Would This Work?

[michaelmew]

Hi All,

I'm brand new to the forum and very new to the world of DC and cyclone separators and baffles. I tried to search for this but I didn't find what I was looking for. Please correct me if it already exists.

I was brainstorming at HD this morning and saw this large fitting and it gave me an idea. I've attached a crude picture to help explain what I think will happen. Please let me know if I'm onthe right track or if this is not going to perform how I want it. BTW, the bucket is simply for demonstration purposes. I be crafting a shorter top hat version, tbd. The red line is the supply coming from the tools/hoses in a 2" pipe. I'll cut out the sidewall of the pipe FACING TOWARD the container sides and AWAY from the other fitting. The yellow area indicates my GUESS at where I need to cut the bottom of the container for the baffle. The blue represents the swirling air as it moves around the sides and into the 3" inlet and finally up and out and back into the shop vac (represented by green). BTW, I only have access to a small 6 gal shop vac. I don't have immediate plans to upgrade to a DC.

My questions:
1) How will this perform?
2) Are the cuts in the baffle correct (yellow areas)?
3) Is the 3" fitting too large of an opening? I can obstruct portions of it, but I can't find the same style in 2" pipe.
4) How much of the sidewall should I cut away?

In general, I'm worried about the air flow from 2" to 3" and back to 2" using a small shop vac. Will this even create the necessary centrifugal force to separate the air from the dust?


Any and all comments appreciated. Thanks in advance!
-mm

[retired2]

"Would this work?"  Not likely, stick to proven designs.

[michaelmew]

Thanks Retired2! I'm a bit disappointed but I respect your opinion. You've clearly been doing this a long time. Was there something specific that could be tweaked or is it a total failure?

I thought I read somewhere that the intent of the forum and lack of published "plans" was to promote experimentation and customization. The latter portion of your statement seems to contradict this. I am brand new, but I did spend some time searching for things like minimum requirements or "start with this" advice, and I came up empty handed. Please correct me if I am mistaken.


Thank you,
-mm

[retired2]

I don't see your idea producing any centrifugal air flow.  The air enters on one side of the chamber, splits and goes two different directions, and then enters the exit in less than 180 degrees.  Some waste may be separated into the waste container below the baffle, but I suspect you will also have a significant amount of bypass.

You mentioned you are planning to use a small shop vac.  What kind of tools are you planning to capture waste from?

[michaelmew]

Thanks for the further explanation. I bought the Duststopper before I knew it was a rip off of Phil's design. So, I'm trying to design something that will perform as well for less money. My idea was born from thinking that coming in from the top would be a lot easier than coming in from the side and there was a beautifully radius'd fitting. I've watched a lot of videos and designs that have a 'clunky' attachment point on the side. But, at this point, it sounds like I need to get back to something closer to what Phil has designed.

I use a table saw and miter saw more than anything else. I also create a lot of dust and mess with a router table/plunge router, an orbital sander, and 2 different belt sanders. I have a band saw, but I'm just beginning to learn how to use it. I also have a planer but I think it puts out way too much for a small shop vac to handle, and really, I don't do a whole lot of projects requiring it's use and its not a fine dust as far as I can tell. I should also mention that I have been using my jigsaw a lot more lately. Other than the belt sanders, everything else listed has a dedicated dust port attachment point. I have aspirations to create a sanding station with a dedicated port.

I've already begun creating the DC 'cart' with the shop vac and collection bucket. I just need the top hat portion to complete the setup.


-mm

[retired2]

I've seen the Duststopper design but have not seen or read anything about its performance, however it is hard for me to imagine that you will be able to improve much on its performance.

All the tools you mentioned pose dust collection problems, particularly for a shop vac.  Shop vacs produce a lot of static head, but don't move much air compared to a DC.  So, if you want to pick up marbles or screws the shop vac is the right tool, but if you want to knock down a dust cloud you need to move a lot of air.

Good luck

[michaelmew]

I can't say that I am surprised about the projected performance of the shop vac. Unfortunately, this is life's lemons and for the time being, I'm making lemonade. I'm working out of my garage currently. Actually, being in Texas, I am usually working out in my driveway; I drag the tools out there to work. But, it's gotten to be unbearably hot so working inside the garage is an improvement. I just need to try to do my best to mitigate the dust going everywhere for the time being. Maybe a dirty car will get my wife to green light a new shop project  ;)

-mm

[DustySanders]

michaelmew, I agree with your point about the forum needing to encourage experimentation. If you have the money and time, why don't you do a quick and dirty version of your design as an experiment?
Retired 2 is probably right, but you never know. Personally I've lost interest in this forum because it seems like nowadays it could just be replaced with plans of R2's separator, and a note to "do it like this."  And also, I've finished building my sweet version of the Thien tophat and it is working nicely. 

[Mikoturos]

Retired2 has more experience with various dust-collection devices and more knowledge of the engineering theories.  Nevertheless, I could see the same issues with my relative lack of experience.  When I glanced at the thumbnail, I thought it stood a chance, but when I expanded the image to see the details it was clear there were problems.  Retired2 was pretty clear about those so I won't reiterate here.  Instead, I'll expound on what I thought could be right when I was glancing at the tiny thumbnail:

If your flow was reversed, you could send dirty air into the chamber and around the sides in a centrifugal motion with only one of those elbows.  Then you could put a vertical slot (rather than a hole) in the exhaust pipe facing toward the wall or at least away from the circular flow of air and place a barrier of some kind between the wall of your chamber and the side of the pipe, just before the slot.

The idea would be to send air and particles circulating but then needing to negotiate a hairpin turn to go out through the slot.  Since wood particles have more inertia than air particles, they'd have a harder time negotiating that quick back-track around the pipe and, hopefully, gravity and friction would have the wood bits dropping to the bottom of the chamber and resting with other wood bits.

But even this idea is flawed because the pipe and its barrier would impede the air circulation and impart turbulence to the circulating air.  That turbulence would make it easier for particles in the incoming air to reach the exit slot, and would also stir up any particles on the bottom of the chamber.  That would leave you with a chamber and two pipes that are basically doing nothing.   One could put a screen on the slot to keep particles from leaving but, at that point, you'd have a large filter on a shop vac that already has a small pleated filter -- why bother when there are simpler designs for that?

I'm sure it's been spelled out several times on this site (and on others, too) but the key elements here are
1) Move a lot of air (high-numbered CFM's) to clean as much as possible as fast as possible to protect your lungs
2) Minimize parts and design complexity, thereby minimizing cost
3) Centrifugal activity moves heavier-than-air particles to the outer rim
Multiple trips around that centrifuge make multiple opportunities for particles to fall out.  As DBhost writes here [http://www.jpthien.com/smf/index.php?topic=137.0] in post #7, "the idea is to keep the air spinning long enough for debris, and dust to fall out of the air stream, air smashing against the sidewalls of the container should do that... In turn the solid center section [of the baffle] keeps the stuff that has already gone into the dust bin from getting sucked right back up into the filter."

--Mik

[DustySanders]

Thanks, Mik - a much better answer than ""Would this work?"  Not likely, stick to proven designs."

[retired2]

Thanks, Mik - a much better answer than ""Would this work?"  Not likely, stick to proven designs."

Actually, I thought it was the best short answer I could give since the OP was clearly headed down a path that was not going to work, so I was trying to save him time, material and money.  When I had more time I gave him a follow-up response.  I have often encouraged others to try an idea they had, but only when I thought there was a chance that it might work.

When you have answered several hundred questions on this forum, and many of them several times, you get a little burnt out.  That is when brevity begins sounding blunt.  I'll show more restraint in the future.