Router Table DC for Jessem Mast-R-Lift Excel

[Dru Dron]

Hello Sawmill Creek,

I am finally getting around to building a custom router table cabinet for the Jessem Mast-R-Lift Excel router table top that I purchased several months ago. I’ve been reading up on router table dust collection and have only recently come across various online discussions about “make up air”. I gather this has something to do with bringing outside air into the cabinet to replace the air removed by the dust collection system. In designing my custom cabinet, this concept had not occurred to me. Is this necessary to improve the efficiency of the dust collection process or is it mainly to cool the router motor?

Having said that, I’m wondering if anyone reading this, who might also be familiar with Jessem’s router table called the Mast-R-Lift Excel, can clarify whether this is necessary with this table design given the location of the built in dust port right up by the router bit on the underside of the table? I also have their router table fence (Mast-R-Fence) with built in dust collection port and will be making use of that as well.

If make up air is required, can anyone provide guidelines as to how best to provide it within an otherwise fully enclosed cabinet? Can it be accomplished by simply drilling a hole or two approximately the same size as the dust collection port(s) (i.e. 2 ¼ to 2 ½” in diameter) in the back panel of the cabinet? If so, should the holes be near the bottom or near the top of the cabinet enclosure, or does it matter?

I’ve been reading some other router table dust collection threads on this forum but I keep coming away a bit confused. If anyone can help me clarify this issue I’d be most appreciative (and relieved).

Thanks a lot!

Dru Dron
Guelph, Ontario, Canada

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[Tom Veatch]

I’ve been reading up on router table dust collection and have only recently come across various online discussions about “make up air”. I gather this has something to do with bringing outside air into the cabinet to replace the air removed by the dust collection system. In designing my custom cabinet, this concept had not occurred to me. Is this necessary to improve the efficiency of the dust collection process or is it mainly to cool the router motor?It's absolutely necessary if you're going to have any dust collection at all. You MUST have airflow in order to pick up and carry away the dust. Otherwise, the dust will just lay there like it will on the table top if there's no breeze blowing it away.
Having said that, I’m wondering if anyone reading this, who might also be familiar with Jessem’s router table called the Mast-R-Lift Excel, can clarify whether this is necessary with this table design given the location of the built in dust port right up by the router bit on the underside of the table? I also have their router table fence (Mast-R-Fence) with built in dust collection port and will be making use of that as well. I assume the "dust port" you're talking about is the opening in the plate insert around the router bit. That will provide airflow to pull much of the dust down into the cabinet. Note, that dust will be entering the cabinet from which the router draws cooling air into itself. I found that enough dust got into the router (PC7518) that its speed control stopped working until I took it apart and gave it a good cleaning. You need to provide auxillary flow to sweep that dust past the router's inlet, or at least reduce the concentration of dust in that area.
If make up air is required, can anyone provide guidelines as to how best to provide it within an otherwise fully enclosed cabinet? Here's how I did it (http://www.sawmillcreek.org/showpost.php?p=1062219&postcount=7). Note that the area of the inlet grill into the back of the cabinet has approximately the same open area as the area of the DC duct. Otherwise, you'll be choking down the total airflow through the cabinet. Also note the baffle in the center of the cabinet that separates the air entering the bottom of the enclosure from the air leaving the top of the enclosure. This keeps dust free air in the area of the router's air intake. Air flows into the bottom of the enclosure through the grill on the back, up past the baffle at the front of the enclosure behind the door, and out the back of the enclosure through the dust port.

[glenn bradley]

Agreed; you have to let air in in order to have air flow out. I put my inlet opening(s) on the door and my exit port directly across to create an air flow that carries the dust away very efficiently.

My susccess didn't come from any intimate understanding of hydraulics or mathematical wizardry. I had simply read everything I could find and listened to what worked or failed for folks. I then went through a session or two of trial and error. I ended up with:

- Exit port out the back with the opening even with the floor of the enclosure.
- Test door that allowed me to increase the entrance opening size till I got the best dust removal.
- Permanent door with identical area of test opening.

I have a full set of of throat plates for various bits. I try to use a bit that leaves about 1/4" of opening around the bit to allow draw from this area as well as the door openings. I use less clearance around the bit when required. I also have a fence port.

[Bill Huber]

I have a Jessem FX lift and here is the way I made the dust collection for my table.

http://www.sawmillcreek.org/showthread.php?t=65058

Like everyone else has said you have to have new air in or you get nothing out. Just think about putting your hand over the end of you dust collector hose, nothing moves until you take your hand off.