I am trying to create a smooth spherical depression in wood that, the depression is 1.75in in diameter and 0.5in deep. I have access to a drill press, fixed router, and some chisels but I am not sure about the best way to go about achieving this depression in the wood (I am working with cherry) any suggestions about how to achieve this? The shape I am hoping to achieve is attached in the link.





  • If I'm understanding you right, I'd do this with a forstner bit in a drill press. Forstner bits make very clean holes. You don't have to go all the way through; just stop once the right depth is reached. May 30 '17 at 4:12
  • The side view made no sense to me initially, I couldn't figure out what the upward-curving lines represented because you didn't mention them in your post. That's a lid presumably? That's going to be quite the challenge! Anyway back to your Question, this may not be possible with the tools you currently have available. You can do this kind of thing with a router (hand-held) and a jig, but I'm not sure if it's feasible due to the small scale. Other than going handtool-only (you'll need to buy either a gouge or two or a scorp, plus a gooseneck scraper) I can't see how you'd do this. [contd]
    – Graphus
    May 30 '17 at 7:06
  • The way to do this is with a lathe, both parts are relatively simple and easily done bits of faceplate turning.
    – Graphus
    May 30 '17 at 7:08
  • Yeah it would be for a lid. Would it make sense to use a forstner bit for the interior part then use a band saw to cut a square in the top and sand it down to a circle?
    – ptrickono
    May 30 '17 at 9:57
  • This doesn't seem to be a "circular" (i.e. cylindrical) depression, it looks to be a spherical depression. (If so, I agree with Graphus, you'll want to either turn this or use a scorp unless you can find a huge core box bit.) Could you please clarify the text of your question? May 30 '17 at 16:26

If you want to create this with the tools you mentioned you'll need a "core box" bit. This is a plunging router bit with a spherical profile.

To determine the size we'll need to determine the radius using the formula:

r = h/2 + w^2/8h

Plugging in h = 1/2 and w = 1 3/4 we get an answer of 1 1/64". Since core box bits are typically sold by diameter you'll need a 2 1/32" bit. If you're ok with something close you could probably use a 2" bit.

I'd be VERY careful with this operation, though. Plunging a 2" bit can be quite dangerous. Make sure that your workpiece is well secured and you have your router very stable. Honestly I wouldn't personally attempt this operation.

  • Since I'm generally always trying to practice safely I think that I would be best off trying to create these shapes using a scorp and gooseneck scraper. Alternatively I was thinking of using a larger drill bit to create a "center point" and trying to sand out the shape from that with a dremel, do you think that could work as well for the interior half spheres?
    – ptrickono
    May 30 '17 at 21:10
  • @user161010 - Yeah, that's definitely how I'd do it. I think you'll have more luck with the scorp than with a dreml though. I'd also consider using an angle grinder. You also don't have to limit yourself to just the center hole. You can put in "target depth" holes all around the area to help guide your work. May 30 '17 at 21:50

You might try using a number of hole saws, starting with the smallest diameter hole saw and cut to the lowest point of the concave hole, then progressively using increasing diameter hole saws cutting to various depths of the concave hole. Ending with the largest hole saw that meets the diameter of the concave. Then break out all the various levels of cuts and finish with a chisel and some sanding. Forstner bits will also do the trick.

  • It is going to be nearly impossible to make those holes concentric to each other -- hole saws and forstner bits still need a centre of some kind...
    – jdv
    Jul 16 '20 at 19:34
  • @jdv my hole saws fit on a central arbor bit. Lining that bit up in the same spot each time would get you pretty darn close, especially in a hard wood like cherry where it wouldn't wobble side to side nearly as much as it would in a soft wood like pine.
    – FreeMan
    Jul 17 '20 at 17:59
  • @FreeMan I suppose, but since you are starting with the smallest and deepest, you'd have to leave a lot of clearance in order to keep using the same pilot hole, which will get deeper and more wallowed out. This sounds like a special sort of hell. The router and jig is the way to go here.
    – jdv
    Jul 17 '20 at 18:04

You could try using an angle grinder with the right accessories:

enter image description here

When it comes to carving, shaping and sanding wood there are many effective tools to consider. Only one however, can be quickly adapted to accomplish all three of these common woodworking tasks with ease. The angle grinder.

If you are a woodworker looking for a fast and easy method to quickly carve, then shape, and finally sand out large gouges and even chainsaw curfs, the angle grinder is the tool for you.

Keep in mind though, the angle grinder will remove much wood in a hurry, and like all power tools, when using your angle grinder on wood, be certain to wear safety goggles and other appropriate PPE.

And for finely detailed woodworking projects you may consider other, less aggressive alternatives.

More information in the original article:

Source: http://logfurniturehowto.com/how-to-use-an-angle-grinder-on-wood/

  • 1
    All I can think of when I see these grinder attachments are all the visits to the hospital a single mistake using them suggests. Those chain-saw blades are nasty, and I'm not sure mere mortals can reliably use them.
    – jdv
    Jul 17 '20 at 16:29
  • Indeed those are dangerous. However the rounded one with spikes looks a bit more safe. Jul 19 '20 at 10:54

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