Metal 3D print of woodwind key

3D printing can be done with plastics but also with metals. To me that seems an attractive way to make my own keys or parts of them for woodwind instrument. So I started a first test with a key for my bass clarinet. It appears to be an succesfull experiment.

The raw sample

The accuracy

The accuracy of the result is very acceptable. In this example above there is a visible pattern of the printer. But it is possible to select an option for polishing in the order. In the next experiment I want to see the results of that.

Some measurement results:

• diameter hinge tube: by design 4.0 and printed 4.1
• length hinge tube: by design 170 and printed 16.99
• diameter cup: by design 30 and printed 29.7
• inside diameter cup: by design 28 and printed 27.6
• width of the arm: by design 4.0 and printed 4.1
• total length: by design 70.07 and printed 70.00

The conclusion is that the diameters deflect a little. But in a predicatable manner that maybe can be compensated. The next experiment will show if that is true.

The first test: bending test

For adjustment purposes it would be nice if the material could be bend like brass can.

So I took the risk and put the key in a vise and tried to bend the end of the key. This is the result: an broken key.

So the conclusion is that it can not be bend not even a millimeter. That is not only a disadvantage. In fact you don't want keys to bend most of the times, but sometimes you need to correct wear and other causes for not perfect fitting keys.

Soldering

The next test was to find out if the broken part could easily be soldered back to the key. That was no problem. In fact it gave the impression that the heat did not flow away as fast as with brass which is nice. 

Sanding and polishing

The other test was to see if the material could easily be sanded and polished. Sanding was possible but not as easy as with brass. The material appeared to be quite hard and it behave different from brass. When polishing brass you get the idea that is becomes almost liquid during polishing. This material did not behave like that. It is difficult to achieve a smooth shiny appearance.

The steel version of the key is not really practical. The fact that it is breakable is not nice for making a accurate and correctable fit of tube to the axle. An option is not the print the tube but solder a brass tube instead of that.