I have seen much on this group on how much efficiency will be achieved
if I change from my current Sears shop vac and 2" blast gates and
piping system to a real DC system. Since most of my tools are
Craftsman, will I need to modify the tool ports to make them larger?
Any info on what others have done would be appreciated.
If you buy a real DC (which I also highly recommend), you don't have to change
the ports on your tools... just hook the 4" line to a reducer and thence to your
tool. OTOH, if you have a choice of ports for your tool, go with the largest.
No matter what you do, you'll be better off than you are now with that howling
I have a Penn State DC with the optional muffler and you can easily carry on a
conversation while it's running without having to shout. Try that with your
BTW, no matter what kind you end up with, invest the extra $30 or so in a
cyclone trash can separator. Your impellors will thank you (for years).
choking down from 4" to 2" will lose you a lot of the benefits of the
DC. it will work, but is unlikely to perform better than the shopvac.
figure on setting up 4" ports on all of the machines you can, even if
you have to cut some sheetmetal.
I would think that choking down to 2" would give better suction. What comes
to mind - a 4" water hose, if choked down will become a high pressure hose.
Wouldn't the reverse apply for suction? Obviously I know nothing about
moving air but it just *seems* logical, like putting a small nozzle on the
It gives a higher velocity at the opening, but does not move any more air.
Dust collection is a low pressure high volume application. You have to move
the volume to move the dust fast enough on some machines. At low pressures,
its legitimate to compare water and air for understanding. Now to
illustrate what I am talking about, look at your various water hose
applications. Fill up a barrel with a 1/2" hose and with a 3/4" hose. The
3/4" hose will win every time. Then think about the size of a fire hose
where the application requires huge amounts of water. A dust collection
application is more like a fire hose than a garden hose.
I actually did some testing recently along those lines. I have one of the
"6 HP" (ha!) ridgid shop vacs with 16 gal tank - typical animal with good
capacity. I've been using it for the top of the router table. I tried the
DC with 4" to 1.5" reducer. The shop vac won. Then I tried the DC with 4"
to 2.5" reducer. The DC won - signficantly better than the shop vac. 4" is
great but just too big for a router table fence. Sometimes you have to
compromise. I do have 4" hose to a pick up above the tablesaw, however.
I've messed around and done the same thing. It was impressive. But that was
when my router table had $30 worth of parts in it. Now that I've got over
$400 in it, I have to look slick, don't you know.
Thanks for all the input. My shop is fairly small and most of my work
is fine dust from cutting balsa for model airplane building. Home
improvement projects and some other wood working make the regular
sawdust but I don't generate much in the way of chips (no lathe or
planer). That being said and not having a dust collector currently, do
I invest in something that has a built in cyclone or just go with the
dual bag types. I like a clean shop.
I have a two lines off my dust collector - one through the cyclone and one
straight. The straight line is dedicated to the bottom of the table saw - a
source of fine dust and no chips and it works well. I don't think you need
a cyclone. I originally had none. I put one in to catch the cutoff pieces
that kept getting sucked up by the nozzle on top of the table saw. I got
tired of the "bang, bang, bang, CLONG" sound that happened when a little
piece of oak disappeared and rattled along the DC network until it finally
went through the impellor of the DC!
Everyone talked about the size difference, but no one addressed the
compatibility issues. What brand of DC are you getting? You'll need either
the Jet/Craftsman adapter or the Delta/Craftsman adapter. Unless you have
the older style Craftsman that use grounded vents. Just clean them with
acetone (being careful not to get it on your hands) before connecting
another brand of DC.
You lost me, Edwin. What kind adaptor are you talking about? What's the
brand of DC have to do with connection to a tool? I thought dust collection
was done with fittings that almost fit plus a hacksaw and duct tape.
Just a note: 4" is fairly standard for real dust collectors but still
imposes quite a bit of efficiency loss. IMO the definitive web site on
dust collection for home woodshops is Bill Pentz' site, you will find
it referred to frequently on the wreck:
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