changer scissor

[Georg]

Scott,
it's wear that is the main problem that "harder than the scissor" steel will solve. The rounded side-edges of the slot must not get wear-marks, as that will increase friction and risk of "hang on return" dramatically. Wear on the scissor-sides - the surfaces that touch those guide-side-edges, won't create problems as long as the guide-side-edges are perfectly smooth all the way down to the stop-edge.

Seem to remember that you took the idea about a guide-plate from the Dekley, and my Dekley has steel plate guide that incorporates the angle with holes for those return spring adjustment screws. When building from scratch I think such a "one piece guide with return adjustments" is the best, as everything can be aligned up perfectly on that one part.


One constructional weakness in my Dekley, and in your construction it seems, is that the raise-scissor should ideally be a little longer so they more or less line up with the lower-scissor below the guide plate. I have had incidents where raise scissors have "jumped over" the guide plate, but that's partly because my guide plate is mounted with a certain vertical flexibility. May not be a problem with a vertically fixed guide plate.

Also, for your newly made (pictured) scissors the front edge on the raise-scissor - the edge that hits the stop-edge on the guide plate (or sub plate in your case), seems to be not very straight. It should ideally be perfectly straight and smooth vertically on both scissors, as both the raise- and lower-scissor use the same stop-edge for neutral.

[Scott Howard]

Georg
You are correct on the idea from the Dekley . I was looking at the scissor that I made last night and planning on making the raise section longer. It looked to me that the facory ones might have been shorter to clear the end of the spring . With the spring located farther back and up it would eliminate the need for the shorter raise section. I have not had a problem yet with my guitar, but I could see how a scissor might jump the plate. There is not much of a contact area.
Also the one pictured was cut on the corner for the spring clearance. I haven't made a new raise section to match my new lower section and these are also my patterens . The final ones will be smooter and finished better. I do not want to spend a lot of time finish one until I have a acceptable working scissor.
It seems to me everytime you make something the 2nd is better than the 1st , the 3rd is better than the 2nd and so on. You gather info and look back and say I should have done it like this ,or it would have worked better like this . My MSA turned out better than the first one I did that my son has. But I still see things I would do different .
Thanks for the input . I am collecting all the ideas I can for yet another extremely modified MSA. Third ones the charm !!! ( I hope , anyway )

[Georg]

Scott,
"the next one" will nearly always be an improvement. Would be strange otherwise...

If you ever figure out a way to adjust the throw-length of the top of the lower-scissor - the tip that moves the bridge-roller, I'd like to hear about it. One of the problems I've had on my peculiarly "Twin Tuned" Dekley S10, is that it's hard to balance the very short travel for raise/lower of the lowest strings to that of the high string.

Having either an adjustable pivot-point - where the lower is rotating on the raise, or adjustable length of the lower-scissor above the pivot-point, would make it soooooo much easier to balance low - extended E9 - strings to the normal "octave-higher" strings on same pedals/levers. Think that goes for Extended or Universal S12s too.

[Bent]

Great idea/suggestion there, Georg. Say, how much adjustable length would be needed in order to make a difference?

[Georg]

IMO, if the throw-length could be adjusted between 70% and 100% of "normal" - "normal" being what works best for string 5 on an E9, raise and lower of high and low strings could easily be balanced out on even the simplest 3-hole bellcranks and 3-raise/2-lower changers.

It could probably be solved by having 2 alternative pivot-holes in the changer scissors, but that's not really "adjustable". Somehow being able to adjust the pivot-point from above, screw it up and down with a screwdriver going down just in front of the bridge-rollers, would be ideal.

I have thought out how to get adjustable pivot-points on a linear all-pull changer, but that changer is a completely different animal altogether, and it isn't quite ready yet either

[Bent]

Not at all sure, but I envision the problem being simpler in your linear pull than a "regular" all-pull

A newly joined designer, Ross Schaefer, just might have some great suggestions. Judging by his web site, he could design most anything. Ross...?

[Ross Shafer]

Don't be makin' promises I can't keep there Bent. I'd need to spend more time than the quick look at this thread that I've done to fully grok this puzzle...and even then I'd probably be talkin' out my butt.... but something like what's shown on this thread this comes to mind as way to achieve more balancing options on an already built instrument. I remember seeing another little piece that does this same thing but it attaches to the changer finger (held on by an existing pull rod) itself and not the cross rod...sorry I can't find that posting....me and the search function on the SGF don't get along very well.

Without opening up the endplate on an already built guitar, it seems like adding length (extra holes or adjustability) to the lower scissor piece might pose some access probs for tuning.

Take all this with a grain of salt...I'm feverish with a bad cold and may well be fulla bulla.

[Pat Comeau]

One thing to think also of before making changes on your fingers is the height of your endplates and how far is the changer fingers from the endplates.

[Bent]

Ross, just talking off the top of my head here. Just wanted to put a bug in your ear

Pat, you raised a valid concern there because the finger assembly already reaches down all the way to the lower edge of the end plate as it is.

OTOH..How important is it to maintain "norms" ie 'standardized' measurements? Say the standard for an end plate is 3 1/2" wide, what's wrong with deviating from this norm and making it 4 1/4" ?
Looking at the Excel, it's gotta be around that width?

How do y'all feel about this?
Maybe I'm just too set in my ways...

[Georg]

I think it is quite important to keep the overall dimensions pretty close to "the norm", and leave out problematic parts, like the adjustable throw, until we can make them fit reasonably well within "the norm". It is easier to play a "normal" instrument, even if it's easier to solve mechanical problems outside "the norm".

I threw in my thoughts about having adjustable throw because the more minds that look for solutions to a problem, the better the chance that we will find one or more solutions that'll actually work. If not today then another day, maybe...