Router Table Intake Air

[Kris Cook]

Building a router cabinet/table. I am planning a 4" suction at the back of the cabinet with a 2-1/2" tee going up to the fence. This will be connected to my DC via 4" flex tubing coming off of a 6" drop.

Wondering if others have seen the need for intake air in the compartment that houses the router (4" suction).

[Jim Becker]

Yes, you want some additional openings to help provide enough air for efficiency and if you do them down low opposite of the port as well as toward the corners, they will help "sweep" stuff away that normally would collect in those corners due to lack of air flow in those areas. I suggest you either do a wye from the 6" to the 4" and 2.5" hoses or take your 2.5" off the cabinet, rather than using a tee. You can do a quick calculation of the area of the 4" inlet and compare it to the area of the 2.5" hose plus the average opening in the table to figure out how many smaller holes you need in the cabinet. It does not need to be exact. You can also use a slot rather than holes if you prefer that.

[Edwin Santos]

Building a router cabinet/table. I am planning a 4" suction at the back of the cabinet with a 2-1/2" tee going up to the fence. This will be connected to my DC via 4" flex tubing coming off of a 6" drop.

Wondering if others have seen the need for intake air in the compartment that houses the router (4" suction).

Yes.
And if you don't do it, your router will be operating in a negative pressure vacuum and the bearings will burn out prematurely. DAMHIKT

[Bruce Wrenn]

A router motor fan is designed so as to blow exhaust air over bit. Otherwise, all that dust and chips would be sucked up into the motor. Too much suction from a DC could offset fans exhaust, instead, drawing dust/chips into router Rather than whole cabinet, I would prefer something that sweeps air between motor and bit, with a fresh air intake in bottom of the cabinet

[Michael Burnside]

I’m extremely happy with my Saw Stop cabinet and fence. Take a look at their design for guidance if you need it.

[Tom M King]

Probably doesn't apply to a regular router table, but I'll show this anyway. For my dedicated router "table" setups for making sash, the PVC pipe riser is the air intake to keep fingers safe and prevent chips from being thrown out.

They get 100% of the chips and dust, and the router looks like new after whatever use I need out of them. More pictures and details on the Windows page of my website.

[Greg Quenneville]

I used a closed (with vent holes) cabinet with only a 4” under table connection. I machined over 120 sheets of mdf on that table and had to service the Triton router twice due to dust ingress into every crevice possible. I now have a big hose connection on the fence which probably gets 90%+ at the source.

Now that I have a 10hp shaper the dust collection problem has started all over again.

[Lee Schierer]

I ran my Freud FT2000 router for maybe 5-6 minutes once without the dust collection turned on and I was amazed at how warm the router cabinet enclosure became in that short time.

[Brian Tymchak]

I ran my Freud FT2000 router for maybe 5-6 minutes once without the dust collection turned on and I was amazed at how warm the router cabinet enclosure became in that short time.

I did the same recently experimenting with how to get better collection when I was "free" routing (without a fence). I have a 3 1/4 hp in a dust box and in just a few minutes, the box was warm to the touch.

The OPs proposed setup, with an air intake at the back of the cabinet, is pretty much what I have and it does an excellent job collecting with the fence in place, not so much without the fence as I mentioned. I tried changing the size of the insert ring openings to get better collection but that didn't help. Still looking for a better idea on that as I do quite a bit of that operation.

[Jim Dwight]

I had a router table setup in the auxiliary table of my old table saw. The router was in a box with a 4 inch port on the bottom. I thought the router got too hot in that setup, presumably because the DC flow was limiting the effectiveness of the router cooling fan. So when I designed my current router table, I put a piece of 4 inch flex inside the cabinet with the inlet in the router chuck area of the router. My lift is home made so it was easier for me to do this, probably. My 4 inch DC connection thus enhances flow through the router motor. The door into the compartment with the motor is an inch or so shorter than the opening to let air in at the bottom of the compartment. I also wye the 4 inch line from the blast gate of my DC to have a 2.5 inch connection to the router table fence. I am very happy with this setup. It doesn't get everything but gets most of the dust and the router seems to stay reasonably cool.

[glenn bradley]

My replacement air opening is directly across from the 6" collection port on my router table. The move to a 6" port really improved the collection of spoil around the bit and table top. I also use fence collection. Your replacement air opening area should be about equal to your collection port's area.

[Jack Frederick]

I have the same 4”/2” connection as you. This is how I built mine. Saw dust does not build up in it. It is made with a plywood bottom, angle iron corners and filled in with sheet metal. There is a small gap at the top of the sheet metal to allow some air in and the three holes in the plexi create the sweep.

[Tom Bussey]

Why not just collect the chips at the top of the router with a vac and sweep the floor when done for the day?

[Tom M King]

Someone needs to come up with an adjustable setup like my dedicated ones. The router never even smells dust. Bits have to be installed from the top though. There is a hole that the shank comes through, and a recess in the top that leaves that ever so slightly bigger than 1/2" hole for the shank.

