# Dust Collector



## markdavidson (May 28, 2019)

I have a small 10' x 20' shop. I've installed a 12 foot run of 4" aluminum duct along one wall and have the ability to attach 3 machines along this run. My worst case scenario is SPL = 3.83 and CFM = 350. I'm looking for a small footprint dust collector that I can keep stationary. Currently I use a shop vac, but the suction is pretty poor. I've looked at the HF dust collector, but this might be overkill and it takes up a lot of shop space. The 1 HP units I've read about have mixed reviews - most say the are only good for very short runs. Does anyone have experience with a small wall mounted unit that can be used on a stationary ducted DC system? Thanks.


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## woodnthings (Jan 24, 2009)

*This is whole can of worms ......*

There are so many variables involved in "dust" collection it boggles the mind, but I'll take a shot at it.


Dust is small, even very fine particles of wood generated as a result of sawing or sanding.

Chips are larger size particles or shavings and are heavier and are the result of thickness planing and using the jointer.

The two different common collection methods are shop vacs and dust collectors. Shop vacs move air at very high speeds (FPS) but not in very large volumes (CFMs) Conversely, dust collector move larger volumes of air at slower speeds. They have an inverse relationship, BUT a well equipped shop will have both, even attached to the same machine..... :surprise2:


Gravity has an effect on airborne dust like that generated by a table saw. Look underneath and you will find a pile of saw dust either inside the cabinet or on the floor, because the volume of air and the speed of the air is not sufficient in most shop dust collectors.
Ya gotta get the dust out of the cabinet while it's still suspended in the air. Once it settles out and down because of inadequate air movement and gravity, it's kinda too late.


In my shop, both my 1 1/2 HP Jet Dust collectors are mobile on casters and I move them as close to the machine I'm using and keep the flex hose lengths as short as practical. Flex hose reduces air flow and should be kept at a minimum. The drum sanders and planers share one Jet, and the table saw and jointer share the other one. I know that the sanders are producing gobs of fine dust while the planers are making loads of chips. By keeping an eye on the fill drum and filter this works well for me.


The best approach to collecting dust is to capture it at it's very source. The RAS has a blade shroud with a dust port which can be connected to a shop vac, BUT the blades rotation spits out a bunch of dust to the rear of the saw. :sad2: A box located directly at the rear is my solution and a hole in the table underneath is ported to a good shop vac. A smaller shop vac is used on the dust port on the blade shroud.... What 2 shop vacs on the same saw? YEP!


The table saw should have an over the blade dust shroud as well as the 4" dust port for the cabinet for best overall collection. I have experiment with different 2" PVC over blade approaches where I combine the blade guard with the blade shroud with pretty good results. This 2" PVC is connected to a good shop vac which is separate from the dust collector used underneath. Here's an observation. If you seal off the saw cabinet so no dust can escape, you have also restricted the air flow to the dust collector. If your dust collector is sufficiently powerful to evacuate the fine dust, most shop versions are NOT, it requires adequate air flow through the cabinet. So, sealing it off is not a good idea, contrary to common sense..... 



A small wall mounted dust collector will just not have the CFMs or air speed to adequately remove all the dust. You can experiment with blast gates at each machine to focus the suction, but I suspect it will still not be enough. The Harbor Freight 2 HP unit can be bought on sale with a coupon for as little as $150.00 or so. More modifications have been made to this DC than on any other and they can be found all over You Tube. You can split the unit apart and hang the parts on the wall as others have done, You can add drums to replace the bags and use improved air filters and separators. This is what I recommend for a fixed line overhead system. :vs_cool:


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## markdavidson (May 28, 2019)

Thanks for the detailed answer. It was chocked full of real shop issues. I'd hate to see all my beautiful duct work go to waste. I think I'll try the HF 2HP floor unit and see what that gets me. I'll let you know. Thanks again for the info.


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