There are already a few options for our higher string playing friends out there looking for the "Tuners of the Future". Pegheds.com - The New Revolution in Tuning and Perfection Pegs - Knilling are essentially crafted to look like normal pegs, but instead of relying entirely on friction, they have an internal mechanism. I'm guessing you can imagine how the majority of violin makers feel about them. The biggest complaint being that if you have a violin setup with a good set of properly working pegs, you don't have any of the sticking/jumping/slipping/various other problems. All of those things are typically the result of poorly fit pegs, or pegs that need to be refit. Coming up with a "solution" like this is usually interpreted as someone engineering their way out of bad workmanship, regardless to whether or not that is the case.
As far as headless tuners go, David Hetherington in Toronto has a special C string tuner on his cello. Instead of the traditional peg which he took issue with because I believe he bashed it into his head one too many times, he has what appears to be something like the mechanized pegs linked above, but the peg head is removable. This site [Invalid or Expired Link Removed] has a photo showing the scroll head on, although I haven't been able to find a photo from the side to show what it looks like from there. It does have a very small footprint though, even smaller than a typical bass machine with the key removed. If I was going to go "keyless", I would take it as far as I could with something like that.
Other than allowing more left hand access to an extension and reducing mass, another benefit would be completely eliminating the potential for bent keys. My own bass has a ever so slightly bent key/worm gear on the D tuner, which makes changing the D string an exercise in hand strength because it is stiffer than the other three. It has plate tuners on it, and I have not been able to find a replacement key that would match perfectly, so I live with it instead of replacing all four keys. I have played several other instruments with a similar issue, and seen school instruments where the keys have been broken off or severely mangled. I guess the downside is that instead of inflicting trauma on the tuners you would be doing so directly to the scroll/peg box in the event that it is knocked, but most of us try to avoid those situations as much as possible anyway.
As far as headless tuners go, David Hetherington in Toronto has a special C string tuner on his cello. Instead of the traditional peg which he took issue with because I believe he bashed it into his head one too many times, he has what appears to be something like the mechanized pegs linked above, but the peg head is removable. This site [Invalid or Expired Link Removed] has a photo showing the scroll head on, although I haven't been able to find a photo from the side to show what it looks like from there. It does have a very small footprint though, even smaller than a typical bass machine with the key removed. If I was going to go "keyless", I would take it as far as I could with something like that.
Other than allowing more left hand access to an extension and reducing mass, another benefit would be completely eliminating the potential for bent keys. My own bass has a ever so slightly bent key/worm gear on the D tuner, which makes changing the D string an exercise in hand strength because it is stiffer than the other three. It has plate tuners on it, and I have not been able to find a replacement key that would match perfectly, so I live with it instead of replacing all four keys. I have played several other instruments with a similar issue, and seen school instruments where the keys have been broken off or severely mangled. I guess the downside is that instead of inflicting trauma on the tuners you would be doing so directly to the scroll/peg box in the event that it is knocked, but most of us try to avoid those situations as much as possible anyway.
