ZCI vs Dust Collection

[Joe Leigh]

I'm eagerly awaiting shipment of my new 1023RL and have been gathering as much information on cabinet saw dust collection as I can. With James' thread on his damaged G690 I can see from his pictures that the dust collection part of the saw is nothing more than a big open cabinet and a 4" hole for a dust collection fitting. Seems to be a very inefficient way to remove dust/chips.
My question concerns how dust collection is affected with the use of a zero clearance insert. With very little air being drawn in around the blade opening where is all the air made up? And how does this affect the pickup of dust from the blade?

[Alan Schaffter]

I'm eagerly awaiting shipment of my new 1023RL and have been gathering as much information on cabinet saw dust collection as I can. With James' thread on his damaged G690 I can see from his pictures that the dust collection part of the saw is nothing more than a big open cabinet and a 4" hole for a dust collection fitting. Seems to be a very inefficient way to remove dust/chips.
My question concerns how dust collection is affected with the use of a zero clearance insert. With very little air being drawn in around the blade opening where is all the air made up? And how does this affect the pickup of dust from the blade?

ZCI's and just about any throat plate affect dust collection. Drilling holes in the insert doesn't help- they are blocked when you run a board over it.

First, a tablesaw should have a 6" port in the cabinet- 4" is not sufficient. Second, if the port is 6" there must be the equivalent of a 6" port (28.27 sq. in.) of openings to allow for takeup air- typical throat plate openings are on the order of 6 sq. in. or less. If you don't have that you are handicapping your dust collection (CFM in MUST equal CFM out). While most cabinet saws have enough openings under the top, around the crank handles, etc. so CFM is not affected, they are not located where they will do much anything else. I don't know why saw manufacturers haven't done so, but dust collection would be much better if the take-up air was directed by duct(s) across the blade towards the cabinet port. An under-table blade chute and/or cabinet floor the slopes towards the port is important as well.

Table saw blades also throw dust captured in the gullets, off the top at the operator. A good overblade dust shroud with good DC suction and a min. of 3" duct is necessary to capture that as well. Of course, most (all?) overblade dust pickups will not work with tenoning or other large jigs.

[Rod Sheridan]

Hi Joe, the make up air will come in through cabinet openings such as the slot for the blade elevation hand wheel, and gaps under the table.

A significant amount of dust is ejected from the blade before it goes back through the throat plate.

That means that without over the blade dust extraction you're not going to capture a lot of the dust.

On my cabinet saw, the dust accumulated to a certain height and pattern, and then was drawn out by the dust port.

More modern designs have a dust shroud around the blade, and over blade extraction.

Regards, Rod.

[Jim O'Dell]

Joe, your 1023RL will have a blade shroud. It's unclear if there is also collection from the cabinet like most other saws have. For years, even the most pouplar cabinet saws (PM66, Unisaw-not new version, Jet, Grizzly, etc) have all been collect the deposited dust from the inside of the cabinet. The shroud, though maybe not a new form of collection, hasn't been popular untill the last few years. I believe the PM2000 was the first to offer this is a popular cab saw.
That said, I have the G0691. I raised the sloped floor about 1/2" at the dust door, and 5/8-3/4" at the motor end, making the sloping floor steeper and closer to the dust door pick up. I also enlarged the pick up opening from 4" to 6". My cabinet stays crystal clean! My saw has a door that comes off the saw that the dust collection hose hooks up to. Some saws just have a port in the side of the cabinet. Having the separate door makes the modification very easy, and reversible to the stock 4" opening with the purchase of a new door for less than 20.00 plus shipping.
I have considered taking my motor cover door to a local machine shop to get them to cut/stamp some more louvers in it. But it seems to work so good the way it is, I'm going to leave it as it is.
Hope this helps! Jim.

[Joe Leigh]

That helps a lot Jim, thanks. I've seen pics of the new setup with the blade shroud. It looks like a 4" flexible line connected to it. I can only assume this flex line is connected directly to the 4" dust port on the cabinet. This makes me wonder about the dust collecting in the cabinet that isn't drawn into the shroud. I'm also wondering about whether the ZCI necessitates the use of over blade dust collection due to the low flow cause by the insert restriction. How bad is it?
Anyone using a ZCI without over blade dust collection have any insight?

[Tony Shea]

People have been using ZCI inserts for years without above the table dust extraction. But now a days they do sell some nice aftermarket guards that necesitate DC above the table which can be a big help. Even with that you'll end up with lots of dust that ends up on the user or on top of the table/floor. There is just no preventing it. Even without the ZCI you'll end up with the same issue. You'll just have to spend more time vacuming up the dust after you make your cuts. It's been this way for years and probably will be for many more. Other than that I don't know what your really asking. There will be dust, just the nature of the beast.

[Neil Brooks]

People have been using ZCI inserts for years without above the table dust extraction. But now a days they do sell some nice aftermarket guards that necesitate DC above the table which can be a big help. Even with that you'll end up with lots of dust that ends up on the user or on top of the table/floor. There is just no preventing it. Even without the ZCI you'll end up with the same issue. You'll just have to spend more time vacuming up the dust after you make your cuts. It's been this way for years and probably will be for many more. Other than that I don't know what your really asking. There will be dust, just the nature of the beast.

At least for now ....

Rather than spend a few hundred bucks, or (precious) shop time trying to make one myself, I've passed on the idea of an over-the-table dust collection gizmo, and made a certain amount of peace with exactly what Tony said.

I tend to wear my 3M 7500 respirator when I'm cutting on the TS. Nothing else in my shop has quite the aim that my table saw has ... chucking sawdust right at my face ;)

[Jim O'Dell]

With or without a ZCI, you get dust/chips off the top of the blade. Most of which hits right in your face for some reason.:p If you want to collect as much of the dust and debris from the cut as you can, an overhead pick up is needed. I have 6" to the cabinet, and 4" to the overhead guard, or at least I will once I get the guard mounted and rebuilt to work with the new saw. I had the same set up on the contractor saw and it worked very well. Mine's a home brew. Jim.

[Chris Padilla]

Joe, your 1023RL will have a blade shroud.

Interesting...I have a ~2001 1023Z...I wonder if the shroud is retrofittable?

[Alan Schaffter]

http://www.ncwoodworker.net/pp/data/1403/medium/PB050012.JPG

http://www.ncwoodworker.net/pp/data/1403/medium/PB050013.JPG

[Don Morris]

Unless you have the blade raised to the top of the height possible, there is space in front of and behind the ZCI while cutting. That's where I assume most of the dust that gets sucked up into my 1100 cfm dust collection system is coming from. OTOH, I don't have an above blade shroud but agree, that would be beneficial, because I sure do get some dust escape. I just wish the ceiling, which is only 4' above my blade, and the about 2' proximity of wall mounted cabinets on the left from the blade, and the close wall on the other side, made an over saw mounted dust collection system a simpler solution than when I last checked on one.

[johnny means]

ZCIs have no affect on dust collection. Air cannot be drawn through the board that you are cutting so the size of your throat plate opening is irrelevant.

[Paul Ryan]

Since your saw will have a shroud you dont need a 6" port. A blade shroud does wonders for dust collection. I recommend a shark guard for over head collection. For about $150 it does a super job of dust collection. The shark combined with your shroud and you will have very little dust to worry about.

[Joe Leigh]

I tend to agree Paul, the shroud should make a huge difference since all of the dc suction will be focused on the lower half of the blade.
Thanks to everyone for their insight and recommendations. I'll look into the Shark Guard.