Thinking bigger

[D Romano]

Sorry for the delay, I still want to send some pics of my setup. In the mean time though, I have putting some wood through my jointer and at first glance, the separator seems to be working. The flapper I installed in the canister was very easy to turn telling me that there are not alot of big chips clogging the pleats.

Also, I took the canister off and turned the DC on to see first hand what happens when the air swirls around. It was interesting. The air emerges from the DC separator ring in a swirl pattern, with only 2 distinct air streams shooting out of the hole, about 180 degress from each other. The location of one of them correlates with the location of the air stream entering the separator ring. (think neutral vane configuration) The air swirls around, hits this air that's entering and gets deflected up through the donut hole. The air does not come straight up. I am trying here to attach a drawing:



I then took a handfull of large chips, the puffy kind the you get from planing or face jointing pine and through it into a dust port. I wanted to see what would happen when it entered the baffle area. It happens very fast, but I could see the shavings slip down into the gap around the outside edge of the baffle. They did not come back out. Some finer dust did, and after running the DC for a few minutes, the shop had a lot of dust in the air. The separation could be alot better for the fine dust.

Since the dust does not naturally want to come up straight through the big donut hole, I think I will install an outlet pipe in it, making it more like phil's original garbage can separator. Making this outlet pipe smaller in diamter and/or lonnger will help the separation but increase static pressure.

[phil (admin)]

Since the dust does not naturally want to come up straight through the big donut hole, I think I will install an outlet pipe in it, making it more like phil's original garbage can separator. Making this outlet pipe smaller in diamter and/or lonnger will help the separation but increase static pressure.

Keep us apprised!  Post some pics of your work if you get a chance.

[phil (admin)]

The separation could be alot better for the fine dust.

BTW, if you perform that test with a large cyclone, you're still going to fill your shop with fine dust.

In fact, there was a guy that posted in one of the WW forums in the last few weeks saying that his shop was filling with dust and he tracked it down to a small 1/8" hole in a weld on his cyclone (I think it was an Oneida).  The hole was in the plenum that feeds the filter stack.  So this was separated air, as clean as the cyclone could get it.  And a 1/8" hole was filling his shop with dust.  Dust that would have normally been caught in the filters.

I guess what I'm saying is, don't believe everything you read about the separation rate of large cyclones.  They still shoot plenty of fines to their filter stacks.

[D Romano]

The separation could be alot better for the fine dust.

BTW, if you perform that test with a large cyclone, you're still going to fill your shop with fine dust.

In fact, there was a guy that posted in one of the WW forums in the last few weeks saying that his shop was filling with dust and he tracked it down to a small 1/8" hole in a weld on his cyclone (I think it was an Oneida).  The hole was in the plenum that feeds the filter stack.  So this was separated air, as clean as the cyclone could get it.  And a 1/8" hole was filling his shop with dust.  Dust that would have normally been caught in the filters.

I guess what I'm saying is, don't believe everything you read about the separation rate of large cyclones.  They still shoot plenty of fines to their filter stacks.

That is a very good point, but in my test, I think that most of the fine dust was being picked up from the collection bag and blown back out. I only threw in a small handfull of shavings. It seemed that the longer I let the DC run, the more dust was in the air. It was as if I'd done alot of sanding with a ROS. If my observation is correct, then it suggests that leaving a DC on for longer than necessary just clogs the filter with fine dust. An interesting test would be to put some blue chalk in the collection bag, turn the DC on and see if the canister filter gets colored.

David

[phil (admin)]

That is a very good point, but in my test, I think that most of the fine dust was being picked up from the collection bag and blown back out. I only threw in a small handfull of shavings. It seemed that the longer I let the DC run, the more dust was in the air. It was as if I'd done alot of sanding with a ROS. If my observation is correct, then it suggests that leaving a DC on for longer than necessary just clogs the filter with fine dust. An interesting test would be to put some blue chalk in the collection bag, turn the DC on and see if the canister filter gets colored.

David

Before you do that you better make sure you can get blue chalk out of your filter media.  I'd hate to see you clog your filter.

If you really want to attack the fines then try adding the outlet tube (just make sure it is at least as large as the inlet).  You can take it as far as you like.