Dust collector 4" inlet assembly

[Nick]

"Air engineers determined that 350-400 CFM at the source works well for chip collection. Air-borne dust is unfortunately not always easy to see and requires a different set of conditions. That is part of the background for the recommendations of 3500 fpm velocity to keep the dust suspended and transportable."

I don't want to pick on you, Tom, but this statement conveys a false impression. I'm not sure what you meant to say because the terms "conditions" and "recommendations" are not defined, but what it seems to say is that dust collectors operating in the same CFM range as the Shopsmith will collect chips fairly well, but are not effective at removing dust because they don't move the air at the requisite velocity to keep the dust suspended. This is not correct.

There are two ways to remove dust from the air and Bill Pentz's excellent web site covers them both. First, you can evacuate the dust-ladden air from your shop into the outside environment. This is the simplest arrangement, but blowing the air outside leaves a low-pressure area in your shop. If your doors and windows are shut, the high-pressure area outside will move air into your shop -- backwards! -- through chimneys and flues. If your heating system is on, this may cause carbon monoxide and other noxious gasses to build up in your shop.

Consequently in most small shops craftsmen employ air filters to remove the dust. Air filtering systems do not necessarily need to keep the air moving at 3500 FPM. This is the speed you need to keep chips and shavings suspended. Dust is suspended at a much lower velocity and the really small dust particles -- the particles that do the most harm to your lungs -- will hang in still air for many minutes before they finally settle out. For this reason, we have a JDS Air Tech filtration system (a fan box with both intake and exhaust filters) to scrub the air in the Academy.

We have also outfitted our Shopsmith Dust Colllectors with the 1-micron filter hoods. These are made by American Fabric Filters, and the fabric has been subjected to both ASHRAE and other standard tests to make sure that it does indeed capture 99% of the 1-micron (and larger) particles needed to qualify for the 1-micron filter rating. (Our other filters are rated at 5 microns and are made by a different company)

Filters rated to remove smaller particles restrict the air flow more than those that remove larger particles. One square foot of a 1-micron filter restricts the air movement more than one square foot of a 5-micron filter. For this reason, we made the 1-micron filter hood 42" tall. This increases the surface area of the filter and the volume of air that can pass through it. The increased surface area of the 1-micron hood will allow a 330 CFM air flow, as will the smaller surface of the 5-micron hood.

For safety and health, we always keep the JDS Air Tech running at the Academy. But we could do without it and still enjoy clean air. The main room at the Academy is about 30 feet by 50 feet by 9 feet -- 13,500 cubic feet. A single Shopsmith Dust Collector with a 1-micron filter is able to "turn over" the air in our shop every 41 minutes. Two of them can do the job in 20.5 minutes.

We do find that the 1-micron filters require more maintenance than the 5-micron filters. Drew and I "shake the bags" several times a day to remove the coating of fine dust particles that builds up on the inside surfaces of the hoods. The fine dust remains clumped and falls into the plastic bag where it can be thrown away with the larger chips and shavings. If we don't shake the bags, the fine sawdust eventually restricts the air movement in the dust collection system to the point where there is a serious drop in both the volume of the air being moved and the velocity of the air stream. But as long as the filter hoods get a periodic shaking, they are effective air scrubbers and they would work well as such in any small shop.

With all good wishes,

[jtomwoods]

No harm, no foul. I certainly did not take offense and did not feel you were/are picking on me.

I appreciate knowing that you have tremendous skills and knowledge, and that I can benefit from the fact you share these in the forums and in the academy sessions. My first woodworking book was authored by none other than Nick Engler. What a guy!

[pfallert]

[quote="forestden"]I am finally getting around to setting up a permanent dust collection system using my DC3300. When I tried to order the 4" inlet assembly (300003), I saw that the item has now been discontinued. Customer service told me that it was due to the fact that so few have been ordered.
Does anyone know where I might acquire one, or what I might use as an alternative?

I have a 4" Inlet Assembly (300003) in the original packaging (never used), if you are interested.

[charlese]

As an alternative - Try Nick's posts on the first page of this thread. Thought I saw a drawing/dimensions on the blackboard in one of the latest Sawdust Sessions, but can't find it now. Maybe It will re-appear.

[dusty]

charlese,

Is this what you are looking for?

http://www.shopsmithacademy.com/SS_Arch ... ection.pdf

[charlese]

charlese,

Is this what you are looking for?

Exactly! Thanks! Now pfallert can have an alternative!

[edski]

Found this on the web. It looks something like I had planned to build.

http://www.shoptours.org/shop_tours/fil ... oxner.html

edski

[Randy]

I have a the 4" inlet that I no longer use since I moved. My shop is now only 12 x 8 and I have no room for a permanent install. I used it for ± 10 years with no problem.

I had around 30' of 4" pipes, 3 90° elbows, 1 tee and 1 Y. Going to 3 points (different directions, smallest run 6', longest 16') 1 with 3 blast gates. I used one point at a time but I had to open another blast gate 1/2" or so to get enough air into the system. I never had a clog or was missing air flow. I even used the longest run with the planer without any problems and I passed thousands of board feet though it from pine to maple.

If anyone is interested contact via PM and we'll work a deal.

[dougrl]

Tom, I enjoyed the dust collection info., Well do
I remember the time and money spent on this subject of collecting shavings and some dust. I was just wondering how many fellow SS people pick up on the air cleaner that was on your ceiling. I did not mind walking around in shavings. or looking for a tool or ruler that I dropped into the stuff on the floor. But I knew that my air cleaner on the ceiling was on and running. I would walk into the shop, turn the lites on, and the air cleaner would start. This dust, that it collected, is the stuff that kills you, not the shavings on the floor. and a dust collector leaves a lot of this fine dust in the air. I just thought, that maybe some of the people missed this air cleaner info you put in your note above. Oh yes, I did clean the shop floor and air cleaner filters and check the dust collector bag, once a week for sure. A Happy New Year to all, Cheers Doug.

[paulmcohen]

A single Shopsmith Dust Collector with a 1-micron filter is able to "turn over" the air in our shop every 41 minutes. Two of them can do the job in 20.5 minutes.

If you wanted to use the Shopsmith Dust Collector to clean the air, are you leaving the dust collector running full time without being connected to an operating tool or I am missing something?