When I was first playing around with building them, I found that a shop vac did better for getting all the dust than the DC. The shop vac air velocity is higher, and the hose still moves plenty of air volume for this job.

Tops are made from free phenolic bowling alley surface scraps.

[George Yetka]

I try and keep opening minimal around bit, sufficient at fence, and the door on the front of my cabinet leaks a bit.

In this way the 2-1/2" hose takes away the lion share of the dust the 4" will pick up anything that hits the cabinet

[Tom M King]

There could be a slide gate around the bit shank to cut that space down. I swear I've used my sash setups for a thousand cuts, and the routers still look like they just came out of the box.

[Kris Cook]

I have the same 4”/2” connection as you. This is how I built mine. Saw dust does not build up in it. It is made with a plywood bottom, angle iron corners and filled in with sheet metal. There is a small gap at the top of the sheet metal to allow some air in and the three holes in the plexi create the sweep.

Hmm. I was going to put my outlet at the bottom. Jack - what is the plastic gizmo protruding into the air flow?

[Kris Cook]

A lot of good input here. I will ponder and post my results.

[Jack Frederick]

Kris, I assume you mean the threaded rod from the bottom. It is my version of a lift. I have the big PC plunge unit in the box. It isn’t without issues, but much less expensive than the very good well thought out commercial units. I reach in release the lock lever an with my socket wind it up t o the right height.

[Kris Cook]

Kris, I assume you mean the threaded rod from the bottom. It is my version of a lift. I have the big PC plunge unit in the box. It isn’t without issues, but much less expensive than the very good well thought out commercial units. I reach in release the lock lever an with my socket wind it up t o the right height.

I got it, thanks. I didn't realize the picture was rotated. I am using a PC 890 without a fancy lift also. I just use the tool that came with the router to raise and lower, nothing fancy. I have a bigger router but currently no plans to install in the box. That could change in the future.

[Tim Andrews]

I just finished building my router dust box, which I posted on the Shop Made Tools forum. It has an adjustable air intake and a breather hose to supply fresh air to the router. Works great.

[Kris Cook]

That looks nice Tim. I will take a look.

[Kris Cook]

I did the same recently experimenting with how to get better collection when I was "free" routing (without a fence). I have a 3 1/4 hp in a dust box and in just a few minutes, the box was warm to the touch.

The OPs proposed setup, with an air intake at the back of the cabinet, is pretty much what I have and it does an excellent job collecting with the fence in place, not so much without the fence as I mentioned. I tried changing the size of the insert ring openings to get better collection but that didn't help. Still looking for a better idea on that as I do quite a bit of that operation.

Bryan - I am using a Kreg table top which has the sliding "doors" to adjust the clearance around the bit. I would think that should help with directing airflow. I am considering putting a blast gate between the main 4" suction and the 2-1/2" fence suction because it seems when cutting dadoes or grooves the fence collection doesn't do much. What do you think?


I had a router table setup in the auxiliary table of my old table saw. The router was in a box with a 4 inch port on the bottom. I thought the router got too hot in that setup, presumably because the DC flow was limiting the effectiveness of the router cooling fan. So when I designed my current router table, I put a piece of 4 inch flex inside the cabinet with the inlet in the router chuck area of the router. My lift is home made so it was easier for me to do this, probably. My 4 inch DC connection thus enhances flow through the router motor. The door into the compartment with the motor is an inch or so shorter than the opening to let air in at the bottom of the compartment. I also wye the 4 inch line from the blast gate of my DC to have a 2.5 inch connection to the router table fence. I am very happy with this setup. It doesn't get everything but gets most of the dust and the router seems to stay reasonably cool.

Jim - where does the 4" flex daylight? Is that the suction line or is it a passive vent?


All - thanks again for the input. I plan to use plexiglass for the front door in the collection box so I can see what is going on. I will do some ciphering on the vent sizes. I was also considering an adjustable intake as Tim just posted.

[Chris Parks]

Use a water cooled CNC spindle and all the dust collection problem go away. Air cooled routers are a disaster in a router table, I will post a photo when I have more time.

[Carl Beckett]

I just finished building my router dust box, which I posted on the Shop Made Tools forum. It has an adjustable air intake and a breather hose to supply fresh air to the router. Works great.

Which direction is the air flow of the cooling fan built into the router motor? I am confused - in your setup is the dust collection pulling from the bit side to the back of the router? Does this need to overcome the motor cooling fan direction?

Any concerns over cutting dust/chips getting pulled through the router?

I ask because I do have DC from below, but also have found it is much more effective if coupled with collection at the fence, and I am worried my setup may have pieces that are fighting each other.

[Tim Andrews]

Which direction is the air flow of the cooling fan built into the router motor? I am confused - in your setup is the dust collection pulling from the bit side to the back of the router? Does this need to overcome the motor cooling fan direction?

Any concerns over cutting dust/chips getting pulled through the router?

I ask because I do have DC from below, but also have found it is much more effective if coupled with collection at the fence, and I am worried my setup may have pieces that are fighting each other.

