I've got a 2hp dust collector with lines throughout the shop to each
piece of machinery. Because emptying the bag was such a pain, I
installed a 30 gal garbage can separator in-line just ahead of the
collector itself. Everything is light duty 4" pvc pipe to the blast
gates, then 3 or 4" hose to the equipment itself.
My problem is that the dust, chips and shavings seem to pass through the
separator into the lower bag of the collector. Once the bag gets
full, it then fill the separator can. Logic tells me I might have too
much suction which I never anticipated as a problem.
So first, is my guess correct and if so, is there a solution?
Any help is appreciated,
I doubt the problem is too much suction. It /is/ necessary to
keep the container under the cyclone lid less than 25% (give or
I have a similar set up (for a single machine) that works really
well. Photos at http://www.iedu.com/DeSoto/dust_collection.html
Morris, Thanks for posting pictures. You describe some things on the
webpage and I have no idea what your talking about. You don't define them
anywhere and I sure can't figure it out from the pictures. Could you please
provide some clarity about these terms:
dust collector shoe
Sorry about that. The web page was built for other ShopBot users
- and nearly everything you asked about is at the top of the page.
This is the machine that the dust collector collects from - the
blue monster with the MDF tabletop. It's capable of producing
/huge/ amounts of dust & chips.
A box that surrounds the router bit and to which the DC hose is
The 'Bot can move the router bit in three dimensions: x and y lie
in the table, and z is up and down. The spindle rides up and down
on a movable frame called the z-carriage.
The dust collector "shoe" without hardware, DC flange, etc - a
box with only 5 sides.
Bob, since posting my original response, I've been wondering if
your 30 gal. can might not be a bit small for the job. I haven't
experimented with different container sizes - but with my 55 gal
drums, very little gets past the first drum...
It's a PC-controlled robot. Mine is outfitted with a 5HP spindle
whose speed can be controlled in 0.1 RPM increments over the
range of 0 - 24000 RPM - and I use it (primarily) for routing.
Some people install plasma cutters, laser cutters, grinders,
saws, etc. It's a (relatively) inexpensive flexible platform with
a reasonable degree of accuracy for woodworking, some mold
making, and some metalworking (milling/drilling) applications.
One of the features I like is the ability to process DXF files
(from CAD programs) automatically to finished parts.
You can see some of what it can do at the ShopBot web site:
DeSoto is a very small town located at exit 110 on I-80 - about
54 mi west of Newton (home of Maytag, the well-known appliance
I suppose those are pretty good (relatively) prices when you are talking about CNC
machinery, but they do make the cost of my
cabinet saw seem almost like pocket change. However, if the Dow hits 20000, and my
index funds follow ...
Wichita, KS USA
Like your cabinet saw, they only make sense when they satisfy a
requirement that can't reasonably be met using a lower cost
alternative. In my case, I wanted to produce a structurally
complicated product of consistantly high quality. Production with
"traditional" tooling would be prohibitively expensive; and so
the CNC solution was the only path available. The ShopBot PRT-96,
while at the lower end of the CNC cost spectrum, provides all of
the features I needed.
Because it does its job so rapidly, I have both personal and
machine time available for experimentation and learning - I'm
discovering that there are joinery techniques possible with CNC
that just wouldn't be reasonable to consider using traditional
methods; and that we've just begun to scratch the surface of
I spent part of my time this past week working on a low-cost
linear bearing design based on an extruded frame to contribute to
an "open source" kind of CNC development. That project aims to
make a basic 3-axis CNC capability available in "some assembly
required" form for less than US$100. If that effort is
successful, you won't need to wait for the Dow to hit 20000...
Sounds like my setup. 2 hp, 4 inch pvc. Same thing happened. The dust
collector kept the can nice and clean. Hah! I imagine if you have to use
one, perhaps a deeper can experiment is in order? I just put up with the
bag but am thinking about attaching a lower bag to a can, somehow.
3" and 4" is really small. More than likely you have too little
airflow and you're not creating a cyclone in the seperator which is
necessary for the chips to fall out. You likely need something along
the lines of 6" mains and 5" drops to your tools. Be careful to
design for as absolutely small a static pressure as possible since
big-bag type systems have a very steep fan curve. Also, make sure
everything is extremely well sealed, especially the seperator. Also,
the seperator will collect chips, not dust. Dust will still go into
I suspect all separator lids are not created equal. I believe the ones like
Rockler sells at http://tinyurl.com/3262c are the poorest design. The Lee
Valley lid at http://tinyurl.com/2ukkh is better. I built my own with PVC
pipe fittings. Its similar in design to what woodcraft sells at
Try attaching a 6 to 12 inch piece of pipe to the center hole inside the
barrel (the one attached to you dust collector) you will have to change the
barrel more often but it should give the heavier pieces more time to settle
out before going to your dust collector. To many of the vortex creators have
the intake to close to the exhaust not giving the air flow a chance to swirl
and thus you do not get any separation of materials.
Check the angles of the lid's entrance and exit fittings. You need
to create a circular, cyclonic flow. If the flow isn't circulating,
the chips can't fall, they get sucked right into the other hose.
Dust will go all the way, chips and shavings should fall into the
The advice that a couple responders gave you about properly designing
for cyclonic flow was right on. I made my separator lid (for a 30
gallon galvanized can) using a 4" 90degree elbow and a separate length
of 4" straight pipe. It's geometry is very similar to the Woodcraft
separator that was posted, except the straight pipe extends about 6"
below the elbow inlet. This allows for development of cyclonic flow,
as another of your respondents suggested.
I empty the separator can when it is half to two-thirds full.
Probably empty it 30 or more times before I have to empty the bag.
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