Pentz design cyclone

Dave Black

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Central PA
I have a cyclone that I built a few years ago from Bill Pentz design. Its made of HDPE plastic. I recently got my drum sander finished and hooked it up the the cyclone and I am having a lot of dust pass through the cyclone. Any thoughts as to how much dust should pass through. I know my ducting is not the best because I have a few turns about 3 feet before it goes into the cyclone and I guess that can cut down the efficiency, and I don't have the right filters for it yet. From what I read on Pentz website there shouldn't be very much dust that gets to the filters. Right:dunno:
 
I have the Clear Vue based on the Pentz principles. I exhaust outside, but have seen no evidence of anything outside. I'd check to see if you've sprung a leak in your dust bin. That would account for the dust going anywhere but in your bin. I don't have a sander, so not sure how mine would operate with one, but you don't hear of it as a problem. Jim.
 
Yep, I agree with Jim, I bet you have a leak somewhere. Mine hardly passes any dust at all.

One way to find a leak is to get something that smokes, a bit of old rope or something and then let it smoke, run the cyclone and hold the smoking rope near anywhere you think it might leak.

Cheers!
 
Jim and Stu are right on. If your system has any type of air leak below or at the 'funnel' you will have all the dust going through to your filters. At the base of the cyclone you must be airtight or have a vacuum.


Brian
 
I'm not sure where I would have a leak. It collects all the larger dust like I get from sawing and planing, but not sanding dust. I'll have to take a look at things tonight. I suppose that even a small leak could cause a problem.
 
Jim and Stu are right on. If your system has any type of air leak below or at the 'funnel' you will have all the dust going through to your filters. At the base of the cyclone you must be airtight or have a vacuum.


Brian

It depends if you are pushing air at the cyclone or pulling it. My new system will be a seperate blower blowing into a cyclone seperator that is outside, and the warm air returning inside. A small leak at the dust bin will not stop dust from settling out as it will be under pressure. If the blower is on the other side then you have a vacuum at the bottom of the cyclone and it will draw air. This can keep the fines suspended.

The downside of my setup is everything goes through the fan, so sparks have to be considered. but I will not have to keep everthing as tight at the collection point.
 
I found a leak in the system, it was in the bung hole plug. For some reason the plug had 6- 1/8" holes in it. So I fixed that, turned on the cyclone and sander and... still I am getting dust coming out of the cyclone. Its enough that I can see it blowing out. 1 thing I noticed was that after I stopped sanding there was still dust spinning around the cyclone and not dropping, it stayed that way for several minutes until I turned off the cyclone. Im not sure if thats supposed to happen. Another thing I noticed was that my blower housing is taller than this blower plan on Pentz website. http://BillPentz.com/woodworking/cyclone/images/budblower.gif

I know I built my blower before 2/2010 which is the date on that plan, I don't know if that has changed since I built mine.
 
The only change to the blower plans on Bill's website that I know of is that he added the layout of the blower housing that I had built for mine that was designed by Ed Thomas and that is for a 16" dia. impeller.

Does your sander have a 4" dust collection port? If it does you might need to open another blastgate a little bit to make up for the lost airflow. My understanding of his cyclone is that best seperation efficency occurs with a 6" connection.
 
heres a pic of my setup, there is a 9" duct above the ceiling that connects the cyclone and the blower. Sorry for the bad pic, I only had my camera phone
 

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May I ask why did you use plastic? Is it harder or easier to work with? To seal? Where did you get it?

Thanks

I used it because I had it. My family has a water treatment business and we have a bunch of old water softener salt tanks made of HDPE so I just cut a few of those up to use. I thought it was easy to work with, I just screwed the plastic to pieces of wood at the joints and sealed them with caulking.

I'm still not sure why its passing dust. I may still have a leak or maybe the transition at the top of the cone is not smooth enough:dunno:
 
May I ask why did you use plastic? Is it harder or easier to work with? To seal? Where did you get it?

Thanks

The kits from Clearview are reasonably priced and you can buy them without the blower. Not a heck of a lot more than the cost of the material really.

I'm making mine out of steel because it will be outside in subzero weather, and I just like to make things out of steel.......
 
I'm still not sure why its passing dust. I may still have a leak or maybe the transition at the top of the cone is not smooth enough:dunno:

Does the intake of the cyclone swirl in the same direction as the rotation of the impeller? I don't know if it makes as much difference since your impeller is mounted away from the unit and has a couple of elbows, but I do remember reading something about it on his site and how it reduced a 5HP draw as much as 1HP when they weren't in the same direction. :dunno:
 
Here goes a bit of a guess on this, based on your layout:

Try throttling the output of the cyclone a little bit. Like cover up the outlet about 1/4 of the way. By pulling directly into the fan, I think you're going to be moving air faster through the blower than you would have been if it went through the cyclone first. It might be making the air velocity through the cyclone too fast.

What kind of level of dust do you have in your bin? I haven't experienced it, but I've read you can get carryover towards the top of your dust collection drum on my grizzly manual.

What is the size of your fan impellar? That link on pentz's site is for a 14" x3-5/8". I really don't think the impellar size or getting to much airflow through the cyclone is going to be the problem, but i thought it worth looking at.
 
Does the intake of the cyclone swirl in the same direction as the rotation of the impeller? I don't know if it makes as much difference since your impeller is mounted away from the unit and has a couple of elbows, but I do remember reading something about it on his site and how it reduced a 5HP draw as much as 1HP when they weren't in the same direction. :dunno:

I don't think it spins in the same direction, I too read something about that on Pentz site the other day but I don't remember reading that in '06 or '07 when I built it. I'm not sure if it would make a difference or not. I suppose if I can't get this figured out I can remake the cyclone to spin the same direction as the blower. I am going to be building a larger shop sometime in the not too distant future and would like to get this resolved before I move everything so I don't have to redo things after I move all this stuff.
 
Here goes a bit of a guess on this, based on your layout:

Try throttling the output of the cyclone a little bit. Like cover up the outlet about 1/4 of the way. By pulling directly into the fan, I think you're going to be moving air faster through the blower than you would have been if it went through the cyclone first. It might be making the air velocity through the cyclone too fast.

What kind of level of dust do you have in your bin? I haven't experienced it, but I've read you can get carryover towards the top of your dust collection drum on my grizzly manual.

What is the size of your fan impellar? That link on pentz's site is for a 14" x3-5/8". I really don't think the impellar size or getting to much airflow through the cyclone is going to be the problem, but i thought it worth looking at.

The air goes through the cyclone first, then to the blower. Right now the dust bin is about 3/4 full so maybe I should empty it and give it another try. My impeller is a 14" I am pretty sure. I bought the motor and impeller that Pentz recommended when I built it.
 
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