Touch Weight Measurements
50 rest down weight TR rest down
40 TR up weight
30 up weight
The left chart shows down weight and up weight measurements for the bass section of a mid 70’s vintage Steinway model M. After traditional regulation
and lubrication, this action remained heavy, despite having 5 leads in each key . The right chart shows the same action after installation of a TouchRail
with down weight measurements readjusted to 52 grams. The TouchRail produces a lighter, more consistent touch response
TouchRail versus Supplemental Lead Weights
75 This graph shows how the TouchRail compares with added
10 gram down weight reduction lead weights when reducing down weight by 10 grams. Key
65 resistance has been measured at several points along the
keystroke. From left to right, each line includes:
55 1. Rest position down weight
2. Down weight just before escapement
45 3. Low key return force *
TouchRail 4. Up weight
The dotted line is the original key. The Black line shows the
same key with added lead weights. The green line shows
reduction the original key with added TouchRail (no added leads). In
the two lower lines, initial down weight drops equally by 10
grams. But as the key travels downward, (moving from
left to right in the graph) the TouchRail preserves
important low key measurements. The TouchRail key
rest depressed low key upweight
down down return feels lighter than the original, and more responsive than
weight weight the lead loaded key.
*low key return force = maximum weight that a fully
depressed key can lift to restore its mechanical repetition
more data function. Low key return force differs from conventional
“up weight” in that it is measured from the fully
depressed key position with the hammer unchecked .
New Opportunities for Reduced Inertia, Improved Repetition
Photos on the left hand side show a
conventional action with down weight of
49 grams. Below is the same key with
lead weights progressively removed and a
TouchRail added to restore the original 49
gram down weight. Top right photo
shows the removed lead weights, totaling
In the graph, down weight (blue), remains
constant (49 grams) as a result of the
TouchRail offsetting the reduced lead
weights. The green line shows a dramatic
increase in low key return force*.
The TouchRail- assisted key retains
progressively (up to 20%) more low key
return force than the lead weight key.
1. Key lead removal in new pianos can
more data alter the warranty.
2. Lead is toxic. Use caution when
handling key leads.
This photo shows a repeated cycle test in progress. The sprung
oscillating paddle, driven by a drill press, is compressing a fixed
TouchRail spring 5 mm at each cycle. After 100,000 cycles, the spring
length remained unchanged. The position of the spring within the
TouchRail body was also unchanged. The TouchRail design remains
stable after extended use.