The router motor is isolated from the box since the hose is tightly clamped, and pulls fresh air from the hole in the bottom of the box. I don’t know the exact mechanics, but I assume the air passes over the motor for cooling and exits inside the box. The suction from the dust collector is much stronger than the air flow of the router, so I don’t think there are any issues with fighting each other.

The photo showing the inside of the box was taken after routing four dados about 8” long with a 3/4” bit. As you can see there is almost no dust. I had originally planned on adding some sloping sides inside the box to prevent dust from collecting in the corners, but it proved unnecessary.

[Chris Parks]

Use a water cooled CNC spindle and all the dust collection problem go away. Air cooled routers are a disaster in a router table, I will post a photo when I have more time.

Have a look at the photos I posted here for 100% dust extraction on a router table.
Router table motor (sawmillcreek.org) (https://sawmillcreek.org/showthread.php?301232-Router-table-motor)

[Kris Cook]

My previous router table was a homemade wing in a Craftsman TS with a fence that had an internal air collection chamber. It worked pretty well with the small 3/4 HP DC I was using at the time. The main issue I had was face cuts (grooves and dadoes) with the DC not picking up hardly anything.

After reading more about router cabinet dust collection until my head hurt, and thinking some more about this, I think trying to pull or drop the dust into the bottom box is generally not that great of an idea for most cuts.

I am planning to plumb my primary collection at the fence.

I will install the tee in the back of the cabinet but would only plan to pull from the bottom when making face cuts.

I can always go back to pulling from the bottom as the primary, if my current plan doesn't work out.

[Chris Parks]

The first question that needs answering is how capable is the DC? The debris can be pulled down through the table but it requires a reset in thinking and a capable dust extractor. Get rid of any concentric ring inserts and make a half insert that only covers the outboard side of the cutter away from the fence then make an elongated slot that goes from the insert and under the fence and box that slot so it goes straight to 4" extraction port (minimum). The air then is sucked through the slot behind the cutter and I think it is shown in the above link I provided. Machining a dado or rebate over a conventional ringed insert means that the debris cannot be sucked out due to the air flow being stopped because the wood is covering where the air should enter. The whole problem is in the end being caused by using hand held air cooled routers in tables and the awareness of the issues this presents is slowly starting to be understood, Jessem's air cooled spindle is an admission of that but the problem is it is still air cooled so only half a step and not totally overcoming the issues air cooled motors present in router tables.

[Kris Cook]

Chris - I appreciate the input. I will give that some more thought.

[John Kananis]

I've never considered removing material from the back of the insert ring. I'm going to have to set some time aside (good luck lol) and do a side by side with modified vs normal. Thanks for the idea.

[Chris Parks]

Getting rid of the insert ring is key to the whole thing. I have some photos somewhere of a table that first used the concept and I will try to find them. You need a hole for the debris to fall into not a ring that prevents that happening. This approach goes against everything the manufacturers have been trying to ram down our throats for many years so it does require a reset in our thinking.

[Chris Parks]

Getting rid of the insert ring is key to the whole thing. I have some photos somewhere of a table that first used the concept and I will try to find them. You need a hole for the debris to fall into not a ring that prevents that happening. This approach goes against everything the manufacturers have been trying to ram down our throats for many years so it does require a reset in our thinking.


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This will clear 99% of the debris if not all of them. The more I think about concentric rings the more they annoy me as the idea simply can't work.

[Tom M King]

My single use router tops work great with dust collection only from the top. There is a hole only big enough for the 1/2" shank that the bit comes up through, only ever so slightly enlarged to prevent rubbing. There is a slight depression under the bit to allow a little clearance there too. No dust exits around the shank to get to the motor. The motors all still look like new, having been bought new just for this purpose.

Fence is made at the same time as the parts run so it's the same thickness. The top serves as holddown as well. A piece of paper folded once is put under the infeed side of the top to give a bit of clearance to get the part under to start it.

I prefer no dust gets to the motor.

The disadvantage of this, of course, is that the bit has to be installed from under the top, but it's not a problem with these portable ones.

[Chris Parks]

I prefer no dust gets to the motor.

Using a water cooled spindle fixes that problem but that would not be practical for site work. My site RT is a flat sheet of MDF clamped to a saw horse, the fence is the nearest bit of straight timber and two clamps. Needs must when time and money become issues on the job.

[derek labian]

I am not worried about fresh air in the dust box if the material isn't building up. My problem with most (square) dust boxes is build-up in the corners of the box. I recently switched to the Harvey box because it has a cylindrical bottom to collect and move material out and the dust port splits the 4" for the upper collection, not just a Y. It's also only $99 and comes as a solid piece of metal, not bolted together like most boxes.

492577

[Chris Parks]

The build up can be thought of as an annoyance and it should not happen or ignored and when it reaches a certain size it won't get any bigger. These photos shows a spindle sitting in the air stream and because it is water cooled dust in the motor is not an issue.

492578 492579 492580

Water cooled spindles solve just about every problem RT's have and are generally cheaper to put together.