Jack Slipping?

[Richard Brekne]

Both of the things you mention could easily be the root of the problem. One
backcheck regulating proceedure I ran into along the way says that you should
put a bit of downward pressure on the hammer with one hand while forcing the key
to push the hammer up with the other... if the tail of the hammer scrapes the
back check.. then its too close.

A jack regulated just a tad too far out can also cause hard blow "missing"...
but then there are several reasons why a jack might be "at rest" in a position a
bit too far out.  Could be dragging on the knuckle (repetition lever too high,
or perhaps even repetition spring too weak), or could be tight jack center
(check for quick and free movement of the jack).

Elsewise I might add that taking a set of regulation and basic tools along on
every job is a pretty good idea. I keep an extra tool bag in my car that just
has extra standard parts. I lost my taste for driving 80 miles back to the shop
to pick up a replacement flange or jack spring or the like several years back.

Sounds to me by your last sentence tho that the back check is the quilty party.
Do the test above, check to see that it isnt checking closer then 12mm from the
string... back it off a bit if you have to. Let us know what it ends up being !!

Cheers

RicB

Greg Casper wrote:

> I just got back from a customer who has a Kawai grand with one key they said
> wasn't working. Turns out it works pretty well UNLESS you strike the key
> hard. When you do that, the hammer barely even moves. It looks to me like
> the jack is sitting too far forward on the knuckle, but since I didn't have
> a jack screw adjusting tool with me (this was ONLY supposed to be a tuning..
> and stupid me didn't take all the tools) I couldn't regulate that out to
> determine if that's the ONLY issue. Any opinions on what else might cause
> this situation? The backcheck almost seemed to be catching the hammer on
> it's way UP to the strings, but since it's only happening on a strong blow
> to the key I think it just LOOKS like it's catching, since there is almost
> no upward movement of the hammer when this occurs. Ideas?
>
> Greg Casper
> San Jose, CA




--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html