Dear technicians,

While doing a pitch raise on my Ibach vertical recently, I noticed one bass string that had much more friction than all the others. In both directions, there was quite a wide window of movement before the pitch would change. When tuning up, I had to apply much more torque and movement before the pitch would change, and when tuning down, there was a significant window of movement before the pitch would actually drop.

It is the top pin of a bichord, and the non-speaking string section touches the coils of the next note to the left. I have not noticed anything out of the ordinary with the termination pin that's fitted to the bass-V-bar. It looks like its neighbors.

I'm worried that when doing the next pitch raise, this string will break at the pin because of the added tension I have to apply to overcome friction when raising the pitch.

Can you recommend a lubricant to ease the friction, or any other remedy?

I have not been able to obtain Protek (because of hazardous materials regulations), and I'm very wary of introducing lubricants into the tuning pin area.

I am considering a small drop of grahite powder in alcohol suspension. At least, the alcohol is volatile - so even if it should wick into the hole of the lower pin, it shouldn't do any damage.

I'd appreciate any advice.

You could try mineral spirits.

It is great that you are noticing these slight differences. I believe it is essential to address every string individually for the best stability. The most important thing is that you tune the note that this note is rubbing on first, then note in question. Otherwise the note could be detuned by it’s neighbor. I don’t see the added tension being a danger to string breakage. I mean how much more of a “window” is there, a few of cents? Certainly not as much as 50 cents.

There are, no doubt, other opinions, but personally I wouldn't use any kind of lubricant. Liquids or even powders would likely migrate, and in that area you have the tuning pins and the string windings that will be vulnerable.

That being said, there was ONE time that I thought I had to lower the tension on a string with a similar problem and rub between the two strings with a graphite pencil. For all my "brilliance" I actually couldn't tell that there was any difference after the treatment. Both strings were still balky for fine setting, so I just messed with 'em 'til they were right.

Sharp blows while turning the pin.

Try tuning the OTHER pin first next time. That will sometimes make it easier. If two coils are touching each other, (not good) that can make for very difficult tuning and stability.

Thanks to all for the helpful answers.

Jeff: I estimate that the "window", where I'm turning this pin but the pitch doesn't respond, would equate to a few cents on a normal string - perhaps 5 to 10 cents? On other bass bichords, I could get a tuned unison to roll with a slight pin movement - but not on this one!

And I estimate the amount of torque required to actually raise the pitch, at perhaps one-and-a-half times the torque that got all the other strings to raise their pitch. That's what has me worried about breaking the top duplex (if that's what you call the section between the pin and the v-bar).

I'll inspect this spot when doing the next pitch raise, and if I see anything untoward, post a picture here.

Mark:

I don’t think the torque you feel means anything in this case. FWIW, the torque from the tension of the string is small compared to the torque from the pinblock. (About 20 inch/pounds compared to about 80 inch/pounds.) That is why I asked about the size of the window in cents. I understand you need to raise the pitch of a string 300 cents before you can expect it to break.

Ah, OK, I get your point, Jeff.

One thing I forgot to mention is that all of the bass strings in my Ibach have a hexagonal core. I noticed this when doing the pitch raise recently. I doubt that the previous owner would have had all bass strings replaced, so it seems that the local factory that manufactured pianos under licence of several German companies (including Ibach) used bass strings with hex. cores - for whatever reason...

A tech on the German forum suggested that the problem may be caused by the corners of the hex. core wire getting wedged between the v-bar and the termination pin.

I can't recall every seeing both a V-bar (as is used above the break) and a termination pin (as is used below the break) used together. And I do not remember seeing any hex cores extending past a speaking segment.

Sorry, perhaps I used the wrong terminology. The plate on my Ibach has a ridge, similar to the v-bar (albeit not quite as sharp), into which the termination pins for the bass strings are fitted. If this is not called a v-bar, what is it?

But yes, the hex core does go all the way to the pins. I took a few pictures (link to higher-resolution original given under each picture):

E3, F3 above the tenor break (the coils closest to the becket do look more like round wire):

Orinal photo:
http://picasaweb.google.com/lh/photo/AkJlUT3ONTStG7PMJiQ_JQ?feat=directlink

Detail of above photo:

Original photo:
http://picasaweb.google.com/lh/photo/ut4XeH29H6tiLWea7WMPZQ?feat=directlink

Strings just below the break:

Original photo:
http://picasaweb.google.com/lh/photo/WYQeosiCcXXFPVVOz8pD0g?feat=directlink

Lowest strings (hex core can be seen on the pin):

Original photo:
http://picasaweb.google.com/lh/photo/IOae8NL3cngSLmOQJ1ehGA?feat=directlink

Thanks for the pictures, Mark. It is what it is, I guess.

Tuned a S&S O recently restrung with hex core bass strings, the hex core runs the full length.

