Dust collection- Saw cabinet very "airy"

[K. B.]

Both my table saw cabinet and jointer "cabinet" have lots of gaps allowing air flow from dust collector. Is this by design? For instance, the saw's motor-access door has a 6" X 10" square hole in the top where it mates with the cabinet when the access door is closed. Wouldn't this decrease the efficiency of the dust collector (1.5 hp Delta dust collector). The Delta jointer is even worse. Should I try to close up these holes?

[Edwin Pawlowski]

If you were to seal all the holes so no air gets in, the DC won't work. The dust collector does not suck dust, it sucks air and carries the dust with it. Perhaps someone will post the perfect method for your tools, but if not, experiment a bit. Leave enough air gaps to at least equal the exit port. The opening would ideally be opposite the cutting blade so the air passes the chips as they are made and carries them along with it.

[John]

Just having a ton of SUCTION in the tablesaw is NOT going to move any sawdust/waste. So you need air MOVING thru the saw, and especially if using zero clearane inserts you need some other way for air to get into the saw.

Bottom line, that hole is probably NOT reducing the ability of the vac to get the sawdust out of the bottom of the saw. If you want it to also get dust from around the blade, etc, then you may want to use a dust collection system attached to the bladeguard as well as dc connected to the main port of the saw

John

[Phisherman]

[Greg O]

I have a Delta contractors saw and a Harbor Freight $159 dust collector. I have run with the back of the saw covered and uncovered and see no difference in dust collecting, so I leave it open. You do need some openings to keep the air moving through the saw. Greg

[Dave Vermilyea]

Bill Pentz has some design drawings on his website for dust collection hoods for various power tools. As I recall, the gap called for in these designs for the jointer & tablesaw is 1/2 inch. Bill's website may be reached at:

Vermilyea

[Bob G.]

============================== I have read all the replies to date and yours is the only one that states that "you" get better dust collection closing off the holes...

From my experience, with my Cabinet saw (using duct tape etc to experiment with) I have to agree with the others..... sealing off the gaps etc greatly reduced the effectiveness of my DC ...that is not to say that I did not seal any of the gaps..

Bob Griffiths

[Upscale]

I'm ashamed to admit that I once tried to sell vacuum cleaners. I failed miserably at it, but one thing I did learn was that even with the greatest vacuum power, it's still necessary to have adequate air flow for it to work properly. The difficult part is to find the optimum level between too little and too much air flow.

[Larry Bud]

I agree with Bob, in that one cannot completely close off all the holes, and the more holes that are closed off, the faster the airflow will be where it counts: at the blade (You'll always have a hole there).

Now, doing this MAY create a small pile inside the cabinet because the amount of air that is moving, but at that point, who cares? The goal is to reduce airborn dust particles.

[nospam_coloradotrout]

my theoretical approach would say leave about as much area in gaps as you have in port size

e.g.

if you have a 6" port, then that is pi*r^2 or 3.14 * 3^2 = 28ish sq inches

So leave about 28 sq inches of "gaps" elsewhere.. probably near the top side of the table (around the gaps where the cast top meets the metal box) such that the airflow is down and into the port. Seems reasonable that you would want the gaps located such that the air flowing through the gaps pulls the dust towards the port.

If you leave less area than that, you are going to create a vacuum and it's not really going to help move dust. If you leave more area than that you have just going to reduce the airspeed and at some point (nothing is enclosed) there would not be enough airspeed to carry the dust.

If you have a 4" duct, that area drops to about 12 sq inches. Now you can see why Bill Penz and others insist on 6" ports!! Makes sense to me.

[K. B.]

Thanks for all the feedback. Dave's link to

was particularly interesting. The pie-r-square theory is pretty good in that it is something you can sink your teeth into- I shall try it. All the advise and comments were helpful. The experiments are on!

[nospam_coloradotrout]