On Nov 14, 7:15*pm, "Colbyt" wrote:
"Colbyt" wrote in message
...
I own most of the tools and would hate to buy a new one for this project
but take your best shot at the best way and tool to do this and I will go
from there.
I have not actually measured it but I think the main trunk line I need to
cut is 12x18, might be 12x24. Standard gauge metal HVAC duct from 40+
years ago. *I have reasonable access on all four sides. Well that one side
is going to be a b**** *but I can do it once if I must. *Most likely, I
want to return the duct to its original position after the project is
completed.. I might choose to step it up to make it easier on the next fat
guy. But that part I can figure out.
I can't unzip it at the seams without a lot of digging in 60+ year dried
dirt as the next seam is resting on the ground. Hey, I did not do the
original install. If I had it would be far different.
So what I want is a clean way to cut the duct without destroying the metal
on either side of the cut. As an example: much like cutting the four sides
of a wood box with a table saw.
Now to inject a little humor to the thread; the reason I want to do this
is because my belly has grown to big and my back to bad to scoot under the
tunnel I made years ago in this crawl space. Did I mention I hate tight
crawl spaces.
Suggest a diet and die. *There isn't time or the willpower to make it
happen. I got to get over there to figure out where the water leak is
coming from. Go ahead and make your fat guy jokes if you must. Paybacks
can be awesome. -
--
Colbyt
Please come visithttp://www.househomerepair.com
I want to thank again all those who made a serious reply in this thread.
The job is finished and I am back to report the results for the benefit of
others who may visit the thread on one of the republication places. I plan
to post an article with photos on my site when I have time to write it.
Due to my inexperience with sheet metal, angles, and math I actually managed
to cut in place and on a work bench so I tried all the tools except the
nibbler at least once.
I found the Dremel using the right angle attachment and abrasive cutting
discs *to be the tool with the best control. *One should use that if 98%
accuracy is required. *Do expect to use a lot of discs. *A standard weight
one will cut about 2-3" of duct before it is gone. Using the heavy-weight
discs did not improve the length of the cut because of the increased stock
removal but they will be required for cutting the 4 layers of metal at the
joints.
The Dremel with a diamond bit was worthless. *Diamonds are for tile and
stone not metal.
The angle grinder with a thin kerf cutting disc was the best for overall
speed and disc durability. *It is somewhat harder to control and makes a lot
of sparks but it is the tool I would use next time if I had the room.
--
Colbyt
Please come visithttp://www.househomerepair.com- Hide quoted text -
- Show quoted text -
What about a jigsaw with a metal blade? I don't do much hvac, only
diy. I use my jigsaw for cutting openings in metal ductwork. First
mark with the sharpie. The air powered double cutters are the best
but I don't do enough to justify one of those. A dremel would just
take forever and use a ton of those little disks.