Dust Collection #2

Herb and I took some ideas and tuned them to our needs for dust collection on our router tables…
the start and evolution… As usual we’re always up to something…

Venting a router table’s motor w/ DC…

This is by Stick486

One very important thing you have to remember is to make sure your router box is vented w/ outside air for the motor or you will cook the motor from excessive heat because of the lack of cooling air for the motor…
Do this by either sticking the motor’s air intake outside of the box or add a ‘‘snorkel’’ to the end of router motor…

The DC alone puts the enclosure at a lower air pressure than the air outside the box. You may be sucking across the base past the bit but where does the makeup air that is going through the router’s fan come from? Air is being sucked out of the box with no intake near the fan inlet at the other end of the router.
Also, the router’s heat is exchanged to the air molecules passing through the motor. A DC lowers the pressure in the cabinet, in turn, reducing motor’s heat transfer…

Different routers provide cooling differently…for example, the Bosch 1617’s internal fan blows air directly upwards (whens mounted in the table) versus the Triton router which diverts air sideways as it exits the router. The Triton also diverts air away from the insert and it’s dust collection plasticware under the bit…

Equally important is dust not entering any of the components in the router as a result of it’s internal cooling system. This includes switches, slides, armature, etc… This can only be determined over time for the different varieties of routers and their cooling configurations.

There are two separate systems going on. First the air flow requirements of the router need to be satisfied. Secondly, the dust collection system needs to do it’s job. I can state categorically that any compromise created as a result of mixing the two is just that…a compromise.

That dust enters the box is a dust collection issue. Edge profiles versus bottom profiles (grooves) create different dust problems…

All this assumes that one has worked diligently to separate the two systems. The Snorkel approach does exactly that. It keeps router cooling separate from dust collection…When using the snorkel, the positive pressure created by the router’s internal cooling needs to be equalized in the box…that is the reason for allowing some suction from the dust collection system to evacuate the box’s otherwise positive pressure. If you separate the two systems, there will be no opposing air flows…except for evacuating the positive air created by the independently supplied airflow of the router’s cooling system.

This is by Herb Stoops…

That is a good point, Stick, I let the router protrude through the bottom of the box. By doing so I had to cut out the bottom to clear the posts for the JessEm lift. I like Stick’s idea better to clamp a flex hose around the router and let it protrude through the bottom of the box to allow the motor to suck clean air. I also have an adjustable port in the side of the box to allow more air into the box to create a maximum air flow through the box.

In my first router table I had the Milwaukee router, it was a real workhorse, the reason I bought the Milwaukee was at that time it was one of the few routers you could adjust the height from the top of the table. I didn’t have a dust collection under the table at that time and could reach under, unlatch the router and do the adjustment from the top ,then reach under and lock the router. But the amount of chips and dust that ended up under the table was a large amount. The fence dust collection just couldn’t get half the chips.

I also doored the router box for easy access to the router and the lift…
Stick did the same and he installed his vents in the door…

Under the table DC is a must, I branched off a 4" diameter hose with a 2½" take off to the fence and the 4" line to the underside of the table’s box.

The Fix…
Now for Plan ‘‘C’’…

A closed dust collector box keeps the inside of the table’s router box at negative pressure. Which limits air flow and to some extent, deprives the motor of cooling air flowing through the motor. This fosters a condition where the router motor will overheat.

Building a box enclosing the lift and router motor w/ DC porting/venting and at the same time providing motor cooling make up air separately allows the DC’s air to flow at optimum efficiency.

Suggestion:
Add a large square boot, (right angle 4’’ outlet minimum), centered to the router motor, on the bottom of the box and dedicate to DC…

Now, cooling airflow to the motor.

Adding a ‘‘snorkel’’ made of plastic or metal to the end of the router motor, of sufficient length to protrude outside of the box, irrespective of motor elevation, would ensure fresh cooling air to the motor.
This snorkel/tube/sleeve goes right through the dust collector boot (you would need to cut a hole in the boot for integration). It allows the motor to draw clean outside air for cooling while not interfering w/ DC.

