Cutting a Stainless Steel Vent Hood Chimney

If a range vent hood is too tall to fit, you can't fudge it. Here's advice on trimming the metal to size. August 8, 2008

I have run into a situation occasionally where the two piece stainless chimneys were too tall for the ceiling height. The vent hoods are set at the height required by the manufacturers, but they are still a few inches too tall. I hate having to tell the customer that they have to find a metalworker to cut this, so I would like to do it myself for them if I could. Is there a cutting wheel for a Dremel that would do this? Or maybe a special jig saw blade that would cut stainless?

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor A:
I've never seen them get cut. All the ones I have run into have a special snap-lock connection. I think if you cut them you can't join them.

From contributor B:
Usually the flue is in two pieces - one slides into the other. They can be adjusted by sliding them. You can try a jig saw blade made to cut metal. Look at the Bosch web site for more information for blades. Are you sure that the pieces can't be move to the proper height? Or maybe they got the wrong size flue? Or maybe the hood was not installed at the proper height? How much do you have to cut off? Can you move the hood down so that the flue will fit? How far off the floor is the hood?

From the original questioner:
I need to cut about 2 inches. The vent sits 30" off the cooktop, which is what is required for the vent and cooktop. It is only the inner piece that needs cutting, as it is too tall. I suppose we could rehang the vent 2 inches lower, but then it would put it lower than the required height.

From contributor B:
I'm assuming that one piece is longer than the other? My suggestion would be to cut it down. Also check the installation guide. Sometimes it's possible to install a hood lower or higher than what they recommend.

From contributor C:
A die grinder (pneumatic dremel) with a cutoff wheel would work. Don't try it with a little pancake compressor, though.

From contributor D:
Use a Bosch 118B blade in a jigsaw. You need backing on the stainless. Use spray adhesive and glue some plywood behind the cut line. Cut with the saw on a slow speed. Use a double layer of masking tape on the steel to prevent metal dust from scratching under the jigsaw base. Go slowly.

From contributor E:
You can get 7" metal cutting abrasive blades that you can mount in a skill saw. This works well but will leave a discolored edge near the cut. All the duct work for our dust collection system was cut this way.

From the original questioner:
Thanks for the replies. I picked up some jig saw blades last night, as well as a couple of wheels for the grinder, so I will give them both a try. To contributor D: Nice idea backing up the metal - I wouldn't have thought to try that.

From contributor F:
I had to cut one once to match a sloped ceiling. I used tin snips and it worked great.

From the original questioner:
Just wanted to let everyone following this thread how it went. I decided to first try my Dremel with a cut off wheel before trying the jig saw blade. The Dremel cut real well, and I used it to complete the cutting. I went through 3 or 4 of the wheels, but it only took 10 minutes or so to make the cut and de-burr the edge. Thanks for the tips on this project, I appreciate it!

From contributor G:
Two things to add - the hood has to be at the height that is dictated by code. If you mount it lower, the building department will make you reinstall it at the correct height, usually 30" above the burner grate (not the stove top). This can be as much as an additional inch or so.

Dremel makes a fiberglass reinforced cutoff wheel. It is much stronger and longer lasting than the regular ones.

From the original questioner:
That is why I set the hood at the manufacturer's height of 30" from the grate. I figured if anyone questions it, we can pull out the manual and show that it was installed at the required height.

Also, after burning up a couple of the standard Dremel wheels, I tried the fiberglass reinforced wheels, and they did last much longer. I did notice that they cut a little slower than the other ones, however.