Solenoids

My first attempt used very simple mechanism. I used small solenoids to hit the chime rods. I bought the chime rods (with their base) and I bought these very cheap and light-weight solenoids.

Problem 1: These solenoids are pull-in type, but I needed to hit the rods. The solenoids have a small spring to have the push-out effect, but those springs are very low-quality weak ones. So I built a plastic hat for the solenoids. The 3D printed small hats converted the pull effect of the front to a push effect of the back. Now I could hit the rods.

Problem 2: These solenoids are weak. When they hit the rods made very low sound only. So I glued a screw-head to the plastic hat to make the sound stronger. And I also overdrove the solenoids. I used up to 30 V (instead of max 12V). That made the solenoids overheat within minutes (I've burnt some of them), but to hit a rod I did not need to run a solenoid more than a half second. So the sound was much stronger.

Problem 3: The sound was very flat in quality. When a hammer hits a rod, the hammer should go back very-very fast, otherwise the rod cannot resonate. My high voltage made the hit very fast, but the hitter returned slowly as the original springs were weak. And the situation become more problematic: the place of the solenoid should have been very precisely adjusted (within 0.2-0.5 mm). When the solenoid was to close to the rod, the hitter pushed the rod, so the rod was silenced immediately. When the solenoid was to far from the rod, there was no hit at all.

So I gave up this mechanism and I began to work with the new one.

Hammers

I bought a grandfather’s clock mechanism from ebay. The mechanism had strong issues, but I needed only the hammers. I begin to dismantled the mechanism. Soon I found out that in the original clock the rods were attached to the back of the box, but the clock mechanism was attached to the front. As in my simple settings both became attached to one pinewood panel, I had to change the direction of the rods. The rods are made of brass, so it was easy and safe to turn those with a simple plier. The Clock Depot has good description about the right positioning of the hammers. (Do not bend the chime rods!)

I dismantled the original striking mechanism because I wanted to drive the hammers one by one. The shaft of the hammers of the melody was so good, that I could easily mount to the plate. I am not satisfied the with shaft of base hammers, so I will need to invent something to make their movement smoother.

The shaft has a kind of spikes. Special cogwheels moved the hammers using these spikes. A very short movement made a big strike. But my solenoids are to weak for this. So I use strings to attache the hat of the solenoids to the rods. The pull in method of the solenoid can pull in the string as well. And the string can pull the hammers far enough thanks to the impulse of the solenoids. And when those return to their original position (about 1/8’’ from the rods) the impulse force them to hit once the rods.

The mechanism works now. Even though it needs some fine tuning yet.