Things that Affect Efficiency

[Vaughn]

About 5 months ago I added a Thien baffle to my Harbor Freight DC. (Here's that story.) So far I've been really pleased with the addition of the baffle. I was getting very little buildup of fines on the pleated filter. Instead of removing and cleaning my filter every 3 weeks or so, I'd not seen the need at all since adding the baffle. I just whacked the sides of the filter from time to time, and gave it a shot of compressed air once every few weeks.Then, a couple or three weeks ago I noticed that the DC wasn't sucking the way it should. Sanding sessions at the lathe were dustier than normal, because the dust hood wasn't pulling in as much dust as it used to. I suspected the filter was getting clogged.

Last Saturday I finally had a chance to take it apart and see what was happening. Before I removed the plastic bag from the bottom of the DC, I whacked and blew on the filter more thoroughly than normal, and was amazed with the volume of very fine dust that fell out of the filter. (A good 6" to 8" deep in a new layer in the lower bag.) When I shook the filter (the whole DC, actually), even more stuff fell into the bag, falling off the top of the baffle through the slot around the outside edge. Something was up. This was dirtier than before adding the baffle.

To remove my filter, it's necessary to first remove the baffle...an overhead job if I want to avoid completely dismantling the DC to turn it upside down. I undid the three screws holding the baffle in place, and lowered it carefully to avoid dumping sanding dust all over myself. Here's what I found:



I guess that's what I get for using the 4" hose to clean up the mess after a turning session. You don't suppose that piece of edging for my foam floor mats might have caused the filter packing do you?   I was laughing so hard I had to take it inside and show my wife. I did check the impeller, and it seemed no worse for the experience. (I've sucked up a few solid chunks of wood or bark that alarmed me enough to open up the DC and have a look at the impeller.) No big surprise, but my DC is sucking mightily once again.

[phil (admin)]

 :o

I've never done anything like that.   ;D

I will also remind everyone that high-speed clean-up of debris on the floor will send more material to the filters.  Slow and steady gives the system a way to work.  If I have piles of dust on the floor, I use a broom and pan to clean up the bulk, and then I use the DC to get the rest.

[bennybmn]

I'm wondering if that may be part of my problem (see my recent post). I occasionally clean out the cabinet of my table saw by turning on the DC and blasting out the cab with the compressor. Might overload it?

[phil (admin)]

I'm wondering if that may be part of my problem (see my recent post). I occasionally clean out the cabinet of my table saw by turning on the DC and blasting out the cab with the compressor. Might overload it?

If the dust entering the pipe is suspended in air, then no.  The problem is shoveling debris into the pipe.

[bennybmn]

Ok, I see, so like if I tossed a big handfull in there at once or something. Which I suppose I may do sometimes... Right now, my DC sucks from the back of the cabinet. I may re-work it into the floor of the cabinet with more of a funnel effect, so it'll get a steady feed of dust, rather than allowing build up in the corners which needs to be cleaned out later.

[El Guapo]

I would really like to know how the baffle works if you rotate it a bit and go without a neutral vane.  I wonder how that would affect efficiency.

[dbhost]

That is just too funny...

In response to El Guapo's post...

Look at my 55 gallon drum build. You can see I have the baffle not set in quite right. (My holes didn't exactly line up where I thought they would...). I have no clue why, but it actually seems to work a little bit better than the ones I did right...
http://www.jpthien.com/smf/index.php?topic=223.0

[El Guapo]

dbhost, I have read a few threads now on the Harbor Freight DC that said not to put the neutral vane in...I did anyway (same design as Vaughn's).  I have tried it both ways and it does seem to function much better with the neutral vane in, rather than out.  This makes more sense to me anyway because it more closely follows the original design.  With the neutral vane in, I am getting a much greater and more concentrated cyclonic action in the collection bag.  I may make another baffle and try to reposition it without the neutral vane to see how that works in the future.  I wish I had the space though to use a seperator such as your doing...but this will do for now.

So as you and I are seeing, it is much better to experiment.  ;D

Still an excellent design though and so inexpensive.

[dbhost]

I never tried the neutral vane, but I did have the baffle in mine. I removed it when I put my 55 gal barrel model together. Not sure there is any advantage to it, but it seemed like the right thing to do... Should I have done that?

[El Guapo]

I dont know if you should or not...but like I said, it seems that a bit of experimenting has really helped out where some have said it would not.  It may be that if you have the baffle in both, it might filter out even more of the larger particles and keep the filter that much cleaner.  Who knows till you try it.