General Woodworking

[Mathnerd]

 I understand the need for a ZCI when cutting small parts on a tabsaw, but it seems to me that using one when ripping sheet goods or crosscutting large pieces limits the dust collection capability of the saw, and a lot of the sawdust is thrown to the front of the saw and winds up all over me.  Am I missing something or doing something wrong?

[Ted in Michigan]

Mathnerd -

     As far as dust collection efficiency goes, I'm thinking a lot depends on what type of saw you use. A contractor's saw (like mine) is an open base so dust collection is minimal at best. There are aftermarket "bags" you can attach and homemade enclosures you can make, but for the most part, it's shopvac time at the end of the day. A ZCI doesn't affect much either way.

     With a cabinet saw, it's a different story as there is normally some (often minimal) effort made to design the saw with dust collection. I don't have experience here but I'm thinking that the cabinet and overall saw setup and construction isn't airtight so a ZCI won't lessen the efficiency of the collection effort. On top of that I believe blade positioning will have the most impact on how much sawdust is thrown back at you. When I position the blade "just right", it'll eject a lot of dust from the gullets toward the front of the saw. Try raising the blade a little bit and see if that helps.

     The ZCI's purpose in life is to minimize tearout and give a better overall cut quality. You really gotta use one to get the quality cut you want.

[MSWOODcraft]

Also, much will depend on whether there's a DC system hooked up to the saw and turned on.     If the saw's got an enclosed base and is reasonably closed up then there would be some appreciable suction happening by the blade.   That goes a fair way towards eliminating the pixy dust from flying all over the place.

[Beaver Creek Woodworks]

A ZCI helps as the blade exits the cut.  It backs up the wood fibers thus minimizing tearout.  As far as dust collection goes, you could drill holes in the insert to give you "some" collection ability I guess.  I wouldn't drill too many though.  You want it to stay rigid.  The dust flying at you from the saw blade is only going to be captured by an overarm guard.  You would still use a ZCI with an overarm guard.

[don33butler]

It will also help to have a blade guard that has dust collection.

An over arm or ceiling supported blade guard with a connector for the dust collector is a fine way to minimize the dust that doesn't get into the saw cabinet.

[Howard Acheson]

>>>  As far as dust collection goes, you could drill holes in the insert to give you "some" collection ability I guess.

Nope, wouldn't work.  The board or panel you are cutting will cover the holes in the ZCI.  For all intents and purposes, the board or panel covers the front and sides of the kerf slot to the same extent as the ZCI.

The only way to capture dust ejected on top of the table is, as you said, by the use of an over arm blade guard hooked to the DC.

[georgenoeth1]

The piece you are cutting covers the insert whether it is zero clearance or not.  It seems to me that dust collection wouldn't be better or worse.  It is the quality of the cut and the issue of small cutoffs falling into the insert hole that make ZCIs desirable.  I always use one.

[grandpabear]

   this makes a lot of sense to me. if you have dust collection and are getting sawdust, you may need less air from other sources.

[william young]

I got my local sheet metal/furnace guy to make this up custom fit for my saw and I hook the DC hose to the bottom of it.

I also have a overhead dust dollector that looks like a pre-historic monster  but works very well .

I only use it when I an doing a lot of ripping. Otherwise I just use my dust mask.

It doesn't show in the picture but there is a clear piece of plexiglass over the front fastened with brass screws.

[Fred Hargis]

Even with a DC pulling huge volumes of air through the saw, the only way to catch what's coming off the blade over the table is with some kind of overarm collection. I had recently added a Shark Guard to mine, and in most cases it catches almost everything.