Dust port location?

[Salty]

Need some advice here on locating a dust port.
I have been building a router table and have got the box built around the router but I am not sure where to put the dust port. The box is just over 1' cubed, slightly deeper than it is wide. I planned the front so that I can put a plexiglass door on and be able to scoop out the bottom of the box area. The top tilts up so I won't have to use the door axcess for bit changes.
Any ideas as to where the port would work best?
Green: On the back wall at the base of the box?
Blue: On the box floor against the back wall?
Red: On the box floor directly below the router?

Or maybe there is a better location?

Thanks for the help folks.

[lkazista]

Personally, I would try to fit two pieces of wood down there, forming a 'V', with the bottom of the V landing just outside of the GREEN hole, this way your vac has less cubic area to suck through, and gravity itself will help to feed the dust to the port.

At least that is how I plan on building mine if I ever actually get to it.

Just a thought.

Lee Kazista

[Salty]

Good idea Lee. Thanks.
This is what I did. There is flat area at the bottom but that is because I am trying to use up some small pieces of MDF which should give the walls a smoother surface.
I think I'll try it this way and see how well the vac works. But that is about a week away.

[lkazista]

Yeah, that's the idea. I assume you must have had that idea already, because I posted that idea like 1 hour ago, and you already have photos of it.

Nice work, post a photo of the completed cabinet when your all done.

Lee

[Salty]

Hehe...I went and did that right after I saw your reply. I was going to try to draw something in Photoshop but decided that would take me several hours and it still wouldn't look too good.
It's coming together now. I needed to get to the point where I could use it to make the drawers. Also, I am waiting on some T-channel from Grizzly which should be here Monday. That will be used to anchor the fence.
Probably have to make another trip to the lumber yard tomorrow too.

[gmack5]

Norm Abrahms put 3 or 4 holes in the plexiglas front face of his table design along the bottom edge, then mounted the Dust Port in the rear back wall at the bottom.

His claim is that it encourages better air flow. The holes were about 3/4" in diameter, if I remember right.

[lcm1947]

What an excellent idea Lee. I will do that on mine. As far as the door according to the American Woodworker book " Woodworking with the router" they too express concern over sealing the compartment off thereby restricting air flow to the router motor. What I'm going to try is just making a 4 or 5 inch lip in front to keep the saw dust from falling off onto the floor if I need to. Haven't finished mine yet either but getting close.

[Les Sayers]

Dust port location?

FWIW - if you have a Central DC go for a direct 4" hook up for the reason of much improved air flow in/through the cabinet and around the router motor.

My first attempt had standard 2.5" vac attached and did not work too well.

I'll post photo (function before form)



BTW my exhaust port is in the floor of both cabinets and seems to work well.

Hope it helps

[Salty]

I have also noticed that many of the designs use a partition which leaves just a narrow path at the floor of the chamber. What is the idea behind this?
Is this just another way to limit the cubic area of the chamber?

[Salty]

Well now I'm not so sure this idea is a good one!
After doing some tests and examinations I discovered that the router is designed to move air through the motor from the top down. This would make sense since they would not want the dust and chips being sucked through the motor fans.
So, if I mount the router upside down from its intended orientation, the router fan will be moving air up toward the table top. Seems to me that putting suction in a chamber this way will be working against the router motor fans. This in turn could, under the right conditions, cause a static airflow through the router motor. That would be bad!
Since there will also be a suction created at the back of the fence, logic would dictate that this would be the only point at which suction should be applied. This would aid the natural air flow of the router and keep the debris from going "down" through the router motor.

Thoughts?
Suggestions?
Am I crazy?

[cgallery]

Thoughts?
Suggestions?
Am I crazy?

You are absolutely correct where edge routing is concerned. But if you ever cut dados in the middle of the board, or do through cuts more than a few inches from the edge of the board, the fence-based collection will not help. The down-draft method is the only way I know that works in all cases.

Now, in terms of the router's fan motor and static air flow, I have read the same concern expressed from a number of people that want to maximize router life. One poster at groups.google.com mentioned that he saw a tip in an older wood working magazine that had him cut a disk of hardboard that he added to the spindle to prevent dust and debris from getting sucked through the motor. He said that after several years of use the disk still looked and worked fine. But I wonder if it wouldn't restrict motor fan air flow.

I guess it is a compromise. I cut some MDF w/ my new down-draft drawer and then took a look at my router and did see the fine MDF dust clinging to the plastic in a few spaces. So I'm going to blast the router w/ my air compressor from time to time to keep it clean.

One more point. As Pappy pointed out in a response to a post of mine in another forum (tool talk), there are quite a few routers located in down-draft tables/boxes. Anecdotal evidence would suggest that the routers are no worse for the wear. I'm not saying that it is the best environment for them, but they seem to manage.

Thanks!
Phil

[Salty]

Good point on the dado cuts Phil. I hadn’t considered that case. I know my brother has mentioned that when he does dado cuts the cuttings are usually packed in the grove. He uses the Rockler table with no box around the router.
I did some additional testing and considered that maybe the most efficient and beneficial arrangement would be to isolate the router intake from the router base.
Implementing that is another matter is would be a challenge.
There is a tremendous vortex of air movement at the base of the router and with the plate mounted the air is being forced at a 90 degree angle from the router along the underside of the base. I could cut additional holes in the base plate but some of them would be covered by the fence anyway. Probably 1 or 2 additional holes in the plate in front of the fence would help. However, I do not see this being done on any router table plates. This may be because the added holes could become obstacles when sliding the material across the table top. Also, the variety of throat plates suggests that there is a need to keep the area between the bit and the table as small as possible.
So, ideally, the air should move through the router and be ejected through and away from the base. That air should not escape to the table top where the dust and chips are being made. Since it would be impossible to completely isolate this air movement, some of the force of air from the router will try to go past the bit. That would be fine as long as the suction behind the fence is great enough to continue the path of the dust into the dust collection. What would not be good is if there was a suction that would draw in such a way as to cause the dust to be pulled down toward the router motor.
My next attempt is going to be a different approach. I plan to use the area where the door would have been placed as a filter area. Normally I would need a large filter area to supply enough air to the router motor fans but this is a different situation. I only want to be able to filter the air that would enter the chamber and allow the air inside the chamber to circulate through the router. The only air that will be going through the filter is to replace what is being drawn out at the bit area.
This would keep the router very clean but I will need to run some tests to be sure the motor is not overheating.

Or maybe I’m just a rank amateur and thinking about this too much!!

[lcm1947]

Boy I'm getting way over my head but here goes. Some months ago when first designing my router table I mentioned the fact here and several guys suggested I use a - sorry can't remember what it is called but if you will look at my pictures above you can see what I'm fixin to try to explain. If you will notice the back wall of the compartment where the saw dust falls down to that this back wall has a gap at the bottom. Now look at the back of the picture and you can see another back wall behind that wall I first mentioned. The theory being that since the pull or draw from the DC is pulling from only the very bottom of the compartment that it will not compete with the routers necessary air flow since it is that far away. Hopefully one of the guys that explained it to me originally can chime in and explain it better.

[Salty]

Then why wouldn't it make more sense to draw the air from the top of the chamber? Like this:

[lcm1947]

Hey Salty don't ask me. I told you everything I know on the subject. I just bought into the theory and am happy with it. Until somebody comes along and proves different then I'll stay stupid and happy. Hmmm. Now that you ask not that I'm an engineer or anything even close but I'd say the closer the return is to the top of the router the more it would compete with the router exhaust and or the fence return. Hey makes sense to me.