Over the blade dust collection

[Brian Behrens]

I have a Grizzly G0691. My DC is a Clearvue 1800 cyclone. With the wide factory insert dust collection is great! I finally installed my zero clearance insert and built a cross cut sled. With the sled, my dust collection is terrible. I have dust flying off the top of the blade. I have begun to research a solution. I am very serious about my dust collection and want to get this right.

So far I have researched the Shark Guard and the Excalibur. Right or wrong I've never used a blade guard, so this will be a big adjustment for me. I would prefer something that more or less "hovers" over the blade, rather than attaching via the riving knife, so I can use it for dados and with my sled. Is there something else out there I should be looking at? I have a 6" drop going into the saw cabinet, so I am assuming I will need to change that to (2) 4" drops, one to the cabinet, and one to the over the table guard? Thanks for any input.

Edit: I called Clearvue and they advised to keep my 6" port on the cabinet and just add the 4" for above the table, using blast gates on each to find the sweet spot between the two

[Jacob Mac]

I have the exact same setup as you, but I use this

http://www.grizzly.com/products/Universal-Overarm-Blade-Guard-For-Table-Saws/T10113

[Brian Behrens]

Thanks Jacob. Are you happy with that unit?

[Marshall Harrison]

Watching this closely as I am looking also. I thought about the one from SawStop but since my saw isn't a SS I'm not sure if it will work with my saw.

[Nick Decker]

Marshall,

I've been following your dust collection posts in the other thread and, believe me, you'll need a lot of suction to run both cabinet and above-table dust collection. I know this because my 1 hp unit barely keeps up with my cabinet alone. I'm running out of floor space for a larger unit, so I'm thinking my broom needs to be upgraded.

[Roy Petersen]

Using a 2HP HF collector, I have a 4" port underneath my saw and another 4" drop from the ceiling (both go to a 5" main line). The ceiling drop is a hinged dowel (so it can be moved out of the way if it's not needed) with the 4" hose attached with ball bungies. The last foot or so of the hose is allowed to dangle just above the blade, so it will move out of the way during sled cuts, but close enough that it will attract the dust spinning off the blade. Very little gets past.

Though I'm sure that overarm gadget works way better, $300+ is a bit much for me.

[Doug Garson]

Have you considered something like this using your shop vac? Combined with your dust collector connection on the cabinet. 384537
Found this idea online, can't remember where but it works surprisingly well for little or no cost (just some scrap plywood and a little time.)

[Jacob Mac]

Thanks Jacob. Are you happy with that unit?

With a clearvue 1800, I can't imagine a scenario where you couldn't run the unit effectively. The question I would ask is are you really committed to working with an overhead guard, and do you have the space.
But the unit itself works well.

[Brian Behrens]

Have you considered something like this using your shop vac? Combined with your dust collector connection on the cabinet. 384537
Found this idea online, can't remember where but it works surprisingly well for little or no cost (just some scrap plywood and a little time.)

I'd really like to use the 5 hp DC I already have running, rather than add a shop vac into the mix. I think that design looks ineffective if I'm cutting a 24" panel, since the hose will be far from the blade at the beginning of the cut. I think I've ruled out the shark guard. I need to be able to use it on my sled, since that is the biggest offender.

[Marshall Harrison]

Marshall,

I've been following your dust collection posts in the other thread and, believe me, you'll need a lot of suction to run both cabinet and above-table dust collection. I know this because my 1 hp unit barely keeps up with my cabinet alone. I'm running out of floor space for a larger unit, so I'm thinking my broom needs to be upgraded.

Nick,

I've come to that conclusion too. If I add an overarm collector then it would probably be hooked to a shop vac. Might not work the best but every little bit helps.

I simply don't have the room in my garage for a huge dust collection system. My longer range plans are to move to the mountains of north Georgia or western North Carolina sometime in the next 5 years. So I'm hoping for a better shop facility when I make that move. My goal is to put bits and pieces of my future shop together now and build on that once I make the move. I'm trying to make purchases that won't limit me in the longer run or be a throw away expense.

Some of my smaller purchases have been somewhat disposable but I'm trying to keep my major purchases part of my overall master plan. Though I'll admit not all parts of the "master plan" are worked out yet.

