DIY Cyclone: Time to throw in the towel? LONG

[Dominic Greco]

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.

[Pete Bradley]

I don't know if you notice it, but there's a recurring thread in your post of getting questionable and conflicting information from the web. Now you're coming back for more? Let's face it, internet woodworking forums are loaded with speculative, oft-repeated, and/or bogus information presented as fact.

My suggestion is to get something running, and then you have a baseline to experiment from.

Pete


Pete

[Dominic Greco]

Pete,
Thank you for your candid advice.

But my time in the shop is limited, as is my budget. Experimenting does not sound like an efficient use of time, or money.

[Jim Becker]

Doninic, those CFM specs on the 3hp blower don't seem "right"...

Tough choice here...you have a lot of investment in both stuff and money. It sounds like you have what you need to have a functional system, even if it's not design-perfect. On the other hand, buying a replacement commercial offering still requires setup time including ductwork optimization. But you are then working with something with known performance specifications and can get predicable results. Oy!

[Charles McKinley]

Hi Dominic,

Get a Clear Vue and fliter sans the blower and mount your blower on it if they say it will fit.

From the feedback I've read they will tell you straight if your fan will work and I have heard very good things ablut the Clear Vue and Bill gets a cut.

I have been on these projects where you change this and do that and it drives you nuts. That is why I still use my dust boy when I take the time to hook it up and really like my 3M Airstream helmet.

Remember it is easier for me to spend your money than you. How much time and $$ will you have doing the welding mods since you farm it out? Building a box for the filter: doable- yes, pian in the but- yes.

I would rather see cool stuff like turned wooden balls!

[Bruce Wrenn]

I used to teach classes on building Wood cyclone. Probably built 50+ of them. I have one in my shop, with a Cincinatti Fan 10" blower on top, with a 1 HP motor driving it. It doesn't have neutral vane though. The output from blower goes to a plentium located below trash can that has seven of the 6"X65" filter "socks" from Onedia. Plentium is toped with 1/4" plywood with holes sized to fit socks. Using 4" sewer pipe and flex hose, for a total length of about 39', it will keep up with my 15" Delta planer (model 380). I do get some shavings in plentium, but only vacumm it out a couple of times per year. Go to Wood Online, and check out DC forum.

[Mike Cutler]

Dominic.

Me personally, I would cut my losses, sell the stuff to someone with more time on their hands, call the good folks at Onieda and be done with it.

This may be a defeatest attitude, but like you, I don't have or want to spend the time building a cyclone. I'd rather be building something else.

[Robert Mickley]

It's all in your mindset. My self I would have to defeat it. But thats just me. I'm bound and determined to get mine working better. I followed Bill Pentz's spreadsheat for cone dimensions.

Mine passes fine dust. But I know why.I didn't get the air ramp just right.
And the output pipe at the top is too small. It should have been 11 inches If I remeber right and I made it 8 inches. Jan gets here its coming down and I'll fix it.

Personaly I feel commercial built cycolnes are over priced for what your getting. But again thats just me.

[Noah Katz]

"Building a box for the filter: doable- yes, pian in the but- yes."

I don't know why a filter wouldn't work in both directions, but you could use Sonotube or large heating duct to enclose it.

[glenn bradley]

Hi Dominic,

I feel your pain. I have made the choice to buy things that I could make due to just the limitation you speak of; time. Unfortunately, we are the only ones who can decide how best to spend our time.

When I am between projects or just haven't decided on what to do next, I will burn some serious shop time on shopmade stuff. If I am mid-project or "jonesing" to get started on something that requires something I don't have, I'll buy it just to get moving.

Best of luck on your decision but, an observation; it sounds like you really want to just buy one and get on with it. You can always sell off the other stuff after the fact, over time. ;-)

[Jim Becker]

I don't know why a filter wouldn't work in both directions, but you could use Sonotube or large heating duct to enclose it.

It will "work", but be very, very difficult to clean. Some cartridges are designed to flow in one direction and others in the, umm...other direction.

[Noah Katz]

It's a lot easier to blow air from the accessible outside than the inside.

It's true the pleats are more crowded together on the inside, so maybe with that particular filter the pleats get clogged solid.

[Jack Diemer]

My thoughts.

1st off, I built the Pentz cyclone, glad I did it, would not do it again, knowing the effort, and what it costs now to get into a cyclone.

If you had built the Pentz cyclone, I would probably recommend staying the course. I have a feeling that the cyclone you designed may not be optimized for pushing as much CFM as you would like too.

The big question on performance stems mainly on the impeller with that 3 HP reliant DC. If its 14 inches, you will likely get 1200 CFM at 4lbs static pressure on a well designed cyclone (not the big numbers you quoted). If the outlet of the blower is at least 6 inches wide, then its worth keeping, if its 5 or less, you are going to lose too much in performance and I would recommend scrapping the whole thing. I recently upgraded my motor/blower on my unit, and now the big difference is that the loudest element is not the motor, but the air being moved by the motor.

As for that filter, if it works from the outside in, I think you would be better off just getting a different filter.

Hope this is helful and good luck in whatever you decide.

[Greg Narozniak]

a few years back I had ordered one of the "kits" and once I added up the cost of the kit (sheetmetal, fastners,etc) the motor, the impeller, cost of building the impeller housing, filter, dust bin, etc. it worked out to over $1k. For roughly $1200 I ordered an Oneida 2hp Commercial and within 3 days it arrived and has been running OUTSTANDING since it arrived.

IMHWWO, it was just not worth the time and labor to build one.

[Robert Mickley]

IMHWWO, it was just not worth the time and labor to build one.

Theres too many variables, I probably don't have $100 in mine.
The DC blower is from a JDS dust force, Bought it complete at an auction for $65
I got the sheet metal from my nephew
The drum for the bottom the wifebbrought home from work
Bought some pipe
Made wasted gates.

Took me about 3 1/2 days. So figure even $350 in labor I'm still under the cost of a bought one. Does it work asd well? Probably not. But if I had to spend $1200 I wouldn't have one

If you buy all the pieces new, you can't do it.