I have some questions regarding my shop built cyclone project and was wondering if I could get input from those of you who are knowledgeable on the subject. I've already checked on Bill Pentz's website and have emailed him. I want to hear from those of you who have built their own cyclones, or are familiar with the technique behind optimizing them.

To be exact, I'm trying to determine if I should cut my losses and sell all of the DIY cyclone components I have now, or try to stick it out and make my shop built cyclone work. And I'm finding my woodshop time to be real rare these days. Spending time and money on a project that MIGHT not work is not my idea of fun.

Since I spent some time working in the Pneumatic Conveying field as a Mechanical Engineer, I do know something about conveying technology (read that as just enough to be dangerous!).

Let me outline the situation for you. Back about 6 years ago, I had a cyclone based on WOOD magazine's 2HP version welded together for me. It has an 18" diameter x 20" tall cylindrical shell, 6" tangential inlet, and 6" discharge at the base of the cone. The entire thing was about 46" tall. It was my goal to couple this cyclone with a 2 HP blower I had yet to buy. Oh I almost forgot. I didn't keep any case notes or "history" on this project. I have to rely on my memory. And folks, it ain't that good!

Just about that time a 3HP Reliant DC just about fell into my lap. While I don't remember who I asked (since it was 5 years ago!) I do remember asking around here on WC to see what I should do to make this 3HP blower and my cyclone work together. It was recommended to me to open the inlet up to 8". I had a welder friend of mine retrofit the cyclone with a 8" inlet and 8" discharge.

It was until recently that I found that modifying the outlet/cone might have been a BIG mistake. This actually cut the cone height somewhat. Not a good move if you want to increase separation efficiency.

As far as the filter cartridge goes, I used a source recommended to me by another woodworker and purchased a filter sized to handle the air output of the blower. HOWEVER, after I purchased it I found out that this cylindrical pleated media filter is the type that needs air to come in from the outer surface, through to the center (not through the hole in the center and out). This is OPPOSITE how most cyclone's filters work. This necessitates me designing and building a somewhat complicated filter housing. Not impossible, just more complicated than I had anticipated.

So, if I stay the course and modify my existing cyclone some more by installing a neutral vane, and fixing the cone/discharge, I can then use a rectangular to 7" round transition that PSI sells a (for about $80!) could be modified to work on the rectangular exhaust of the blower. From there, a 7" diameter pipe would feed the shop built "filter housing".

If I continue with this project I'd need to buy an expensive fitting, some 6" flex hose, fabricate a special filter housing for this "blow through" style cartridge filter (and oh yeah, make it easy to clean), pipe it all together, and HOPE it works! See I'm an engineer. I like things cut and dry. If I'm going to spend all this time on a project, I want it to work, and work GREAT! Otherwise I'd drive myself crazy always trying to tweak it.

I believe that the blower is spec'ed to perform (clean line pressure) at approx 1900 to 2200 CFM CFM @ 11" to 14" SP. I've tried running my own calcs using some Cyclone Sizing spreadsheets I found on the Internet. But I get conflicting results. These spreadsheets are more geared towards building your own cyclone from scratch. Not getting the performance of one already built.

What would really help me out is some type of spreadsheet where I could plug in the dimensions on my existing cyclone, then input the blower specs, and see if it would work in a DC system. But I've searched the internet and haven't found anything. Hell, I'd even settle for a source of the calcs themselves. I can write a mean spreadsheet when I have to.

I guess I just need to see if this cyclone project is worth seeing to the end, or is it better to just cut my losses and run. I could just wait and save up money for a manufactured cyclone. BTW, I'm in no hurry to have a cyclone just yet. I have a little 1HP DC that I hook up from machine to machine. It will work fine for time being.

Your thoughts and recommendations would be greatly appreciated.