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Hi everyone!

I haven't posted in a while. Hope all is well. I have a question about hammer blow distance.

I'm regulating my Yamaha U1, and currently have the hammer blow distance set to about 47 mm. I have noticed that the bass hammers are closer than 47 mm. The hammers are not resting on the jacks. Checking and key dip are fine, and the hammer rest rail does not appear to be bent. This is causing greater aftertouch in the bass.

How is this corrected? Is there something else that might be causing this?

Any advice would be greatly appreciated :-)

Thanks,
Jonathan

You can add a strip of bushing cloth of appropriate thickness under the hammer rail cloth under the treble hammers only. This will bring them the same distance away from the strings as the bass hammers. Then adjust the blow distance.
Good luck.
Tim

I have seen a couple of uprights where the offset between the overstrung section and the understrung section is not the same as the difference in bore between the treble and the bass hammers. (This may well be the case with your U1; Tim has already pointed out the remedy.)

I have also seen several uprights (both my own included) where the string "plane" is anything but a "plane". When checking with a straight edge along the strike marks on the strings, all sorts of aberrations become evident. Sometimes the sections in themselves are warped/curved, and sometimes the two sections (over- and understrung) are not parallel with each other. Plate geometry doesn't appear to be a very exact science.

Less after touch in treble is not a concern, more a natural tendency.

The knuckle touch the Jack with Yamaha U1, but it should go back to rest.

The good jack to knuckle relation is perceived in the start of the key, in the end.

If it feels good to you, it is OK, but a jack allowed to tap in the butt will wear the "skin" sooner.