How to produce a good touch with the Blüthner action in a Blüthner Grand.
The necessary operations must be carried out strictly in the following order. The fitting of the BLÜTHNER-action is based on a touch-depth of 9 mm and on a hammer-blow of 45 mm.
1. The hammer-flange screws should be tightened. The hammer-heads must then be spaced exactly on the strings.
2. Setting-up. The jacks can be adjusted by means of the carriage which is screwed on to the key It should fall quite easily under the nose of the abstract. The guide-pin of the abstract must be straight and vertical.
3. Set-off. The hammers should release 1,5 mm from the steel strings and half a string thickness from the bass strings. The set-off screws for this adjustment are situated on the hammer rest rail.
4. Touch. Contrary to the ERARD action, the touch is made quite firm. The jack should be released from under the nose of the abstract when the key is lightly pressed on the touch-baize, after which the hammer should continue to rise 1 mm, until it releases, so that it checks only on striking the key strongly. (No after-touch.)
5. Checks. The checks should be adjusted at a slightly greater angle than on the ERARD action. The hammers should be checked 24 mm above the hammer rest. The surface of the check is adjusted parallel to the hammer tail.
6. Drop. The right-angled repetition spring which controls the drop, should have a thickness of 0,85 mm in treble, 0,95 mm in the middle range and 1 mm in the bass; the guide pin of the abstract must move freely in the bridge leather so that the abstract drops by its own weight. The repetition springs must move freely in the abstract felt clips. By bending the spring forward or back the tension is altered which controls the drop. The hammer head should drop to 3 mm from the steel strings.
7. Now the touch has to be checked again.
8. The dampers should lift when the keys are depressed 5 mm.
9. The height of the damper shade-rail should allow 1 mm play for the dampers when the white keys are depressed.
10. When the key is in rest position the leather button on the coiled spring which is attached to the abstract should be at 3 mm distance to the jack.