[Brian Behrens]

With a clearvue 1800, I can't imagine a scenario where you couldn't run the unit effectively. The question I would ask is are you really committed to working with an overhead guard, and do you have the space.
But the unit itself works well.

I can't keep using the sled with the dust it puts out, so I will have to adjust to the guard. Space is not an issue.

[Nick Decker]

Agreed, Brian, about turning on both a DC and a shop vac just to cut a board. It's annoying.

[Alan Schwabacher]

... If I add an overarm collector then it would probably be hooked to a shop vac...


If you want to use a shopvac for the blade guard dust collection, a design like that of the Sawstop is beneficial. It takes advantage of the airflow caused by the blade, and captures the dust from the front of the blade where that air brings it -- very effectively using either shopvac or DC. For shopvac use, you want a fairly small cross section with rapidly-moving air, which means the air intake must be placed quite precisely. This is easier with the guard mounted on the riving knife or splitter, but possible with a drop-down mount. It needs to be positioned more carefully than would a bigger inlet designed only for a DC that moves more air.

A DIY design that appears to work as well as the Sawstop can be seen on youtube if you search for "Justin Depew overarm dust collection for my tablesaw".

[Brian Behrens]

With a clearvue 1800, I can't imagine a scenario where you couldn't run the unit effectively. The question I would ask is are you really committed to working with an overhead guard, and do you have the space.
But the unit itself works well.

Jacob, how easy is it to adjust the height on the grizzly. For instance, I will probably need to raise it a few inches whenever I put the sled on to clear the rear fence of the sled, and give me the full range of motion

[Jim Becker]

Back when I had my cabinet saw, I had the Excalibur overarm guard and really liked it. I actually plan on creating something similar for my slider at some point because the current guard/collector attaches to the riving knife and I don't prefer that arrangement.

[Rod Sheridan]

384545384546Hi, I have both a riving knife mounted over head dust collection guard and an overarm type.

The overarm is great for non through cuts such as dado or rebate, the riving knife guard will function well with a sled if the sled fence is low enough.

The riving knife guard will work with a shop vac due to low area, the overarm will require connection to a dust collector.

Marshall, you're certainly correct on how nice it is to have over head collection at the blade...............Regards, Rod.

[Mike Kees]

I have used both a sharkguard and the Excalibur overhead. I am not sure how the overhead will work with a crosscut box if you lift it high enough for clearance of the box. (will it still capture most of the dust.) The sharkguard captures dust very well,but wont work with the crosscut box or dados. The answer is of course buy a sliding tablesaw. Just kidding,it was my solution though. I remember a fine woodworking article I think, Kelly Mehler or something where he made crosscut boxes with a lexan safety guard in the center. Something like that with a dust port attached is going to be what you need. Good luck,Mike.

[Don Kondra]

Here's an inexpensive solution, Full thread here (https://sawmillcreek.org/showthread.php?243381-Table-saw-overhead-dust-collection-for-40)

The metal duct is high enough I can still use my sled.

384550

I've since added a brush, ordered overseas for less than $10 shipping included :)

The brush is attached with Velcro so I can remove parts if necessary.

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To set the width of cut, etc. the whole contraption swings out of the way !

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Cheers, Don

[Jacques Gagnon]

Nice work Don!

[Doug Garson]

Agreed, Brian, about turning on both a DC and a shop vac just to cut a board. It's annoying.
Not if you have the power switches set up like I have, they are attached to my overarm assembly by magnets and I can reach both of them and the power switch on my saw without taking a step. And you would be surprised at how well it works for almost no cost.

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[Mark Carlson]

I have a shark guard and the excalibur. I prefer the shark guard because it forces me to use a spliter does a better job of dust collection and offers a less restricted view of the cut. I dont like the boom arm of the excalibur or the size of the guard. I also use a jessem slider, so dont need a cross cut sled, and the shark guard works well with the slider.

