[pianotech] New custom agraffe design

[Encore Pianos]

Thanks, Ron.

Will

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Overs Pianos
Sent: Wednesday, June 13, 2012 7:41 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] New custom agraffe design

Hi Mark,

>Thanks for sharing the photo. I'm sure these are expensive to produce, 
>but I think you would still have a some willing buyers if you wanted to 
>supply them. If so, do you think you would be able to make them with 
>different thread sizes (such as 5.65mm x 33 and 6.65mm x 33)?

This is possible but I decided on getting only three thread sizes made,
7/32" X 36 tpi (Steinway), 1/4" X 32 tpi (Kawai) and 7mm X 0.75 (Yamaha).
Changing the thread size is relatively easy once the machining centre is set
up, but the cost of set up is quite high. So doing a set up for one thread
is quite expensive.

The thread sizes you mention are the current Bechstein threads, where you
will have to pay the cost of half a rebuild just to get hold of a couple of
thread taps from Bechstein, not to mention the cost of the agraffes, which
are only free-machining-brass items anyhow. This company has turned 'making
life difficult for technicians' into an art form.

I would suggest that when you rebuild Bechsteins (ie. those that are out of
warranty), simply fit Yamaha agraffes after drilling and tapping the
Bechstein plate to accept them. The Yamaha thread size is
7 mm X 0.75 mm pitch. The minor diameter drilling size for this thread is
6.1 mm. 7 X 0.75 thread taps aren't hard to come by, so it is an easy
solution to a big problem, when dealing with this make of piano.

We've had some of our custom agraffes made with Yamaha thread size, to
enable us to fit them to some of the pianos with mongrel thread sizes, in
addition to Yamaha grands.

As to cost of our custom agraffes, this matter with regard to supply is very
much up in the air. I got this batch made by a local CNC machinist who
quoted me a price, then found he needed to slow the machine down when
cutting the internal 'doughnut', to prevent chattering. So he cut the supply
quantity down by 20% to keep his machine time to quote. So I paid a premium
of A$8 per agraffe + plus my custom-cutters price, and that's before I've
polished the outside, then had them EN plated.

I'm currently looking for another CNC machinist to deal with, since I had
other issues with the guy I dealt with over and above price. I would be
happy to supply our agraffes, but I still need to work through the
production process, and to find a CNC machinist who is in interested in the
project. I paid $800 for special cutters to be made. So when my relationship
with this guy fell over, I insisted that I got the cutters with my agraffes,
since I paid for them.

To answer your question Will, the agraffes were machined from SAE
4140 12 mm diameter bar stock, so the entire agraffe is made from a single
piece. The photo link in my previous post was taken after polishing and
before the EN plating.

Ron O.
--
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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Web http://overspianos.com.au
mailto:ron at overspianos.com.au
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