Decimated Decor Decorum

Finial UnfinishedOr, finials finally finished.

The Pacific Northwest has proven to be amazing, and as we felt it was worth putting down roots here, we purchased a house! Of course, with any house comes the “to do” list. This time, though, I have my trusty 3D printer to help out.

Immediately there were two things that needed my attention, one mechanical, one ornamental. First was a sliding door guide — nothing terribly interesting, but easy to recreate, 3D print, and have it work like nothing was ever wrong. You can view and download this guide piece on Thingiverse.

Second, the ornamental, were some finials—you know those things at the end of the curtain rods—for the dining room curtains. The ones there were not ugly, just not our style. My wife looked around online and found some that she liked, but they were rather pricey. She said they were on Restoration Hardware’s site, so I went snooping. I found a few that were nice, but I saw some “hand forged” ones that were in the $50 range for two, and looked like something I could recreate and 3D print. So for fun I modeled one, 3D printed it, and showed it to my wife who replied “great – we need three more”. So I got busy.

This post will focus on how to create the “hand hammered” style using various tools, and my choice for finishing it the way I did; a bit of design process, and a bit of crafty craft.

Before I actually started my first ball finial, I needed to determine some sizes: the size of the existing screw holding the old finials in place, the diameter of the curtain rod itself, and the size we wanted the finial.

The screw was easy — I measured the diameter with my calipers and added a fraction of a millimeter, knowing to account for plastic shrinkage; what measured as 6.1mm diameter, I wrote down 6.2mm.

The curtain rod was, again, easy — 12mm on the smaller side of the rod, 14mm on the larger side. A diameter of 15mm on the inside of the finial would fit over both and allow a “professional” look.

Finally the finial itself wasn’t going to be an exact measurement, as much as what felt right. They needed to be substantial, but not as big as the old ones. But they couldn’t be too small because the drapes were thick velvet-like material and covered large sliding glass doors.

size test designI started with a 40mm x 40mm x 50mm block as the size test; it wouldn’t take long to 3D print, I could test the screw and rod sizes, and not use too much plastic. In its own way, it was a neat, modern, minimal finial… a minial. It printed fine and gave me a chance to see if all my measurements were correct. They were! But in the end, the block finial wasn’t terribly attractive. Maybe as a cube. Maybe.

Knowing the technical measurements were good, I started looking at the size of the block. I was surprised to think that it was too small. Looking at it in your hand and then up on the rod form across the room, the difference is noticeable and you feel the need for weight. I decided to make the ball part of the finial 50mm in diameter, and the overall height around 60mm.

Design Time – Part 1

At this point I was going to walk through all of the steps to recreate the finial in Blender, but realized that it would be easier to just record a video showing the steps as they happen. The entire process takes less than 10 minutes. It’s probably closer to 5 minutes if I wasn’t talking. :-)

So watch this if you want to see the process from start to finish, and then return for another, much more nerdy way, to create the finial. NOTE – it’s probably best to watch in full-screen and at least 720p if you want to clearly see what I’m doing in Blender.

As I mention in the video, after I 3D printed the finial, I finished it using a Modern Masters’ Metallic Paint named “Smoke”. After placing them on the curtain rods, we really liked the end-result. I feel the stem is a little thick for the rod, but we can always change the rods themselves later if we want.

Finished Finials Finial on rod

Design Time – Part 2

As I mentioned above, I have another way to create the “hand hammered” finial that is way more nerdy than using a 3D modelling application: writing code in OpenSCAD!

If you really think about the object, it is a joining of a few very simple pieces: a sphere, a torus, and a few cylinders. These are the types of objects OpenSCAD can create in its sleep. The tricky part was going to be the random-like variations to the sphere to make it appear non-uniform and “hand hammered”.

If you’ve ever had a grinding/sanding wheel, the answer may have already come to you: randomly sanding down very small sections around the outside, rotate the ball, do it again. In real life, this is something I’ve done numerous times by accident, but now I can use the idea for creating instead of destroying. The question is, how to do this in code?

Turns out this was relatively easy. The idea was this: subtract a bunch of small, flat cubes from a sphere, at random points around the diameter. This is basically the digital code version of randomly sanding down bits on the ball. To test it out, I tried the following code:

difference() {
     sphere(20, $fn=24);
     translate([19.5,-5,-5]) cube(size=[2,10,10],center=false);
}

Sure enough it worked:

That's no moon!

That’s no moon!

The only thing I needed to do was repeat this process many times at random places around the sphere. OpenSCAD doesn’t do random numbers like other languages, so figuring this part out was the trickiest part of the whole script. Basically, you create an array of random numbers – one for each rotational axis, with as many elements as iterations of sanding. Add a rotation command before the translate in the test above, iterating over how ever many “scuffs” you want, and you’re good to go! Once done, the result was pretty awesome:

"Hand Hammered" ball finial in OpenSCAD

“Hand Hammered” ball finial in OpenSCAD

Feel free to grab my OpenSCAD script to play with it, but be aware that rendering the file to create a STL file takes a really, really, really long time; your machine may be faster than mine.

I’ve also uploaded my Blender-created STL file to the same Thing, but I’d encourage you to create your own. As you play with settings and parameters, you never know what inspiration will be sparked and you’ll go somewhere you never thought of.

"Hand Hammered" ball finial in OpenSCAD with the flag set to show process steps

“Hand Hammered” ball finial in OpenSCAD with the flag set to show process steps

ball finial rendered

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