Regulating a Bluthner Action in a Bluthner Grand

Up until about 1918 Bluthner used their own Patent Action in their pianos. For a grand piano, this action was strikingly different from the more standard ‘Roller’ action. Regulating these actions cannot be done by trying to apply the procedure used for the roller action. 
These instructions are based on a leaflet produced as a guide to regulating these pianos. Some familiarity with these actions is absolutely necessary before attempting this work.

The necessary operations must be carried out strictly in the following order. The fitting of the Bluthner Action is based on a tough depth of 9 mm and a hammer-blow of 45 mm.

1. The hammer heads should be spaced exactly to the strings and the hammer-flange screws should be tightened.

2. Setting-up. The guide-pin of the abstract must be straight and vertical. The jack must be so adjusted - by means of the carriage which is screwed on to the key, that it drops quite easily under the nose of the abstract.

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 are situated on the hammer-rest rail.

4. Touch. Contrary to the Erard Action, the touch is made quite firm. The key is depressed slowly on to the touch-baize, after which the hammer should continue to rise 1 mm up to the set-off point. Only on striking the key strongly will the hammer be caught by the back check. (No after-touch).

Bluthner Patent Action

5. The checks must be cranked and spaced equally. The checks must each be parallel and central to the hammer woodwork. Now the hammers are checked. There is no special height but it should be about 24 mm above the hammer line. 

6. Drop. The guide pin of the abstract must move easily in the bridge leathers so that the abstract drops of its own weight. The repetition springs must move freely in the abstract felt clips and by pressure of either side of the right-angle spring, the drop is controlled. The hammerhead should drop down 3 mm after setting-off.

7. It is now necessary again to check the touch throughout.

The abstract

8. The dampers should lift when the keys are half depressed.

9. The damper shade-rail has to be adjusted so that when pressing down the sharps, there is very little play.

10. The coiled spring which is attached to the abstract should, in the normal position of the key, not rest on the jack, but remain about 3 mm from it. An even touch is of the greatest importance.

Technical File

© Steve Burden

Regulating an Upright Piano

Regulating a upright piano is perhaps just a little more straightforward than regulating a grand piano. The following method for regulating is not the only way, but it works well on most pianos.

Please note: while regulating pianos, some improvisation is required to get the best out of any given piano. If various felts have been replaced, there are many more issues to deal with than can be addressed in this article. The finer points of the slap-rails are not mentioned here either.

Most actions work well if the depth of touch is 10.5 mm. and the hammer blow 47mm. 

Assuming the action has been reassembled and everything is spaced properly.

1. The first job, somewhat surprisingly, is to adjust the set-off point! With the action in the piano this can be done without the keys - indeed, it is better they are not in the piano! Lifting the front of the lower part of the action the set-off is easy to find and adjust. If access to the set-off screws is awkward you can even take off the hammer-rest bar. Set-off distance is 2 - 3 mm from the strings.
It is also helpful if the back-checks are bent away from the balance hammer to allow the set-off plenty of room to let hammer to fall away at the set-off point.

2. Replace the hammer-rest bar and set the blow to 47 mm (no more than 50 mm). With the keys back in the piano, and the hammer blow set, take out the lost motion between the key and the lever. (The lower part of the action).

Starting with the white keys, establish that when depressed and held down, the tops of the key-covers are level. With this done, set the depth of touch. Using sample white keys - every 5 or so, (e.g. a 'C' a 'G' a 'D') measure from the top surface of a 'held down' note to the top surface of a neighbouring key when at rest (ready to be played). This should be 10.5 mm. After setting the sample keys, level the remaining keys to be in line with them.

Now for the sharps: When depressed and held down, the top surface of the sharp keys should show about 1.5 mm above the top surface of the white keys when at rest. Adjust accordingly. once again, using sample keys - every 4 or 5, set the height of the top surface of the sharp keys when at rest, to be 12 mm above the top surface of the white keys when at rest.

3. Set the checking-off  - the point at which the hammer is caught by the back-check when the key is struck and held down. Usually measured as the distance between the strings and where the hammer has come to rest. There can be no fixed measurement here as it seems to be different for every piano. I would reckon on anything from 8 mm to 15 mm. This is a subjective point but when it is right you can feel the whole key-stroke reach its proper destination!

4. Regulate the dampers so that they all lift together on the pedal AND during the stroke of the key, the damper begins to lift away from the string when the hammer is about halfway to the strike-point.  
Technical File
© Steve Burden