Does a ZCI help or hinder dust collection?

[Jules Dominguez]

I now have a Sawstop, but used a Rockwell contractors saw for 25 years previously and for 24 of those years I used the standard metal insert that came with the saw. It had a wide opening with plenty of clearance around the sawblade. I never had a problem with narrow waste strips, they either stayed on the table until I stopped the saw and removed them, or they "fell through the crack", but the wide slot in the insert was never a problem to me.
Now that I have a cabinet saw with a dust collector hooked up to it, I'm wondering whether an insert with a slot width comparable to my old Rockwell might help rather than hinder dust collection. Air flow is what picks up sawdust and moves it, and a wide slot would allow significantly more air flow from the tabletop down into the cabinet. Anybody know the answer?

[glenn bradley]

If you do not have an above table hood / guard you will get more dust on top of the table. I have seen folks drill a few 1/2" (?) holes in their ZCI to allow the dust to get pulled under without losing the ZCI benefit.

[George Summers]

If you do not have an above table hood / guard you will get more dust on top of the table. I have seen folks drill a few 1/2" (?) holes in their ZCI to allow the dust to get pulled under without losing the ZCI benefit.

I have seen the suggestion about drilling small holes in the ZCI before and although I have not tried it, I don't understand the physics of it. Air flow needs both an inlet and an outlet. When you cover the holes with the work piece (the board you are cutting) you block off the top of the holes and thus have no air flow. How does the dust and the air get into the top of the holes and get sucked by the DC?

George

[Jim Grill]

I have no clue one way or the other, but I've heard people say DC is better with a ZCI. I don't own a DC yet, so beats me.

[glenn bradley]

I have seen the suggestion about drilling small holes in the ZCI before and although I have not tried it, I don't understand the physics of it. Air flow needs both an inlet and an outlet. When you cover the holes with the work piece (the board you are cutting) you block off the top of the holes and thus have no air flow. How does the dust and the air get into the top of the holes and get sucked by the DC?

George

Good question. I don't do it either. I use an overarm collector. I would assume any cut that covers the plate would make this band-aid method pretty useless. Thin rips and narrow crosscuts might benefit.

I would recommend an overarm guard/collector but, there are plenty of folks out there who don't like these. I use mine as much as possible. There was a thread on them and it seemed like the $200 ones did as well as the $500 ones to varying degrees. A few folks made there own or modified something else. There were some really cool ideas.

[Joe Chritz]

Dust collection above the table (i.e. coming off the top of the blade as it comes back around the back) may be worse.

Dust collection under the table (the majority of it) may be better.

How's that for a non-committal answer. :rolleyes:

As George says the board will block almost everything except the slot so I doubt there is any note worthy difference in collection. There is a big difference in cut quality.

If you are cutting less than a blade width it may help to have an open insert, but without an overhead guard there will be dust on the top.

I use a ZCI in a Ridgid with a "custom" cabinet to enclose the base and it works very well.

Joe

[Jim Grill]

I would tend to agree. I think once the stock is over the insert it doesn't matter anymore.

I like the idea of the overarm guard/collector. I think I'm also going to strap a DC port on my chest because that's where most of my above-the-table dust seems to go! :)

[Cody Colston]

Without an overhead guard, you will get more dust on the table top with a ZCI. But, the ZCI isn't meant to improve dust collection. It is meant to give a cleaner cut by supporting the stock from underneath.

[Jim O'Dell]

I don't expect my ZCI to help with dust collection. I only hope it helps with chip out in the wood. The overhead guard is needed to catch what is spit out above the work piece. Having a TS properly designed for dust collection would be a help. The only ones that come close for this though is the ones with the shroud around the blade for collection. I'd like to see holes in the cabinet at the underside by the table top that would allow air to come into the cabinet, and channel toward the blade, so that the blade is within an "air stream" to wisk the particles toward the pickup hose. I plan to make my router table with this principle in the design. Once I get to that project one of thesee decades, I'll let you know if my theory works or not.:D Jim.

[Matt Benton]

DC on my Delta contractor saw is significantly better with the ZCI in place and suction from the top with an overarm guard.

I just cut 2 full sheets of MDF last night and had very little dust on the top afterwards.

[Jay Keller]

for sure.........drill holes in it

[John Bush]

Hi Jules,
I use the ZCI on my SS and it seems I have more topside dust than my old CS. When cutting sheet goods it doesn't seem to develope as much. I got a good planing type rip blade and have been getting such good "glueline" quality edge cuts when milling stock that I don't need to use the jointer very often. When trimming off 1/16-1/8" the dust blows of the side of the blade instead of being trapped in the gullets and pulled into the dust shroud. I have an efficient 2hp cyclone and still get a lot of blow by. My plan is to get a Sharkgard and mount it to a custom riving knife/mount(Lee has already made one for me) and suspend 2 1/2" flex hose from the beams. Let me know if you come up with another solution. Thanks John.