Erard under dampers

[John Delacour]

At 11:03 am -0700 28/5/07, Jurgen Goering wrote:

>JD - thanks for the information on recreating dampers for vintage 
>pianos.  Do you have a special trick for cutting the damper felt on 
>an angle?  I find it hard enough to cut cut it nice and vertical! :^)

The main trick is in the sharpening of the knife.  I lay the felt in 
a board of soft wood (without hard winter growth) that is rough 
enough through use to grip the felt and prvent it from sliding.  For 
a straight-edge I use a strip of hardwood about 30 mm by 6.  First I 
cut the edge at an angle, with the knife angled away from the 
straight-edge so that it keeps contact with the rule.  I press hard 
down on the rule with four fingers as I go.  After 6 inches or so I 
stop the knife, leaving it in position while I move my fingers to 
press on the rule further along, and so on.  The knife must be sharp 
enough and the pressure hard enough to cut right down to the board in 
one pass.

I then cut two pieces of card to the widths I need to get the taper 
of width I need.  I turn the felt over and use the card gauges to 
line up the straight-edge the proper distance from the edge of the 
sheet and then repeat the above process.  So I end up with a strip 
that is wider against the board than at the top.  I then turn the 
strip over and make my dots, over again and squeeze out the line of 
glue along the centre, etc.

The knife must be curved and preferably not of stainless steel, which 
is hard to get sharp enough.  I put the final edge on the knife using 
the buffing wheel (cheating, maybe, but very effective!) and a razor 
strop.  For this job I will even strop the knife again before the 
second cut.

Pictures to follow when the gods send me both an assistant and a 
camera at the time I'm doing it.

I've occasionally thought of building a proper machine with a long knife, but
I always decided against it, although I use this method for all 
dampers, not just for antiquities.


JD