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I'm specifically trying to drill hole saw holes of 2.5" in a 4"x4".

How do I create a hole with a hole saw that is deeper than the tool? (The saw itself)

Are there alternatives to hole saws for thicker material?

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  • I've never used one but drill bit extensions do exist, perhaps you can find one big enough for the shank on your hole saw.
    – Jason C
    Feb 25, 2016 at 1:07

4 Answers 4

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You could drill as deep as the hole saw allows, then use a chisel to remove the "plug" left behind. Then drill again with the hole saw. One thing I would highly recommend anytime drilling using a hole saw is to give the chips a place to go. In this scenario I would drill a smaller hole using a spade/forstener bit inside the hole but overlapping with where the hole saw will be cutting. Like the red hole in this diagram:

enter image description here

In my experience this allows the hole saw to work much more efficiently.

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One trick that will go (in this case) up to 5" is to drill as far as you can from one side, Drill a hole using the guide hole all the way through the wood, and then flip the board over using the guide hole to align the new cut from the opposite direction. they should meet up. enter image description here

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  • Is there any added measure for keeping it straight? I tried this but ended up with slightly offset holes despite the guide hole. Perhaps it is just the user (me).
    – NipFu
    Feb 24, 2016 at 18:04
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    Well doing this with a hand drill most needs skill and practice. If you have access to a drill press (and the board isn't too big) that is ideal. Using a bit as close or slightly smaller than the guide bit could help some too.
    – bowlturner ♦
    Feb 24, 2016 at 18:37
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Hole saw may not be the best tool for the task. A Forstner bit or something of that sort might be more appropriate. Even a spade bit might be a good choice depending on the material and the diameter of the hole.

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  • Not sure I'd want to try using a 2.5" Spade bit, but a forstner would work very well for this application.
    – ench
    Mar 1, 2016 at 21:09
  • Used a Forstner -- with shaft extension -- to drill a hole for running a pump exhaust outside. Just handle carefully; if you pull too suddenly on the drill trigger with a large bit, the drill can wrench itself out of your grip or put a lot of torque on your wrists.
    – keshlam
    Mar 1, 2016 at 22:05
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Three other options come to mind, none are perfect although # 3 is not bad.

  1. Toolmonger.com has very deep hole saw bits. (http://toolmonger.com/2009/08/14/extra-deep-hole-saw/) But damn, these babies are pricey and you may need a drill with horsepower! And good luck getting the wood block out of the drill if it wedges.

enter image description here

  1. You could cut the hole using multiple drillings and then clean out the edges with gouges. It will be tough to make the hole as clean as a drill bit would do it.
  2. Cut the wood piece into two vertically, cut the cylindrical shape on the band saw, then glue the two pieces back together. I did this on a series of carved wood vases with cylindrical glass vase inserts and the seams are impossible to find.
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