The Brass Comb and Sectional Centerpinning

Thank you, again, Isaac Oleg, for your far-ranging comments. One phrase particularly caught my attention and initially baffled me: "grands, with their combs and one long horizontal center..."  The AC is broken and something in the humid heat-bath I'm immersed in tonight has melted some flexibility into my random access processor. Suddenly, I get what you're referring to.

In fact, we have a Pleyel upright in the shop at the moment that employs the comb system for attaching action parts. The hammer butts and whippens are strung on sectional centerpins and each pin is clamped between an action-wide brass rail and sectional pieces with matching tines. Further, spacing and shape of the tines position the parts, limit their side-travel, and facilitate agreement between rails - a brilliant solution to the high cost of traveling, squaring, and spacing parts. Because hammer clearance in is a higher priority than best address of hammers to strings in this piano (hammers 1-40 have a 30 degree flare!), the hammer crowns were filed unsquare to match the plane of the strings at strike. This system presumably took less skill to assemble. prep, and regulate, less time, as well, and therefore cost the company less money to produce.

But simplicities of travel and spacing in the factory present challenges to the piano technicians who later have to service them (although less need for service is a selling point of this system). A general blackening of shanks has occurred during this piano's long life, including some proper charring, an indication of difficulties keeping what was above the comb tidy. Inconvenient maintenance was ignored in favor of producing an inexpensive piano that could still make a profit. As Isaac noted, this is not a reasonable tradeoff for expensive grand piano manufacturing. Unstringing and restringing a section of hammers from their common center pin for a pre-concert repair?

Anyway, we started off hanging hammers to match what we found in the piano and ended up being confronted by the tilt these hammers were assembled with in production. A decision to match crowns at strike with the general plane of the strings (putting my money where my mouth is?) produced a huge squaring overhaul, followed by an equally huge spacing orgy, followed by some adjustments to hammer shape for clearance. Thank you, Ben Webster, RPT (from Gloucester, MA) for being the hands and patience that executed this plan! The extreme wear of the original hammers had obscured the compromised nature of the factory setup. The hammers had been "miss-filed" (IMO) to accommodate the strings for economic reasons, not best musical interests.

Look at this hammer butt, though:

It was elegantly designed to do exactly what it needed to do, fitting into a least space, with simplest assembly. Manufacturing complex shapes was not a problem for Pleyel. But for me, fixturing to bore the several that needed new shanks? Nothing about them was square. So, this small French upright displays a curious intersection of high craftsmanship and budget considerations. On top of these choices, they added over-dampers to the mix...

The sound at setup, with the hammers skewed (but not filed to fit), was terrible. The sound, now that the squaring overhaul has been invoked, is musical. An early gauge was the lowest monochord bass notes who went from sounding tinny to having a gutsy voice with great projection. Ray Negron ( made a wonderful set of Weikert felt hammers. But some artful sculpting was necessary, in the end, for many hammers to clear... Clearly there is cost to unfudged hammer-string-fit, but I've found the payback musically worth it.


Isaac OLEG

BTW the less strong mix to adjust the new centers is a 70-80% water mix. The more alcohol the more the cloth will shrink and the deeper in wood the water will gho so the mechanical tightening is stronger with more alcohol. Drying time ,8 hrs. Be careful I worked on a grand Pleyel with similar “cedar” flanges and 50% mix was way too strong I needed to raise the centers thickness twice.Also, the Renner pre glued strips are OK but they are _intended for 1300 centers so you may be too free easily. Better do your own strips. Use a support foir the falge when inserting the cente rpin(pinning plank) so the flange/fork is square to the center. it is easy at free hand to be not well centered/square. The pinning plank even allows you to correct a center tor a part that is not square on its axis, by pushing the other side while entering the wire…

Isaac OLEG
Isaac OLEG

Hello, I have worked on such older designs .. About the centers and bushing cloth, if you can change the cloth, cool, but if not please do not ream, they can be adjusted by moistening and passing trhu a smooth needle in a drill press. The centers are very thin in diameter on Pleyels, I recently worked on one small grand, centers 1.1mm , I needed to change may be 4 on the whole action (individual centers for whippens on that one) Not any play, no sluggish centers, never any lube or product( applied. If you want to ream , very very sparingly just to clean the cloth from the nickel traces. On Erards you may find silk bushing cloth that cannot be reamed, but will adjust well with moistening (3 times if necessary) Be careful that the cloth of Pleyel retracts a lot, and that the wood is very dry , the moistening is in fact too efficient (this is a sort of "yellow cedarr, which is not really cedar but the name of the wood escapes me at the moment) The shanks twist/bow a lot, (may be with very dry homes) this is not an original problem, and the work may have been done very precisely originally. . Those butts have not an ideal shape for me, the beginning of the touch is easily heavy, and if you use too thin cushions, it is for sure ! The top of jacks are graphited and polished simply with a hard paper pencil type H or more) burnishing with a hard wood stick , but the pencil does yet much of it . The “combs” have some “advantage” but they are a hassle to work with. The hammers are often sliced for space (yours seem to be large I understand the problems you may have) the wood can be shaped too. But in any case you cannot have the hammers square of the rail and square on the strings. Fenner says the vertical atcion have the bass hammer flanges bore displaced 3 mm left so the hammer will center on the strings at strike . 3 mm lateral is huge, but it is easy to verify that in the piano or with an exaggerated model made in cardboard, and that you can then rotate from a flat surface to 90°, there you really see what happens to both sides . I think it may be a good idea to decide to have the hammer 90° from the strings at mid blow .so the slant on the crown is liùited (unsuspected in fact due to the trapezoidal shape of the felt on each hammer when we see something square it is not really ! You are lucky to obtain cold pressed hammers with Weicker ’Wurzen" felt. Those pianos may like that sort of felt. The problem is more in scaling, I think Pleyel used German strings (Poehlamnn ) at that era, but if you find a low tension , the modern steel will miss a lot of constrain,so the wire will be not resilient/elastic enough, and the iH will raise too much (it may have been about 0.55-0.6 max at A49 level. Plus, the soundboard is tired, one of the views on that is to rescale with even less tension so the panel is more free. In those cases, out of the Stainless wire (difficult t(o use as it break too easily at the eylets, sometime in the full middle of a st(rings and in mediums (no high solicitation) , the only choice today is to use Paulello wire type O (in principle designed to replace the French Firminy wire that was softer, an excellent wire, possibly phosphorus somehow) . In the begin of long bridge I even use softer than that (type 1) so I obtain more than 40% solicitation – trying to have 50 to 60% up to A440) The basses may be wound on Paulello wire too (often the bichords are done on Modern type as they are generally highly solicited, at last near the break) That way the piano will have a round tone, with much partials not too high iH… etc. No acidity or agressivity. – THoley propos on those kind of pianos to get within 550N tension. Sorry I am trotally OT – Pleyels are chalenging. If you find one with strings changed inb France up to the 60’s you may try to keep them, as the Firminy wire was still sold then. It is rare, in 30 years I have seen 2 Pleyels with new wire that sounded magnificent. There are some reputed models for the verticals , mod P (130 cm, sometime a little more) The model 9 is smaller but not bad.THe soundboard wood was excelleent, and dryed very long , about 10 years was said. ALl went int(o fire with German bombing… (I have some soundboard wood planks from the “real” factory" int enough to make a soundboard unfortunately, they are amazingly nice. Best regards.

Isaac OLEG

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