Cutting a smooth concave curve with a lip

[Aaron Liebling]

I'd like to make some soap dishes as Christmas gifts (something like the attached image) and I'm happy to use either power tools or hand tools (or a mix of both). The issue I'm having is how to get the nice smooth concave surface. I drilled out the majority of the material in a stepped fashion, leaving a stepped gradient, but I cannot get my spokeshave inside due to the lips on the sides and doing it with a chisel is difficult for me to do perfectly evenly. There must be a better option than just sanding - which I'm likewise sure I could never do evenly.

I could definitely do the majority of the bottom flat and then just use a router for the two sides, but that would give a flat then sudden curve profile while I really want a more gradual curve.

Other ideas?


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[Paul F Franklin]

What about doing it bandsaw box style and ripping off the two sides, shaping the curved portion, and then gluing the sides back on. Done well the glue line should be nearly imperceptible.

[johnny means]

I haven't made soap dishes, but when I need to make larger radius cove cuts like that, I drop them on top of a table saw blade. I'd surround the blade to limit where the stock could go. Then raise the blade a 16th or less at a time, sliding the stock across the blade at each height. I might even do this on a miter saw, but that's not something I would feel comfortable advising anyone else to do.

[Bruce Wrenn]

I haven't made soap dishes, but when I need to make larger radius cove cuts like that, I drop them on top of a table saw blade. I'd surround the blade to limit where the stock could go. Then raise the blade a 16th or less at a time, sliding the stock across the blade at each height. I might even do this on a miter saw, but that's not something I would feel comfortable advising anyone else to do.


Router on a curved carriage, or mounted like a pendilum.

[Frederick Skelly]

What about doing it bandsaw box style and ripping off the two sides, shaping the curved portion, and then gluing the sides back on. Done well the glue line should be nearly imperceptible.

I'd give this a try before doing anything more complex.

[Bill Carey]

Router on a curved carriage, or mounted like a pendilum.

What Bruce said. Works great with accurate set up.

[Aaron Liebling]

I already have a sled for my router which I could modify to use curved tracks. That seems like the easiest solution. Worst case, I'll fall back on slicing in half, but that will be the last resort.

[Rob Luter]

I'll bet you could clear out the waste with a sharp chisel turned bevel down. It wouldn't be machine accurate but with care I think you could make it presentable.

[Jim Matthews]

The soap dish pictured was likely made using a tablesaw - raise to desired "depth", scrub sideways along a crosscut rail and drop the blade at the other lip.

If you're making it as a lamination, use marine grade epoxy for lasting joins.

[Jim Becker]

Cranked chisels to help you complete the carve of the curve and then use a small scraper to smooth.

Or...you could buy a CNC machine. :) :D But I don't think you'd be up to speed before the holiday gifts are due. LOL

[Tom Bender]

A wooden soap dish? With drain holes? I'm imagining it after some use.

[Jim Becker]

A wooden soap dish? With drain holes? I'm imagining it after some use.

It can work with an appropriate species and the design has drain holes so standing water will head downward.

[Tom Levy]

Power carving seems to be exactly what you are trying to do. Angle grinder with one of the king arthur wheels? Seems somewhat safer than some of the above mentioned methods.

[Aaron Liebling]

I think generally better for use in intermittent locations - a bathroom sink or the like. Maybe not left in standing water in the shower.