Is the saw blade in the photo appropriate to cutout a window in HardyPanel? Wood paneling?


What exactly is the nomenclature for this blade (if I wanted another I would ask for ????)?

The CDC recommends polycrystalline diamond tip (PCD) blades.

enter image description here

  • 1
    it would burn through wood paneling more than cut through it. hardiboard would take forever.
    – dandavis
    Mar 5 '21 at 23:55
  • that blade is designed for cutting things like tile and stone. MK Diamond doesn't have an exact match on their website, but this: mkdiamond.com/tile/bld_00_dry.html shows very similar blades.
    – dbx
    Mar 6 '21 at 0:02
  • hardie board siding panels or hardie backer? I have cut both many times and there really is a difference.
    – DMoore
    Mar 6 '21 at 4:49
  • @Dmoore Thank you for the clarification question. OP update to address question
    – gatorback
    Mar 6 '21 at 7:10

Blades are described by the number of teeth. For example, 24T , 40T, 80T. Just ask for a hardboard blade which will be labeled as such and have very few teeth. One sold at the orange big box has 4 teeth, is made by Diablo (top of the line quality) but sells for $45. Store Sku 619584. This is a specialty blade that you won't find everywhere.

DIABLO 7-1/4 in. x 4-Teeth Polycrystalline Diamond (PCD) Tipped James Hardie/Fiber Cement Saw Blade https://www.homedepot.com/p/DIABLO-7-1-4-in-x-4-Teeth-Polycrystalline-Diamond-PCD-Tipped-James-Hardie-Fiber-Cement-Saw-Blade-D0704DH/100627137


I think your real question is "How can I cut backer board with a circular saw". The diamond blade in your picture is a grinding blade. It's designed to work with a variety of hard surfaces from tile, to cement, to even metal (not ideal for metal but I digress).

Backer board can be hazardous to cut because it contains silicates (as your CDC link notes), which can become airborne and get into your lungs and make you sick. The "weekend warrior" one-room-job answer doesn't involve power tools at all. Just use a simple utility knife, score the board, and then snap it (works well for drywall too). Minimal dust, but hard to make precise cuts where there's no long straight edge.

Your CDC link notes this

Use polycrystalline diamond-tipped (PCD) blades de-signed to be used to cut fiber-cement siding. Compared to Carbide-tipped blades, they provide a cleaner cut of the siding, exhibit a longer wear life, and may reduce the dust generated.

The power saw answer involves a special type of blade specifically made for fiber board

Fiber board blade

You can buy these in 4-10" sizes commonly. Note the low number of teeth, which are designed to minimize dust. A diamond grinder blade can do it too, but it's not designed to minimize dust because it's literally designed to chip away at material, not cut it clean like a saw blade. Always wear a respirator if you use a power tool to cut fiber board, regardless of the method


Go to your local hardware store and ask for a "fiber cement blade" in the size your saw takes (6.5" or 7.25"). They're pricey, but they're the right tool for the job.

  • This is absolutely the right answer for the hardie siding... but is he asking about that?
    – DMoore
    Mar 6 '21 at 6:21

That's a stone/tile/masonry cutting blade with a diamond 'turbo' rim.
enter image description here
It will work for Hardie Backer board or similar fiber-cement products but it'll make a lot of dust, and would almost certainly be awful at cutting any sort of wood or wood paneling - more likely to burn through than cut it.

Some other rim types for diamond blades are:
Continuous enter image description here Segmented enter image description here Segmented Turbo enter image description here


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