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Thread: Can I drill a 1 3/4” hole through a manhole cover

  1. #16
    Join Date
    Dec 2005
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    West Lafayette, IN
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    6,478
    Could you please tell us if you own this storm drain? How is it not the property of the city/county?

  2. #17
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    Quote Originally Posted by Matt Day View Post
    Could you please tell us if you own this storm drain? How is it not the property of the city/county?
    It’s the city’s. No problem now. I ordered a plastic one. I’ll just put the cast iron one aside someplace.

  3. #18
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    Dec 2021
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    Southwest WI
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    254
    In case your plastic cover doesn't work i would suggest an annular cutter in a mag drill that is by far the best way I have found to cut big holes in thick steel.

  4. #19
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    Sep 2016
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    Modesto, CA, USA
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    Quote Originally Posted by Bruce Wrenn View Post
    The way I resolve snapping off pilot bits is to use a piece if 1/4" rod in hole saw in place of bit. Using 1/4" bit, drill a pilot hole first.
    Exactly what I was going to say.
    Bill D.

  5. #20
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    Sep 2016
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    Modesto, CA, USA
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    Invert cover to see where the support ribs are located. Drill center hole from the backside so as not to cut support ribs. Flip lid right side up and drill with a hole saw. Use heavy gloves and place leg to stop reaction force of drill or keep legs and arms out of the way. Use vegetable oil for lube if needed.
    If you lived in the west water laws would probably outlaw dumping poisioned water into flowing water where the chlorine will kill life.
    Bill D

  6. #21
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    Mar 2016
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    Millstone, NJ
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    The Manhole cover isnt your property so no as far as legality. What you could do is excavate a little on the side and drill through the concrete that its most likely in.
    If you do go through with drilling the cover use a pvc Union right next to it so if needed they can get into it.
    You shouldnt need a mag drill its very soft steel.

    I made the mistake when I was young of using blind flanges to make a shooting target. Sat at the bench 200 yds out and didnt see them swing or here them. 223 ripped through 1-1/4 of the same soft steel

  7. #22
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    Quote Originally Posted by Mitch schiffer View Post
    In case your plastic cover doesn't work i would suggest an annular cutter in a mag drill that is by far the best way I have found to cut big holes in thick steel.
    the plastic cover is really made for a well or septic tank. I don’t think it would have any trouble supporting a person. It even has two blank spots in the honey comb for attaching pipes.

  8. #23
    Join Date
    Oct 2007
    Location
    Waterford, PA
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    296
    Tampering with that heavy sewer cover could put you directly in line for responsibility in any future loss of life caused by your action.

    If kids figure out how to unscrew and remove your light cover, and one ends up in the hole and drowns, will you be able to look in the mirror or face a sobbing mother? A heavy cover is put there for a reason. It’s wise to leave it alone, no matter how inconvenient.

    The city itself may be willing to assist you with your problem. Just ask the proper authority.

  9. #24
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    Cast iron is easy to drill, think of it like a very hard wood. No lubricant is necessary. Just follow the previous suggestions of using a solid 1/4" pilot. And a quality bi-metal hole saw.
    NOW you tell me...

  10. #25
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    Quote Originally Posted by Tony Zona View Post
    Tampering with that heavy sewer cover could put you directly in line for responsibility in any future loss of life caused by your action.

    If kids figure out how to unscrew and remove your light cover, and one ends up in the hole and drowns, will you be able to look in the mirror or face a sobbing mother? A heavy cover is put there for a reason. It’s wise to leave it alone, no matter how inconvenient.

    The city itself may be willing to assist you with your problem. Just ask the proper authority.
    I see your point, Tony. If this was a full size rain sewer under our property, I would leave the cast iron cover in place. This particular manhole isn’t really a manhole. It only goes down a few feet to an 18” galvanized pipe that eventually feeds into a real rain sewer.

    far more dangerous is a well in the front of the property. There’s a (about) 24” diameter section of concrete sewer pipe sunk verticall in the ground. The only cover is a chunk of slate or bluestone that weighs a lot. I can slide it aside but our grandkids can’t…yet. I would like to fill it in with something but I just haven’t taken the time to look into it.

  11. #26
    One of my college profs asked the class, "Why are manhole covers round?" Do you know?

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  12. #27
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    May 2008
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    Peshtigo,WI
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    Quote Originally Posted by Mike Henderson View Post
    One of my college profs asked the class, "Why are manhole covers round?" Do you know?

    Mike
    So they don't fall through the hole.
    Confidence: The feeling you experience before you fully understand the situation

  13. #28
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    Jul 2015
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    Central IL
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    Round, with a lip is the only geometric shape that will not at some cross section be smaller than the longest cross section

  14. #29
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    Aug 2021
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    Redmond, OR
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    Annular cutters are perfect for such projects!

    https://www.amazon.com/Annular-Cutte...node=340028011

    You can usually pick up odd sizes on ebay for cheap.

    If you don't want to rent the magnetic drill press try securing a piece of plywood to the man hole lid (a couple of clamps). Then drill through the plywood which will then act as a guide for the Annular cutter or hole saw to keep it from running all over the top of the cast iron. A magnetic drill press would still probably be my preference though. I would also recommend some kind of cutting fluid (or even just dirty engine oil).
    Last edited by Michael Schuch; 05-03-2022 at 2:50 PM.

  15. #30
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    Aug 2021
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    Redmond, OR
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    Quote Originally Posted by Mike Henderson View Post
    One of my college profs asked the class, "Why are manhole covers round?" Do you know?

    Mike
    I would answer... because the hole they are covering is round!

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