Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Steinway upright action geometry

Hello,
I'm setting up a new Renner Steinway upright action, and i have it in what i thought was a good position, but when i tried a few samples, i found that i need to lower the let off button way too far down!...


What would cause this??-The position for the let off rails was pre drilled by renner, and looks normal..
Obviously, i could re drill the holes for the rails lower down, but i would rather not do that before understanding why!

The hammer bore is the same as original, but the action was a bit different,(in that the hammer flanges were linked to the dampers before.)

I'm also confused about the relationship between the adjustable hammer rest rail and the action mount adjustment (these)...






As the hammer rail is adjustable too, at this stage,how do you know whether to set up the blow distance by using the hammer rest capstan or the action mounts?

I'm concerned that the action is too far back/forward but i have just adjusted the hammer rest capstan to compensate.

I have a 5mm difference throughout between the top of the shank and the bottom when the hammer is hitting the strings.magic line is good. key ratio is 1.5:1.

Any upright action designers out there fancy this challenge??-I would be most grateful for ANY help and general tips on upright action geometry!

Bonus question: What angle should the jack be at let off?

I also have the PTG journal DVD, if anyone know of any articles that may be helpful?

Thanks,

Lewis.

If the let-off rail is too high, I give a whack to the hangers and bend them down.

I would decide whether to move the hammer rail or the action mounts according to how it affects the dampers, and the angle of the hammer bore. When I am doing this sort of work, I set the top hammer so that it hits the string #88 perpendicular about 1/4 inch into the speaking length. Then everything else follows from that. There are lots of options. Most of them do not make a significant difference in how the piano plays.

If I understand correctly, you are replacing a complete action on this piano. The old action had the Steinway double flanges, the new action is a standard Renner action.

I assume Renner bored the action rail according to your specs. Can you check your specs against the old and the new action rail to see if there are any inconsistencies?

New action components may have different dimensions - if the length of the jack is different or other wippen dimensions deviate from the original parts (which is quite likely) then drilling the action rails according to the old rail may not work.

This is the correct way to determine the position of the action bolts. From here, the blow distance is set by moving the hammer rail or shimming its cloth strip.

Thanks for the replies. Ok so it sounds like its nothing to worry about.
Yes,i will check out the original whippen dimensions, i'm sure that will provide some answers!

[exit lurk]
Thanks for this bit of (highlighted) information, I've learnt something new yet again - had been wondering about this for some time.
[re-enter lurk]

Many verticals have hammers bored so the tip is slightly downward from perpendicular. Steinway does that.

Yes - in many (most?) verticals, hammers do not strike the strings at a 90 degree angle.

Well, they should strike the strings at a 90° angle, but the shanks will not be parallel to the strings. I will go downstairs and dig up a Steinway vertical hammer and report back later.

Steinway hammers are bored at 83°, not 90°.