This is a 3D printed project I made for my college-age son. I'll walk you through the steps but also include the files if you just want to download the STL file and print my version.
This project borrows from the 2D conversion technique from TJ McCue's posted on LifeWire here (opens in new tab) using a free copy of Inkscape. .
It's important to have an image with well defined edges, so edit the image if necessary before trying to use it. In this case I found an image of the shape I wanted online.
At the end of working through Inkscape you'll have a flat representation of the 45 rpm adapter ("sketch") opened in AutoDesk Fusion 360 (downloadable from here and free for hobbyists - THANKS AutoDesk).
Step 1: Import Image Into Inkscape
Select File > Import...
Choose the file and use the default options as shown.
Step 2: Convert Image to Outline Trace
With the image selected run Path > Trace Bitmap...
I used the default settings and chose Edge Detection. If you want to play with the options I found it better to click the "Live Preview" box so I could see the changes immediately.
Note: After you click Okay on the bitmap window you have to exit out of the window. You won't see the bitmap trace on your screen but we'll take care of that in the next step.
Step 3: Delete the Original Image
Right now, your trace is probably hidden. Select the original image and move it. You should now see the trace image. If yes, then delete the original image. If not, then you'll have to work on the previous step until an image is produced.
Step 4: Resize the Image to 20cm
I found this easier to do in Inkscape than after loading to Fusion 360.
Select the trace by clicking on a line of the trace.
Change the unit of measure to "cm" and adjust the width and height to 20. Or select the Proportion Lock option and just change one of them (comes in handy when your image isn't square).
Step 5: Save the SVG File
(SVG = Scalable Vector Graphics)
Step 6: Import the SVG Sketch Into Fusion 360
Open Fusion 360 and import the SVG file that was exported from Inkscape.
Step 7: Extrude 2.5mm
Select the sketch and extrude 2.5mm.
Step 8: Cut the Impression of a Center Hole
To make the appearance of a center hole, we'll cut a half mm from the center.
Note: I did this project twice. The first time was a bit of trial and error. The first time, I did the cut as 0.5mm and the cut went in the back. The second time I cut -0.5mm (negative) and Fusion cut from the front. Also, the first time I cut a circle at roughly the right diameter. This time I selected the center hole from the sketch and used that; I notice later that it's not perfectly round.
Step 9: Fix the Scale
Okay, I noticed the figure didn't import in at the 20 centimeters I intended.
This is a good place to learn how to scale. I'd tried rescaling the sketch, but that didn't work. On the other hand, scaling the figure does work! Turn off the view of the sketch (see previous step where we turned it on)
The auto-grid feature throws me off a bit, so set the scaling to 1 cm. Then select the object and, since we can see it's a little under 5cm we'll increase its scale by 4 to get close to 20cm.
Step 10: Drill the Hole for the Clock
Finally drill the hold for the clock movement's spindle.
Note: In my first version I used an 8mm diameter but then had to used a drill bit and, by hand, open the hole up just a tiny bit. So no this example I used a diameter of 8.1mm.
Select Modify > Hole, set the diameter to 8.1mm, the cut depth to anything deeper than the thickness of the clock, and use the hand to center the hole.
Step 11: Print the STL File
Select the object and generate the STL file.
Step 12: Print the 3D Object
Okay, you're a bit on your own here.
My local library offers 3D printing, for a fee, so I just sent the STL file to them and they ran the slicer and printed the object.
Step 13: Buy Clock Movement, Hands and Assemble
I'm not making a vendor recommendation here, but I bought a movement and hands from an online clock parts company and the movement arrived cracked and the mounting bracket missing plus customer care was unresponsive.
However, I bought this silent movement from AnBCollectibles and it arrived in perfect condition and included instructions. So I trust AnB as of now. (Seiko High Torque Continuous Sweep Quartz Clock Movement)
Remember to order hands too and follow the instructions. I used 3 1/8" hands and a 3" sweep hand.
Step 14: Files
Here are the STL and Fusion360 files.
There are two versions: my original version and then the files from this example ("rerun"). The main difference is how I handled the cut for the center hole (not the actual hole for the clock spindle). The other is that in the orginal version I drilled a 8mm hole for the spindle but then had to clear excess material from the hole to get the clock spindle through. So in the rerun version I increased the diameter to 8.1 mm.
P.S. This is my first Instructable so comments and suggestions for improvement are encouraged.