Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Best glue/ method for fixing hammer felt

To all the professionals on this platform, I seek to know which is the best way to fix some hammer felts which have removed .Would using staple pin be better or using glue/gum. If any one thinks of glue/gum as the best option, I'll appreciate to also have a recommended type of glue/gum.
Thank you

There are various approaches to this. A traditional method involved using glue and wrapping with thread.

A fast method is to use glue - either CA glue or Titebond - and small electrical cable ties (zip ties). The ties bite into the hammer felt and don't slip off, and if positioned carefully, don't interfere with adjacent hammers. Next visit, with the glue thoroughly cured, you can if you like snip off the cable ties.

The repair suggestions are correct. However, keep in mind that "repair" is not at all in the sense that the hammer has been restored to its original, pre-glue-failure capability. Because the tension/compression is lost, it cannot have the same performance as original. How much of a difference will actually be noticed depends on how much compression/tension the hammers had before the felt came loose.

A good point Keith, forgot to mention that!

In practice, I've found that there isn't a significant difference, and a couple of techs on the pianotech google group, where a similar question recently came up, have said the same.

If a significant number of hammer felts have become detached, the proper fix is of course a new set of hammers. But it must be recognised that many pianos simply won't be worth that expense.

Great repair suggestion David! Thanks!

I too have noticed loose hammer felt can be reglued with no tone loss. I think this shows that the hammer making process is intended to place the most wear resistant face of the felt to bear against the strings. Thus the felt is "deformed' into a curve during the hammer making process. The felt deformation is permanent enough that a slight gluing pressure can restore things to proper function should the glue joint fail.

The hard part is getting the felt back in the original position. If you can get it to stay there, the hammer will sound pretty much like it did before it came unglued.

LOL which probably wasn't all that great a sound I bet
By the time hammer felts have degenerated to the point of coming off- you may as well do whatever repair you can, if you are not replacing them...


Are there no used hammer heads you might have to replace them with? Fighting to get them glued down and staying on may take as much time as sticking a used head on in replacement. Didn't say how many you were needing to repair.


David- that is a nice repair...But, on some piano actions, don't you find it impossible to keep the hammers from hanging up?...I just know that if I tried this on that old junk spinet I faced couple month back, I would never have gotten it to work

Now I know what to do with all those left over zip ties from Dampp-chaser installations! Great idea David!

Pwg

You know, the zip tie method is remarkably quick! I understand what you mean about the possibility of hammers fouling each other on some pianos, but so far, I've not experienced it. And I've used the technique on a couple of spinets. Gel CA glue is probably the fastest-sticking glue to use with the zip ties. But Titebond might be stronger long-term - I'm not sure.

Perhaps I should give it a try next time I'm in that situation then--- I could definitely be wrong...Never done it.

I find it best to glue and clamp the top half in the original position and let it cure overnight then do the same with the bottom half.

If you use the zip tie method the job is virtually instantaneous and you don't need to make a return visit. On the next tuning visit you can snip off the zip ties if desired.

I really appreciate all who have contributed and the various professional methods given.I am sure the best would come out of this, with all the contributions.
Thank you all I am starting the repair rightaway today.

If you search the term "exploding hammers" you will find more discussion about this.

I've also heard good things about using Gorilla glue (the original kind that foams when it dries) on these.

I like to use Titebond. Apply to the felt and allow it to soak in a bit. Then, apply a second coat and push the molding into the felt. Then, clamp and quickly wipe off any excess that squeezes out before the glue stains the felt.

I prefer to remove the hammers from the action and use spring clamps. Edit: Discretely number them on the side of the hammer butt if numbering seems necessary.

If several hammers are coming unglued, it would be best to test all the hammer felts to make sure they are solidly attached. If most of them break free with moderate pressure, then reglue the entire set if replacement is not an option.