On Tuesday 02 June 2009 13:37, Craig Falconer wrote: > Wesley Parish wrote, On 02/06/09 13:11: > > Sorry to be so off-topic, but are there any stepper motor suppliers in > > Christchurch? I'm wondering if there are any small enough to fit in a > > cramped location, yet powerful enough to change tension on a wire already > > under considerable tension? And electrically robust enough to handle > > regular on-off switching, while using as minimal an amount of current at > > as low a voltage as possible? > > This is for my Pedal Steel Guitar The Next Generation ;) > > You want to make it self-tuning or something ?
No. The pedal changes the tuning of a string from say B to C or C#, while you play it; it gives you all sorts of nice effects, eg, the strings BDEF# get changed to ACEG or ADEF or BDFG which are totally different chords. My idea is to make the changers electrically-powered and use the amp to power them, instead of using the bulky rodding system they have now. It wouldn't be the first time the changer system's changed - the first ones used cables, the current ones use rods. > > Possibly need some kind of reduction gear instead of making the stepper > do it all. That could make sense. But you'd have to do it for every motor on every string. And the distance between B and C or C# or Bb or A isn't that great when you've got strings this thin and under this sort of tension. > > And it would have to lock still under no-power, else the string would > pull back to slack. Probably need some other controlled clamp to hold > the string once its been tensioned. There is a working system for that already in place; it's called the all-pull changer system and it is a thing of technical beauty. The only movement it allows is to pull on the changer finger: the changer finger is a lever and to raise the string it pulls on one side of the lever while to lower it it pulls on the opposite side of it; the default position is the basic tuning of the string. A thing of technical beauty. The only thing I'm proposing to change is the means of making the changes. The biggest challenge I can see is ensuring that one can use the one motor to make all the raises and lowers, no matter whether they are a mere semitone or something drastic like a couple of tones. And that's where the control offered by the stepper motor comes in - you want to be able to turn it in both directions to specific positions, controlled by the voltage and amperage you feed it. I think you'd be wanting short woven-metal straps to link the motor with the changer finger. (BTW, this must be the strangest discussion ever seen on a LUG - discussing a quite technical matter relating to a twentieth-C. musical instrument, the sort of discussion that Yamaha or Fender or Gibson would be having behind closed doors and with lawyers at ten paces at dawn, and that sort of thing! But LUGs are more civilized, it would appear! ;) Wesley Parish -- Clinersterton beademung, with all of love - RIP James Blish ----- Are couch potatoes good to eat? ----- Mau e ki, he aha te mea nui? You ask, what is the most important thing? Maku e ki, he tangata, he tangata, he tangata. I reply, it is people, it is people, it is people.
