I am mounting a 24 inch vanity light into wood panel walls. The light fixture is lightweight and there is no stud available, so I intend to use this 1 gang old work round electrical box.

I need to know if a 4” hole saw and my drill is a good choice for these wood panel walls. How can I minimize damage to the paint and the wood panels? I’m very concerned about splintering since the wood splinters easily.

The bathroom used to have a recessed medicine cabinet with a light on top and the light switch on the side, so I attached a thin piece of wood to cover up the hole. Next, I’m wiring the new fixture to a combo switch with an outlet. The outlet and light are protected by a GFCI outlet upstream.

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3 Answers 3


It's difficult to say how bad the paneling will splinter, but here are a few pointers.

I have done exactly what you propose to do and find that if I tape over the spot I will be drilling with blue painters tape, the splintering is usually minimal.

Also start with a slow speed and light pressure. Once you have the initial groove formed increase the speed a little. The paneling is soft and will cut easily. Just be sure there isn't anything behind it that you don't want damaged.

  • 9
    In particularly splinter-prone materials, you might try running the holesaw backwards to make the initial kerf. Mar 29 at 11:46
  • 1
    @AD, I tried that...it made the splintering worse.
    – RMDman
    Mar 29 at 11:47
  • 3
    Interesting… and a good case for testing on similar scrap before committing to the final piece. Mar 29 at 11:52
  • I ran in reverse and worked a treat - so not sure why it did not work for you? blunt?
    – Solar Mike
    Mar 29 at 14:23
  • 2
    A new hole saw will cut better going backwards, than my 20yo set does forwards. YMMV. 55yo paneling will splinter. That's what caulk and paint is for. Replacement panel: should've been big enough to hide the old caulk and your butchered hole. And added at the last moment possible; you covered stuff up but haven't finished the work yet.
    – Mazura
    Mar 29 at 19:04

You might consider a spiral saw instead. They're much less likely to splinter than a large hole saw. Such saws are unwieldy, and if you let the drill tilt at all they tend to grab and sprain your wrist or zing across the surface when used in awkward situations like this. A spiral saw in a rotary tool (or a dedicated panel cutter) should do well.

  • At first, searching "spiral saw", I mostly found: "Spiral: Saw (2021 Movie)" =). Are you talking about "RotoZip Spiral Saw"? Mar 31 at 23:49
  • RotoZip is a brand name known for their dedicated spiral-cutting saw, just as Sawzall is a brand name known for reciprocating saws and Skil is known for circular saws. Other companies make spiral-cutting bits which can also be used in rotary tools (like Dremel). You can also buy spiral bits for routers.
    – isherwood
    Apr 1 at 13:09

You need to use a 4 1/8" hole saw. It will fit much better. I'm an electrician, and that's what we use for round electrical boxes.

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