Thread: Enclosed Router Table - Dust Extraction

Blast gates ?

I've used a vacuum ducted to the cowling on my router in table mode and it removes about 90% of the stuff. Personally I think the under table vacuum is more important than the overhead/fence and if you get good flow you won't have much to remove via the above table system.

If your cutting blind, like dadoes etc, then the underside is the only real exit point. It's the only exit point that's always available.

When I build my next table the plan is something like Big Shed's with a cupboard and ducting attaching to the door. I'm putting a saw and router in the same box with a panel to divide them so dust from one operation doesn't clog the tool not in use, and to cut "leakage" from the top around the tool not in use. I believe Big Shed found putting the hole a bit up the wall worked better than putting it adjacent to the floor of the tool compartment.

Have a read around, there is good stuff here.

Damian,
Blast Gates?

A plastic or aluminium gates that fits into duct hose so the air flow rate can be stopped to create a dead leg. Have a look at the Carba-Tec cattle dog
p61.

When I finally get around to doing my router table cabinet the router will be enclosed. I will shape the inside of the router enclosure with a slope towards the back and the sides in towards the middle with extraction from the lowest point in the unit. Theory is vibration and gravity will assist the suction and hopefully not have any black spots where extraction is weaker. Have read that somewhere and it made sense to me.

How's this for a novel suggestion, pressurise the cabinet and keep the dust out. The routers will run cooler and the bearings and motor will last longer. This might be worth following up as I just thought of it. I wonder how much dust would actually get into the cabinet if this were done? It has always seemed to me to be very stupid to run a high speed motor in a dusty environment like an enclosed cabinet.

If your dust extraction is sufficient underneath you shouldn't have any problems with the router. Pressurising the bottom will blow all the crap up into your face then you need pretty good extraction above (dust and chip) and then you have issues if doing blind work as indicated in Damien's post. Not saying don't do it, just saying I wouldn't for those reasons.

I will bet money that all routers in cabinets suck dust laden air into them, prevent the dust getting in and you stop it happening. The over pressure would not be great enough to create clouds of lifted dust but would only be strong enough to assist the dust extraction within the fence etc. It just seems stupid to me to help the dust get into the cabinet instead of trying to prevent it. I am tossing the router table issue around at the moment and the more I think of an enclosed router the sillier it seems, the only advantage I can see is it looks prettier and most probably keeps the sound levels down a bit. I still reckon a torsion box would make the flattest top and a round table would be better than a square one. Gee, that should get some good responses so I will duck for cover now.

Originally Posted by PEN

I am currently making a double router table cabinet. One router will be mounted in a UniLift, the other in a simple plastic type mounting. The unit will be fully enclosed with doors and drawers and will be mobile.

I have searched the site and seen different solutions to dust extraction, but am interested in how effective the extraction of dust from the enclosed section is. Most of the chip and dust above the table will be removed via the dust extraction in the router fences, but a limited amount will enter the area where the routers are mounted. At a guess lets say 10 - 15% of the total waste from the router bit. This raises the optimum size of the enclosed area and the size of the dust extraction pipework.

the amount going into the enclosed space will depend on the type of cutter you're using.

I was using an upcut spiral the other day with dust collection from the back of the fence and recon about 50–60% of the chips went under the table

also, remember to leave some sort of vent to allow air into the enclosure to replace that extracted by the dusty


ian

Originally Posted by Mini

I will bet money that all routers in cabinets suck dust laden air into them, prevent the dust getting in and you stop it happening. The over pressure would not be great enough to create clouds of lifted dust but would only be strong enough to assist the dust extraction within the fence etc. It just seems stupid to me to help the dust get into the cabinet instead of trying to prevent it. I am tossing the router table issue around at the moment and the more I think of an enclosed router the sillier it seems, the only advantage I can see is it looks prettier and most probably keeps the sound levels down a bit. I still reckon a torsion box would make the flattest top and a round table would be better than a square one. Gee, that should get some good responses so I will duck for cover now.

if I wasn't a nice person I'd take you up on that "bet"

A 15mm up-cut spiral bit doing 25,000 revs is doing about 20m/second (say 70km/h) at the cutting edge. To a first approximation, this is the speed of the air stream travelling up the bit.
Your over-pressure would need to be greater than that, say equivalent to sticking your head out the car window at 100km/h — that would certainly raise some dust


ian

Originally Posted by ian

if I wasn't a nice person I'd take you up on that "bet"

A 15mm up-cut spiral bit doing 25,000 revs is doing about 20m/second (say 70km/h) at the cutting edge. To a first approximation, this is the speed of the air stream travelling up the bit.
Your over-pressure would need to be greater than that, say equivalent to sticking your head out the car window at 100km/h — that would certainly raise some dust


ian

So you reckon that the overpressure won't prevent it, ok maybe you are right as it was only a flash thought. What it does mean though is the dust is being forced into the cabinet as you point out, so the motor is working in dust is it not or have I got it wrong again, quite possible of course.

