An easier approach to "top hat" setup

[rieferman]

edited 05/25/11:  I've changed the title of this thread to make it easier to understand that you don't need to do a big compllicated process to make a top hat style separator.  You can use the DC ring, and some easy fabrication to make a system that is very efficient and cheap to build.  This thread documents how I got there (read the whole thing though because my starting and ending place are fairly different).


Darn it, lost my post somehow.  Anyways, my pics are too big to fit, but here's a link that explains what I did picture by picture (each picture has a caption explaining what is being shown)

http://rieferbarn.shutterfly.com/345


Basics:
- one man shop, blast gates
- 4" main and drops, PVC (I do understand 6" is preferred, but I got the pipe for free)
- average run is about 15-20 feet including bends.  longest run is close to 35 feet so that may be a problem, we'll see.
- stacked assembly to save foot print
- suck through a bag (instead of barrel) for ease of discarding dust - therefore, cage/skeleton inside the bag
- vent directly outside
- minimize connections and bends - motor directly above intake, 12" straight exhaust, direct connection to main trunk

Hope this is helpful to anyone, would love any comments on the approach I'm testing.  Duct work begins in about a week.

Thanks!

Bob Riefer

[Bulldog8]

How much sawdust do you generate? When I am planing stock down for a project, I find that I empty my barrel 2-3 times. It seems to me that if you have to empty your bag a couple of times when planing the bag would likely be torn by the wire fence. You may also find that emptying the bag for reuse (if that is your intent) puts you in the cloud of fine dust that you were trying to avoid in the first place.

Of course if you don't run a planer you could very likely operate for weeks without the need to empty the bag.

I would like to see video of the system running if you could.

Steve

[rieferman]

Hi Steve,
The intent of the bag (rather than a barrel) is that I will dispose of the bag (along with the dust inside it) when it's full rather than creating the dust cloud you get when emptying a barrel (although, tip, I've heard of people spraying a little water into their barrel on top of the dust before emptying to help reduce the plume).  So, I will need to have spare bags on hand at all times... then again, if I was emptying a barrel, I'd need bags to empty into as well (albeit, probably cheaper lawn/garden bags).  So, as I see it, I'm skipping the "make a dust cloud while pouring into a bag" step with this setup.

Now, if I find that keeping up with the bag demand gets expensive (at harbor freight, I think the bags work out to about $1.25 apiece if memory serves) I may have to consider alternatives, but we'll see.

I'll try to get a vid tonight and post a youtube link.

side note:  the skeleton cage inside the bag has all sharps nipped off and taped over with electrical tape.  We tried to rip the bag with the cage as a test... couldn't do it.

Thanks!

Bob R.

[rieferman]

OK, so I took a quick phone video.  A full dustpan worth of table saw dust emptied into a temporary pipe that I rigged up.  You can see the dust sort of "explode" into the bag (whereas when I previously tested in a setup where I was blowing through the bag, it would swirl into the bag.. now, sucking through the bag, the cage skeleton causes that swirling to be a bit messier, but all the dust gets where it's going no problem).   The temporary filter bag I have in place (because outdoor exhaust isn't installed yet) is slightly tan after one of these tests.. about the same amount of color/dust as you'd get if you used the filter bag to dust off the top of your table saw surface.  That is, I'd say 95% or greater is getting into the bag for disposal, and the rest will go outside. 

http://www.youtube.com/watch?v=9MSOCePr35s

[rivilee]

Hi,
Interesting design- looks like the most economical way to go. I've got the same HF DC and am planning to build an outside room to put the DC in and then will vent to the outside. Instead of a plastic bag I'll fit the lid to a big city supplied garbage can.
My question: when you made the separator did you modify the HF cylinder at all? Does the down sloping part affect performance negatively? I'd love to get more detail of how you modded the lid.
Rick

[rieferman]

Shoot, I haven't been here in awhile, didn't notice a question.  My bad!

Anyways, my blast gates were finally installed this week so I could officially test the full system. 

What I learned:
4" pipe with poorly optimized runs (i.e. I have 90 degree bends) up to about 35 feet still work fine with the hf 2hp blower unit.  My band saw is the furthest away with four 90's on the way, and it keeps my shop so much cleaner.  Yeah, sure, fine dust is killing me still, but I wear a respirator to reduce the issue (and my shop is detached, so my family is not affected).

