I'm changing the lights installed in a kitchen cabinet. The old display lights are recessed and installed through two holes at the top of the cabinet (see photos below of the holes). The new lights will be installed the same way, but require holes approximately 2/10ths of an inch larger.

The top of the cabinet is MDF. What's the best way to expand existing holes in this case?

My current plan is to use a Dremel with a carving bit (194HP) and use circular motions to incrementally expand the existing hole. There's going to be a bunch of dust due to MDF, and it's not clear to me if that's the best bit to be using.

holes at the top of the cabinet

close up of one of the holes

  • Honing tool until you get the bore you need?
    – Huesmann
    Feb 21 at 14:18

2 Answers 2


Use a hole saw with the correct size.

The technique is easy.

  1. Get a scrap of wood like some 3/4" plywood generously wider than the hole.
  2. Use the hole saw to cut a hole in that scrap.
  3. Fix the scrap over the existing hole where you want it. Make sure is solidly held in place.
  4. The scrap will now keep the saw in position while you expand the existing hole.
  5. Drill the new hole. Remove scrap. Done.
  • I've used holesaws many times for cutting into drywall. But I read a few posts saying that they get stuck in MDF because the material is so dense, and because there's nowhere for the material to go.
    – BSchlinker
    Feb 19 at 21:53
  • @BSchlinker A holesaw in drywall is overkill. In MDF, with a half-decent drill it will work just fine. Feb 19 at 22:23
  • 1
    With the center hole already cut out, the stock removed has a very large hole to fall into. A decently-sharp hole saw and a fully-charged battery drill will cut these holes like butter. There is also a trick to allow sawdust a place to go in a solid plate getting hole-sawed: Drill a large hole or two at the edge of the hole saw kerf, on the side that will get eliminated, using a regular drill. The sawdust will fall out through the drilled holes. Feb 19 at 22:44
  • 2
    Common holesaws will cut wood, plywood, MDF, aluminum, steel (not all wil o metals, but many will.) If you're concerned about chip buildup, simply pull back to let it fall out, or be sucked into a vacuum cleaner. Easy enough to notice the cut slowing down and stop pushing, pull out to clear the dust and let it cool if it's overheating, then continue.
    – Ecnerwal
    Feb 19 at 22:45

I would use a hole saw of the correct new size with a “plug” fitted in the hole saw to provide the centering in the existing hole.

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