Hi William, Your regimen looks good and efficient. I like the key words "warm" as in not too hot and "teflon" as in lubricating the bushing felt... very important. I use the Spurlock High Density Polyethylene Cauls. I don't see any difference in using brass calls. It's all about the combination of dimension of the hole and thickness of the cloth. I like the hole sizing method... nice flat sides to the wood.... The "too much" I referred to is the tendency that techs have to rely on the iron instead of easing. Usually this happens when the new bushings hit summer humidity and the keys get tight across the board and they think a quick fix is to hit them all with a hot iron. Over-ironing just makes the felt harder and less resilient and it's easy to damage the complex molecular structure of the wool fibers and make them brittle and lifeless. Cold or warm easing to actually crush the wood fibers slightly is the permanent answer in these cases even though it time consuming and takes focus and skill. I imagine an ideal bushing as always being tight but not too tight. Of course the safest, from a stand point of avoiding sticking keys, is to make them loose or too loose but for a pianist to feel connection and control, loose doesn't help. A bushing that is tight all the time but not too tight will give the pianist a feeling of connection, and confidence that they are off to a sure footed start as the finger first connects and starts to move the key. So I would put forth this ideal as an aiming point: That when a key bushing is it's loosest - in the driest part of the year, the bushing felt is just slightly pushing against the key pin.... So that there is actually a little friction there. When the bushing is it's tightest - in the most humid part of the year, the bushing cloth pushes a little more against the pin but not so much that the bushing will seize become so tight as to significantly impede the movement of the key. The resiliency of felt makes it possible to have a key that is tight (snug) in the dry and tighter in the humid because the felt allows for dimensional change. If the bushings were just wood they would be tight in dry and jammed in the humid. Here's a technique I just tried and on a set of pesky bushings that had been replaced but not played on too much. They had a nice divot in the felt were the balance rail pins rested... The pins were a standard .146" so I used a spare pin of the same diameter to check the tightness by moving the loose pin in the bushing with key in hand. A very fine degree of judgement as to the tightness was possible with this method. With a heat gun I quickly heated up the easing pliers so they were hot to the touch and eased and flattened the bushing. Only so much heat resides in the metal so it's harder to over heat the felt this way. If I over eased I would hit the bushing with steam from an electric kettle to expand the crushed wood and felt, then re-ease. David Stanwood >Hi David, > >Can you define "too much." Do you use Teflon or brass cauls in your >work? I'm guessing you've tried both at some point, what do you find >the tradeoffs to be? > >I'm using (have always used) Spurlock's sizing cauls followed by >warmed brass cauls and hot hide. As I said before, I like to remove >the cauls after cure, apply Teflon to the bushing, then do a final >size with a warmed caul, either wholesale, by inserting the same >size brass caul as was used during the cure, or with a warmed >specific size caul on the soldering iron, inserted for about 1-2 >seconds in each bushing. Seem very uniform, very smooth, and very >quiet upon installation. > >As with most things in this work, it seems to me a balancing act >between density and resiliency. For me, I'd feel like bushing cloth >that get loose or dimpled too soon after a job would not be dense >enough, those that are noisy are perhaps too dense, whether because >of ironing or glue saturation. > >I'd be interested in your feedback, David. > >William R. Monroe > >>Hot Hide Glue is the glue of choice here for two reasons: >> >>1. It's easy to remove down the line. >> >>2. When applied to the felt it cools off and gels before it has >>time to soak too deeply into the cloth thereby reducing the >>resiliency in the felt. >> >>Ironing, by the way, reduces resiliency while increasing density so >>care is needed not to rely too much on the iron. >> >>David Stanwood >> >>>Glue that soaks in too deeply can/will cause squeaks and clicks as >>>the glue in the cloth rubs against the keypin. We want a very >>>firm, yet resilient surface against the keypin, not a hard >>>unforgiving one. We're going for adhesion here, and not much >>>"penetration" into the cloth is necessary. >>> >>>William R. Monroe >>> >>> >>>SNIP >>> >>>>Tell me, though, why do we NOT want the glue to soak in? Or will >>>>it adhere just as well to ironed bushing cloth? >>>> >>>>Also, do you iron both sides, then? >>>> >>>>Thanks, >>>> >>>>John Dorr
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