[pianotech] Re. Hide Glue was Wat Glue

[Ron Overs]

>Joseph Garrett wrote:
>>Ron,
>>That's been my experience as well. Also, it helps if the shanks are 
>>knurled properly. The purpose of knurling is to compress the wood, 
>>slightly. When the water base hide glue hits it, it starts to 
>>expand. If you have done the drilling and knurling correctly, there 
>>will be NO failures, IMNSHO!<G> Ya almost have to use plastic 
>>explosives to remove the hammer head(s)!<G>
>
>Hi Joe,
>I don't knurl them beyond what they are stock. I expect a process to 
>meet me half way when I've gone to the effort to figure out how it 
>works. Seems only fair. Otherwise, I need a different process.
>Ron N

I knurl the shanks again just before hanging the hammers (but I don't 
knurl them too hard), because the shanks will swell after knurling to 
varying degrees over time. I have found quite a lot of diameter 
inconsistency from shank to shank within a new set, even though they 
were knurled at the time of manufacture. The process of knurling them 
again causes the diameter deviation of the set to be much reduced, 
which results in much better control of the clearance between the 
hammer bore diameter and the knurled shank at the time of glue-up. I 
also agree with Joe that the diameter-growth which occurs once the 
shank comes into to contact with the glue makes for a faster set up 
if the clearances have been carefully controlled.

It a sheer pleasure to hang a set of hammers when things are going as 
intended. Hammer hanging is one of my specialties at our place.

Image of the hammers being hung on our piano no. 6
http://users.tpg.com.au/ronovers/hmmr.hng.no.6.jpg

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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