Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Loose pins, good block. Glue, oversized pins, or new block?

"In case there is need in the future to change the pinblock, it does not mean that you have to change the strings again." - Enrique

"The most cost-effective and permanent solution would be to go ahead and replace all of the pins to the next largest size" - David Kozak

This is incorrect, in my opinion at least. When the technician puts in a new pinblock, the strings, pins and cast iron plate all come out of the piano. Unless the technician is willing to unwind the coil from each bass string, and pull the end of the string through the agraffes (which would be a real pain), the bass strings that are in the piano are going to be scrapped and replaced.

Even less cost effective would be trying to save the treble strings. Miking the old strings and simply replacing would be much less time consuming.

The only time I save the old strings (when consideration of costs is an important factor), is when I'm installing oversized pins. Then, the coil may be pried off the old pins and placed on the new pins without much difficulty.

If other technicians reading this disagree, please speak up, but I can't imagine attempting to save existing strings on a pinblock replacement to be a recommended procedure, at least one that I would enthused about tackling. Chuck Behm

Chuck, doesn't this assume that there are agraffes? Not all pianos have them, so maybe it's not a really big issue. - Dale Fox

Work with someone who can SEE the piano. Any opinions we can give will be general, and could change fundamentally if we could see the instrument and check the block and pin torque.

Wise advice, this.

There are a couple of questions that come to my mind that I don’t see answered in this discussion. First—keeping in mind that this is a 100 year old Brinsmead grand—just how is the pinblock installed? Is it a straight-forward separate block attached to the frame sort of block? Or was it constructed as part of the skeleton? Is it an open-face block or does the frame cover the face of the block? What is the construction of the block? Many old blocks were rather crude three-ply affairs; others were more thoughtfully engineered. I’d not venture a guess on the best repair without being able to personally examine this piano.

I’ll offer a couple of observations, however. In general I’m not a fan of oversized pins; I don’t like how they feel when tuning and, in certain conditions, they can make tuning difficult. The reason the original pins have become loose is because the wood surrounding the original pins has succumbed, over the years, to long-term compression set. The wood fibers surrounding the original pins have been irrevocably damaged and now we are going to damage them further by adding even more compression. It’s a poor solution to a common problem. Having said that I have also restrung many pianos—mostly uprights—using oversized pins. In the past it was the only alternative to replacing the pinblock. Nowadays in uprights I tend to install new pinblock inserts but that’s another story.

These days chemistry has presented us with several alternatives. The CA treatment one of your technicians has suggested is not altogether a bad one. We are told it is temporary and perhaps it is. But then by some standards a new pinblock is also temporary—after all, the original block is only 100 years old and it is already worn out and in need of replacing. In geological terms that is pretty temporary. We don’t yet know how long these treatments will last; suitable CA adhesives have only been around a decade or two. So far this treatment—properly applied—seems to be holding up pretty well.

There is a third alternative—and this is my current choice if the block is not going to be replaced—and that is to saturate the original block with epoxy, redrill and string with the original size pins. This is the process favored by the folks restoring instruments of historical significance when it is desired to save as much of the original construction as possible yet end up with a useable and serviceable instrument. (If the piano were of historical value we’d be recommending restringing with the original pins, of course.) The process is fairly simple; remove the original strings and pins, saturate the holes with a suitably viscous epoxy making sure the entire surface of the hole is thoroughly coated and, when the epoxy has cured, restring. A variation of this process that is used when the block has completely broken down is to completely fill the holes with epoxy, topping them off as the epoxy saturates the cracks and loose original glue joints—badly deteriorated blocks can absorb an amazing amount of epoxy—until it is obvious that the block is fully saturated. Once the epoxy has cured the holes are redrilled—a smelly job demanding masks and good ventilation and the piano restrung. It is not known how “temporary” this repair might be—it’s only been used for thirty years or so.

ddf

I am not sure how deep the compression damage is to the wood but I often will resize the hole slightly with a hand reamer to remove a thin layer before going with an oversized pin. This has worked well for me with the O.S. pin holding up as well or better than the originals.

I am somewhat unclear as to what the new pin holes are going to be like with an epoxy saturated block. I would get the impression that mostly an epoxy surface will be holding the pin. Is this desirable. Also, would it not be extremely difficult to position the new holes in epoxy filled old ones. I would think that the drill will want to wander into the softer wood perimeter; or is the epoxy very similar in density to the surrounding wood and this is not an issue?

So when you swab the holes Del, do you drive the pins in right away or do you wait for the epoxy to set up? Also, I presume you use a thin mixture like Wests or something like a model builder’s thin finishing epoxy?

I have an old piano with a dozen or so pins out here I want to try this and compare it to a couple pins done with CA.

I've stayed away from epoxy and tuning pins in the past because I know that some techs don't like the feel of pins sitting in some high epoxy content delignit. i realize that glazing is most of the problem there if drilled wrong but others feel its because there is almost as much glue/epoxy in the delignit as there is wood.

Driving the pins in right away while the epoxy is still liquid makes me very nervous. I’ve done it a couple of times just to see what would happen and it worked but it still makes me nervous.