No Dust Extraction With Zero-Clnc Insert
kentmich
| Posted in Power Tools and Machinery on
My Jet 10″ hybrid table saw has a closed cabinet with a dust extraction port, but the cabinet isn’t really airtight. It has gaps in the corners, around the legs, and even a louvered vent on one side. So when I use a zero-clearance insert a lot of dust doesn’t get drawn into the extraction system because there are so many bigger openings for the air to go into.
The teeth carry some of the dust down below, but a lot of fine dust seems to kick back towards me and into the air.
So is it worth my time to try and close up those openings with good ole duct tape, or is that slit just too small to get a decent suction? Has anyone else experienced this?
Replies
If you try and make the cabinet more air-tight you will only make the situation worse. You need air flow around the blade in order to capture the dust. With a ZCI, the dust is coming off of the backside of the blade as it rotates back around and without an overhead DC/blade guard you can't capture all/most of the particles. Put a regular throat plate back in the TS and much of the problem will be eliminated. A ZCI is not a dust collection solution since its value is to reduce splintering in cross cuts and ripping thin slices that could become trapped between the fence and the opening. You can use an open throat plate and deal with splintering by using a well-constructed cross-cut sled.
Doug
Have you considered drilling small air holes in the insert plate to gain some local air in-flow?
Ralph,On the surface, that sounds like a reasonable idea. Have often thought of doing it or perhaps a pick-up in back of blade under table -- kind of emulate new SawStop system. (would reeeely have to be secure.) Never liked the Beis overhead guard/pickup. It doesn't. much. well a little. well.. vacuum too far forward I think.BB
BB,
vacuum too far forward I think.
Are you talking about DC pickup on a guard at the rear (towards you)? I've thought of that several times and the issue I see (pun intended?) is it might block your view.
I should think that a DC connection to a blade guard should be pointng toward the rear of the guard. I did try an experiment once, using a floor sweep placed just to the rear of the blade and held in place with a magnet that was quite effective. No DC connection on the guard though.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 11/16/2009 4:18 pm ET by KiddervilleAcres
Bob,As far as under the saw, what I want to try would be a hose (2-2.5")just aft of the blade as she rises. Ported out and "y'd" into the main DC.On the guard:On top, my current one (a Biesemeyer overhead), the vac pick up is set about 3 inches behind the front of the guard and comes in from the top at an oblique angle from the rear. Right in front of a hinged plastic flap on the guard. The front and sides are transparent. It does more to pick up the flap than it does to suck dust and of course once the hinged flap is in sucked up position, the falling blade gullets throw everything out toward the operator like little trebuchets. The saw thinks it's the Roman legions and I'm the castle to be sieged. I'm thinking a move to the rear of the guard and either straight down or angles to the rear might be a more effective collector. Make it more like Sarges.I think the solution may be have a high school kid in a bubble do the cutting and the sneezing and then hand me the milled goods :)By the way, were sending you a mega storm. We're clocking 39 knots at the house right now, gusting at 70. You should see it there by this weekend.
Guess I should take the dogs out afor it gets worse.Take careBoiler
I agree for what that is worth from me.
I for one think the air inflow has to be at least the outflow. And a hunk of masking tape to block off the area that is not over the 'stick'.
Who cares where the air flow comes from!
Just installed the Biemeyer Overarm Guard with dust pickup and am quite happy with it. I have it hooked up to a big shop vac and separate from the dust collector. There is plenty of draw and very little dust escapes.
>>> Have you considered drilling small air holes in the insert plate to gain some local air in-flow?That won't work. Any board you are cutting is completely covering the ZCI and will be covering any holes you drill in it.Carrying this a little further, dust collection is all about air flow and direction. In fact, you should have at least as many square inches of air inlet as you have for your exhaust port. The idea is to maintain maximum air flow volume. Vacuum has little to do with it. Sawdust coming off a saw blade is ejected at over 100 MPH. No matter how much airflow you have from your DC, it will not be enough to change the direction of the flow. To change the direction, you need a shield or cover around the blade as some of the newer saws have. These shields direct the dust toward the exhaust port.So, determine the direction of the airflow and don't impede it.Howie.........
I had a similar problem with my 5-HP PM-66 which left lots of specks on my teeth until I happened across the "Shark Guard" available from the following site:
http://www.leestyron.com
When I ordered mine, it took about 3 weeks because he was kind of backed-up in production. I've been using it for about 2 years now and couldn't be happier. I have a 4" DC and droped a flex hose directly from over the Shark Guard and it has proven to be a great investment for me. My Dentist is having more free time as well!
Good luck on conquering the dust, I have spent a small fortune, with the latest $100. on the new "Oneida Dust Deputy" in which I find the efficiency numbers untrue.
The above website has plans for a DC system that he built and seems to be not only effective, but cheap as well-IF you're handy with that sort of stuff. My time in the shop is limited, so I'd rather not spend it on anything except making dust!
Kemo
Closing off the cabinet "leaks" won't help. What you need is more air flow around the blade.
I have the Jet "Supersaw" and use home made ZCI's made from 1/2" ply. After I cut the blade slot, I drilled a 1" hole thru the ZCI at the back of the slot. It doesn't keep all the dust off the table, but it helps. I also use the factory throat plate unless I actually need the ZCI.
I did exactly the same thing as Kemo did - put one of Lee Styron's Shark Guards on with a 4" port on it. Here is how I have it all set up:
http://forums.taunton.com/fw-knots/messages?msg=48585.1
A certain amount of the dust coming off of the back of the blade and being thrown upward is fresh sawdust being generated by the saw's teeth brushing the sides of the kerf, so no amount of in the cabinet dust collection will catch it. A readjustment of the rip fence and miter slot alignments to get them parallel to the blade will reduce the dust being thrown off the rear of the blade.
Shop Manager for FWW Magazine, 1998 to 2007
Check the article in issue 205 it talks about your very problem.
Alright, I almost had a stroke of genius. Or, it was a stroke of genius, but only up to a point.
When you guys were talking about dust coming out the back of the blade at the insert, I had that very thing going on as well.
Well, I said, this isn't such a tough fix. Sometimes people just think a problem is hard, but it's really not. You know how they make the paddle for the air to run into inside a dust collector, where the dust hits the paddle and drops, and the air moves right on past?
Well, I'll just use that idea on my saw. I'll make a shield that goes stright up and down, but is positioned the lower half of the blade, inside the cabinet, at about six o'clock. The dust that comes off the piece of material being cut will almost immediately hit that paddle, which will knock the speed off it and from there will be easy pickings for the dust collector attached to the bottom of the cabinet. The dust won't have a chance to come back around to the throat plate and shoot out!
Now really, this is genius. I have it all planned out in my head. I just need to attach that shield to the motor somehow so it will tilt with the blade when I need to make a bevel cut. Oh yeah, I'll just attach the shield to the shaft of the motor, because that shaft tips right along with the motor. And what's more, it's threaded, and solid as a rock. Safe!
The lights came on, the world lit up, and I could see millions of dollars pouring into my bank account. I'm on the front cover of Fine Woodworking. Of course, I'm still humble.
The next day I went down to the shop and took the insert plate off the saw to look how easy it would be to connect a shield to that shaft. Right then it hit me. The one little flaw in my plan.
All my dreams vanished in an instant. I do take some (small, very small) consolation in not actually making a shield and attaching it to the shaft and turning on the saw.
Details, details, I'm an idea man.
--jonnieboy
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