A planer molder or any large dust producing wood shop tool needs some serious dust collection. There are two main levels of dust collection which are chip removal and fine dust removal. Chip removal is fairly easy because the chips tend to stay fairly close to where they are produced so modern dust collectors can suck them up as they are made. Fine dust however is much more challenging as it tends to spread fast and far like a gas and thus requires a huge amount of suction near the point that the dust is produced. The fine dust is the most dangerous dust for the lungs so proper dust collection is a must.
There are many many details involved in dust collection and many sites that talk about them. After sifting though so much of this we wanted to go straight to doing it correctly so that one does not have to spend a huge amount of time doing research. This article is for the smaller one to three car garage size shops rather than professional wood shops that have many tools all running at the same time. Use the information at your own risk however, because it is up to you to know what your doing when it comes to dust collection.
"Keeping the fine dust out of your lungs is one of the most important safety tasks in the shop."
If you read the forums on many wood working sites, you read that many hobby wood workers start out with a dust collector that is too small, make many mistakes along the way in their ducting selections by choosing too small or many different sizes of ducting, breath a lot of dust and basically have to start over to do dust collection correctly. They also end up regretting making proper dust collection one of the last, rather than first real investments they make in this shop. This article is about doing it right the first time so each investment is a wise investment that is well spent. Plus, if you think about it, how many times do you want to redo your dust collection system and how much time do you want to spend doing that?
Goal Meet EPA standards for dust in the home shop...
In order to create an understanding more swiftly lets understand our goal and work from there. Ideally the dust collector should be outside of the shop in a blast proof room with one straight duct coming into the shop leading down the center of the shop with the largest dust producer first in line (usually a planer) and the second dust producer second in line and so on. Each machine should be feeding from that one duct with drops of the same diameter of the main duct. A 3-5HP Cyclone dust collector with one to two large pleated HEPA grade filters (rather than bag filters) is really what is required to pull the finer dust and keep the air reasonably clear of dust. To create such a system is fairly expensive but we want to illustrate what is actually needed rather than what is affordable or easy and work from there. Although this might seem like extreme over kill on terms of a dust collector for the home shop, if you study dust collection you will realize that this is really the minimum for fine dust collection and fire safety not over kill.
Fine Dust There is a lot to know and your lung capacity is at stake...
Once we have the goal in mind we can use our skills to bring about that goal in the easiest and most affordable way we can. A 3-5 HP cyclone dust collector can range from a home made version to buying parts and assembling a system yourself to something you buy pre-made and complete. Grizzy, Jet, Powermatic, and other well know manufacturers all make cyclones this size. Clearvuecyclones and others also make cyclones to build your own system and there are plans online if you want to make your own. Ducting can range from low cost irrigation pipe to professional ducting with quick connects. In some ways the ultimate seems to be the clearvuecyclone and that is the most affordable complete solution for a dust collector but requires more time - time vs money. Otherwise buying something like a 3-5HP collector like a Grizzly 3HP Canister 2320 CFM that at the time of this writing is on sale for $575 and adding a cyclone (secondary filter) to that.
You can also budget more on the dust collector and try to save more on the ducting. One way to do this is to build your main line yourself. A 3HP collector might use an 8" duct. If you check prices, everything you buy in 8 inches is quite expensive. 4" on the other hand is not. For example an 8" Y might cost $125 while a 4" Y might cost $4. So building your own 8" main line (as a rectangle) out of wood or plastic or metal might save you thousands of dollars. With the right hole saw and some $4 plastic 4" ports that are quite easy to connect to a rectangular duct you are set to save some serious money Since an 8" duct is the equivalent to four 4" ducts you can connect more than one four inch duct to each machine for better dust collection at the point where dust is produced.
We bought a 3HP Grizzly Dust Collector (DC) with that in mind. A 3HP has an 8 inch IN port. Most wood working machines like planers or saws have a 4" OUT port. To use a dust collector efficiently there are some factors to consider: The fine dust takes more suction than the big chunks to have much efficiency - because you are trying to grab that escaping gas like dust. You will lose efficiency because of any corners, resistance, length or leaks in your ducting. An 8 inch port (1570 CFM) equals four 4" ports (395 CFM). If you have 8 inches of IN you need to have 8 inches worth of blast gates open (four 4" ports) - Otherwise you put strain on the DC (motor and your 220 volt wiring) a bit like putting your hand over the tube to your vacuum cleaner and the vacuum gets loud and hot.
With four 4" ports to burn you have options: One port will be used up by the machine you are running. You can use one more for "at the source" dust collection - like a port aimed at your band saw or table saw blade for example. You can use one more port for a down draft table or wall that just sucks general dust out of the air - you could have a down draft wall/table near or as part of the machine. You can have yet one more port open for your floor sweep or for sweeping the floor and benches (or can be open high or low or clear across the shop to catch that rouge dust - this last port can be used to "tune" the DC to make up for the lose of efficiency related to the ducting.
Ideally you want to vent the OUT of the DC out of the room because as you know, it does not catch the dust below .3 microns - plus no filter clog (loss of efficiency) or filters to buy. Note that some DCs have timers also. A 3HP DC is way over kill for a one man shop, and yet totally not.
Note that most filters catch the fine dust once they start to cake up. If you you have 8" pushing air OUT of the shop you need an 8" opening to let air in and that IN can be heated or cooled using the sun or other means.
Be aware that if your DC is 8" (for example) your ideal blast gate system will need to maintain 8" no more or less. So if you have 10 blast gates that are all 4" you need four of them open at all times. MORE than 8" and the chips fall out or suspension just like in a cyclone drum and LESS you have DC strain.
1Cyclone Dust Collector on Amazon.