There was a time, towards the end of the last century, when some top line European manufacturers used hex wire for bass strings. I'm just taking a break from servicing a small blūthner grand from the 1970's or 80's with hex core bass strings as we speak.

Mark:

My mistake. I confused the V-bar with the pressure bar.

No problem, Jeff.

rxd:
Indeed my Ibach was made in 1970, but in South Africa, under license. I wonder whether German-made Ibachs of that time also have hex-core bass strings...

Anyhow, one tech on the German sister forum suggested, all else failing, to use a minimal, almost homeopathic amount of EP-grease (extreme pressure) on the contact points of the string, i.e. the stuff with high viscosity, high adhesion, high melting-point and high pressure resistance, used e.g. in hinges and slides. In fact, I wonder whether that's not what I'm seeing in my third picture above, under the termination pins: 40 year old grease.

I could picture grease on the termination pin, but I wouldn't want it on the neighboring coils.

Well Mark, if your concern was possible string breakage, hopefully that has been put to rest. But if the concern now is a tuning problem, let me mention something.

Rendering friction is not a bad thing. A piano can be very difficult to tune if there is little rendering friction, especially if the pins are very springy. As long as the tuner can know that the speaking and nonspeaking parts are very close to the same tension, rendering friction can keep a piano in tune. The string is less apt to slip when the tension changes on the speaking part due to the soundboard's crown changing with humidity. Since the nonspeaking lengths are different, when the strings slip, they won't slip the same amount and the unison will go out.

As long as you can tune the string stably, there is not too much rendering friction.

I can't see how the hex core would NOT extend beyond the speaking segment. Piano wire comes in two ways - round core or hex core. The core is what it is, for the whole length of the wire (swaging excepted, of course).

I have seen hex core bass strings on Steingraeber uprights built as recently as a few years ago. Needless to say, the pianos sounded great.

Jurgen, thanks for the reply:

What I do remember seeing is flattened portions of the core just past the windingd, and then a round core from there on. Maybe these were not hex cores then.

I tuned a new Blūthner concert grand this evening ......Hex bass string cores...thunderous bass...filled the huge auditorium it was in. Nothing wrong with them strings!!! I never noticed them before, most likely because they have never given any trouble.
Hex cores get a bad rap because they are mainly associated with repair strings which are not usually properly installed and even when they are, they rarely match the string they are paired with.
Mark, The pictures show some scruffy winding terminations but, even so, I wouldn't mind betting that they are the original strings.

Yes, I'm pretty sure as well that those are the original strings. The widow of the previous owner (who bought it new in 1970) said that it was only played and tuned - nothing else. And it was obviously not tuned very often, so I'm wondering whether this hard-rendering string has actually been there from the very start...

Interesting to read that hex cores aren't all bad, and still in use!

Alas, it has not. One of those high-friction strings broke during the third and final pass of my pitch raise(using slight overpull, perhaps 5-10 cents).

In my third picture above, it's the fourth string from the right.

I tried lowering its pitch first, to make sure that any rust or blockage on the termination would break loose. But even to achieve a lowering of pitch, I had to turn the pin much more than on neighboring strings. Then, when the pitch finally did start to drop, I reversed direction and did a smooth pull close to pitch, but couldn't manage to hit the right pitch "on the fly". (I was tuning it to the octave, 12th, etc.) So, while fine tuning, and in spite of using hard test blows, the friction was so high that the string broke at the tuning pin:

First nudge clockwise, several test blows - no change in pitch.
Second nudge clockwise, several test blows - no change in pitch.
Third nudge clockwise... SNAP!

So, indeed, string breakage is a concern, as I had suspected. Well, it's a learning curve, and here's my chance to practise splicing.

Bummer! Well, you know what to do.

Yes, I'll try to splice, and failing success, replace both strings of the bichord.

I've started to practise knots on soft wire first, then on stiff wire.

Did you get any further information, responses or experience with the square knot (reef knot) as an alternative to the piano tuner's knot?

No one seems much interested. If you give it a try, start each bight by making a 90 degree bend which will spring back to about 45 degrees. Then make a 270 degree loop which will spring back to about 225 degrees. Now bend the standing part about 90 degrees back the other way, which will spring back about 45 degrees and complete a keyhole shaped loop. Finally cant the loop from the standing part so that the keyholes will be able to engage and hopefully marry (ahem…). The cant in each part must be in the same direction, otherwise it will be a granny instead of a square knot. Getting them to lock together is hard to explain. After clicking one standing part into the other’s keyhole they need to be rotated so that the other standing part clicks into the keyhole and then the cut off ends will slide into place. It is probably best to give each standing part a little bend so that they do not become separated (Breaking Up is Hard to Do…). I have not had the opportunity to try it on a piano. I do not have a project piano right now.

Jeff, your humor gives me the, um, bends.

Thanks, I'll give this a try - but first I'll think some more about the respective pros and cons of reef vs. piano tuner's knot - given that one of the two wires will be a hex-core.

