David ??I agree.?A loss?of resilience occurs?in?Pre pressing, which is the?practice of pushing the felt into the caul before the underfelt is laid in,to crease the felt in the middle. The purpose of this is?so it is easier/possible to center the underfelt all along the length of the? felt strip in the final pressing. Pre-pressing or pres-stretching??is more often over done & it is?this process where?the felts ability to?be?tenisoned?is reduced.?I believe every maker? pre-presses? to one degree or another but pre pressing should be kept to a minimum, just enough ot crease the felt slightly so the underfelt can stay centered with the final press happens This is the the case with Ronsen hammers. ?Technically there are no Cold pressed hammers. There is always so heat present to cure the glue.??Something like 130 degrees when the felt?is pressed?in & then it's turned off. Ronsen hammers stay in the press 3 hours after the heat is turned off. ?Other hammer makers whiz them in & out of the press using far more heat to cure the glue faster. Of course this aids production but the hamners are?losing resilince, tension & compression under this protcol.? I think this is the way buffing wheels are made. LOL ?Dale >Dale Wrote: <snip> Pressure is pressure but pre pressing removes >resilience as does too much heat. <snip>? ? Dale,? ? I've always felt (no pun intended) that tension in a cold pressed hammer develops resiliency and density at the same time and that this tension is always diminished by hot pressing. Imaging bouncing something off a stretched nylon rope... (nylon being very stretchy). If the rope isn't stretched tightly you can't bounce off it very well...? ? David S? -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20081018/43f36621/attachment.html
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