[marty fretheim]

Hey Brian, Ive got a slider similar to Rods. I tried a zero clearance insert and the below table dust collection became non existent, so i ditched it. I have an Oneida 5hp DC, I use the splitter mounted overhead guard like Rods and without the ZC insert I get great dust collection. I'm positive your DC set-up is plenty, no need for a shop vac. I also believe Clearvue gave you good advice on hose size. What I don't know is if your cross-cut sled will act as a ZC insert and require the overhead DC to do all the work, and in my experience they just can't. Maybe the larger boom arm type collector/gaurd would do a better job.

If you have to raise it up high enough for the sled to pass under its not likely to do much good. Thats just my experience for what its worth.

Marty

[John K Jordan]

I have a Grizzly G0691. My DC is a Clearvue 1800 cyclone. With the wide factory insert dust collection is great! I finally installed my zero clearance insert and built a cross cut sled. With the sled, my dust collection is terrible. I have dust flying off the top of the blade. I have begun to research a solution....

I have the 5hp CV1800 and have an Excalibur not yet installed (PM66 with a sliding table). I was told a 6" duct to the saw cabinet with a wye to feed a 4" to the overarm would work best. The beast of a DC seems to have an excess of suction!

I've wondered about the poor dust collection with a zero clearance insert - it seems like it must restrict the air intake enough that the air flow inside the cabinet is choked. I had an idea I want to try to increase the airflow near the blade: bring in a short piece of PVC pipe (2", 4"?) from outside the right side of the cabinet and position it close to the blade, perhaps on the downside (front). The end outside the cabinet would not be connected to anything, just open to the air. My theory is the vacuum in the cabinet will pull air through the PVC pipe and maybe create enough air movement to "blow" the dust out of the blade gullets so it can be pulled out by the 6" duct, something the wide opening in the factory insert probably does.

Any positive air duct would have to consider the blade height and tilt adjustments. I haven't taken a close look at this yet with an engineering eye but plan to. I can't see how extra air intake there would hurt anything but it would be easy enough to remove and patch the hole if it didn't work out. Has something like this been tried before?

JKJ

[Pete Janke]

Watching this closely as I am looking also. I thought about the one from SawStop but since my saw isn't a SS I'm not sure if it will work with my saw.
It will work fine. It was a simple retrofit to attach the SawStop blade cover to the Grizzly splitter on my G091. Just a couple of screws. I run a 4" dust collection hose from the ceiling to the blade cover. I still get a little saw dust, depending on the cut, but it is way better than no over the table dust collection at all.

[Jerome Sidley]

Watching this closely as I am looking also. I thought about the one from SawStop but since my saw isn't a SS I'm not sure if it will work with my saw.
I have the saw stop and it sucks well not really I get dust everywhere. I am planning to upgrade to something with a 2" hose where there will be some airflow.

[Osvaldo Cristo]

I have the 5hp CV1800 and have an Excalibur not yet installed (PM66 with a sliding table). I was told a 6" duct to the saw cabinet with a wye to feed a 4" to the overarm would work best. The beast of a DC seems to have an excess of suction!

I've wondered about the poor dust collection with a zero clearance insert - it seems like it must restrict the air intake enough that the air flow inside the cabinet is choked. I had an idea I want to try to increase the airflow near the blade: bring in a short piece of PVC pipe (2", 4"?) from outside the right side of the cabinet and position it close to the blade, perhaps on the downside (front). The end outside the cabinet would not be connected to anything, just open to the air. My theory is the vacuum in the cabinet will pull air through the PVC pipe and maybe create enough air movement to "blow" the dust out of the blade gullets so it can be pulled out by the 6" duct, something the wide opening in the factory insert probably does.

Any positive air duct would have to consider the blade height and tilt adjustments. I haven't taken a close look at this yet with an engineering eye but plan to. I can't see how extra air intake there would hurt anything but it would be easy enough to remove and patch the hole if it didn't work out. Has something like this been tried before?

JKJ

I share your idea. DC works with high volume but low negative pressure. Your idea makes lot of sense. Pls let us know your results when you can do that.

All the best.

[Marshall Harrison]

Thanks for that info Pete and Jerome. Kind of money strapped at the moment so plenty of time to figure this out.

John, it seems an easy way to check out your theory would be to just crack open the motor cover on your saw as that would let extra air into the cabinet.

