I posted this in Home Improvement as well but figure I could get some advice here as well.

I have a project (tornado shelter) where I will be cutting down ten 4'x8' sheets of 14 gauge sheet metal to various sizes.

I have considered:

• electric shears
• wood framing circular saw (just buying a metal cutting blade)
• metal cutting circular saw.
• paying a sheet metal shop hundreds of dollars to shear them.

Regarding the option of circular saw with a metal cutting blade, or a metal cutting circular saw, does anyone have experience with this? how many blades would I go through while ripping my ten sheets?

Thanks in advance.

Is it galvanized? If not i would see if possible to borrow a plasma cutter 14GA seems like it would be tough to cut mechanically especially that many cuts...

Something I have done and should work is a circular saw with regular type of wood cutting blade but......turn the blade over (reverse). Has always worked great for me and your project does not sound big enough that you'd burn up but one blade. Carbon tip rough cutting sort of blade.

14 gauge is only 0.075 inches thick. This will cut that fine: http://www.homedepot.com/p/Diablo-7-1-4-in-x-48-Tooth-Steel-Demon-Ferrous-Metal-Cutting-Saw-Blade-D0748F/100098833

^^^Yes, buy a metal cutting circular saw blade.

A nibbler. These things are awesome.

https://www.milwaukeetool.com/power-tools/corded/6880

For the recommendation of the "metal cutting blade" in my standard circular saw: Has anyone actually used their standard wood circular saw with the metal blade? From what I've researched, a standard wood saw will have something like 5800 rpms, while the metal cutting circular saws are more like 3000-4000 rpms. I'm concerned that the higher rpms will dull the blade much faster.

I considered the nibbler too, but dismissed it based on the circular saw option appearing to be superior for my straight cuts needed.

How well will 14 gauge sheet metal stand up to a tornado?

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How well will 14 gauge sheet metal stand up to a tornado?

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When stacked on the inside of (2) 3/4" plywood layers, it will stop a 2x4, or 2x6, or fence post, travelling at 100 mph. (100 mph is the speed that projectiles will fly in a F5 tornado (250mph wind).

FEMA recommends it as part of the wall assembly. here is a link to their drawings.
http://www.fema.gov/media-library-data/1418837471752-920f09bb8187ee15436712a3e82ce709/FEMA_P-320_2014_508.pdf

What are you using them for? If they're exposed, hot filings from using a saw can adhere to the surface and cause rusting later.

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Has anyone actually used their standard wood circular saw with the metal blade? From what I've researched, a standard wood saw will have something like 5800 rpms, while the metal cutting circular saws are more like 3000-4000 rpms. I'm concerned that the higher rpms will dull the blade much faster.

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Yes I've done it. What really causes the dulling is getting the blade too hot (500+ degrees), which you can offset by pushing slower. If you had a 3400RPM saw, you can do like 7 feet of cut per minute, but for a 4800RPM saw you'll need to slow down to about 4 feet per minute. If the blade ever does get too hot, cutting while too hot will warp the teeth almost instantly; warped teeth will never cut well again. I recommend pushing slower than you think you have to.

With that all said, for only 14ga and only one sheet, I doubt you'll notice.

For a smaller project, go buy a cheap B&D circular saw from Home Depot & get the warranty. Sandwich a few sheets together between 2 2x4's with some vice grip c clamps and cut to desired length. When the saw burns up, no loss. To cut to width nothing beats a mechanical shear.

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For the recommendation of the "metal cutting blade" in my standard circular saw: Has anyone actually used their standard wood circular saw with the metal blade? From what I've researched, a standard wood saw will have something like 5800 rpms, while the metal cutting circular saws are more like 3000-4000 rpms. I'm concerned that the higher rpms will dull the blade much faster.

I considered the nibbler too, but dismissed it based on the circular saw option appearing to be superior for my straight cuts needed.

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I've used my old Black & Decker circular saw for cutting metal and bricks (pavers) with the appropriate blade installed. That's what I would use if I needed to rip those sheets. Just slow down as Ornlu suggested, take your time, don't force it and let the saw/blade do the work.

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How well will 14 gauge sheet metal stand up to a tornado?

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When stacked on the inside of (2) 3/4" plywood layers, it will stop a 2x4, or 2x6, or fence post, travelling at 100 mph. (100 mph is the speed that projectiles will fly in a F5 tornado (250mph wind).

FEMA recommends it as part of the wall assembly. here is a link to their drawings.
http://www.fema.gov/media-library-data/1418837471752-920f09bb8187ee15436712a3e82ce709/FEMA_P-320_2014_508.pdf

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Are you putting the sheet metal on the interior or exterior side of the wall? I might do this in my shop.

This seems to be begging for a cheap HF plasma cutter

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quote:

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quote:

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How well will 14 gauge sheet metal stand up to a tornado?

---

When stacked on the inside of (2) 3/4" plywood layers, it will stop a 2x4, or 2x6, or fence post, travelling at 100 mph. (100 mph is the speed that projectiles will fly in a F5 tornado (250mph wind).

FEMA recommends it as part of the wall assembly. here is a link to their drawings.
http://www.fema.gov/media-library-data/1418837471752-920f09bb8187ee15436712a3e82ce709/FEMA_P-320_2014_508.pdf

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Are you putting the sheet metal on the interior or exterior side of the wall? I might do this in my shop.

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I am putting the metal on the inside face. Exterior side of studs was preferable, but I am building it in an existing closet, and I couldn't figure out a reasonable way to build it to the exterior side.

Call Rik-Mar Fabricators in Bryan and ask them to shear the sheets for you. They will do a great job for you.

Agree with above... measure what you need and have them sheared. Otherwise, clamp an angle guide and torch/plasma cut them to length.

Dewalt has a new shear attachment for a cordless impact. I got to play around with it and, at about $49, it works pretty good. Combine that with a metal cutting blade on a circular and you are good to go. Also, Dewalt and Milwaukee both make a cordless metal cutting saw. Each is designed with just the right torque/rpm for what you are trying to do.

If you've got an air compressor or access to one I'd just print out a harbor freight 20% coupon and go buy one of these air shears from HF.

http://m.harborfreight.com/air-tools/specialty-air-tools/inline-air-shears-98833.html

Shouldn't have a problem cutting all you need as long as you keep it oiled. I've been using one for years I got from there.