Completely hairbrained idea

One of the reasons why I purchased my Shapeoko XL was to help with a major bathroom overhaul in my house. I had an idea to put a sink like THIS into my bathroom. It would be made of wood and created in layers that would be joined and covered with epoxy resin.

I’ve got the spiral down, but cannot figure out how to:

  1. Ramp to the bottom
  2. Create a “lip” on the inside edge of the spiral to contain the water in the spiral
  3. Create the sections that will need to be machined separately (I have watched videos of models being "sectioned, so that’s not too hard to do) I was wondering if anybody had ideas for “keyways” that would aid in lining up parts and making assembly near-perfect

Am I asking too much from a new user and a “hobby” CNC? I got the XL because it was large enough to make the countertop. Yes, I could just cut a hole and hang a Home Depot sink, but that would be zero upgrade on what I have now.

The problem that you’re having doesn’t relate to the machine — it’s a function of CAD/CAM — which CAD program are you using and how far have you gotten?

Rather than a lip, I’d angle towards the outside which seems to be what was done in the image you show.

For keyways use butterfly keys which will force alignment.


Sorry, I had been looking at other machines that had microscopic work areas and very tiny Z-axis movement. I’ll be pushing the Z-axis to its limits. If the sides are fairly steep, will the XL be able to go deep without interference? I’ll be going deep and carvin’ big. I’m using Inkscape at the moment, but trying to learn Fusion 360® which appears to have more capability.

“Rather than a lip, I’d angle towards the outside which seems to be what was done in the image you show.”

I like your thinking! That would be the ideal, but I’d be looking at a compound angle all the way down. Headache?

“For keyways use butterfly keys which will force alignment.”

You lost me on how those would work. Details? I know what a butterfly is used in woodworking, but have never used one on complex (not dead flat) work before.

The problem w/ using Inkscape is it won’t do the compound angles using any CAM I’m familiar w/.

You could draw each layer and carve each w/ a separate CAM process using Inkscape — might be able to make a fixture to place the stock at an angle to cut the pockets but you’d want to be able to modify it after each layer to do the next.

Learning Fusion 360 will allow you to design the entire piece, then slice it to cut each layer. Add through holes which you can use the top and bottom of each for alignment dowels.

Cut vertical butterfly key half pockets along the edges (top on one edge, bottom on other) if need be to ensure vertical alignment of each layer — pitch is key for this sort of thing.

I like endmills which will allow 1" thick layers.

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I think it might be worth your time to look at this video, where they machine a sink similar to yours, make a mold out of it, and then cast the entire thing as a single piece, thereby preventing any issues with leakage, etc. I think this approach may also help with the depth issue, since you could do it shallower segments, prior to molding. Anyway, might be something useful here.


This is exactly what I was thinking when I saw his design. Take 1 inch sheets of machinable foam and make layer upon layer until you have a complete mold, then cast it in a nice colored (dyed) fiber renforced concrete.

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Regardless, that is VERY cool and I applaud you for giving it a shot. I am a fan of all things Golden Ratio / Fibonacci.

A couple thoughts:

For alignment, just use holes. There are a number of ways to do this, depending on what you are trying to align, the most obvious is for vertical alignment of layers, where the holes would be dowel holes. Horizontal alignment doesn’t seem to make this feasible, since the machine won’t cut into the side of the material, but if you cut a half-cylinder in the top surface, you can get alignment using a cylindrical or half cylindrical key.

I would section this as layers and cut the layers as lamina (vertical edges), then do final shaping by hand, unless you have a real interest in getting into some of the more involved features of Fusion or Inventor or Solidworks. There are awesome videos for using the shaping tools in Fusion and Inventor on the autodesk website, but they can be a bit hard to find and the tools are not simple, no matter how it appears in the videos.

To do it in one shot in inventor (and, I think, Fusion), I might start by making a helical curve on a cylinder and using that as a guide for a loft sweep. Then I would start using the surface modifying tools.

If you are going to do this as a mold, as others have suggested, and I would also suggest, then using foam and hand shaping and finishing is a rea good way to go. For foam, I like surforms and microplanes. Surforms (Stanley made them, as do others) are the hand plane/rasp hybrid that takes replaceable blades. They were originally designed for use on foam when making surfboards. Microplanes are minature versions, and are awesome for detail work, and come in shapes that let you do inside faired surfaces. I think they actually started as a hoopty do kitchen tool, but they were adopted by woodworkers and modelmakers. After getting the form you want, a thin layer of mold surfacing material (I am not a pro, so I have used a number of things, including both cheap polyesther resin and epoxy) that can be smoothed and polished so you transfer a good finish to the final product. Planning it as a mold may make cutting it a lot easier, since you will be less concerned with perfect out of the machine, and you will have predominantly external curved surfaces o prepare, rather than internal.

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This was the video that got me started. I wanted to do it in wood for a more “organic” look and cover it with epoxy floor covering tinted an ocean blue.

See above ^^^^^

That makes 2 of us. :slight_smile:

This may end up being the easiest solution.

“I might start by making a helical curve on a cylinder and using that as a guide for a loft sweep.”

Great idea!