2026-04-04

Last modified: 2026-04-04 10:39:02

Keyboard Glockenspiel Tone Bars

I made a start on making the tone bars:

12 down, 19 to go.

I am cutting them slightly oversized with the hacksaw, then testing them against the Tuner app from F-Droid to ensure it is below the intended note. Then filing the ends, approximately 1 stroke per "cent" that it is flat. Checking again, filing more, checking again. When it is within 20 cents I deburr the ends and check again. When it is within 10 cents I say it's good enough.

If a "semitone" is the ratio that when raised to the 12th power gives you an octave, then a "cent" is I think the ratio that when raised to the 100th power gives you a semitone.

Is 10 cents actually close enough? Don't know. But I do kind of expect that when I drill the mounting holes they may all end up changing tone slightly so I may have to tune them again. I think all is fine as long as all tone bars are approximately the same number of cents away from being perfectly tuned.

I also don't know if I'm going to paint them, which would presumably make them lower frequency because they're effectively getting thicker. The good news is that if paint does alter the frequency then I may be able to tune them by adding extra paint to the ones that are too high.

In any case, it will be easier to measure the tone once they are mounted on an instrument with keys to press, rather than trying to approximately hold them at the nodal points with my fingers and hit them in the centre with a hammer.

Oh, also I realised that hitting them quite close to the centre is very important, so I may need to take that into account when designing the mountings.