Originally Posted by PEN

Damian,
Blast Gates?

A plastic or aluminium gates that fits into duct hose so the air flow rate can be stopped to create a dead leg. Have a look at the Carba-Tec cattle dog
p61.

Ah, where I come from we call them valves

Regarding the dust extraction, I'd already thought about dust in the router, and dead spots.

If you have corners you'll probably get dead spots. If you fillet the corners well and offset the hose to the side you'll get a cyclonic effect and the chips will spin outwards and end up in the hose.

If you pressurise the cabinet you'll make a mess. If you make the cabinet leaky and make sure your flow rate is high the chips will mostly not go into the hose and there will be relatively clean air for the router to suck, moreso if you use the cyclonic effect as air is lighter than wood and the router tends to be in the eye of the storm. You could also duct your hose right up to the base, even put in a false top under the real one and suck through the gap in the tops. The false top could be as flimsy as cardboard as long as it remains at a gap from the real top. Trouble with this system is it crowds the router a bit.

Others here have built sucessful tables using a variety of similar techniques.

I enclosed my table a few years back, with a 4" port at the bottom and the vac attached to the fence. Depending on the bit, cut, etc, sometimes more dust comes out the top (straight bit cutting around a template) sometimes out the bottom (anything blind). However, when it was not enclosed, the sweeping up sometimes took longer than the setup and cut, now there's occasionally some dust on the table but almost all ends up in a bucket

Best advice I found was to cut some holes in the door to roughly equalise the open area in the table (including the opening at the top) with the 4" outlet in the back. I put the outlet at one corner, and though it leaves some dust in the other corner, generally does a good job.

Did see an article for a table where the author cut a 20-30mm slot at the back, hooked a floor sweep adaptor to the slot, so the suction from the DE was spread across the floor of the table. The article said it left no dead spots, and sucked it clean. Looked really schmick.

Tex

Tex,
Time has not permitted me to complete my double router table up until now but over the Christmas break the end result has been achived with only the dust exraction issue to be resolved.

You mentioned in you last post on this issue an article. Can you give me a better lead on this article?

I have fitted blast gates to the rear of the enclosed router cabinets and hooked up my three phase extractor to it this afternoon with no ventilation in the opening door. Plenty of suction, in fact it jams the door tightly closed. I have worked out the area of the extraction inlet and I will need to cut a 330mm x 19mm slot in the door to balance the air flow. I will also have to make an allowance for the smaller fence outlet, but I can calculate that. I will start out at say 200mm x 19mm and work up from there.

But before doing that. I would be interested in reading the article you referred to.

Regards
Paul
PEN

Paul,

20 minutes on google and I can't find the article on line, so probably not FWW.

It looked a lot like this one, and Norm has a similar one available from the damyankee workshop here. The idea is to have a slot at the bottom of the cabinet so dust has no corners to hide in. And it is pretty important to have holes in the cabinet door to get the air flow to move the dust.

I thought it was a great idea, but with my limited shed time have decided I can live with some dust lurking in the corners of my cabinet. Every now and then I leave the DE on, open the cabinet door and push the dust to the 4" hose. But this one looks more elegant and efficient.

On mine, a quick calculation of the area of a 4" hose, less the area of the opening at the top of the router table, and I drilled a couple of smaller holes towards the bottom of the door to roughly equal out.

Tex

Tex B,
Apologies for not replying earlier but I am back at work and time is limited.
Thank you for going to all that trouble on Google which is greatly appreciated.
I have taken on board what you said about a slot/hole to avoid the dust sitting in dead corners. That has lead to the belief that a solution will be to build a manifold across both blast gates and to the extent of the closed cabinets. That way I can accommodate your suggestion, which I will do.

I intend to run the hoses from the router table fences into the manifold and in that way I can isolate either side of the table (router) as required.

When I finish that section I will again calculate the air flow requirements and slot the doors to allow for sufficient air flow to pass through.

A lot of experimentation but the end result willl be worth the effort.

Again thanks for your help, much appreciated.

Regards
Paul
PEN