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Harvey Pascoe
01-22-2011, 5:55 AM
This is to alert you to the problems associated with router table dust buckets, and the solution.



Anyone who buries their router bit in the work piece knows that above table dust collection is worthless. I routinely route 1.5” wide troughs to make shallow trays and the amount of dust this throws on me and into the shop is horrendous. Recently I saw offered in catalogs something called a “dust bucket” a steel enclosure that fits around the router under the table to which a dust port is attached. This looked like it would be effective so I built one of my own, 12” square and sitting on the shelf within the cabinet and sealed to the underside of table top with weather stripping. It proved to be 95% effective at capturing dust. Wow, I was amazed, but not for long.


Just one small problem: within three weeks I burned up two brand new Porter-Cable routers. After the second motor burned up, I took it apart to see what went wrong. Holy smoke! The motor was totally impacted with dust, which also had caught fire. The reason for this was obvious as all routers have a fan at the collet end that pulls air up through the motor toward the bit. The dust bucket simply accelerated the flow of dust through the motor. Equally obvious was the solution which was to provide and outside source of clean air for the motor.


Making a sketch and analyzing air flows led to the idea of drilling a hole in the bottom of the dust bucket and attaching a vinyl accordian dryer duct to the router top with a hose clamp. I drilled a 3.5” hole in the bottom of the dust bucket, so the hose would fit tight, and then routed it to the outside of the router table cabinet. I used 18” of bellows hose so that I could still lift the router up and out of the table with ease. I also reduced the 4” dryer duct to a 1.25” intake with plastic plumbing parts. The total cost for this modification ran about $20, it took me about 6 hours to complete and it is 100% effective in keeping dust out of the router. Dust capture has been reduced from 95% to around 85% but a far cry from zero percent as previously.


The only mistake I made was placing the dust port at the top of the box near the router collet. The dust port should be at the bottom of the box.



If your router table is a cabinet, beware that it is shortening your router life by putting too much dust in the motor. You can avoid this by blowing out the router with an air hose just a couple times a year.

Cyrus Brewster 7
01-22-2011, 7:25 AM
Harvey, I have a question as I just finished one myself. Was you dust bucket originally connected to your DC? From what I was reading it sounded like your router was completely enclosed. Mine is connected to my DC and I also have a way to adjust the airflow into the enclosure. I have not had any problems so far. But is is quite cold so I have not used it much. The last thing I want to do is burn up my new PC 7518.

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Phil Thien
01-22-2011, 9:06 AM
Cyrus, nice job on that down-draft box. May I ask the diameter of your air inlet "thing," and also the diameter of the three holes you drilled in it?

Cyrus Brewster 7
01-22-2011, 9:48 AM
Good Morning Phil. The disk is 4.5 in and the holes are 1.25 in. I actually traced around the adapter ring from my PRL. I made the holes as big as I could and still have them close completely.

glenn bradley
01-22-2011, 10:41 AM
Right, allowing adequate airflow to carry the dust out of the box is crucial. I wonder if the size and location of your return opening to compensate for the draw of the DC was properly sized? The throat plate hole alone is totally inadequate to allow the airflow, especially making the cuts you describe. I too make buried cuts and so did not even include the throat plate opening in my calculations.

The point is, of course, if the air can't flow unobstructed, the speed will not be adequate to carry the dust away. We don't want a vacuum, we want air-speed. I have run my Mil 5625 for several years almost daily and have opened the door to the lower compartment maybe a dozen times to change speeds for the occasional 3"-plus bit. A few month ago I took an air-gun to the motor and got very little material out of it. To further qualify this; I am only a hobbyist. An enthusiastic hobbyist but, only a hobbyist. So what seems like a lot of use to me may be a pittance to someone else ;-)

Bill Huber
01-22-2011, 10:44 AM
This is what I did and it has worked very well. I have the Bosch switch problem and then is why I started working on something different.

http://www.sawmillcreek.org/showthread.php?65058-Different-Dust-Collection-for-router-cabinet....

Bob Vallaster
01-22-2011, 10:44 AM
Cyrus,
I admire your system: compact and tidy. The variable damper for aux air is a clever feature.
One question about the wye (in the first picture) where the hose from the fence gap merges with the box discharge. Wouldn't you have better flow if the wye were flipped to aim the top hose in the direction of flow?

BobV

Cyrus Brewster 7
01-22-2011, 11:48 AM
Bob, we are both on the same page. Originally I intended to attach the wye as you stated. But this put too much of an 'S' bend in the 2.5 in hose. To compensate for this I would have had to extend the wye further out than I wanted. I was worried about the suction of the current set but have had no problems - all dust/chips are captured. I actually open the damper slightly to improve air flow at the fence, but I believe doing this would improve suction no matter which way the wye was installed.

As for buried cuts, the DC is excellent with the damper wide open.

Harvey Pascoe
01-22-2011, 3:41 PM
Yes, Cyrus, the bucket was connected to the DC. What I did not have was an air inlet control, rather there was a 1/4" gap at the top of the bucket and I thought that would be sufficient. Apparently not, and in the wrong location. Now, with an inlet duct right to the router, do I still need to add an air inlet control? Where would be the best location for it, top or bottom or does it matter? Seems like bottom would be best to me.

Cyrus Brewster 7
01-22-2011, 6:17 PM
Harvey, like Glen said, as long as you are not starving your DC you should be OK as is. I chose the damper to adjust/redirect airflow between different operations. I am actually thinking of putting a secondary damper on the side. The reason for this is that I would rather have excessive open space that I can close vs being maxed out on my allowable airflow. The only time I think I may need this when the opening around the bit is totally closed when bringing the bit into the work piece. This would help more air travel through the box instead of from the fence. To this effect I am thinking of attaching a gate for the fence inlet but this might be overkill. I do that at times.

As for top or bottom, I am not an expert here but since you have something at the top then why not create some flow at the bottom.

Cyrus Brewster
01-22-2011, 7:54 PM
Cyrus,
I encourage you to study Bill Hubers post above. It makes a lot of sense to me -- gets the chips out before they can even start to harm the motor. As you know I'm about to enclose my router and this is the best design I've seen yet.

Cyrus (6) your retired dad

Cyrus Brewster 7
01-22-2011, 8:03 PM
Hey dad... Yeah, I looked at Bill's design and it really makes sense (I wish I had seen it before building mine). If I can find any problems with mine I may borrow from him this spring.