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Discussion Starter · #1 ·
Colleagues: I need another Dust Collection line for a Table Saw over-the-blade dust collection/blade guard.

To run it off the existing 6" TS DC sheet metal duct, need a hole in the duct then install a saddle tap Y connector on the 6" duct. See:
www.oneida-air.com/inventoryD.asp?item_no=SCOLLECT33

Seems to be rather straight forwarded, but how-in-the-heck do I cut the hole in the existing 6" diameter duct?

Considered a 6" 45 degree Y -- See: https://www.oneida-air.com/inventory..._no=SCOLLECT41 -- but I would need to dismantle the existing duct and blast gate to install it.

Any ideas?
 

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For the saddle fitting referenced, just cut a hole in the existing duct facing in the direction that you want the "Y" to point. You should be able to reach inside the "Y" and mark around the inside with a Magic Marker, then just cut the outline. Put a bead of the silicone sealant shown on the page around the outside, and fasten the saddle in place. One way is with self-tapping screws - think the heating duct in your house - but I think I would consider some type of hose clamp so you have nothing sticking down inside for debris to catch on.
 

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Discussion Starter · #3 ·
Tomp913: what I need to know how to cut the *[email protected]#$$ hole and what do I need to do it ?

Tin snips--which I have -- came to mind right-off-the-bat with a hole drilled to start the cutting. But are there specialized snips to cut a circular/oblong hole??

Some one suggested a grinder with a cut off wheel to cut out a rectangle hole in the duct. If that is feasible, I have a air powered grinder and cut off wheels.
 

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tin snips or a jigsaw...
 
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Ray; tin snips or Aviation snips? Aviation snips come in three styles Right hand curve cuts, Left hand curve cuts, and straight cuts
.https://www.amazon.com/Wiss-Aviatio...=2025&creative=165953&creativeASIN=B00KXF26AE
Basically you perforate the metal in the middlle of the circle and get the tip of the ships into the hole, then start cutting in a spira outwards to the outline of your hole.
Drawing the hole outline is a bit more interesting.
The easiest way, assuming you have a bit of scrap of the smaller size to, is to draw the arc of the 6" pipe onto the side end of the smaller pipe, cut tat arc on both sides so it saddles the 6"pipe then trace that profile onto the 6" face.
Now, this is important, you need to make longitudinal slices maybe every inch or so around the crved end of your smaller pipe. This will give you tabs...anbe about an inch long(?). Fold every second one outward. Insert the pipe with the straight tabs into the 6" pipe.
Fold those ones outward , tight against the inside of the 6" pipe; the smaller pipe is now locked in place.
I would have used a short pipe stub for this item. This would allow you to get your hand inside to do the detail work. Now you install wahtever you need onto the small pipe stub.
 

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to draw the circle for the cutout...
place the saddle...
use a felt tip to trace mark the hole through the saddle's tap...
cut the hole about a ¼'' large to avoid a lip that will be prone to catch debris..
use ordinary elcheapo rubber cement to make a gasket... paint it on the inside of the daddle's flange, let dry, and assemble...
hose clamps are your bestest friend here...
 
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Now, this is important, you need to make longitudinal slices maybe every inch or so around the crved end of your smaller pipe. This will give you tabs...anbe about an inch long(?). Fold every second one outward. Insert the pipe with the straight tabs into the 6" pipe.
Dan,,,
Ray is installing a saddle and not a crown...
no tabs required...

note...
the rubber cement forms a most excellent seal and won't let the saddle creep...
 

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Tomp913: what I need to know how to cut the *[email protected]#$$ hole and what do I need to do it ?

Tin snips--which I have -- came to mind right-off-the-bat with a hole drilled to start the cutting. But are there specialized snips to cut a circular/oblong hole??

Some one suggested a grinder with a cut off wheel to cut out a rectangle hole in the duct. If that is feasible, I have a air powered grinder and cut off wheels.

@Ray Newman

Sorry, misread your question. Tin snips are your best bet, and I would use offset snips so that your knuckles are away from the rough edges. As Stick said, cut outside your Magic Marker line so there's nothing to catch on. You don't need too big of a hole to get started, maybe use a 3/4" holesaw if you need more room - drill inside your cut line and arc from the starting hole to blend with the cut line. Probably easier to take short "nibbles" rather than a full length cut and just walk your way around the hole. I don't know your access to the duct that you're cutting, it may be that you need both right and left cutting snips in order to do the job.

https://www.amazon.com/ABN-Offset-R...8-1-spons&keywords=offset+aviation+snips&th=1

My father-in-law was a HVAC mechanic and could do amazing things with sheet metal, I've seen him make a starting hole in a duct with a flat blade screwdriver and a hammer, work the snips around the hole and have the edges look as if they were sawn rather than cut with snips - he tried to pass his knowledge along to me, but did a lot of head-shaking watching me work.
 

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hints..
use a Unibit to make your starter hole...
there is nothing like nipples or electric shears...
 
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I'm lazy...

.
 
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Still got all your fingers, Stick?
Best advice I ever got was "If you drop a piece of glass or sheet metal just let it go. DO NOT TRY AND GRAB IT!!!"
(Well OK; there was that advice about women...but I digress)
 

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