Dual Drum sander dust on board

[Bob Stritzke]

I purcsased a used Grizzley dual drum sander last week. I been checking it over and have it connected the two 4" dust ports on the top hood to my 6" dust collection system. I have plenty of air movement and no dust escapes in the air.
However the board will come out of the sander with a compacted layer of dust on the top of the board. I've done a quick search here and have not found much except that it is a normal problem.
Does anyone have any suggestions for fixing this problem?

[Scott Hildenbrand]

Add a brush suction head to the outfeed side?

[george wilson]

Yes,those type sanders do that. My Delta 18/36 leaves NO dust on the wood. It has a superior and close fitting dust hood designed to maximize suction over the drum. The paper is SO much easier to change,too. I'm never going back.

[Bob Stritzke]

Add a brush suction head to the outfeed side?
Is the brush suction head also connected in to the dust collector in addition to the two on top? Would like to see photos of such a addition.
Thanks..

[Scott Hildenbrand]

Photos? Hard to do that.. It's in my head... ;)

Lets see, you've got a 6" collection hose going into two 4" ports, which would be a large loss of pressure. Might get away with piping in a 2" wye before the split to the 4" ports and keep enough pressure to suck off a sealed brush with 1/2" clearance off the work piece. But then, maybe a squeegee back brush and open front would be more fitting as a brush at the front would just push the dust onto the floor.

Best I can do is toss an illustration together laying out what's floating around my brain.

All in all though, it'd just be a bandaid to assist with poor dust collection design.

[Bob Stritzke]

Photos? Hard to do that.. It's in my head... ;)

Lets see, you've got a 6" collection hose going into two 4" ports, which would be a large loss of pressure. Might get away with piping in a 2" wye before the split to the 4" ports and keep enough pressure to suck off a sealed brush with 1/2" clearance off the work piece. But then, maybe a squeegee back brush and open front would be more fitting as a brush at the front would just push the dust onto the floor.

Best I can do is toss an illustration together laying out what's floating around my brain.

All in all though, it'd just be a bandaid to assist with poor dust collection design.
Thanks for the followup.
I'm playing with the thougth of a PVC pipe mounted on the outfeed end with holes drilled in it to provide a blast of air to blow the dust back toward the sander. I would hook up the PVC pipe to the air compressor. It would be an easy prototype to try.

[Bob Stritzke]

I placed a 3/4" PVC pipe on the outfeed end of the sander. I drilled 5/64" holes in a line every two inched on the pipe. Cap on the end of the pipe and fittings to connect to the compressor air hose. The pipe was mounted so that it would clear the wood out of the sander by about 1/8". it was mounted on the guards on the output roller so that it would move with the conveyor as it was raised or lowered. However upon review it will need to be mounded on the frame so that it will always be the same height above the board.
My compressor will provide 10.3 cfm at 90 psi and it would keep up with the air demand.
It worked great and the board was clean upon exit from the sander.

[Steve Jenkins]

Nice solution Bob. It seems to me though that it would be better to mount it to the hood rather than the conveyor. If you want to sand different thicknesses won't it be in the way mounted as you have it? Say you sand something 2"" thick instead of 3/4.

[Scott Hildenbrand]

For some reason I keep picturing "Space Balls" where they say, "My God, she's gone from suck to blow!".. ;)

Guess blowing off the dust works too, though just means you have the floor to clean up afterward.

[Bob Stritzke]

Nice solution Bob. It seems to me though that it would be better to mount it to the hood rather than the conveyor. If you want to sand different thicknesses won't it be in the way mounted as you have it? Say you sand something 2"" thick instead of 3/4.
It is mounted on the ends of the conveyor. However after thinking about it I will need to be mounted on the frame so that it is allways the same height above the board. Hey, this was just a protype to see it it would work.

[Bob Stritzke]

For some reason I keep picturing "Space Balls" where they say, "My God, she's gone from suck to blow!".. ;)

Guess blowing off the dust works too, though just means you have the floor to clean up afterward.

No I do not have to clean up the floor. I use this tube in combination with the dust collector. No dust escapes out of the sander except to the dust collector.
As I looked at the output of the board during sanding there was no dust comming out the back of the sander or visible in the air. I think the blast of air from the tube is going under the dust deflecter that the sander has and blows the dust off the board up into the air and then the suction of the dust collector can get it picked up and collected.

[Scott Hildenbrand]

So it basically just blows it back into the head? Huh.. That's a pretty spiffy idea.

[Bob Stritzke]

I made a mistake on the protype of mounting the air tube on the conveyor. That would have caused problems with different thickness of wood.
I have moved the mounting to the top cross rail so the tube is allways the same distance above the wood. Because the end guards are above the top of the wood comming out of the sander the tube is now about 1/2" above the wood. It still works great.

[Steve Jenkins]

Excellent. You sure don't waste any time.

[Jeff Duncan]

Neat solution, but I'm wondering if a lot of the dust blown off your board is ending up in the air? A 6" to 2- 4" connectors does not create a problem for pressure, this is a very common transition. The problem I would guess is you don't have enough oomph in your dust collector and/or not enough filter area.
I don't know what your running. but when I was running 1-1/2 - 2 hp portable units with my drum sander, none could keep up for very long. They're just not up to the task. With the cyclone things are very different. I still have a 6" drop to 2 - 4" connectors, but now my filters don't clog and no dust left over on the boards.
good luck,
JeffD

[Bob Stritzke]

Neat solution, but I'm wondering if a lot of the dust blown off your board is ending up in the air? A 6" to 2- 4" connectors does not create a problem for pressure, this is a very common transition. The problem I would guess is you don't have enough oomph in your dust collector and/or not enough filter area.
I don't know what your running. but when I was running 1-1/2 - 2 hp portable units with my drum sander, none could keep up for very long. They're just not up to the task. With the cyclone things are very different. I still have a 6" drop to 2 - 4" connectors, but now my filters don't clog and no dust left over on the boards.
good luck,
JeffD
Sorry the DC is not the problem. It is a Bill Pentz design clycone with a 14" impeller on a 3 hp motor. Air exits through 2 340square foot filters.

[Steve Clardy]

Back when I had mine [sold it] I mounted a piece of 1/2" ply on the outer upper angle iron, just past the rear drum.
There are 2 bolts there that I used to mount it. Can't remember which ones offhand. Seems I used longer bolts also.
Fashioned the ply so it was just above the bottom of the rear drum. This kept the dust that was thrown off the rear drum confined under the hood.
I had no piles of dust on the boards.