HEAT will destroy your motor in very short order without good clean airflow.

When you attach the snorkel to motor make sure you don’t seal up the air inlet vanes.
Round routers only need a round tube. Oversize the tube and use a reducing bushing with an ID to fit your motor.

Square ended router motors need a little more creativity. There are a host of square to round PVC adapters found in the “Big Box” chain stores’ plumbing departments and they are also used in storm water drainage systems. Fernco also makes an extensive product line. In addition, look to vinyl guttering components. Also, don’t skip by the HVAC section either. There is a vast variety of adapters available. There isn’t anything saying that you can’t use a length of square tube. There are a host DC fittings that may work. You could even fix the tube aka snorkel to the bottom of the box and let the router motor slide freely up and down in the tube. You could make this square tube from thin plywood or even FRP.

Now, as to the mounting. There are many options available; hose clamps, Velcro, Tywraps, mechanical (screws, nutserts, etc.). Mechanical method would be preferred if you have a thick motor cap and there’s plenty of clearance under the cap to give the end of your mechanical fastener room so the fastener doesn’t damage anything.

Velcro:

For that to work, (slide on - slide off can be tad difficult) barrier the hooks and loops w/ a plastic putty knife(s). Set the snorkel. Remove the putty knife(s).
To separate the H&L to remove the snorkel, slide/work the putty knife(s) in between the H&L to release one from the other.) Remove the snorkel…

Concepts

Router Table Airflow Concept 1

Notes:
An open bottom box won’t work all that well if there are drawers under the router box, nor will the snorkel through bottom or a bottom mounted DC boot unless they are designed into the table. Venting and DC will work if installed through the back or side of the box. Whatever you do, you need to arrange for make up air (venting/cooling) and pickup for for the DC simultaneously. There many variables here but all in all this should give you plenty of ideas to work w/ for/on a finished system that will work well for you. See the pictures for more ideas…

Improving Top of Table DC…

Increase the pick up line size and increase the CFM…
W/ a little modification - adapt a soil wye to the top of your table…
this big plus when edge or slot…

PVC DC hood.pdf (138.0 KB)

Here are some pictures of my router table DC system. The first is the Jessem table .It has an old 3hp PC motor and a jessem Master lift. the router is plugged into a speed control on/off switch. so I set the router switch on the hi speed since I can’t get to it under the table. Then I made a box the motor protrudes through the bottom for air through the router motor. The cutout for the motor lift is larger to allow air flow for the dust collector. Then the DC hose on the back Wyes off with a 2" that goes to the fence. behind the bit. There is also an adjustable opening in the side of the box to adjust makeup air for a good airflow in the duct.
Why you ask? Because if there is not enough air flow in the duct, on long runs the chips can settle out in the duct,thus eventually causing total decrease of airflow in the system.

The second picture is the MCLS router table. I did the same and also put drawers in both tables. the MCLS table also has a Rockler lift

Herb

1 Like

I’m so close to what you have done…
I snorkeled the motor out the bottom of the box and vented for the DC through the door…
we are using the same motors…

Suggestion …
shorten the 2" flex to the top side to get rid of that loop…

NOTES and Tips…

it you do away w/ any 90° corners in the box. the DC will generate a vortex… a big plus for the efficiency…

the table…

the door… it’s magnetically held in place…

the box w/ the kanted corners…
the dust you see is all that ever collects…
the snorkel which protrudes through the bottom of box was removed for clarity…
DC pick up is through the back of the box…

Observation…
the vortex is so strong that the abrasive wood chips and dust removed the paint from the floor of box and has left swirl marks
for sure, the box is a total vacuum… w/o the snorkel the the motor will be deprived of the cooling air it needs causing the motor to overheat and become junk…

@HerbStoops
your older motor allowed you to add an external speed controller straight up…
I had to rewire mine to bypass my internal speed controller…