Grand Regulation In Detail - Part 3

In this third part of our grand regulation guide, we will continue with discussing the Section II, The Top Action. Remember that action centres were discussed last week, so now we will begin by talking about hammer traveling, which is Point 16 on the 50-point checklist.

Point one on the checklist was tightening all of the screws. Now if all of the foreign material was cleaned out from under the flanges, usually by using compressed air, we are now ready to travel the hammers. What we are looking for is a hammer that swings to one side as it is raised from the rest position to normal striking height.

I find it best to use a long rod such as an old pedal rod in traveling a whole section of hammers at one time. Insert the rod under the hammershanks near the hammer, at about the rest felt/rest rail area. Hopefully the rod is long enough so the ends will protrude over into the next section of hammers. If not, make sure the rod rests on at least one shank at each end so as to be level.

 

If any hammers are badly angled (Point 17), I find it easier to correct these first before traveling. On the other hand, if the hammers are traveling way out of alignment, then it might be easier to travel first, angle later. Anyway, keep in mind that a travelled hammer must be angled in order to keep the striking surface square to the string, assuming that the striking surface was square in the first place.

To find hammers that need traveling, lift the rod up and down approximating the hammer-to to string distance and watch for hammers moving towards their neighbours. All hammers should lift vertically, with no sign of movement to the right or left. If necessary, use a square or a board with vertical lines drawn on it as a guide to make sure the hammers all lift perfectly straight. Without the use of a guide it is possible to travel all of the hammers, but end up with them all moving slightly to the right or left. Any horizontal movement will result in a loss of power, abnormal wear on the hammer and its bushing, and voicing problems. Do not bother to travel the hammers any higher than a few inches, since they do not function any higher in the piano.

Any shanks which are moving to the right or left are corrected by placing a thin shim under the flange so the shank will travel vertically. The rule is to place the shim on the side of the flange toward which the hammer is traveling. In other words, if the hammer is moving to the right, place a shim under the right side of the flange. I prefer to take the flange off completely and place a gummed piece of paper such as packing tape or a strip of masking tape as a shim. This works better than just a piece of newspaper so often seen here, since they stay with the flange whenever it is removed in the future.

 

Also, in taking the flange off to shim it, I always check it to see if some foreign material is causing the hammer not to travel correctly. If more than two shims are necessary, filing the flange on the opposite side is preferred to installing many shims. In really bad cases, rebush the centre.

Since shimming the flange actually tilted the hammer, now we need to go back and correct the hammer angle. In case you do not know what I mean by hammer angle, it is correcting those hammers which are leaning to the right or left. Do not confuse this with the angles which the hammers are glued on to so that they are aligned to the string angles. This is in a different plane. The angles we are talking about are caused by the shank warping or by shimming the flange to correctly travel the hammer. To correct the hammer angle, take a heat gun or an alcohol lamp and heat the shank by quickly passing the heat up and down the length of the shank.

At the same time, apply a tilting pressure to the hammer head in the direction it needs to go to correct the angle. You will feel the shank twisting when it gets hot enough. Don’t burn the shank! Keep in mind that some pianos are designed for the hammers to be slightly angled a couple of degrees in certain sections, usually the tenor or bass. Note that if the same rod is used here in angling that was used in traveling, the hammers will all be uniform in height (remember that we have not got to regulation yet) and therefore easier to spot those which are misangled. Do not lightly pass over these two procedures, as they really make a difference when it comes time to voice the piano.

Next on the checklist is Point 18, reshaping the hammers. At some time in the future, we will discuss when to tell if the hammer has enough life left in it to reshape it or if it needs to be replaced. As this post is based mostly on reshaping in the shop, we will also discuss in the future ...

Read more:

https://www.professionalpianotunerlondon.co.uk/post/grand-regulation-in-detail-part-3