Fred, What about Spurlock's method of choosing cloth thickness(on his website)? Doesn't that work for you? Jim Busby ...My complaint about it being too loose is that the caul doesn't hold the felt quite tightly enough for cutting purposes, and I have to bear down/sidways on the caul while cutting to avoid the felt pulling). I just experiment with various sizes I have in stock until I get what feels right. Sometimes that is two slightly different sizes (one in each side of the mortise). I have found that if I get that loose fit when installing the finish caul, ironing with the parallel sided brass cauls from Pianotek leaves me with a perfect fit, and I don't find myself needing to do any easing a year or two down the road. Absolutely no custom easing (except for balance hole). If I use felt that is not all that much tighter, I find that no amount of ironing will create a permanently correct size - I have to squeeze wood, which I vastly prefer not to do, both for practical and theoretical reasons. Regards, Fred Sturm University of New Mexico _______________________________________________ caut list info: https://www.moypiano.com/resources/#archives
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