consistent downbearing measurements

[Greg Newell]

David,
         Thank you for your post. Also, thank you for re-posting the links. 
I probably still have them but this saves the digging.
         I have indeed had the trouble as you re-stated below about zeroing 
on the bridge segment. I have tried to get the gauge to stand almost by 
itself but still I have difficulty returning to the same zeroed out 
condition in trying to repeat the measurement. I have also tried to keep 
the feet the same distance between the front and rear pin. I will have to 
check the "V's" to see if they are aligned or not. Seems like they would be 
as I deepened the grooves a skosh by using a triangular file dragging 
through both at the same time. I was aware that I could go too deep and was 
careful not to let that happen.
         My idea of using a rare earth magnet to replace the existing feet 
was for strength of grip. The magnet provided is both not strong enough and 
far too long to fit between most bridge pin spans.  Using a rare earth 
would give good holding power even for a small contact patch because a 
rather small magnet is necessary. The dilemma is how to attach it without 
redesigning the entire tool.
         In the mean time I will look up your previous discussions on 
evaluating in a strung piano. Were these discussion on this list?

Greg Newell



At 01:25 PM 6/2/2004, you wrote:
>Hi Greg and Dale -
>
>Dale said:
>
>>     Gregg
>>   I made some of John Hartmans stick bearing gauges & am just getting 
>> around to using them. They don't lie. He posted picture a month or so back.
>
>Before I loose them, here are the image links:
>
[link redacted at request of site owner - Jul 25, 2015]
>>
[link redacted at request of site owner - Jul 25, 2015]
>
>
>Dale - As you say, these gauges don't lie, but neither do they provide 
>specific information about the front or rear bearing.  For a number of 
>reasons, these were not of concern to John.
>
>Greg -
>You've got a couple of different issues going.  The mechanics for one, the 
>purpose being another.
>
>
>>I'm having some difficulties achieving consistent downbearing 
>>measurements. I'm struggling with the Lowell gauge and each time I move 
>>it and then attempt a repeat I start with a completely different reading 
>>that I zeroed in before.
>
>In discussions like this, it's better to avoid descriptions like 
>"completely different".  Like, how completely different WERE the 
>measurements?  Dale is right when, in an earlier post, he said that a 
>light tough works best, but even here, there are two separate issues.  I 
>suspect that the inconsistency you observe occurs when trying to zero the 
>gauge on the bridge segment.  As an experiment, try taking numerous 
>measurements on the sounding length.  With the touch Dale described, you 
>should get the same basic results.  Try getting the gauge to stand, almost 
>by itself.  Zeroing on the bridge segment is more difficult, because the 
>same gap that you need to leave so that the gauge is not binding between 
>the bridge pins will allow SOME amount of variation, depending upon 
>whether you are favoring the position of the gauge towards the front or 
>rear pin.
>
>>  The little "V"'s in the bottom of the feet don't seem to sit very well 
>> upon the string in any segment. I think it's because the tool isn't 
>> heavy enough so it rocks too easily. Are there any better tools 
>> available and if not has anyone modified theirs to give less trouble? 
>> I'd like to modify the Lowell gauge to use rare earth magnets as it's 
>> feet if there's nothing else available. Any idea's on how to accomplish that?
>
>I had one gauge where the 'V"s in the feet were not quite aligned.  I 
>don't recall whether I replaced it or filed it.  The channels can by filed 
>a bit deeper, using a jeweler's file, but you have  to be careful, as if 
>is cut too deep, the tips of the "V" can contact the top of the bridge, 
>thus distorting your reading.  As for magnets, I have also thought about 
>adapting the feet to be magnetic, but haven't figured out how to do it, 
>yet.  The gauge did originally come with an alternate magnetic base, which 
>can be used to compare front and rear segments (net bearing), but not 
>isolate front and rear bearing.
>
>I think you are right that the tool would benefit from some redesign, 
>especially the weight distribution.  I have adjusted to its shortcomings, 
>for the most part.  The way I use it in evaluating a strung piano, would 
>be challenging for you until you develop the "light touch".  I had 
>described it in some previous discussions about downbearing.  It requires 
>keeping the feet as CLOSE together as possible while reading the bridge 
>segment.
>
>David Skolnik
>Hastings on Hudson, NY
>
>
>
>_______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives

Greg Newell
Greg's piano Forté
mailto:gnewell@ameritech.net