Jeff,

I've tried both types of knot with copper wire, then with no. 13.5 and finally with no. 17 music wire. Here are my first attempts with the music wire:


I see three disadvantages to the square (reef) knot:
1) The loops are more difficult to form correctly (nice, symmetrical keyhole with working end and standing end parallel and flush). It's the 225 loop, and putting a final bend in it to complete the keyhole, that's the problem.
2) The amount of fussing that's necessary to get the loops right, puts a lot of scratches into the wire (not to mention the time lost).
3) If the loops are less than perfectly shaped, especially with thicker wire, it requires immense force (and/or time?) to pull snug. I don't see this contributing to tuning stability. And even then, the knot doesn't really look neat.

The piano tuner's knot tends to correct its own shape, and even with thick wire, pulls up snugly into a neat, symmetrical shape. That pretty much settles it for me!

Mark:

I am impressed with your perseverance! Glad you let us know how the two different knots worked for you.

Really good first attempt. For a really neat job, clip off the excess wire as close as possible to make it almost unnoticeable.

I've taken some pictures of the termination pins in this area, including the one that had high friction and led to the string breakage. It has a somewhat more acute angle than its neighbors.

D3:


D3 and D#3:


All of the pins are gouged to some degree by the hex-core strings. Yet, most of them render fine, including the partner note on D3, which even has some metal debris sitting in the termination.

What, if anything, would you advise to do with the open termination pin before I re-fit the spliced string?

I tried to remove or turn it, but didn't succeed. It's quite soft and easily marred by my vise grip. Ron Koval suggested simply bending open the angle slightly.

I'm not sure whether I should try to clean up (file) the gouge mark - after all, all the pins have such a mark.

If you have any thoughts on lubrication (yes, no, if yes then what), please let me know. I have some CLP, but am wary of any lubricant creeping down the string into the windings. Perhaps a minute dot of high-viscosity grease?

I also need to treat the other 4 or 5 strings with high friction, before I break those strings as well. I was thinking of widening any obvious acute angles, then applying a bit of lubricant at the top of their terminations, then lowering pitch to pull the lubricant into the grooves, then do the same from below and raise back to pitch.

Arthur Reblitz does not mention these issues, so I'd appreciate your help (as always).

I haven’t come across this problem either and am looking forward to other posts.

Filing and then polishing with a strip of crocus cloth seems like a good idea in order to have a bit larger radius on the bend of the string and could also be used to lessen the angle without bending the pin. I think the little bit of metal that would be removed would be less weakening than bending the pin. Since the other strings render well, LEAVE THEM ALONE!

Well, Jeff, like I wrote in the previous post: most of them render fine. (And yes, of course I'll leave those alone!) But I did mention that there are 4 or 5 others that also have high rendering friction, and I do feel that I need to treat these - a.s.a.p. (if only for my nerves' sake when tuning the next time).

I'd never heard of crocus cloth - will ask in the local hardware whether they have it. Would you think a pipe cleaner with metal polish would also work?

By the way, my parents' Ibach, practically identical, has had several of these termination pins replaced. I now have a hunch why...

I don't think a pipe cleaner with anything would do much.

I was thinking of feeding it around the pin, similar to a string, and pulling to-and-fro on the opposite ends while applying tension (just like the string moves while tuning), using some polish or abrasive paste.

What more would fine abrasive cloth (which I gather crocus cloth is) be able to achieve?

I can see the pipecleaner maybe making the surface shiny, but not removing file marks. And if the pipecleaner (or anything else that is wrapped around the pin) did take much material off, it would make the radius of the bend smaller, not larger. Fine emmery cloth, or even a strip from a fine sanding belt should work well, too. You could probably skip the file this way.

Hopefully someone who has actually done this will chime in.

I lubricate upper bridge pins with Protek frequently on older pianos with rendering issues. I've never had a problem with it, and it can noticeably help. I apply it with a very small gauge hypo-oiler. You can really control how much comes out, and it comes out in very small drops.

Jeff,

I'm still not sure I see how the taut pipe cleaner (coated with metal polish) would be so different from a taut strip of fine emery cloth, in terms of geometry, radii, etc..

But anyhow, I'm the one looking for advice, so I'll step back and listen.

Perhaps with "radius" you mean the arc that's in a plane with the termination pin, not the arc of the string that's in a plane with the soundboard?

Ryan,
I have access to very fine syringes, so the application of Protek is no problem - as long as it doesn't creep down the string and mess up the copper windings.

Feedback for those who may be interested:

I used a strip of fine emery cloth, about the same width as the free length of the termination pin, to take the worst string imprints out of the pin and the worst grinder burrs off of the V-bar. The pictures show the steps.







I couldn't get it much better and didn't want to remove any more material. Hopefully it's good enough to run with normal friction now.