rollers for keyhead changer...

[richard37066]

Ross -

I'm suspecting that the presence of an old set of strings is an indication of the attention payed to the instrument by the former owner. I never let a set of strings get even close to the point of no recall. As time permits, Georg will probably turn it upside down and start probing around in its' innards and bring things up to snuff. All should then be well.

Although the mechanics are darned good for a relatively inexpensive instrument, there's always the possibility of a small manufacturing defect which is rearing its' ugly head. That 6th string problem is suspect.

I'm still working on the PS210 type changer. Can't let go of it.

Richard

[mac639]

Richard.... I didn't know you were working on a PS210 changer concept. As you might remember I had a working version of that type of changer last fall. It worked OK generally, but recently I got a couple of ideas in my head to hopefully correct the shortcomings that I had with the guitar. Haven't had any time or inclination to work on it lately as I'm busy building 2 more "regular" pedal steels to sell. I'd be interested in hearing(seeing) what you've come up with though if you have the time to show it to us.
Cheers,
Mac

[Georg]

I'm still working on the PS210 type changer. Can't let go of it.

I am basing my keyhead changer on parts from that one, but not to pull the strings directly. Instead I will couple it to the divided keyhead to pull/release the individual keys. Just need to redesign the two major pieces (which are all I need from that changer) at the lower ends so I can use regular pulling rods with nylon tuning-nuts for an all-pull construction.

[richard37066]

HOW INTERESTING!

While the rest of the world is messin' with axles, fingers, scissors and what not, there are a few who recognize the virtue in a 37 year-old design.

Mac -

Didn't know of your interest in the PS210. I've sorta got a general plan worked out which does not deviate greatly from Gene Field's original. I'm aware that the original was die cast. The change in the overall configuration is solely to address the ease of machining the parts as opposed to casting them. One question which needs be answered is the optimum angle of the string over the roller bridge - hence my other post concerning the same. I will most certainly share whatever I have with you when I can manage to put it into reasonable shape for viewing and understanding. In the meantime, do you have anything which you can post here on the forum?

I do not have a machine shop in my garage and can't afford the cost of machine shop time thus I'll probably resort to woodworking skills and make a mockup at, perhaps, 2X or 3X actual size. Sort of a "proof of concept" thing. Such a model should tell me if it's going to work and, maybe, reveal a shortcoming or two. We shall see.

Richard

[mac639]

Richard....

If you go to my website you can see pics of what I was up to last fall

http://www.mkguitars.com/proto/proto.html

Thanks,
Mac

[Georg]

I only need to redesign these parts to go with regular pull-rods...

...and design in the knife-edge they'll be resting on...

That will give me a knife-edge version of an otherwise pretty regular all-pull changer to "hook up" individual keys onto. The entire changer will then disappear under the "top-plate" (actually under the keyhead), and the individual keys hooked up to it will move linearly.

BTW: the string-angle over those rollers in the image looks pretty OK ... can anyone turn that angle into numbers? I may have to slope the keyhead about that much to keep the angle even across the strings.

For clarity, this is the shape of a "PacMan roller on knife-edge"...

...which seem to be the optimal keyhead roller solution for the PSG I'm designing.
Means there won't be an any axles on the top-side. Not sure about the underside with bellcranks and all yet


(Two images copied (cropped) from this Steel Guitar Forum post...
http://bb.steelguitarforum.com/viewtopi ... 24#1717424)

[Bent]

Georg,
I am a tad confused. Are you saying that you have abandoned your "number 7" design in favor of this one?

[Georg]

Bent,
No, I haven't abandoned the figure 7 for the keyhead, but I can't use pull-rods directly on a rocking figure 7 - it will end up being a push-pull then and will rely on springs to take up string-tension.
The idea has always been to have an all-pull changer with regular adjustments through the end-plate, coupled to a keyhead consisting of 10 figure 7 for the individual keys.

Since the string pull (tension) is pretty high and a properly built knife-edge changer is friction-less, I may get away with using 10 sliders instead of 10 figure 7s. Sliders will simplify the entire construction and free up space(*), but I have to make sure there's no problematic friction for sliders before making up my mind on what will work best.

(*) For a figure 7 to pull strings near linear it has to pivot at a knife-edge as far below the keys as the PSG-body allows. With regular changer adjustments through the end-plate this means the pull-rods have to pass between the figure 7s, which means the vertical part of the figure 7s must be relative thin. Also, individual pivot-points for the figure 7s means there has to be a plate/cover at the bottom of the entire keyhead section, which will make it a bit more difficult to rod up the PSG than I like. I'm not in doubt that it will work fine, but if I can avoid such a tightly packed "box" around the keyhead changer parts I certainly wouldn't mind.

Sliders take up no space down where the pull-rods are, so rodding will be as easy as on any PSG. Sliders can all be full length (the length of the entire keyhead) and be hooked directly onto the changers, thus eliminating separate coupling-pieces as the figure 7s will need - fewer parts means fewer problems with build and maintenance in most cases.
If I can keep friction low enough by letting sliders ride on the changer-tops and two ball bearing balls high up on the sloped keyhead mount plate, I can't see any reason not to use sliders instead of figure 7s to mount individual tuning machines on.

(Shit I can't produce or scan proper drawings on my laptop, as that would make it all so much easier to explain )

[Bent]

(Shit I can't produce or scan proper drawings on my laptop, as that would make it all so much easier to explain )

Georg, That sure would help if you could get a scanner or a drawing program. See, I am kind of stuck on the 1/3 done sketch of the 7-changer you produced here a year ago. I am having a hard time getting my head around the rest of the explanation.
Some people would call me dumb for it. I know it is just my head wrapped around the mill, trying to learn it these days.