Hammer bore distance update

[Michael Magness]

On 10/23/07, David Love <davidlovepianos at comcast.net> wrote:

> Paul's idea is better.  Call Lloyd at Renner and talk to him about the
> problem.  If it's their mistake I'm sure they will redo it.
>
> David Love
> davidlovepianos at comcast.net
> www.davidlovepianos.com
>
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
> Behalf
> Of David Love
> Sent: Tuesday, October 23, 2007 7:49 PM
> To: 'Pianotech List'
> Subject: RE: Hammer bore distance update
>
> Sometimes when you send samples they add a few mm's to compensate for
> estimated wear.  Sometimes they get it wrong.  Better to measure and send
> specific dimensions.
>
> A little tricky to redrill an entire set when the hammers are tapered and
> tailed but it can be done.  You will need a boring jig.  Take them off,
> plug
> them with dowels and proceed slowly and carefully.
>
> David Love
> davidlovepianos at comcast.net
> www.davidlovepianos.com
>
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On
> Behalf
> Of Cal Munson
> Sent: Tuesday, October 23, 2007 7:03 PM
> To: pianotech at ptg.org
> Subject: Hammer bore distance update
>
> Thanks List for your responses.  The piano is a Steinway A and the
> bore distance, I am told should be 46 mm
> My own 'A' has an ideal bore distance of roughly 44 with some
> sections at 44.5 and others at 43.5
>
> The hammers in question, Renner Blues, have been drilled with a bore
> distance of 49 mm (center of hole to striking surface of hammer) so
> they are 5 mm off.   The old hammers with shanks were sent as samples
> so it is a mystery........ However,  I don't see a downside to having
> the hole filled and then re-drilling.   But I have not done it
> before... Anyone?
>
> Cal Munson
>
>
>
> I agree with Paul B and David Love, it's not as if they bored them at no
> cost to you! Nor is it cheap for you to plug them and re-bore them yourself,
> that is time/money out of your pocket. Plus the cost of a boring jig if you
> don't have one.


David Ilvson asks <snip>explain how one get the correct bore distance from
samples?   I was under the impression you needed string heights and center
pin height?   How does an old hammer give you the correct blow distance?

In the Renner catalog it says " If you wish to preserve the original
placement of the hammers, we will duplicate your original samples to
determine the original strike point.

It says nothing about the necessity of string height or center pin height.
In this particular case since the hammers being replaced are most likely
very similar to the new ones it would be a simple matter to align the
hammers at specific points by the swell of the felt and the alignment of the
tails to ascertain the proper point for the bore. Yes the strike point will
be worn/shaped away on the samples, however by aligning the hammers as
closely as possible otherwise it is fairly easy/obvious how much felt is
worn/shaped away. Leaving the bore of the sample hammer in line to mark the
new hammers.

It is precisely this sort of "mistake" on the boring either a few mm one way
or the other and angles not quite right that convinced me that I was better
off boring my own. If those get screwed up I know who's to blame!
I also have the opportunity to bore a few samples and test fit them prior to
boring the set, so if I'm wrong I only have a few to fix, assuming I wasn't
using "extras" which I customarily do.

I purchased the boring jig from Renner about 3 or 4 years ago and use it
in a tabletop drillpress from Craftsman. The very same jig they show in the
picture in the Renner catalog on the hammer services page. So far so good.

Mike
-- 
Learn from yesterday, live for today, hope for tomorrow. The important thing
is to not stop questioning.-- Albert Einstein



Michael Magness
Magness Piano Service
608-786-4404
www.IFixPianos.com
email mike at ifixpianos.com
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