Jet JJP12 Jointer Mode Dust Collection Problem

[Ben Kenison]

I bought a used JJP12 jointer/planer combo to upgrade my old 6" jointer and DW735 setup, and I'm working on a few deferred maintenance issues to get it running correctly. One of the ones I can't seem to figure out is the dust collection - it works near perfectly in the planer mode, but in jointer mode, the chips will spew up the small gap between the dust shroud and the bottom of the infeed table, and it doesn't seem to be collection much, if anything. I'm attaching a few pictures of the remnants of a 1" edge joint done right at the middle of the cutterhead. I get the same issue regardless of the width of the board being jointed.

It seems like most issues with this machine involve poor dust collection in planer mode, and I haven't been able to find anyone with this issue in the jointer mode. I'm running a 2hp Grizzly DC with about 5' of 4" PVC and 4' of 4" flex hose to the machine which should be plenty of airflow. There's an internal baffle in the dust shroud that some people have reported being stuck open, but mine moves pretty freely in either mode.

Does anyone have any experience with this issue, or have any ideas I can look at? Should the dust shroud not have a gap between that and the infeed table? I feel like this should be pretty straightforward, so not sure what I'm missing here, and I'd appreciate any help with this!

IMG_20210830_203150944.jpgIMG_20210830_203207307.jpg

[Erik Loza]

My gut reaction is that it's a DC problem, not a machine problem. That looks like a clone of our dust extraction hood, LOL. There does need to be some gap between the cutterhead assembly and the dust shroud, in order to get good draw. In my experience, you always get "some" chips on the planer table but most of it goes out the chute. I don't have any experience with that dust collector but will say that 5" is the preferred diameter on jointer/planers.

Erik

[Paul F Franklin]

I have the king canada J/P which is pretty similar to the Jet. There's a baffle in the DC hood that flips when you change modes. On mine, the dust collection suction was high enough that it overcame the weight of the baffle and caused it to be in the wrong position. On mine, it happens mostly in planer mode, but I also saw it a few times in jointer mode. Or perhaps the baffle is just jammed up somehow with chips or whatever. I jury rigged couple of spacer blocks to lock the baffle in the correct orientation for each mode.

[David L Morse]

That's definitely not right. I just did the same (I think) test on mine. I did four 1/16" passes on a 1-5/8" x 24" board and looked inside:

JPDust1.jpgJPDust2.jpg

My dust collector is a Harbor Freight with a 12" impeller substitution, so maximum pressure similar to yours. The major difference is my use of a six inch hose up to the hood outlet but that wouldn't make anywhere near the difference you're seeing.

JPDust3.jpg

Take another look at that baffle. It should look like this:

JPDust4.jpg

Not this:

JPDust5.jpg

[Dick Mahany]

My cyclone used to pull the movable flap inside the shroud shut in planing mode. Never had that problem in jointing mode. There are two holes on the front of the shroud. Placing a properly sized dowel pin or bolt in the lower hole solved the planing chip collection problem. I'm wondering if the other hole would do the same for the jointing mode?

Picture1 (2).jpg

[Ben Kenison]

My cyclone used to pull the movable flap inside the shroud shut in planing mode. Never had that problem in jointing mode. There are two holes on the front of the shroud. Placing a properly sized dowel pin or bolt in the lower hole solved the planing chip collection problem. I'm wondering if the other hole would do the same for the jointing mode?

I would be so annoyed if all this ends up being is "stick screwdriver in hole". Good idea, I tried that and didn't seem to change anything. I can see why it would work to fix the situation in planing mode though.

Thanks for the input, I've got a few things to try now, and I'll update when I try these out. The pictures are all very helpful--the internal baffle does work correctly (and when the DC is running). I do like David's idea of running a 6" hose and stepping down at the machine, and since he and Erik had the idea it's cfm related, maybe the 4" is losing too much pressure to the machine. I'll try hooking it directly to the DC with as short of a run as I can and see if that improves (also in case there's some undiagnosed leak, which I suppose I shouldn't rule out given the responses)--if so, I'll look at increasing the duct size.

Thanks for the direction, I'll report back when I have a chance to try these out!

[Curt Harms]

I noticed on my machine that if I flipped the dust collector without removing suction that flap wouldn't flip and chip collection in planer mode would suffer. I first used Dick Mahany's fix but discovered if I removed suction when flipping the dust collector I didn't need the dowel. I never had a problem in jointer mode though (straight knives, don't know if that matters). I too have a 6" hose reduced to 4" at the machine.

[Bill Dufour]

Would it help to place a piece of stock in the planer throat? I am thinking just thinner then the cut thickness and as wide as possible. This is just to fill the empty volume under the cutter head and hopefully increase air speed to help catch chips.
Bill D

[Ben Kenison]

Thanks to everyone for the help, I think this is in a good place now. The ideas that this is cfm related, running 6" to the machine, and that there may be too much open space around the cutterhead was key to getting this right. I'll post several pictures and some notes on what I did in case this helps anyone searching for this in the future, or if anyone has other suggestions. For those that have this model, is this about what you would expect?

1. I ordered a 5 foot piece of 6" flex hose and a 6-to-4 inch reducer to try that instead of using the 4" run to the jointer, attached with a fernco fitting. I took down the existing 4" run to hook this 6" directly from the DC to the jointer. This setup is a Grizzly G0548Z dust collector, as shown (ignore the marks on the jointer table, that was me testing the beds for flatness):
   
   1. IMG_20210906_092150024.jpg
   
   
2. I'm testing this by face jointing a 10x32 piece of red oak, with a cut depth of about 1/32", checked with a feeler gauge. After 3 passes, here's what was left--this is SIGNIFICANTLY better than before:
   
   1. IMG_20210906_092921415.jpg
   
   
3. I was thinking about Bill's idea of the gap in the throat causing some issues, and noticed that when lowering the planer table to the ~6" mark (the minimum distance it needs to come down to allow the shroud to flip over into jointer mode), it left a pretty large gap between the infeed table and the dust shroud, you can see the amount of exposed cutterhead here, and this is where chips are spewing up from. I lowered the table fully, which has the effect of raising this end of the shroud to reduce this gap:
   
   1. IMG_20210906_093318194_3.jpg
   
   
4. I then re-ran 3 passes of the oak board, and saw a huge improvement--you can see the planer table fully lowered in this picture. Not perfect, but pretty darn good:
   
   1. IMG_20210906_092921415.jpg

Seems like the right solution here is to switch my 4" duct with 6". I only have a 1 car garage and just need to hook up the tablesaw/router, bandsaw, and jointer/planer, so this isn't an unreasonable expense.

[Erik Loza]

That amount of leftover chips on the planer bed looks about right to me.

Erik