Re the missing bubble thread, I have tried every string leveling technique under the sun, and have and viewed the process with extreme skepticism. Not skepticism as to the utility of having the strings sit in a flat plane @ strike, but skepticism about the measuring accuracy of that plane. The repeatability of measurement with the tools I have used seems extremely subjective and liable to be misread, or at best unbelievably clumsy to use. The down side of misreading is that a misread string level is an absolute waste of time.
As often happens in the shop, it is when I try to teach someone else one of these ridiculous processes, processes that I have put up with for far too long, that the ridiculousness becomes obviously and completely untenable.
So my son Dave works with me in the shop, and is quite good at these picky-ass skills. However when I put him on this task and watched him struggle ineffectively with the measurement and then the adjustment, watching his frustration, I just said, "No more"!
It took a couple of hours and several tries to get this tool working…I had tried the concept a couple of years ago, but it didn't work, because close machining accuracy was required…ie there was too much slop in the plunger. I got the accuracy nailed this time
So once I got this working, I tried it out, and literally flew though the process with repeatability that escaped me before. I put him on the task, as a newby, and he moved pretty well too…none of this paying your dues crapola…the process sucked. It is in fact relatively easy if you have an appropriate tool.
Here is the interesting part for me. I had previously fingered the wrong part of the process as "the problem".
Many techs have complained, including myself, that adjusting the travel of the wire off the termination seemed to be the problem in this task…ie you read the out-of-level condition, adjust the bend, re-read level, adjust bend, ad nausem. The problem seemed to be that it was too hard to calibrate the exact force needed to adjust that bend to the precision needed. The result being that one was always going too far with the bend, then having to yank all the others further than they wanted to go.
But I was incorrect about the calibration of the bend being the problem. With a tool that stays seated on the string, and gives a consistent, repeatable reading of the string plane quickly, first, you don't have to figure out which string is high or low by tilting the reading tool or reading a bubble, etc. You just place the tool on the unison, allow the light plunger to drop of its own minimal weight, and lightly pluck the strings…actually not the strings, but the string in the singular. You don't even do the 3 string comparison, rather, if you hear the string vibrating, adjust it up. One at a time, since the tool remains on the string giving repeatable readings, gently incrementally increase tool pressure to the bend until that single string's vibration is stopped by the plunger.When adjustments happen quickly in succession, ie very soon after the last try, the body retains a memory of the previous force used…the relative increase from try to try becomes much easier to incrementally calibrate. The difficulty of calibrating bend force is really a matter of being able to quickly read the change in string height, so you can incrementally increase adjustment force in a period of time that allows the body to remember the how much force was used last try.
So my take is it is not calibrating the force that is the difficulty in this task, but the difficulty is being able to read the out of plane condition very quickly with repeatable results.
Very nice Jim! Isn't that actually an invention you could patent?
When it comes to string bending sensitivity, I find this lever tool is much better than a string hook. At least for me.
Thank you Fred for the best photo array on this topic (or most others for that matter) ever to appear on this list. Easily accessible (well posted) and clearly displayed.
Chris Solliday RPT
I didn't have much success with either of those tools. I prefer just making thin sandpaper strips along with carbon paper marks for fine tuning the mating.
I sure like that understring level idea mentioned above. I have altered my 2 string height gauges by replacing those heavy springs with lighter springs so that the gauge just touches. I can easily give that a try tomorrow, see what happens.