I dropped by the dealer today to pick up a 90 degree 4" ell for a temporary
dust collection setup. I've never purchased in PVC dust fittings before.
This was a Jet part number, but I think its the same universal
Taiwanese-made fitting that everyone sells (other brand Woodstock?). It
looked like reasonable quality, then I looked inside of it. Expecting a nice
smooth sweeping curve, I was shocked. The inside of the fitting appears to
be two pieces of PVC that have been cut on a miter and bent enough to come
together. The outside of the ell is simply a nice looking shell. Its not
smooth and it actually swages down to restrict the flow - not exactly what
you want for a nicely designed smooth flow network.
Bob
Good point, Roy.
Bob Davis
"Roy Neudecker" <[email protected]> wrote in message
news:[email protected]...
>
> "Bob Davis" <[email protected]> wrote in message
> news:[email protected]...
> > I have read up and done extensive calculations. There is a balance
> between
> > ideal flow conditions and making things fit in the shop. A 90 degree
ell
> > doesn't add that much drop. Its almost academic. What is really
surprising
> > (but not if you think about it) is the drop associated with flexible
dust
> > collection hose. A 2 foot length of flex hose has twice the drop of a
> single
> > 90 degree ell. Most people use flex hose to turn corners. That's far
> worse
> > than using a well made 90 degree fitting.
> >
>
> But you shouldn't really be using 90's anyway. Mainly because it is a
> potential clog point. You should be using two 45's to round out the
corner.
>
> Roy
>
>
>
"Bob Davis" <[email protected]> wrote in message
news:[email protected]...
> I have read up and done extensive calculations. There is a balance
between
> ideal flow conditions and making things fit in the shop. A 90 degree ell
> doesn't add that much drop. Its almost academic. What is really surprising
> (but not if you think about it) is the drop associated with flexible dust
> collection hose. A 2 foot length of flex hose has twice the drop of a
single
> 90 degree ell. Most people use flex hose to turn corners. That's far
worse
> than using a well made 90 degree fitting.
>
But you shouldn't really be using 90's anyway. Mainly because it is a
potential clog point. You should be using two 45's to round out the corner.
Roy
"Bob Davis" <[email protected]> wrote in
news:[email protected]:
> I dropped by the dealer today to pick up a 90 degree 4" ell for a
> temporary dust collection setup. I've never purchased in PVC dust
> fittings before. This was a Jet part number, but I think its the same
> universal Taiwanese-made fitting that everyone sells (other brand
> Woodstock?). It looked like reasonable quality, then I looked inside
> of it. Expecting a nice smooth sweeping curve, I was shocked. The
> inside of the fitting appears to be two pieces of PVC that have been
> cut on a miter and bent enough to come together. The outside of the
> ell is simply a nice looking shell. Its not smooth and it actually
> swages down to restrict the flow - not exactly what you want for a
> nicely designed smooth flow network.
>
> Bob
>
>
Use standard borg plastic pipe fittings. Its cheeper. Now the sizes
are a little off for the connectors but I watched a show on TV where a
guy did custom pipe work with a heat gun. Aparently with a little bit
of heat you can stretch, shrink, bend and shape PVC just about anyway
you want. He took a piece of 2 inch and warmed it up and made a 2 - 4
reducer by using a broom stick handle to slowly encrease the size of the
pipe till it fit in a 4 inch fitting.
If he can do this the slight 1/4 inch change needed to get standard 4
inch PVC to fit into duct collector ports should be a sinch.
Sometime I think it is a plot. Dust collector and shop vacumn fittings
are intentially made just a little bit different from standard PVC so
you cant use the cheep high volume stuff.
Now I caution you that I haven't tried this yet but I am going to.
After all a couple of dollars worth of PVC should provide you with
plenty of stuff to practice with. And if it doesn't work out then all
you wasted is a little time.
"David Merrill" <[email protected]> wrote in news:foOXb.187845$U%
5.929952@attbi_s03:
> http://cnets.net/~eclectic/woodworking/PVC.html
Great web site. This is just what I was talking about. I will definitely
bookmark this one.
"Bob Davis" <[email protected]> wrote in
news:[email protected]:
> I couldn't stand it. I happened to have a heat gun that I've used for
> years for heat shrink tubing (electronics wiring). I wondered if it
> would enough output. I needed a 4" x 4" square nozzel that adapts to
> 4" S&S pipe. So I took a 4"x4" fence post and put a 10 degree taper
> cut on four sides to make a jig. Then I took a scrap of pipe and
> began heating it. I could tell when it "went rubbery" and slipped it
> over the end of my wooden jig. Voila! I had a perfect nozzle ready
> to hook up to my dust collection piping.
>
> Bob
>
Cool! Sometimes all it takes is to do it!
I have read up and done extensive calculations. There is a balance between
ideal flow conditions and making things fit in the shop. A 90 degree ell
doesn't add that much drop. Its almost academic. What is really surprising
(but not if you think about it) is the drop associated with flexible dust
collection hose. A 2 foot length of flex hose has twice the drop of a single
90 degree ell. Most people use flex hose to turn corners. That's far worse
than using a well made 90 degree fitting.
