bentley pianos

[alexelgier]

Hello =)

This week I've had the opportunity to tune two Bentley uprights. (serial numbers 60220 and 70565)
I was surprised to find that on both pianos the hammers don't strike the strings straight on.
On 3 stringed notes the hammer hits mostly the middle and right string, but just barely the left.
On 2 stringed notes the hammer hits mostly the right string, and barely the left.

Since both pianos have the same problem, I was wondering if perhaps this was due to some manufacturing particularity.

Has anyone had a similar experience?

Thanks in advance

Alex

[Colin Nicholson]

Hi
Not a manufacture problem.... standard procedure.

Perfectly normal for older pianos (yours suggested are dated in the 1950s)
Hammer spacing and alignment comes under piano "regulation"/ servicing, and it is quite common for the odd few hammer heads to strike right or left of centre. This can be caused by:

1. warping/ swelling/ twisting of the hammer shank
2. Flange movement caused by vibration/ loose or worn flange bushings (excess side to side movement)
3. Loose/ not fully tightened flange screws.
4. Piano subject to excess moisture (if 1) or dryness

If there is just the odd one or two out of line, use a hammer flange spacing tool to crank the flange over - best to loosen the screw ever so slightly first, adjust then re-tighten. Hammer head felt will then need to be refaced with an emery board, so the old grooves do not damage the felt.

If most of the hammers are badly aligned (bass aswell?) .... then I suggest a small refurb.
1. Disconnect bridle tapes X 88/85
2. Remove undercarriages
3. Remove all hammers
4. Reface hammers
5. If tapes break - replace as necessary
6. Check condition of leathers - replace as necessary
7. Assemble hammers first - align as you go along
8. Assemble undercarriages/ connect tapes (check jack striking hammer butt leather in centre)
9. Regulate mechanism (lost/ positive motion/ set off etc)

Also make sure the action brackets/ rails / alloy standards are very tight and secure.

If you are not experienced at this.... best left to a professional.

[Johnkie]

If you take a look at the hammer noses ( viewed looking from the front, not directly from above), do the string grooves look pretty much even across the felt? If not, and the left unison is barely coming into contact with the hammer nose, then sure, there is a problem with spacing.

If though, the grooves are merely at an angle rather than straight up an down, then it's likely to be a result of an optical illusion caused by spacing taking into account of the strings non perpendicular angle.

[Barrie Heaton]

A photo says a 1,000 words


Barrie

[Colin Nicholson]

I know what you mean there Johnkie.... common in the bass, especially if the hammer heads are thin, or thinner than the bi-chords width..... they can sometimes be positioned to strike across the 'face' of the hammers.

Another scenario......

It is possible that the hammers may have been previously removed (perhaps for just tape replacements/ re-pinning etc) .... and re-assembled on a work bench, instead of assembled in the piano - using the strings as a template. If so, this will create a "domino effect" - (seen it done!) and although the spacing may be uniform to look at (on the bench), when the action is installed - every hammer is shunted slightly to the right....

On an upright Steinberg I have just refurbished.... two treble hammers (left side at the start of the break), wouldn't align for the life of them.... top treble hammer flanges are very close together.... so I had to chamfer the bottom corners on each flange to 'rotate' it slightly to the left.... job done. Common on some Bechstein uprights aswell - especially when old & warped. "Historic movement" should always be considered aswell.