I would like to hollow-out the backside of a mantle board, and I'm trying to think of the best way to do it. I have various tools at my disposal, or can procure a needed tool.

The purpose is to hide various cords. Ideally, the hollowed section would be 4-6" deep and not noticeable from the sides.

My current thinking is to use a handheld plunge router with a bit at least 4" long and many shallow passes. Would a spiral upcut bit be best? Or would a double flute bit be better? Perhaps the router is the wrong way to go.

What is the best tool (and cutting attachment) for this task?

  • 2
    The router might work, although it could be easier said than done. It kind of depends on the thickness of the mantelpiece, the kind of wood, etc...and finding a 6" router bit might be tricky. Along the same lines you could bore out overlapping holes with a Forstner bit and clean it up with a chisel maybe.
    – gnicko
    Commented Jun 4, 2019 at 18:51
  • 1
    If the bottom doesnt need to be smooth, I would just use a big chisel and cut it like a stop mortise. Commented Jun 4, 2019 at 23:27

3 Answers 3


If the hollow back doesn't need to be perfect, use a Forstner bit and cut overlapping holes in it to get the desired depth.

You could also treat it like a big bandsaw box, and cut all of the sides off, and glue them back together. The glue line on a clean cut with the grain is hardly noticeable. You could also just build a new mantle as a hollow box and cut up the existing one and use it as veneer.

  • This is a good point. I hadn't thought that it doesn't need to look clean back there and I have plenty of forstner bits (though this would be quite a bit of drilling). I like this more than the table saw idea since it seems safer.
    – Sam
    Commented Jun 4, 2019 at 20:07

I'd use a handheld circular saw.

Clamp the workpiece securely. Plunge at one end, run full depth all the way along. Stop before the end. Repeat, on ~1/2" spacing. Clean out the mess with a chisel.

You won't get 4" (unless you find a saw with a 10" blade), but you should get a decent enough depth for cords.

** When plunging, do not be tempted to drag the saw backwards to get to your starting line. If you missed the mark, plunge again.


You might consider passing it along a table saw with the blade set to protrude 4" from the reference surface (if the blade is big enough for that!). Make several cuts as long as you want the hollowed out area to be, up to an inch apart, and use a big chisel and mallet to chisel out the waste pieces in between the cuts. The challenge would be to make it invisible from the sides. If the mantel piece has any molding or trim pieces on the ends which could be removed and re-attached later, that would make it easy.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.