[Nick Decker]

JKJ,

Not sure how it would affect your problem (Too much suction? A totally foreign concept, to me.) but I've wondered about drilling some holes in my ZCI, left and right of the blade slot. I've seen a picture of that somewhere, but no explanation of how well it worked. Don't see how it could hurt, but I'm open to anyone's thoughts.

[Nick Decker]

The problem with my SawStop PCS, and maybe it's like this on all cabinet saws, is that there is no semblance of sealing the various openings in the cabinet. It just relies on an open channel to direct sawdust into a 4" hose that twists around and exits the rear of the cabinet, where it attaches to the DC.

[Brian Behrens]

Thanks for all the replies so far.

I don't have a problem collecting inside the cabinet, even with the zci installed. I see videos all the time of saw cabinets full of dust, with people saying "the dust only gets up to this level and stays that way". Well, with my clearvue, there is literally NO dust in the cabinet AT ALL.

I think the problem with the zci is that it takes away the path for a downdraft from above the table. With my factory insert installed, I can throw a handful of saw dust on the table about 6" from the blade and it gets sucked down through the insert. With the zci, it has to be much closer.

[John K Jordan]

JKJ, Not sure how it would affect your problem (Too much suction? A totally foreign concept, to me.) but I've wondered about drilling some holes in my ZCI, left and right of the blade slot. I've seen a picture of that somewhere, but no explanation of how well it worked. Don't see how it could hurt, but I'm open to anyone's thoughts.

I've read several discussions about holes in inserts and the consensus has been that if the insert is covered by a wide piece of wood or a sled the holes are blocked and do nothing. That would go for the wide opening in the non-zero clearance insert too.

My experience with making my own bandsaw inserts is holes with suction behind them do help for at least one case, skimming cuts on the edge of a block where 1/2 of the holes are not covered by the wood. Even then, a lot of sawdust gets thrown sideways to I use a 4" auxiliary pickup on the top of the bandsaw table, held with a strong magnet in a position which seems to catch the most.

As for plenty of suction, I have one DC pickup just behind my lathe and it works better than I imagined. It pulls in so much air that I've watched fine sanding dust travel a couple of feet horizontally to be sucked up. I lose sandpaper and paper towels when I'm not careful. There is never sawdust in the bandsaw cabinet and after drum sanding with a 22-44 the particulate monitor doesn't show an increase 10' from the sander. The table saw is the worst.

I joke that you don't want to let your cat get too close. A video from ClearVue shows a vertical 6" duct snatching a 25' measuring tape, carrying it through the horizontal duct, and dumping it in the bin.


https://youtu.be/WFPtC3kfmeg

JKJ

[Jim Becker]

Brian, the design of the cabinet makes a difference relative to good collection with ZCI. Most cabinet saws have enough holes to provide makeup air to keep things moving efficiently. Some sliders that use a shroud design make for a more closed system and ZCI can affect collection negatively. But the benefit that a ZCI provides can be made up for with a scoring blade to keep the bottom of the cut clean.

[Brian Behrens]

Brian, the design of the cabinet makes a difference relative to good collection with ZCI. Most cabinet saws have enough holes to provide makeup air to keep things moving efficiently. Some sliders that use a shroud design make for a more closed system and ZCI can affect collection negatively. But the benefit that a ZCI provides can be made up for with a scoring blade to keep the bottom of the cut clean.

Thanks Jim. I didn't know that. I will run some experiments by leaving the motor cover open a bit to let some more air in.

I've done a lot of reading (online only) and right now I think I am going to get the Grizzly unit. It appears the Excalibur is no longer available, the PSI has poor feedback, and the sawstop unit is $100 more with no advantage I can see. But I haven't seen a lot of info on how the actual guard mechanism functions on the sawstop unit. It may be the superior unit but I would have to drive a few hours down to Atlanta to see it in person.

[Mike Kees]

Brian the Excalibur guards are now called a different name. I believe the one in Rod's post is the same one (pictured). Mike.

[Tom M King]

On my Unisaw, I covered up every hole, and stuffed the gap between the top and base. I built a wooden box to go over the motor, that accepts a slide in 12x12 furnace filter as the air intake. The filter is to keep dust in, rather than to filter anything out. This setup uses the Exaktor overarm assembly. I use ZCI's, and a 3hp DC keeps any dust out of houses I work in.

