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Thread: Cutting ductwork holes in floor

  1. #1
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    Cutting ductwork holes in floor

    Anyone with some advice for cutting holes in a 1.25” plywood floor for 6” DC ductwork? Was thinking about maybe trying a RotoZip Or just use my jig saw. Since I’ll prob seal the gaps or use some type of supporting metal collar the holes don’t have to be perfect.

    I’m not sure I want to deal with the torque (and cost for a one time use) of a 6” hole saw and definitely not interested in using a hand held fly cutter. My wrists still haven’t forgiven from last time I went the hole saw route.

    Thx

    Jon
    Last edited by Jon Snider; 04-16-2019 at 2:14 PM.

  2. #2
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    Small router on a trammel or honestly, a decent jigsaw with a quality blade. Using a fly cutter manually is VERY unsafe...they are only for use in a DP.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
    Template and a router if you know there are no nails to hit.

  4. #4
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    Quote Originally Posted by Jim Becker View Post
    Using a fly cutter manually is VERY unsafe...they are only for use in a DP.
    This cannot be over emphasized. I have a fly cutter, but it only gets used on the DP with the work piece securely clamped. They are extremely dangerous in a hand held drill.

  5. #5
    Do Not use a 6" hole saw freehand. They give me the willies in a DP, let alone freehand. You say it is not important for them to be clean holes, so go at it with the jig saw and if there are no nails trim it smooth with the router.

  6. #6
    Jasper jig

  7. #7
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    I don't believe a Rotozip will cut it. Pun intended... Best/easiest solution would be a 6" hole saw but only if you have a HoleHawg or other low speed drill with a long torque handle. Jigsaw if that is what you have.
    Last edited by Ole Anderson; 04-16-2019 at 12:55 PM.
    NOW you tell me...

  8. #8
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    Quote Originally Posted by Jon Snider View Post
    Anyone with some advice for cutting holes in a 1.25” plywood floor for 6” DC ductwork? Was thinking about maybe trying a RotoZip Or just use my jig saw. Since I’ll prob seal the gaps or use some type of supporting metal collar the holes don’t have to be perfect.

    I’m not sure I want to deal with the torque (and cost for a one time use) of a 6” hole saw and definitely not interested in using a hand held fly cutter. My wrists still haven’t forgiven from last time I went that route.

    Thx

    Jon
    I drew circles and cut with a jig saw, quick and easy. Mine were in the ceiling, not the floor, thinner than 1-1/4" but should still work fine. If you wanted a longer blade a sawzall would be my next choice. The hole wouldn't be pretty but as you mention, that won't matter.

    JKJ

  9. #9
    6" holesaw is fine, but put it in a cordless so you have the brake and take your time. Also drill the pilot without the holesaw so it doesnt jam. I've been thrown from enough ladders to know when the holesaw gets over 2" use something with a brake.
    Make and sell a cornhole set, it will more than pay for the bit and be another use for it.

  10. #10
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    Thanks all. Just to be clear. It was the hole saw I once used freehand that gave me a good wrist torque. Never hand held a fly cutter. In fact the only time I’ve used one is to cut out sound holes on a drill press.

  11. #11
    Save the hole cutouts, so when you change your system, you can screw a block of lumber under the hole, and put the cutout piece back in the floor.

  12. #12
    Join Date
    Nov 2014
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    NC Piedmont
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    I cut holes in my floor for 6 and 7 inch ducts up from the basement. My floors are 2 1/4" thick. Started with a drill then used my jig saw with a long blade. Simple and quick. I also put weatherstrip around the joint but you wouldn't have to. I think it lessens noise transmission. Buy a pack of blades though because you will probably hit an occasional nail and dull the teeth of the blade.

  13. #13
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    I would cut just slightly under size and then a router with a template to clean it up.

  14. #14
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    Quote Originally Posted by Larry Frank View Post
    I would cut just slightly under size and then a router with a template to clean it up.
    I would follow Larry's process, too...I'm anal like that. LOL
    --

    The most expensive tool is the one you buy "cheaply" and often...

  15. #15
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    Quote Originally Posted by Jim Becker View Post
    I would follow Larry's process, too...I'm anal like that. LOL
    Chainsaw and 4 tubes of caulk. Kidding, KIDDING!

    Kidding aside, that is actually how my original mentor, some 40 yrs ago, would've tackled that scenario. I learned a lot of what NOT to do from him!

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