Cyclones and MDF Dust

Replacing a cartridge filter with a large filter bag pays off for a woodshop owner. April 18, 2015

I have the 3.5 HP tempest cyclone from PSI. It seems to work very well with my other machines when collecting chips, and the limited amount of fine dust produced by my belt disc sander. However I have noticed that the cartridge filter will start to clog up when I am cutting MDF on my CNC router. This creates a further problem because that reduces airflow resulting in less collection efficiency leading to a situation where, the filter really gets plugged up.

As a result I have had to clean my filter more frequently, but usually by the time I realize I need to do this, I am in the middle of a project and this isn't so convenient. I have worked with other systems, that haven't had this problem. I may very well go with a more industrial system in the future when I move to a larger facility, but right now my only option is to work with what I have. I don't know if this is just a problem with cyclones in general, or maybe there are filters that work better. I would appreciate any advice on any solutions that would help with this.

Forum Responses
(Dust Collection and Safety Equipment Forum)
From contributor L:
Itís not a problem related to the cyclone but to the lack of filter area. Get a much larger bag made for your collector or add additional cartridges.

From Contributor G:
Make sure the collection barrel has a tight seal. Any leakage here will allow fine particulates to get to the filter.

From contributor F:
You have gotten some good advice already. First check your system for any leaks, even tiny ones will reduce the separation. Even on professional grade cyclones youíre going to end up with some of the fine dust getting through to the filters. MDF is the finest of the fine, that stuff is a real PITA. I'm guessing yours is a basic model with a single cartridge on the smaller side. The idea of replacing with filter bags is not a bad one at all. I run a 7-1/2 hp Torit for which I use cloth bags. I added an extra 50% of filter area when I bought my bags in order to maintain airflow under just about any conditions.

My personal opinion is that cartridges work best in two situations. One is in small hobby shops that don't generate a lot of fine dust and the other in bigger collectors that use some type of self-cleaning system, like pulse jets. These blow out the cartridges every time you shut down the machine. Youíre in the middle with a cartridge that's not able to handle your output. Bypassing it with a bag house may be a viable option for improving your airflow for relatively short money.

From the original questioner:
I like the idea of replacing my cartridge filter with a couple of filter bags. I have seen a few commercial systems installed by Oneida that have this configuration. I will also see if I can improve the seal a little at the barrel. This really seems to be a problem with ultralight density MDF, such as Trupan.

From Contributor H:
We have an Oneida 5hp system with a 5' tall cartridge. After dealing with fine dust clogging the filter I called Oneida and discussed the problem. Their response was that cyclones will not as a rule separate out the fine powder like dust created by cutting MDF. Additional air flow and a solid seal on the drum side will help but not solve the problem. We don't cut a huge amount of MDF on the CNC so it's not an issue. However even the sanding dust was causing some problems so I took both sanders off the cyclone and put them on smaller dedicated Delta collectors. One more thing - if you do replace the cartridge with a bag get a good one. A very good source is American Filter Fabric. We have two of their custom bags and are very happy with the performance.

From the original questioner:
I am going to try two or more bag filters. I think my cartridge filter is reaching the end of its lifespan as well.

From contributor E:
After having less than good results with pleated filters on two different cyclones I talked to various people only to find out that they are intended to be used where the dirty air is on the outside, not the inside. This to me explains why just about anything other than shavings would end up trapped down in the "folds" of the filter. As time and money allows I am planning on changing my filters to bags.

From the original questioner:
I ended up ordering a custom bag from, American Filter Fabric sized for my CFM requirements. The price was very reasonable, (under $200) I am going to put the extra money that would have gone into a new cartridge filter, towards some upgrades to my duct work. When it arrives I will definitely share my thoughts on how it works.

From the original questioner:
The AFF bag arrived. Wow. I did not know how much the dirty cartridge had been restricting my system, even after I cleaned it. I installed the AFF bag and I think that this is the first time my cyclone has worked properly since I have owned it. I bought my system installed from the previous tenant in my shop, and he remarked that he had only ever filled one-two barrels, but I would imagine the old filter was loaded up by his wood master sander. Not only is the suction and airflow substantially better, now the cyclone is doing a much better job separating dust. This is the best $200 I have spent in a while.