Question about dust collection on a Bosch 4410 Sliding Compound Miter Saw

I have been setting up a newly purchased Bosch 4410. I am in the midst of a project where I have to do a bunch of miters so I wanted to use the saw before building a proper dust collector for it later something along the lines of this:
http://www.bburke.com/wood/jigsandtools.html
I had hoped that the dust collection bag that comes with the 4410 would capture maybe 75% of the dust. After a couple of test cuts, my floor has saw dust all over it and the collection bag is nearly spotless. Is there something I might be doing wrong or is the bag just some kind of placebo?
TIA.
Dick Snyder
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You know, I was just going to post a similar message. My Ryobi dust bag catchs less than 10% of the debris, and I was wondering if that was normal. I guess you have the answer to that one.
I sure wish I had room in my shop for a hood like your link!

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You probably aren't doing anything wrong. Miter saws just don't do a good job of collecting sawdust. I finally put mine on a rolling cart and do most of my cutting in the driveway.
Dick Durbin
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Dick Snyder wrote:

midst of a

saw
the
would
has saw

placebo?
I built a collection hood similar to the one shown in your post for my Bosch SCM. It has a 4-inch port connected my Jet dust collector. I also removed the saw bag and connected the saw port directly to the dust collector. Even with that setup about 10-15% of the dust blows out the front of the hood. The reason is suction from the dust collector doesn't create enough velocity at the front of the hood to counteract the "fan" effect created by the blade. And when you slide the blade all the way out it's worse. Consequently I use a dust mask when I use the SCM.
I've been considering adding a blower to the top of the hood which would exhaust into some type of large dust bag. Or maybe not. My observation is a dust collection system only delays dust and chip build up in a shop, it doesn't prevent it.
David W.
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David, your reply is kind of discouraging but I appreciate the real world feedback. I will still go ahead and make the dust collector but I will plan to use my dust mask. Thanks. If you make any improvements that improve things, please put up a posting so I can learn from your experience.
Dick Snyder

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Dick...
My HItachi slider and my friend's DeWalt slider do the same thing. Frankly, I'm not ready to commit the space to one of those "ducts" because I've heard they don't work all that well anyway. If you had a 5HP cyclone drawing right behind it the dust might be OK, but I actually find that letting it kick onto the floor and then vacuming it up actually keeps the air in front a lot cleaner.
A 1.5HP DC with a floor sweep behind where you cut might help.
Mike
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