[pianotech] Please check out the "Bow Clamp" video, and comment on its uses for us.

[Ron Nossaman]

On 1/18/2013 9:08 AM, Jim Ialeggio wrote:
> Ron wrote:
>
> <For us, clamps aligning soundboard panels for assembly, and clamps for
> holding key sets are crowned to maintain pressure in the middle.
>
> I've never had a curved clamping caul perform very well, and basically
> gave up on them.  They apply pressure in the middle at some point, but
> pressure is uneven, unto zero along other intermediate points along the
> clamp. The deflection under pressure never turns out to be a fair curve,
> but one that dips and dives. Maybe within a 2ft length, but not @ 4ft
> which is what I usually need them for.

That's the big problem with them. If made from a material of uniform 
moe, and the crown is shaped appropriately and accurately, you can get 
good results. I rely on a pad to take up irregularities, which works 
well enough for my uses. Defining the curve is critical, but I'm not 
entirely sure how. Logically, a constant section uniformly loaded beam 
should describe about the right curve.


> On my soundboard panel clamps, I have a set of 1 or 2 degree wedges I
> use to align along the length of the clamp, if I see that I need them.
>
> I also now use spring loaded go-bars if I need intermediate convincing
> in other wide glue-ups...but dont find I need them too often.

Have you seen these? http://www.frontlineengineering.com.au/
Ron N