The Korf Blog

The inside story: our research,
development and opinions

2 May 2017
The Prints are Here! First Prototype.
I know I promised to tell you about constrained layer damping. This will have to wait till next post, because just before Easter, the postman left a small box on the porch.

Inside were the 3D printed parts to test the geometry and overall fit. They were pristine white, but I managed to smudge them before taking a picture. Parts turned out well, considering the printing (SLS) limitations.

In go these tiny bearing balls and a spring clip from the Ortonfon arm...
...and TADAM! We have a first prototype!

I am using an old Telefunken S600 as a test platform for now. The arm fits perfectly (of course it should, this is the deck from which the Ortofon arm was originally taken) and it's easy to work on. The light printed parts prevent the arm from balancing, so more weight is added by the way of a steel nut and thermo glue.

For the prototype arms I will use the following basic geometry:

Tonearm pivot to
spindle distance 212 mm

Effective length 228 mm

Overhang 16 mm

Offset angle 23°

These numbers roughly correspond to a Stevenson alignment.
I will need to make some changes before going for CNC, though. The counterweight stub needs a few more turns of the thread. And the headshell looks fragile and in need of some reinforcement. Here's what the updated parts will look like. You can check them out in the Onshape CAD document.

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