I need to drill through Hardieplank cement fiber board for a 1” PVC irrigation pipe.

Common bi-metal hole saws will be dulled from even a single hole and likely wouldn’t even complete the hole. Carbide or diamond hole saw would work but aren’t readily available in the size I need to fit the 1” elbow (which of course is bigger than the 1” pipe alone).

I’m sure the use of 2 bi-metal hole saws would get the job done but is just wasteful as they would be dull afterwards. Just looking for other ideas.

  • are you running PVC irrigation pipe through your house wall?
    – jsotola
    Jan 17, 2021 at 18:11
  • 2
    The right hole saw is the right answer, of course, but if you were desperate, you could chain drill around the perimeter and hack (chisel/knife/whatever) away at the webs between the holes. You'd need an escutcheon to cover the horror. Sometimes you just have to accept that hole saws (as drill bits as saw blades etc) are consumables. Jan 18, 2021 at 1:03
  • Thanks Aloysius for a suggestion outside of a carbide hole saw (which as I stated in the original comment wasn’t available). I needed to complete the job so sacrificed 2 bi-metal hole saws and got er done. Cheers mate.
    – Ethan
    Jan 19, 2021 at 3:58

2 Answers 2


According to this page, masonry bits + carbide hole saws are the way to go. If you think (and you may be right) that a carbide hole saw will be ruined by a few holes through HardiePlank, then just get one of the right size rather than a set - because if you get a set then Murphy's law says the next 3 times you need hole saws they will all be that same size and the rest of the set will go to waste. A quick search (Home Depot and Amazon) finds plenty of carbide hole saws larger than 1".

  • A carbide bit would be great but as I said they aren’t available in the size I need in my city and not waiting 4 weeks for ordering one online.
    – Ethan
    Jan 17, 2021 at 18:10
  • Aha. I'm used to 3 days max to get this kind of stuff delivered (or pick it up locally). Not knowing where you are, can't guess delivery times Jan 17, 2021 at 18:17

Carbide hole saws for 1” conduit are made by greenlee and Milwaukee I get my replacement cutters at Platt, they stock conduit sizes from 1/2” through 2” again in standard conduit sizes. I save my dull or broken cutters because if I take 10 in I get them repaired for 1.25$ per carbide not bad it’s a brand new hole saw after replacement. I know both brands sell individual cutters and arbors, if you don’t want to go high end there also carbide tipped saws by Morse at big box stores again. A 1-3/8” bit is the proper size for 1” conduit.

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