooth also seems to help eek out that last smidge of performance (I did basically that more or less).

With your setup the challenge will definitely be to figure out how to support a thinner baffle. My best idea (I've seen some other builds that did similar and claimed to work so its not really "my" idea) would be to suspend it from the lid with some standoff posts. You'd want to make sure any penetrations through the lid were sealed up really good but it would be a fairly simple change and I believe it would also make emptying the collector easier. Interestingly the supporting posts don't seem to have any meaningful impact on airflow.

Here's an ancient post by some random guy named Vaughn ;) that illustrates roughly what I'm thinking of (except as usual its upside down from the way I think)
http://www.jpthien.com/smf/index.php?topic=145.0

Side note: there is a ton of good info in on Phils forum.. if you can find it!!

The width of the opening I went with is 1 1/4". It is less that what Thien, called for in a PDF file I found. He stated the baffle can be scaled to what ever size but the gap size of 1 1/2" is a constant.

I'm not going to tune this unit for the planner or jointer. I have an old Grizzly 1hp with 4" hose for those. I feel the important machines to tune to are the ones that make the finest dust, IE my sanding machines, router table, and band saw (if I can figure a way to get my bs closed up enough)....

Yeah as general advce the 1.25 - 1.5" gap is generally good but my experience (and comments I've seen from others) indicates that a narrower slot == better separation up until airflow or material flow is compromised. I started at 1" and got really good separation with the table saw and sander. When I hooked up the planer to it it instantly clogged. Opening up the gap allowed the planer to work but now I see a bit more bypass with the tablesaw and sander dust (not a lot but it went from sparkling clean filters to observable dust). Since this is a high pressure low volume setup my intuition claims that a narrower slot will work quite a bit better - I might try 3/4" or even 1/2" and see how it works. If you do the suspended baffle then opening it up more is pretty easy to do so the risk would be fairly low.

I will try moving the existing baffle up closer to the inlet and see what happens. I need to caulk around the bottom of the bucket too so there are less air leaks. Another "work in progress"!!

I'd bet any gains will be marginal with the thicker baffle but am definitely curious to hear how it works.

Speaking of air leaks, ANY air leaks in the bucket/baffle system (and I mean ANY) will throw all other enhancements, tuning, adjusting, performance completely out the window. This goes for both the top and bottom of the airspace. If you haven't done it yet I'd put some sort of gasket material around the lid seal and aggressively hunt down all air leaks (a stick of incense is handy for this.. just move it around and see if the smoke moves). This was definitely one of the harder parts of getting my system to work and when I spent the time to do it helped a lot.
 
I'll run a test the way it is now, then start tinkering.

Ah one more thing I forgot. When testing don't overload it by shoving the end of the hose into a pile of sawdust (unless that's normally how you would use it :D). The separation capability seems to have an "overload threshold" so if you test it with a similar rate of inflow to your normal use case you'll get better data.
 
funny that you said that.. that is what I did, as that is what I've seen done! It may have been why I had so much powder in the shop vac. I did think it odd that you would overload a system but thought that is the way it is done! LOL OK. I'll hook it up to my router table with it's nice new fence I build and run a given length of wood X number times for a bench mark. Hope I don't get a headache over thinking all this!! LOL
 
:D Heh.. don't over think it to much, I just put down a sparse pile and sucked that up at a not to fast of a rate. I know when I stuck the end in a big pile it wasn't that great of a result.
 
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