Last modified: 2026-08-10 10:53:51
< 2026-08-08 2026-08-10 >I made an unbelievable blunder with the box for the ballast. I put the holes through in the wrong direction! It was meant to be a tight fit in between the chassis rails, but the holes go front-to-back instead of left-to-right, so instead it is an extremely loose fit between the chassis rails.
I think I can live with this, I'll just need to pack out the sides with pieces of wood or washers or something. It's not worth reprinting it over. Quite annoying though.
The current status on this is that I can't get the tone bars in the right places because the offset on the tone bar holders is wrong, or the holes are drilled in the wrong places so they won't line up even if correct.
So I tried each tone bar in turn in its correct place and eyeballed how far out it was:
The pegs on the tone bar holders are never too close together, they range from correct to about 2mm too far apart.
So the plan is to 3d print a range of variations and then hand-pick them to make each tone bar fit properly. Unsure whether I want to go to the trouble of somehow labelling them with their offset, or just wing it? They will be practically indistinguishable when finished so it will be very annoying if I one day pull it apart and have to put it back together by trial and error. But maybe I don't care, and plan not to do that?
I also experimented with putting silicone o-rings on the pegs to isolate the vibration from the plastic, and it looked to be a winner. The note rings for longer and sounds less like a "thunk". Even with an o-ring above and below the bar on each peg, to hold it in place, it still rings nicely and doesn't damp the sound.
https://www.youtube.com/watch?v=u03MNqwkGa0
I did note that the o-rings were tighter on the pegs than the holders are in the wood, so when I tried to lift the tone bar off it pulled the holders out with it. So probably I will add a little feature to the holder where it fits inside the wood to make it just a light interference fit in one spot, to hold them in a bit better.
If my new holders are 0mm longer, 0.5mm longer, and 1.0mm longer, how many of each do I need? Well let's look at the total offset required across a pair of pegs.
And we make these with:
So in total per overall offset we need:
So in total per 3d print we need:
And that adds up to 62 which is a good sanity check.
< 2026-08-08 2026-08-10 >