The cage skeleton wants to collapse under the pressure, so I need to reinforce it.  It's passable for now, but will eventually fail if I don't beef it up.

Exhausting outside is great, at least in this warmer weater.  I may filter during winter months, but otherwise, I'm very happy with venting outside, and there's almost nothing besides air getting out of the building due to the baffle.

Dust collection for the drill press is kind of a pain.  I tend to just leave it running and move the hose around manually to cleanup as needed.

Reducing to 2.5" hose works fine, but not great.  It's worth doing as a way to have a quick/easy cleanup without dragging a shop vac out, but it's not as powerful as a shop vac.

Running two ports at the same time is not an option.  I wanted to run a 4" and a 2.5" for my table saw.  No way, not with this blower.  It was worth a shot.

HF blast gates and clear 4" hose are fine.  I used electrical tape wrapped around the couplings of the blast gates to make them fit snuggly into the PVC pipe.  Then I secured with two 1/2" screws through the PVC and through the coupling.  Solid as a rock.

As for the question above, I didn't change the ring (with it's funnel shape inside) at all.  I just attached my baffle shape and moved on.  Works great.



Overall, I'm very happy with the results.  My shop will stay much cleaner, and I spent less than $250 total to complete the entire effort (and that includes purchase of the DC, the duct work, blast gates, and flex hose).

[rieferman]

I have decided that the "suck through the bag" design is too wimpy for continued use.  I still believe in the idea in terms of efficiency and cleanliness, but do not feel like spending the time to create a sturdier internal skeleton.  So, bag is being replaced by 35 gal fiber drum with locking lid. 

[phil (admin)]

I have decided that the "suck through the bag" design is too wimpy for continued use.  I still believe in the idea in terms of efficiency and cleanliness, but do not feel like spending the time to create a sturdier internal skeleton.  So, bag is being replaced by 35 gal fiber drum with locking lid. 

And you don't want to try push through the bag?

[rieferman]

Hey Phil,
Perhaps my mind isn't wrapping around it well enough, but the only way I could figure to get the small footprint that I have (the stacked assembly) and nice direct intake and exhaust without lots of fabrication of hose connections etc. (I used the DC's ring as the integral part holding the baffle) was to suck through either a barrel or bag.

All the configurations I could come up with (probably a "me limitation" so please enlighten) that pushed through a baffle and bag doubled the footprint or otherwise made the setup more cumbersome.

What do you think?

[phil (admin)]

Hey Phil,
Perhaps my mind isn't wrapping around it well enough, but the only way I could figure to get the small footprint that I have (the stacked assembly) and nice direct intake and exhaust without lots of fabrication of hose connections etc. (I used the DC's ring as the integral part holding the baffle) was to suck through either a barrel or bag.

All the configurations I could come up with (probably a "me limitation" so please enlighten) that pushed through a baffle and bag doubled the footprint or otherwise made the setup more cumbersome.

What do you think?

You're right, it would increase the footprint.  I wasn't considering that.

[rieferman]

I believe this officially marks the first time I've been sort of close to correct about anything woodworking related ever (forget that my design failed and we're talking about a redesign!).  ha ha

[rieferman]

Redesign complete and successful.  If I were to build a new setup from scratch, this would be it.

I took a carboard fiber drum (free from local plastic molding company) and made a small window from scrap plexiglass I had laying around.  To make the connection from the drum to the DC ring (where my baffle is installed) I used a scrap piece of rubber pond liner (rubber flashing, or inner tube would work just as well) to create a diaphragm style of connection.  It took about 5 minutes to create the connection, and now it's easy to remove/replace the drum.  The connection is so tight that the DC lifts the bin off the ground slightly when I turn it on.  No strapping is necessary on the bin side of the diaphragm, the elasticity of the connection itself is enough to create an airtight junction.

Tests of about 10 dustpans full of various sizes of dust/chips (from extremely fine through course) on my longest run showed a cyclonic motion visible through the window, and zero visible dust expelled through the exhaust out the side of my building.

Very very very pleased with the new setup.

[rieferman]

OK, so I changed the title of this thread in hopes it will be more helpful to others.  I can't see having to do all sorts of complicated fabrication when the method I've detailed will get to the same result for very low cost.  I have updated the pictures at this link as well:

http://rieferbarn.shutterfly.com/345