Not too happy with cyclone

[Perry Holbrook]

I'm not really sure installing a cyclone was the best idea for me. Actually I'm beginning to question the conventional wisdom that a cyclone is always better than a standard single stage collector.

I agree that a cyclone is the best choice when it has a filtered return back to the shop. However, if you are venting outside why use a cyclone?

Here is what has led me to this point of view. I installed a cyclone outside my shop under a shelter roof last fall. Due to a lack of time, I didn't install the return filter system in the shop and decided to just vent outside until I had more time. Although the outside venting does increase my heating bill, I tend to agree with the position that it is the best approach for the lungs.

I am happy with the suction side, but the collection side has some basis flaws. The main problem is how quickly the collection bin fills up as compared to a single stage unit. The collection bin of a cyclone has negative pressure, so the chips fill the bin at a low density, causing it to fill quickly. On the other hand, in a single stage system the collection bin is under positive pressure, packing the bin at a much higher density. I've even been known to use the collection bag as a punching bag while it is running to assist in a good tight pack.

A larger bin for the cyclone is not really the best fix.

So today I realized that if your collection system is outside and you are venting outside, a larger single stage system is probably a better application. I know one of the problems with single stage systems is the lost suction once the filter bags get dirty. I would think 30 or 50 micron bags would help there. (BTW, a little fine dust in the air outside is not a problem in my location.)

Am I missing something?

Perry

[glenn bradley]

[quote=Scott Rollins;1058076]I'm not sure how to take this either.

[Matt Benton]

I have a HF 2hp DC mounted on a cyclone body, with a trash can underneath. I vent outside with 6" ducting, and love it.

I chose this configuration because I can't blow debris all over the lawn, so I needed to capture the dust/chips. Additionally, in virtually all the shop pics I have ever seen, dust collectors with bags or filters are almost always covered with dust. My shop is a 2 car garage, and my wife would kill me if I got dust all over the car...

[Bill Stoffels]

I have had and really like the cycole for the seperation aspect,
Really confused on this post filtering the discharge with todays filters is about as clean as yuo can get??


Confused in Chicago????????? Just like the politicians

[Tom Veatch]

I don't agree with the "low pressure/high pressure" packing conjecture as applied to the cyclone collection bin. While it is true that the pressure inside the bin is less than atmospheric while the cyclone is running, it's a static situation. There should be no airflow in the bin other than some swirl near the bin's inlet.

The conjecture that the reduced pressure reduces the packing density of the sawdust pile is the same thing as saying "sawdust poured into a bucket on the top of Mt. Everest (29000' above sea level) won't pack as tightly as sawdust poured into a bucket at the bottom of the Dead Sea (1300 below sea level). Or, on a similar note, saying that sand poured into a bucket 100 feet below the surface of the ocean will pack tighter than sand poured into a bucket on the beach because the "atmospheric" pressure is 4 times as high. Sorry, I just can't buy that.

The only way I see the lower pressure in the bin having an effect on the packing density is if there is leakage allowing air from the higher external pressure to flow into the bin through the sawdust pile, keeping the sawdust aerated and preventing it from settling. But even then, when the cyclone is turned off, the pressure equalizes and the sawdust settles. My cyclone bin is airtight, and the sawdust packs very well.

[Perry Holbrook]

Sounds like I've had a leak since I installed it. In the trash can I just emptied, the chips were not packed at all, I would even call them "fluffy".

Perry

[Chris Padilla]

I will add that my cyclone bin is pretty well packed as well but honestly, I do not know how tightly packed your single-stage was so I don't have a basis of comparison. It definately isn't fluffy...that much I can attest to! Maybe light some incense or a smoke stick or a candle or toss up some fine sawdust around the bin while your cyclone is running and see if you noticed anything.

[Peter Quadarella]

Not sure what the confusion is, what he is saying makes sense to me. If you are just venting the dust outside, I don't see what the point of having a cyclone is either. Just vent it towards a big garbage can or to the floor if you are in a more rural area.

Not sure about the packing.

[Sonny Edmonds]

Shucks, you just need a bigger bin, and/or an easier way to clean it out.
If you are producing enough waste to have it be a hassle to empty, then a bigger receptacle is definitely in order.
Maybe a large plywood box under the dump of the cyclone with a side door to shovel it out would work for you.
I use a 55 gallon open top type drum with my cyclone hosed to it. (so the lid is easy to unclamp and set aside during removal of the drum.)
Otherwise, sell the cyclone and get a big blower and just blow the stuff outside.
But don't come crying if there is dust in your bacon and eggs....

[Perry Holbrook]

Looks like it's me against the world on this one (usually happens when you question conventional wisdom). Let me try to explain this again.

Assume that you have made the decision that you are going to install your dust collection system somewhere outside the walls of your shop and that you are not going to return the air back to the shop.

You are looking at 2 systems, both need about 100" head room and both have plenty of suction side specs to meet your needs of a small shop. Both cost about the same.

One system does a very good job of filtering out the fine dust that is in the air that will be exhausted outside. Its standard collection bin holds less than 7 cubic feet and must be airtight for the system to operate correctly. Although it is possible to design a bin that uses a drop-in plastic trash bag liner that is easy to replace, most bins require that the chip be handled again, either shoveling out a dusty bin or empting a trash can into a plastic trash bag.

The other system filters the air you are blowing to the great outdoors down to 30 microns. Its collection bin holds 22 cubic feet, is made of clear heavy weight plastic so you can monitor its chip level and requires no additional handling, just remove the bag and install another.

Which of those systems make more sense under the assumed conditions?

Perry

[Rod Sheridan]

Perry, if you are going to exhaust the air outside and don't need to worry about fine dust emmisions, a cyclone without a filter would be the best solution because;

- a two stage device is capable of being used where debris such as blocks of wood are in the airstream or

- whenever a floor sweep is used as there is always the chance of picking up small metal objects such as screws and nails (or in my case one of the knobs from my drill press jigs).

If you don't have any of the above issues, a single stage machine can be the optimum solution.

Cyclones are used because of their ability to seperate out most of the material before the airstream goes to the filter, and the ease of emptying them.

( The cyclone where I worked had a chute at the bottom that allowed the waste to be dumped into a tractor trailer, no bags to fuss with.)

So if you are in area without any restrictions, you could simply vent a single stage blower outside.

Regards, Rod.

[Perry Holbrook]

Shucks, you just need a bigger bin, and/or an easier way to clean it out.
If you are producing enough waste to have it be a hassle to empty, then a bigger receptacle is definitely in order.
Maybe a large plywood box under the dump of the cyclone with a side door to shovel it out would work for you.
I use a 55 gallon open top type drum with my cyclone hosed to it. (so the lid is easy to unclamp and set aside during removal of the drum.)
Otherwise, sell the cyclone and get a big blower and just blow the stuff outside.
But don't come crying if there is dust in your bacon and eggs....

Thanks for the ideas Sonny. I use my shop to make a living. The last thing I want to do is spend time shoveling out a dust bin. or any other activity that requires handeling the saw dust twice. I don't have the head room for a 55 gal drum and if I did, what is a good way to empty that drum so the chips can be transported to the dump or do you have several drums in inventory.

As far as just blowing the stuff outside, although I little fine dust in the air is not a problem, a big pile of chips that will have to be disposed of some time is a problem.

I'm not a cabinet shop, but when I run the planer and/or Shop Fox moulder, that trash can fills up awfully fast.

Looks like I'm talking myself into a new 4 or 5 hp dual bag single stage system to replace the new 5 hp cyclone.

Perry