Building Hayden Duett in Instrument Construction & Repair Posted 21 hours ago · Edited 18 hours ago by Łukasz Martynowicz 6 hours ago, resistor said: I'm not going to claim to really understand how your "antlers" system works, but I was curious why you're choosing to immobilize the thumb in a downwards-pointing position? It seems like holding the thumb in a bent position like that for an extended period would be painful. Would it be possible to achieve the same effect with the thumb pointed straight, but still in a thimble? There is a very good reason for this orientation, but first I want to stress one thing - this whole setup is aimed at relaxing the hand as much as possible, so no, there is no pain involved, at all. The main concept behind this handle design is based on the same principle as rock climbing chock techniques - because of how the thimble, anvil and handlebar parts of this system interact, the thumb is locked in all planes but one (plus the leeway described below) and in all axis of rotation but two. Because of this, the hand is effectively attached to the concertina in a very "glove like" fashion, with all positioning absolute and all lateral thumb movements directly transferring to the bellows movement. You mount/dismount your hand by a move that does not naturally happen when playing but when locked in the hand simply rests, hanging from the thimble in the same position you hook the thumb on e.g. backpack straps when you want to rest your arms, or on a jacket button etc... For the handle to act as described above, it must be rigid. Any elasticity reduces the absolute nature of finger positioning. Now the main reason why the thumb has to be oriented this way is that in order to reach various areas on the keyboard in finger configurations required by Hayden chord shapes, the thumb must rotate a bit. The thimble is oriented exactly along this axis of rotation. A rigid handle like this, if made with the thumb straight wants to literally break your thumb as you try to reach extremes of the array and even if it didn't you'll loose the hook-and-lock aspect of the handle. During prototyping this I gradually expanded the concept from a simple, english style thumb "strap" (only made from rigid filament) and then iterated it about 20 times to the final shape you see here. There is a short video on the previous page of this thread when I present how the lock aspect of this handle works and how the movement is transferred onto the bellows, and in the final seconds od the video you can see the unlock move. Now, the common confusion I got about this thumb position is that it is a 90 degree bend. It isn't - it varies between close and far rows fingering and the thimble is not "snug fit" vertically, you can move the distal part of the thumb enough for all movements required. In the "ready" position of the thimble there are two forces acting, one upward acting near the joint and one downward acting at the tip of the nail. Then when playing those forces vary, both in direction and strength, so there is very little fatigue. After a 45 minute session my hand is more relaxed than after playing the same time with a hand strap setup on my CC Elise. This is mostly because my handle design does the gripping for you.