Bob
"Subw00er" <[email protected]> wrote in message
news:[email protected]...
> I'd take it back. If you read up a little, 90 deg bends are not really
> optimal anyway, you may be better off just using tubing to make the
largest
> bend you can afford in your space (or hook a couple 45's together).
Ideally,
> the tubing would be straight for the highest possible flow rate - every
bend
> you add lessens your cfm.
"Roy Neudecker" <[email protected]> wrote in message
news:[email protected]...
> But you shouldn't really be using 90's anyway. Mainly because it is a
> potential clog point. You should be using two 45's to round out the
corner.
>
> Roy
If you're using regular DC fittings, they are already "high flow" design. If
you're using 4" PVC, (2) 45's work better, or find a local plumbing
supply(NOT a BORG) and get high flow 90's(wouldn't know this, but SIL is
commercial plumber, and our code calls for high flow 90's in sewer lines).
--
Nahmie
Those who know the least will always know it the loudest.
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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I'd take it back. If you read up a little, 90 deg bends are not really
optimal anyway, you may be better off just using tubing to make the largest
bend you can afford in your space (or hook a couple 45's together). Ideally,
the tubing would be straight for the highest possible flow rate - every bend
you add lessens your cfm.
"Bob Davis" <[email protected]> wrote in message
news:[email protected]...
> I dropped by the dealer today to pick up a 90 degree 4" ell for a
temporary
> dust collection setup. I've never purchased in PVC dust fittings before.
> This was a Jet part number, but I think its the same universal
> Taiwanese-made fitting that everyone sells (other brand Woodstock?). It
> looked like reasonable quality, then I looked inside of it. Expecting a
nice
> smooth sweeping curve, I was shocked. The inside of the fitting appears to
> be two pieces of PVC that have been cut on a miter and bent enough to come
> together. The outside of the ell is simply a nice looking shell. Its not
> smooth and it actually swages down to restrict the flow - not exactly what
> you want for a nicely designed smooth flow network.
>
> Bob
>
>
You might consider doing that in a well ventilated place. See toxic fumes
warning at http://cnets.net/~eclectic/woodworking/PVC.html
David Merrill
"Joe Willmann" <[email protected]> wrote in message
news:[email protected]...
> ...snip... >
>
> ... I watched a show on TV where a
> guy did custom pipe work with a heat gun. Aparently with a little bit
> of heat you can stretch, shrink, bend and shape PVC just about anyway
> you want. He took a piece of 2 inch and warmed it up and made a 2 - 4
> reducer by using a broom stick handle to slowly encrease the size of the
> pipe till it fit in a 4 inch fitting.
>
> If he can do this the slight 1/4 inch change needed to get standard 4
> inch PVC to fit into duct collector ports should be a sinch.
>
> Sometime I think it is a plot. Dust collector and shop vacumn fittings
> are intentially made just a little bit different from standard PVC so
> you cant use the cheep high volume stuff.
>
> Now I caution you that I haven't tried this yet but I am going to.
> After all a couple of dollars worth of PVC should provide you with
> plenty of stuff to practice with. And if it doesn't work out then all
> you wasted is a little time.
I couldn't stand it. I happened to have a heat gun that I've used for years
for heat shrink tubing (electronics wiring). I wondered if it would enough
output. I needed a 4" x 4" square nozzel that adapts to 4" S&S pipe. So I
took a 4"x4" fence post and put a 10 degree taper cut on four sides to make
a jig. Then I took a scrap of pipe and began heating it. I could tell when
it "went rubbery" and slipped it over the end of my wooden jig. Voila! I
had a perfect nozzle ready to hook up to my dust collection piping.
Bob
"Joe Willmann" <[email protected]> wrote in message
news:[email protected]...
> "David Merrill" <[email protected]> wrote in news:foOXb.187845$U%
> 5.929952@attbi_s03:
>
> > http://cnets.net/~eclectic/woodworking/PVC.html
>
>
> Great web site. This is just what I was talking about. I will definitely
> bookmark this one.
On Sun, 15 Feb 2004 15:21:29 GMT, "Bob Davis"
<[email protected]> wrote:
>I dropped by the dealer today to pick up a 90 degree 4" ell for a temporary
>dust collection setup. I've never purchased in PVC dust fittings before.
>This was a Jet part number, but I think its the same universal
>Taiwanese-made fitting that everyone sells (other brand Woodstock?). It
>looked like reasonable quality, then I looked inside of it. Expecting a nice
>smooth sweeping curve, I was shocked. The inside of the fitting appears to
>be two pieces of PVC that have been cut on a miter and bent enough to come
>together. The outside of the ell is simply a nice looking shell. Its not
>smooth and it actually swages down to restrict the flow - not exactly what
>you want for a nicely designed smooth flow network.
>
>Bob
>
I looked at the commercial fittings and was similarly underwhelmed. 4"
light sewer pipe is much higher quality.