Dust collecting enclosure

[Nick Keenan]

I've been experimenting with dust collection alternatives for a while, and I'm pretty excited about what I've come up with.



There's three parts to it. First, above the table is a Shark Guard, which gets everything above the blade. Second is the enclosure I made, which captures everything coming out of the bottom and the back. Third is sealing off every opening in the saw on the sides, top, and front, except for the throat plate and the tilt/elevation slot on the front.

I'm pretty satisfied with the combined effect. The only place that dust can escape is under the front of the Shark Guard. That happens only at the end of a cut; normally the piece of wood blocks the front of the guard. No fine dust escapes this way; what gets out are little chunks several times the size of a grain of salt. I cut five pieces of MDF and there were maybe a dozen chunks that escaped.

I made the whole thing from a piece of 2'x4' 1/2" MDF that I had, and some scraps. The back is 5"x11", and on the right side I cut a 4x10 hole and attached a 4x10 to 6" HVAC adapter that goes into my 6" DC piping. The bottom is 2 5/8" thick. I attached the enclosure to the saw with polyurethane glue (LePage PL). I was afraid it would be somewhat rickety, but it is actually quite solid. For now I have it on the stock BT3 stand but I intend to make a mobile base soon.

There is very little clearance between the dust port and the clamp that holds the rail when the blade is tilted 45 degrees, so the top of the back is made from 1/4" pressboard. The bottom is held on with screws so it can be removed for blade changes.

To seal off the openings in the saw base I used pieces of scrap wood and copious amounts of silicone. In the picture you can see a piece of scrap shoved into the upper front left corner of the case.

Let me know if you are interested in more details.

Nick

[dedaddy]

Looks like a good idea. Nothing can get away. One thing that bothers me. The only inlet you have for air it the blade slot. That does not allow enough air to get in to transport the dust in a 6" duct. Also, the motor needs cooling. I would open up the slots on the sides to let in more air for transportation and cooling.

You have given me ideas for my own set up. Thanks for sharing.

[Bob Crosley]

Nice looking work, Nick. Since you have good airflow moving in there, I wonder if the shroud and the 2.5 inch dust port are now working against you, since they would restrict the amount of air moving around the blade. You might consider taking the steel plate off the side of the dust shroud. It's only held on by a few screws. That would open up the blade area to the full airflow you have going on now, instead of restricting it.

Bob

[Nick Keenan]

quote:Originally posted by dedaddy

Looks like a good idea. Nothing can get away. One thing that bothers me. The only inlet you have for air it the blade slot. That does not allow enough air to get in to transport the dust in a 6" duct. Also, the motor needs cooling. I would open up the slots on the sides to let in more air for transportation and cooling.

You have given me ideas for my own set up. Thanks for sharing.

Thanks.

I thought about those issues. I am going to monitor performance, and it would be a simple matter to open up some of the holes I sealed. The front tilt/elevation slot is open, which actually allows a good deal of air in. The motor has a fan on it, so as long as the inside of the cabinet stays at a reasonable temperature the motor should be OK.

In terms of air velocity, the slowest spot in the system is going to be the bottom part of the enclosure. The exit from the bottom has a cross section of about 50 square inches; the exit from the side is 40 square inches and the DC piping is about 30 square inches. So if it makes it out of the bottom it should have no problem getting through the piping. If it doesn't get out of the bottom it's not really a big deal as I can clean it out easily. I didn't plan it this way, but the bottom is almost like a clean-out trap.

When I was cutting small pieces of MDF, the cut-offs would get sucked into the bottom. I looked through the front slot with a flashlight and it seemed like they all got carried away.

Nick

[Nick Keenan]

quote:Originally posted by Bob Crosley

Nice looking work, Nick. Since you have good airflow moving in there, I wonder if the shroud and the 2.5 inch dust port are now working against you, since they would restrict the amount of air moving around the blade. You might consider taking the steel plate off the side of the dust shroud. It's only held on by a few screws. That would open up the blade area to the full airflow you have going on now, instead of restricting it.

Thanks.

I may make that modification. My current thinking is that as long as there is enough air coming into the base, all the dust that goes into the base will go out, and it doesn't matter whether it goes out the back or the bottom. I don't think the shroud affects how much air enters the base through the throat plate, but I may be wrong.

I'm not sure, but I think the shroud has some safety benefit in keeping pieces of cut-off that fall through the throat plate from hitting the blade and getting catapulted around.

What I think would really help would be a Shark Guard with a 4" intake. Before this modification pieces of cut-off used to fly up into the Shark. Now they fly down. This tells me that I'm getting more pull from below than above, so more pull above would probably help.

Nick

[lrogers]

Interesting idea. I'll bet with all that MDF adding ballast, you could stand a dime on it's edge with the motor running and it wouldn't fall over.

[Nick Keenan]

quote:Originally posted by lrogers

Interesting idea. I'll bet with all that MDF adding ballast, you could stand a dime on it's edge with the motor running and it wouldn't fall over.

I guess inquiring minds want to know.

I couldn't get a dime to stand on its edge, but I did try the "Nickel Test." Not only will a nickel stand on its edge while the saw is running, but when it is started and stopped as well. Not every time, but pretty consistently. I find that my pushing the switch is more likely to topple the nickel than the motor; the test is much easier if I start the saw by plugging it in already turned on.

Of course, I had to do the test with the dust collector off; with it on the nickel gets sucked up if it's anywhere near the blade!

Nick