[Matthew Curtis]

If every hole is closed up how do you get airflow? To get dust being sucked out don't you need air flow. Where is the air coming from if the saw is sealed up?

[Jim Becker]

If every hole is closed up how do you get airflow? To get dust being sucked out don't you need air flow. Where is the air coming from if the saw is sealed up?
This is correct...there must be air source equivalent of the area of the port/duct minimum and where that air source or sources is/are located can affect efficiency in clearing a "box" of debris.

[Tom M King]

If every hole is closed up how do you get airflow? To get dust being sucked out don't you need air flow. Where is the air coming from if the saw is sealed up?

Since this came right after my post, I'm not sure if it was directed at me or not. If it was, air comes in through the 12x12 filter, as I stated. There is a big opening where the end of the motor sticks out on cabinet saws, which is typically covered by a plastic, or sheetmetal cover. My wooden cover with the filter replaces that stock motor cover. It works great with a 6" main duct, and 4" to the overarm assembly.

Edited to add: If any hole is left open, some sawdust will find its way out through inertia. You still need to move enough air to get past the point of wishful thinking.

[Derek Cohen]

Some time back I asked a woodworker friend - who specialises in dust control - about drilling a ZCI to increase airflow to the main dust collector (I have a Hammer K3 with a ZCI from Felder). He said "don't do it". Apparently, after much research, any holes drilled actually restrict air flow. I thought this illogical, but he showed me the studies, and it required very careful placement of holes, and of a certain size to make any positive difference. Simply drilling holes at random makes the airflow worse!

Well this information came back to me today after I tested out my over-the-blade collector. I am still shaking my head at the results.

My dust collection is a 2 hp Carbatec with 5" hose. I would prefer 6", however all my machines are by Hammer - the tablesaw is a K3 - and they have 5" outlets. I plan to add 6" ports when I upgrade the DC. The suction from the DC is adequate for all the machines I have. It is not as though there is inadequate suction. It is not enough, however, to suck up via both the main outlet of the tablesaw and the blade guard .. (or so I thought - now I am having second thoughts ... the plot thickens :) ). The outlet from the blade guard is (from memory) 2".

So a few months ago I added a hose via my Festool CT26E to the blade guard ....

https://s19.postimg.cc/e2939aqz7/Overhead1.jpg

It seemed to work, but I must admit it was more work and I got lazy, and so did not use it much.

Today I was fitting some dividers to an apothecary chest I am building (see here (https://sawmillcreek.org/showthread.php?264347-Apothecary-chest-part-one) for the build), and decided to use the overhead dust collector. I was curious (with this thread in mind) to see how well it collected the dust ...

https://s19.postimg.cc/oc96qt0r7/7a.jpg

On went the CT26E, and this is the result ...

https://s19.postimg.cc/8192uh143/2a.jpg

Dust!

I then had a lightbulb moment and decided to switch off the CT26E, and tried with a second divider ...

https://s19.postimg.cc/erpk3wgk3/image.jpg

No dust!

hmmmm ... so I decided to use the CT26E again, and cut half way through the third (and last) divider ...

https://s19.postimg.cc/ftzqmfrnn/image.jpg

No dust, again!

I then tried the dust collector on the remaining half ...

https://s19.postimg.cc/69g3zkx6r/image.jpg

Dust!!

I think even blind Freddy can see the pattern that has emerged.

One last trial. This time I disconnected the hose to the blade guard and capped it. Tried again ...

https://s19.postimg.cc/nmqeefks3/6a.jpg

And that is the way it will remain now.

Summary: overhead dust collection is overrated.

Regards from Perth

Derek

[Nick Decker]

Interesting, Derek. Maybe the suction from above is just nullifying the suction from below and you've succeeded in creating "dust limbo"?

Or, could this be akin to that Down Under thing where water rotates the wrong way around a drain? :)

[John K Jordan]

... I tested out my over-the-blade collector. I am still shaking my head at the results....

Curious as to the location and size of the air intake to that saw. Some table saws apparently rely on only what room air leaks in around the height/tilt controls and through the insert around the blade. A 5" DC port is about 20 square inches.

