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I have a question…. I am sure that many LJs' can help me. Now that my workshop build is nearing completion, I want to make a new Dust Collection "Box" for my De Walt DW708 Compound Mitre Saw. I have trawled the net and see any number of ideas. I am looking for an idea that REALLY works!! Every concept that I could find seems to have one or another shortcoming. Maybe some kind of venturi type of box is what I am leaning towards. The SCMS is in a permanent position in the shop, I don't do many compound cuts and I have a large space availalable behind the device.

Any offers?

Thanks in advance
Cheers
Tobiasza
 

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Is it a slider mitre saw? I found MS dust collection one of the most frustrating aspects of my shop; I use my MS a lot and it is the biggest dust producer. I tried a number of different blade shroud designs and different hood designs; they improved the dust collection but it was still poor. Eventually I upgraded my DC to a 5hp Clearvue; this pretty much solved all my MS dust collection problems. I have a simple hood with a 6" port; the increased airflow from the larger DC made the design effective.
 

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Hi. Thanks for the reply. Yes, it is a sliding compound MS. I am running a 5hp installed Dust extraction system with a large steel cyclone and plenum box with filter bags. There are some pics on my workshop page. Do you perhaps have a picture of your setup on your MS?

Cheers
Tobiasza
 

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I wish you the best of luck, and I'm fairly certain you'll won't meet your criteria of "really works". If the 708 is open under the blade it adds another place to catch dust; that's the way my Dewalt MS is made.
 

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Given the light weight dust coming off the miter saw, it would also serve you well to use a dust collector instead of a shop vac as high air flow is much more important than being able to generate a high vacuum.
 

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Discussion Starter · #8 ·
Thanks very much for the replies.
BBY: I am using a full DC system. see pics on my workshop page.
Fred: The saw is not fully open under the blade, its more of a tiny shallow trough with an extremely small opening at the rear.
WhyMe: Nice work. Thanks for the pic.

I have a 4 inch port with blast gate going to the DC system. Somewhere I remember seeing a box that acted as a venturi, creating an area of faster air speed at the opening caused by the mid section low pressure of the venturi, just cant find the image. It seems to be a very sensible idea.
Cheers
Tobias
 

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OOOh, this is a thread I can really get into, cause I'm faced with the same thing. I have a antique craftsman compound mitre saw that I use a lot. It came with this little bag that sticks out the back of the blade mech and I guess it was supposed to collect dust, but of course that is a fallacy cause the dust has no reason to travel up that path on it's own and into the bag since there is no natural airflow that way, however removing the bag and sticking a shop vac hose does wonders to cut down on the amount of dust it generates, but it still spits a ton of dust especially to the rear of the saw. I had envisioned a arrangement like Why4ne is using behind the saw, hooked to my 4" DC system with a router table style split that would suck air from behind and thru the weird blade thing. I've already bought a Rockler router table connector and associated fittings and hoses for connecting it all up. Why4me, I love your idea of using drywall corner material to join things up, I would have never thought of that. I actually have some of that on hand, but unfortunately it is already allocated to other purposes, but the stuff is so cheap it not a concern. I'm definitely going to watch this thread for a couple days for ideas.
 

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I'll add a caveat. The dust shroud does a fair job of collecting the saw dust but is not perfect in anyway. I usually place it so the shroud is slightly tilted up so the saw dust that collects on the bottom has a tendency to slide down closer to the port to be sucked in. The use of the drywall corner bead was a one of those brain farts when I was trying to think of an easy cheap way to connect the thin lauan together. Obviously I could have used some same square strips of wood to connect the panels but I had the corner bead left over from some drywall work.
 

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I haven't done anything to mine yet, but I noticed that alot of dust goes sideways and down. Thus, the rear feet of the saw get covered. I'm thinking of doing a traditional dust hood for the rear, and then make a large chute under the saw that has cross-members to support the saw. Only issue is, I dont think my harbor freight dust collector can handle two 4" hookups.
 

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Discussion Starter · #12 ·
I agree that the dust coming off a mitre saw is light and small. The problem is that although it is quite contained in it's horizontal plane when doing a cut, but the vertical plane changes dramatically from the beginning of the cut to the end of the cut. Have a look at the following video that I found on YouTube, and let us know your thoughts

Cheers
Tobias
 

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Mine is just a storage tub with a toilet flange on the bottom to connect to the DC hose.
I have to be able to remove it to use tools behind the SCMS. That's why it's on a stand.
Mine's not perfect either. But, it contains MOST of the dust not caught by the saw's bag.


 

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Discussion Starter · #16 ·
Hi Gene, That is the kind of thinking that amazes me, extremely lateral thinking! Great idea for anyone who needs to move the capture box around often. I love the wooden knob, great touch. Thanks very much for sharing yet another angle on this thread. I shall look at plastic tubs and bins in a whole new way from now on!

Cheers
Tobias
 

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I'm on my third miter saw dust collection build and two things about collecting dust with a miter saw. Either you have a shroud that has a powerful enough dust collector connected to it that it can pull fast moving sawdust out of the air or you enclose the back, sides, and front of the hood to contain the dust so that it can be cleaned up later.

With dust hoods, the dust is ejected with enough force that it bounces out of the hood at you. Either suck it out or cover the front so it can't leave the area. Placing a suction vent at the bottom of a hood is almost meaningless. Half the dust bounces back into your face before it ever falls down to the suction port. Here's something I've done but still have not contained all the dust.
 

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I made a diamond shaped hood, flat on top, with the front open , just enough to fit my DeWalt SCMS used at any angle. I have a six inch dust collector venting it at the bottom with a screen on it. It exhausts the light dust but not all the heavier sawdust, so I shovel it out of there every six months or so.
 

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Discussion Starter · #20 ·
Hi C on the L….. Thanks for your input. I am seriously of the opinion that the venturi effect can be successfully applied to a SCMS hood/box. I just don't know enough about venturi application, other than a very successful vacuum venturi that I had in my compressor line some years ago for my vacuum press.

Lets keep thinking

Cheers
Tobias
 
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