I tend to work in millimeters, as I feel they’re the most accurate for small objects. The hour hand was about 45mm long and 3mm wide, the minute hand about 57mm long and 6.4mm wide. The diameter and width of the areas that attach to the clock can vary depending on the clock, but in this case the hour hand has a 5mm diameter hole and the minute hand has a somewhat rounded hole 2.7mm x 4mm. (My messy sketch is below.)
Sketching Out the Basic Shapes in 123D Once you’ve opened up 123D go to the viewing cube in the upper right-hand corner and choose the view you’d like to sketch in. I tend to choose the Top view.
Go to the top toolbar and go to Sketch>Draw
Left click where you’d like the first point to go, input the length of the first line into the Precise Input box, then the length of the second, and so on until you have a basic rectangle the size you want it.
Go to the top toolbar and Sketch>Circle. For the center of the circle try to get it in about the middle of the rectangle.
For the radius of the interior hole I’m going to put 2.4mm, which will end up with a diameter of 4.8mm.
In his tutorial Josh R. recommended making the holes just a tidbit smaller to ensure a good fit, and sanding them later if they’re a bit too small. That’s why I’ve left the diameter 0.2mm smaller.
Since you may have to sand a little off, make sure it’s thick enough to be durable. I’m going to offset the first circle by 2mm
In the top toolbar go to Sketch>Offset
Then select the interior circle, type in 2 (mm) and left click.
If you just wanted a simple rectangular flat clock hand you could extrude the shape by at least 1mm and then export the model as an STL.
*Don’t forget to save your file every few minutes as a precaution!
Sketching Out Fun Shapes You can of course sketch out whatever random shapes you want, but I'm going to try for a sort of abstract flame shape with Sketch>Spline from the top toolbar. You can use Sketch>Draw if you like more angular shapes.
For each segment of the spline drawing I right-click and click OK. If you keep going with a shape it won’t have any sharp edges, but if you stop and start you can get sharp edges in areas. Make sure you start and stop on the edges of the rectangle.
Once you’re done with the basic sketch move the points around if you don’t quite like the shape.
Time to Add a 3rd Dimension Next to the top right viewing cube there’s a little home icon. Click on it to view your sketch from a perspective view.
In the top toolbar go to Create>Extrude
Chose the top decorative area and the rectangle with the circle at the bottom. Choose everything except the center circle that will be the hole. In the precise input box put at least 1-2 mm as the thickness.
Right-click, click OK.
*If you decide on thick clock hands (more than 2mm thick) remember that the hands should be as light as they can be and both should be as close to the same weight as possible to keep the clock movements working properly.
From here you can go to the very upper left hand Application Menu (with the little blue 123D logo) and choose Save As then choose STL from the drop down menu.
Now it's ready to print, but if you want to make it more sculptural and less flat take Part 2 of this tutorial!
Part 2 coming soon! We'll get more in depth to make the flat clock hand even more 3 dimensional with extrusions and smoothing corners!