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Which co-polymer do you recommend?
Mcmaster-carr acetal co-polymerI bought a 3/4 x 12 x 12 last time, and bandsaw it as needed. I might consider a 1/2 thick piece next time...not sure. It machines well with woodworking tools. I prefer to bandsaw it when doing beveled rests. It doesn't like to be jointed when the piece gets too thin.
As far as cold creep, no, I haven't noticed. Bottom line is the pianos are stable, and that is the point of this excercise.
By the way, I thank Ed Mcmorrow for doing the leg work on co-polymer rests. I had been thinking about this for a while, and experimenting with it, when Ed came out with his FTDS patent. When I saw he had already done the legwork on the susbstance, I was already ready to go.
Also, I came to try this substance after numerous disappointments using brass half-rounds. I had committed myself, earlier on, based on the advice of mentors, to use the brass instead of bearing felt. However, I was very disappointed with the results, and that propelled me to look for a different solution. Based on the advice of mentors regarding brass counter-bearing bars, whenever I saw a brass half-round set up, I was in eager expectation of an easily rendering tuning experience. Unfortunately, my experience has been that these setups if not done well can be really difficult to tune, creating problems of their own (my own experience, can't speak for others). There are situations where they provide for horrible rendering. Specifically:
-Long tenor duplex to the Brass, combined with thick dense felt on the pin side...impossible to tune...a Chinese specialty
-Brass well up the ski slope with quieting felt in the duplex (can be soft, and only 1/4" wide but its there), and then some more 1/4" wide soft felt on the pin side. These setups usually are like this because the termination angle is quite aggressive. Foeresters have this, at least the 170 I care for has it. The long elastic length of the tenor duplexes before they hit the bar create a third segment to equalize. Very hard piano to tune. I've learned how to do it, but it can be real slow and sneaky.
-Brass close to the agraffes to eliminate a duplex, then a second piece of brass to allow a decent string takeoff angle to the pins...awful rendering from the second friction point and elastic space between the two.
The difficulty is often in the tenor where the ski slope makes it problematic to get decent string angle takeoff to the tuning pin. The string is lifted to achieve this string takeoff angle, and it makes life difficult. Each piano id different and it takes some thought and time to work out all the parameters. Putting a high value on compliant rendering , the co-polymer has made this design dance easier than the other options for me.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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Original Message:
Sent: 02-23-2017 05:43
From: Chris Chernobieff
Subject: Steinway D String Bearing Assemblies
Hi jim
The pics look great. You've inspired me to give this a try. Which copolymer do you recommend? And any concern or observation of cold flow?