I just upgraded my DJ-20 jointer, replacing the straight knife head with a Byrd Shellical Head. While I was in the lower cabinet I noticed that the duct that connects the cutterhead with the external dust port is an open top trough. Now I have always felt that shavings/dust collection on this machine was pretty weak, and I was quite impressed with how many shavings had accumulated both inside of the base cabinet and in all of the air space under the outfeed table ahead of the chipbreaker. Of course I am cursing Delta for being so damn cheap that they did not use a closed duct for that connection, even though I do understand that to them it was merely a shortcut to save some more money per unit. (Sort of like how they have used jam nuts instead of regular nuts for many mechanical connections.) My question is has anyone else closed in the top of that trough with sheetmetal to improve the dust/shavings collection for that machine? What was your experience with doing this? Do I need to leave a small air gap in that sheetmetal for any reason? (I am considering leaving a small 1/2" gap right under where it connects to the top of the lower cabinet/upper assembly.) Any input about this would be appreciated. Thank you.

For the record, all of my machinery is connected to an Oneida 5HP Pro V DC using spiral pipe, welded Y's and elbows in a designed system, with almost zero flex hose. So airflow and CFM's are not a cause for this problem. This is the only machine that I have ever questioned the DC efficiency in my shop.

Let me tackle this query from another angle. Does anyone know why jointers were built in this manner? While looking around online I saw that it appears that the Powermatic 60 C/HH were also done the same way in their bottom cabinet. It just seems stupid to waste potential CFMs of dust collection in this manner, at least to me.

Theyre not production machines. Not that well thought out. We have a 20" Martin. With the cutter head off and the infeed table up, you can turn on the DC and itll suck a board down over the opening. Kinda get what you pay for. I had a 20" SCMI years ago. Same as the Martin.

They are designed for free fall chip removal. They aren't designed for a dust collector. If they were it would have a port on it to begin with or at least holes to attach it with.

I put a 4" port on mine. Big flat face with the 4" male port on it. The hose slips over it.

I don't have issues with my collection unless I don't use the vacuum a few times and it builds up to much in front of the port and the DC can't suck it through. Other than that it works pretty good, not fantastic as I get some blow back on the infeed fence.

I'm sure you could make more of a duct out of the chute if you wanted to by using some flashing metal, rivets and metal tape. I find it not necessary.

I run a 2 1/2HP Oneida Dust Gorilla and it's at the end of the run.

I get some blowback, and some shavings coming out either side as the knives clear the outfeed table. Delta actually sells a flat face with the 4” collar for this machine, for a highly inflated price. Because a 4” collar does not allow as many CFM’s as that machine needs, and also because I have CFMs to spare, I attached duct boot with a 5” collar and hard pipe.

I am planning on experimenting with some sheet metal to enclose all or most of the top of that chute. 100% collection of shavings and dust should always be the goal, IMHO. Airborne fine dust is a no go.

I recall something from others on this site talking about their insert cutter heads howling from DC airflow, and so was hoping to avoid that. I guess I am going to see how this works in my shop.

One of the things that I did was to close off the vents in the case to force the airflow to come from the cutterhead. I haven't had any overheating issues from the motor because of this.

The chips from the jointer are unlikely to cause air pollution in your shop. The smaller dust that is produced will be grabbed by the airflow if you have as many CFMs as you can get with a 5" pipe.

I have a 6" hard pipe and then about 7' of 5" flex which goes to a 5" to 4" adapter right at the port.

Don't forget you need to have make-up air, or flow thru air or dust collection is doomed to the vagaries of certain cavitation. Allow air in at the ends of the cutterhead and between tables and cutters so it can pick up and carry away the chips.

I am enclosing that shavings collection trough with sheet metal and tape. However I am doing it with 2 pieces so that I can "tune" it if need be by sliding the top piece down to allow some airflow from inside the base cabinet if need be. The shellical head does allow some airflow around it to the collection trough as the inserts are raised up from the main body, unlike the OEM head that had the knives set down into the head and made a tighter seal to the jointer beds and the collection trough. My initial concerns were more about noisy airflow over/thru the spinning cutterhead while using dust collection. I will keep an eye on adequate airflow to allow for good shavings collection also. I appreciate the heads up on that.

I haven't fired the jointer up yet. Checking everything, and correcting anything that needs it while the jointer is torn apart. It turns out that I need to do part of the 8-way alignment for the infeed table as it is off some. The outfeed table aligns perfectly with the new head, so I don't need to monkey with that one. I will have some time later on to mess with it. Will be glad when this is done. It will be almost like having a new machine in the shop.

In response to David Scholar's post about allowing for make up air or air around the intake for dust collection. The Delta DJ-20 was designed for a 3 3/8" dia cutterhead. The OEM cutterhead was ~ 3 5/16" dia with the knives protruding ~1/32". The Byrd head is 2 13/16" dia with elevated cutter seats and cutters about 9/32" proud. So there is a fat 1/4" air gap around the new Byrd cutterhead.

I have been using the DJ-20 with the new head installed. It is quieter than stock and the jointed edges and faces are impressive, to say the least; so far absolutely no tearout with some figured woods that would have been problematic before. Switching to this cutterhead was well worth the effort and expense.

My dust and chip collection has also been improved, partly due to enclosing the drop chute in the jointer's base cabinet. Still not 100%, but better then it was before. So I am happy.