[pianotech] New custom agraffe design

[Overs Pianos]

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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mailto:ron at overspianos.com.au
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