Hi Garold Saw your post and enjoyed your enthusiasm. It takes that and much desire to take this road less traveled by.On the subject of presses etc. I use a go bar deck with a steeper than 60 ft. radius ( actually about 50 OR LESS) I'm also crowning my ribs less than some of my associates and drying my panels a little bit more .I do end up with the 60 ft.ish crown in my finished product and personnaly like the sound of boards that have a little more compression. This is frankly an unprovable notion but it,s mine all mine .The truth is everybody,s boards have compression in them or they would spilt like ripe melons after the first midwest or eastcoast seasons.Many of my colleagues dry there panels to 30%or 6% e.m.c.then apply ribs crowned at 60 ft. radius they sound wonderful and hold up well in severe climates provide damp chasers are used.I am in calif. where the climate is mostly wonderful ( eat your heart out Ye snowbound brethren).and much of my clientle are in the greater bay area where moderate climate are usual year round. All that to say that you make your boards work as well as possible for the region you are in.When I am making a board that is going to neveda I dry it down a to a low 4.5% to 5% Emc as r.h. levels average below 40 % year round .Nev. is a desert.My usual practice is to dry the panel to around 25%R.H. or 5.5% to5 % and crown My ribs in the treble ,top 5 or 6, to a 60 FT. crown and in the larger portions of the belly I cut about two thirds of a 60 ft. radius in that area.I.E. instead of cutting say a10 m.m. amount of crown I,ll cutabout 7.5mm.With a steep crown in my press and some curve in my ribs I get a result that I like that insures panel compression without the destructiveness of pure forced crowning.The method I,m describing can be found in Samuel Wolfendens book A treatise on Art of Pianoforte construction originally produced 1916 A must read for the rebuilder.One final word ( yeah right) I have heard wonderful sounding boards built in a variety of ways And although it is possible to build forced crown boards( i.e. flat ribs curved press and more drying 4% e.m.c. or less ) and be successful at it, the parameters are very narrow and strict adherence to a drying schedule that works for the type of spruce your using is essential to avoid the crushing of wood cells that leads to premature tonal loss and board failure. Best of success Dale Erwin from the great central valley modesto ,calif.
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