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When I run into Hammers that strike more than once I usually can fix it easily by adjusting the capstan.....but, sometimes this will not suffice so then the dance begins by adjusting this and that. You know what I mean.

In your experience what would you adjust next if raising or lowering the capstan is just not the answer.

I realize there are various methods to employ and I suppose it depends on what is happening with the action overall but what would you try next if the capstan wasn't enough. The next best thing.

As you can see I'm trying to move quickly but efficiently through a tuning. tks, Duane.

Complete regulation. If that does not work, then you need to start replacing parts.

Gerald,

Please identify the piano type, brand, and age. These things make an awfully big difference.

Generally, regulation is needed as BDB said.

Is the bobbling all across the compass or limited to a certain range?

Check and set the let-off distance and that the back checks catch the hammer(s) at the correct distances. All the above presumes that you understand how the action works ! If you do not there are a couple of very good videos on the internet.

Regulating isn't a dance - Check this out:

http://spurlocktools.com/index_htm_files/vreg.pdf

It is sporadic but may run for several hammers in a row then taper down to a few and one here and there. It is on a grand piano NOT a vertical. It's a 25 (at least) year old Yamaha mini grand. It's in a piano that I have been tuning in a large hotel. I have very little time to work on it when I go there for instance the other day I took the fall board off and without removing the key bed I reach in and adjusted some a couple of capstans but that was not helping so adjusted them back, put the fall board back on and left as I had already just tuned it.

If the piano gets played very hard, it may be that the backcheck "leather" is worn or chewed up by the hammer. This can cause inability to check. Also, look at the repetition spring strength. If it is too strong (for the current overall situation) reducing that strength may help. Of course, try adjusting the back check (but not so close that it drags on the hammer).

Just a few things. Doubtlessly other possibilities too.

Pwg

Make sure aftertouch is correct, and as P W Grey said, make sure the rep spring isn’t too strong. Make sure that the hammer goes into check fine.

Well Duane, what's the prognosis at this point? Any new report?

Pwg

Nothing to report Peter. I need to set up a visit to the hotel. Probably will ask for extra time when they call again to try to clean this double striking up. I will say this, though. I am now armed with real good advice which gives me more confidence.

One thing I know is that one cannot approach piano tuning and repair with "gall" alone. You need to have experience and knowledge (and a plan) to do it properly. I've only been at this for six years and have tuned about 500 pianos and fixed at least half of that amount I suppose.

I agree that's really not many compared to most of you but you would not believe what I have learned by way of appropriating what has been said here and by way of continued study and application.....and, as I see it, I haven't even put a dent in the bucket really in that nearly every piano brings new challenges....and so it goes on. It is an interesting line of work for sure.

Happy New Year to you all......Duane.

👍 We're all still learning too!

Pwg

Jeez, guys...

I think it best to think about general concepts first, rather than looking for individual adjustments, or even all the possible adjustments (complete regulation). Otherwise you might not "see fthe forest for the trees." Like, WHY would a hammer bobble? Because after hitting the string, it comes back and rather being caught it hits something causing it to rebound to the string. So either what is supposed to catch it (the back check) wasn't in position or condition to do so; or what is supposed to get out of the way after propelling the hammer (the jack and in the case of a grand the rep lever) didn't get out of the way.

Keep in mind HOW it works, divide the problem into either a checking or a let off problem, and track it from there.

Jeff,

Very good points made. Proper cure requires an accurate diagnosis.

Pwg

.....very good....tks

Key dip is too shallow. The quick fix on an upright is to shim the balance rail. Usually you can see the sag in key height and the key has too much lift before contacting the fall board felt. Key beds warp as well as sag in the center. Felts compact equally for the most part.
Find the screws holding the balance rail. Usually there are other shims because that's how they set the balance rail originally. Loosen the screws and pry up the rail. Slide someone else's business card under it to shim the keys to the height you decided on. I like 1/4 inch of pin in the key. Yes, you set your key height by the amount of pin in the key and the height of the fallboard.
However, unless you want to set key dip, you take that into consideration when deciding how much pin is in the key.
Much of the time, if the piano hasn't been messed with, the back checks return to proper regulation too.