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I just replaced the moth eaten front key punchings with newish ones that are too fat (that's all I had) and I suddenly find myself with a working 5mm keydip! Is it as easy as that?

yes

So with $12 worth of punchings I've now got a kind-of Viennese 1780's touch? If a little heavier?

If the rest of the action is designed for it. If you reduce the key dip, you may not have any escapement.

Well, yea, it's working.

What's blow distance? The blow distance may around 25mm with this keydip. You have to play harder to make loud enough. So you feel its heavier.

If the dip is shallow enough you don't need escapement: the hammer won't quite make it all the way to the strings. A 5mm keydip might only move the hammer 30-35 mm. I would think there'd be some bobbling hammer issues though...

And the dampers may not clear the strings, if they lift at all.

And then the sostenuto wont work either.

We're talking about my 1830/40 upright here. I still can't quite get my head round the fact it seems to work fine with the keydip of a clavichord. The punchings are about 6mm - I've sent off for 4mm ones instead. Quite what the extra keydip will be for, I'm not sure.

If the front punching were moth eaten, then the balance rails punchings may also be about disintegrated. If the balance rail punchings are replaced then that will also increase the key dip.

8-9 mm key dip seem to be a minimum.
I have an original Pleyel jauge from 1905 at 9 mmm

Thanks for that but they're paper!

So the original balance pin felts are gone completely? This is not good. It would be hard to make sense of any regulation measurements in that case.

I don't think there ever was felt there.

On this point our opinions differ.

Does this piano have a back stop rail for the key sticks? If so, and it hasn't been fiddled with or rotted away, then that may help to determine the key dip.

Before the moth there was some felt, never seen a piano without.
And never seen one with 5 mm keydip, may be 7 mm for a very short stroke.

You may have about 3 mm of the pin in the mortise.
You may have an acceptable thin space between the back of the keys and the case part. the wood discoloration on the blocks may be show where the key height was .
With very low keyboard I think the sharps must be very high against the white keys when both are down.

You may need to unscrew a lot the "capstan" (that does not mean much if the hammer rail is bowed or the hammers are farther from the strings at rest than they should.

You can take a bubble jauge and see at what point the keys are level. I think they are possibly level at mid blow.

Any balance punching was probably very thin, 0.9 mm at the max.

test with carboard paper punchings to see if the touch is better.

It is too noisy if there is no balance punching.

Look under the keyframe for shims, so in case the punching you install are still too thick you can lower by subtracting some ( under the balance rail)


What counts is that the jack is in a good position with the key at full dip, and that the dip is not really far of even old standards

You may like 5 mm as it strengthen the touch and tone but rise the keys a little and test for a more supple playing.

Not so much Chris without the good key level.

There would be some tiny degraded bits left if that was so - there's nothing.

Thanks folks for all your help. I can't do anything till my new front punchings arrive from the US then I'm off on holiday for 6 weeks!

The actual point of all this is how tired I've grown from playing on the modern keydip. I can't face it much more, it's so clumsy.