JKJ

[Tom M King]

It doesn't work like that with mine. Without the overhead suction, there will be dust, not only on top of the saw, but also in the air, regardless of how much air gets moved through the saw. It should be noted that my setup is completely different than Derek's, in every respect, so don't think it's fair to state, one way or another, how any different setup will work.

[Rod Sheridan]

Some time back I asked a woodworker friend - who specialises in dust control - about drilling a ZCI to increase airflow to the main dust collector (I have a Hammer K3 with a ZCI from Felder). He said "don't do it". Apparently, after much research, any holes drilled actually restrict air flow. I thought this illogical, but he showed me the studies, and it required very careful placement of holes, and of a certain size to make any positive difference. Simply drilling holes at random makes the airflow worse!

Well this information came back to me today after I tested out my over-the-blade collector. I am still shaking my head at the results.

My dust collection is a 2 hp Carbatec with 5" hose. I would prefer 6", however all my machines are by Hammer - the tablesaw is a K3 - and they have 5" outlets. I plan to add 6" ports when I upgrade the DC. The suction from the DC is adequate for all the machines I have. It is not as though there is inadequate suction. It is not enough, however, to suck up via both the main outlet of the tablesaw and the blade guard .. (or so I thought - now I am having second thoughts ... the plot thickens :) ). The outlet from the blade guard is (from memory) 2".

So a few months ago I added a hose via my Festool CT26E to the blade guard ....

https://s19.postimg.cc/e2939aqz7/Overhead1.jpg

It seemed to work, but I must admit it was more work and I got lazy, and so did not use it much.

Today I was fitting some dividers to an apothecary chest I am building (see here (https://sawmillcreek.org/showthread.php?264347-Apothecary-chest-part-one) for the build), and decided to use the overhead dust collector. I was curious (with this thread in mind) to see how well it collected the dust ...

https://s19.postimg.cc/oc96qt0r7/7a.jpg

On went the CT26E, and this is the result ...

https://s19.postimg.cc/8192uh143/2a.jpg

Dust!

I then had a lightbulb moment and decided to switch off the CT26E, and tried with a second divider ...

https://s19.postimg.cc/erpk3wgk3/image.jpg

No dust!

hmmmm ... so I decided to use the CT26E again, and cut half way through the third (and last) divider ...

https://s19.postimg.cc/ftzqmfrnn/image.jpg

No dust, again!

I then tried the dust collector on the remaining half ...

https://s19.postimg.cc/69g3zkx6r/image.jpg

Dust!!

I think even blind Freddy can see the pattern that has emerged.

One last trial. This time I disconnected the hose to the blade guard and capped it. Tried again ...

https://s19.postimg.cc/nmqeefks3/6a.jpg

And that is the way it will remain now.

Summary: overhead dust collection is overrated.

Regards from Perth

Derek

That's not my experience with cabinet saws and sliders.

No overhead collection results in a shirt pocket full of dust, and the particle counter off scale.

Regards, Rod.

[Josh Kocher]

I'd echo that too.

I've been using a Felder guard fitted on the splitter of my contractor saw and it's far better collection than before. I use 3" to the guard and 5" below from my 2hp cyclone.

There are always going to be some cuts that end up with dust on the table. But overhead DC improves the collection overall.

I like the Felder guard because it's not bulky, it's effective, and it's cheaper than all the other overhead DC options I could find: sharkguard, sawstop, excalibur, etc... I guess Don's is cheaper though.

[Dominik Dudkiewicz]

My experience with overhead collection on my Table saw has been very positive. Without it, despite having a CV1800 and 6" bell-mouth cabinet port I still get a lot of dust firing off the blade, whereas with the overhead port I get virtually zero dust or chips depending on the cut. Worst case I get some small amount of chips but no dust.

I made my own out of perspex and scrap aluminium. I have a 4" hose / port to the overhead. I think reducing the 6" in the cabinet to a 5" would provide a better balance as the overhead is far more effective than the cabinet port so more flow to that results in better overall performance.

The guard is easily moved up or down and left to right so that I can use the crosscut mitre gauge closer to the blade or move the fence closer to the blade for narrow rips.

384688

384689

384690

Cheers, Dom