Damper Spring Tension
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Terry Farrell
Mar 14, 2014, 7:50:57 PM3/14/14
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Is there any good data available on recommended damper spring tension?
What kind of force should dampers be pressing against strings?
Anyone ever ease Asian piano damper springs because their high tension made the action feel heavy?
How did you do it - I mean how did you do it to make tension even - how did you measure it?
With touchweight as a guide, how many grams should dampers add to key downweight? I should think there is some minimum pressure the felt should apply to the strings - perhaps less in the treble/tenor, more in the low tenor and the most in the bass - especially the monocords.
Thanks (there is more to come on this.....)
Terry Farrell
What kind of force should dampers be pressing against strings?
Anyone ever ease Asian piano damper springs because their high tension made the action feel heavy?
How did you do it - I mean how did you do it to make tension even - how did you measure it?
With touchweight as a guide, how many grams should dampers add to key downweight? I should think there is some minimum pressure the felt should apply to the strings - perhaps less in the treble/tenor, more in the low tenor and the most in the bass - especially the monocords.
Thanks (there is more to come on this.....)
Terry Farrell
Joseph Garrett
Mar 14, 2014, 8:00:24 PM3/14/14
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Terry,
I have "eased" damper springs and tried to make them consistent. I did that by increasing or decreasing the curve of the long part of the spring. I measured the dampers with a gram gauge, as is used to measure center pin friction. The gauge is a higher range gauge.
I'd venture there are spring tension charts hidden in several manufacturer's cobwebs, as in the files of the Action Designer. I've never seen such a chart, if, in fact it is a chart.<G> It used to was that damper springs were different gauges for different areas of the piano. It somehow, through expediency I suspect, gravitated to one size fits all. :-(
Joe
Captain of the Tool Police
Squares R I
gpianoworks.com
I have "eased" damper springs and tried to make them consistent. I did that by increasing or decreasing the curve of the long part of the spring. I measured the dampers with a gram gauge, as is used to measure center pin friction. The gauge is a higher range gauge.
I'd venture there are spring tension charts hidden in several manufacturer's cobwebs, as in the files of the Action Designer. I've never seen such a chart, if, in fact it is a chart.<G> It used to was that damper springs were different gauges for different areas of the piano. It somehow, through expediency I suspect, gravitated to one size fits all. :-(
Joe
Squares R I
gpianoworks.com
William Benjamin
Mar 14, 2014, 9:21:45 PM3/14/14
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Joe,
When I was young too, I tried my best to make dampers springs perfect. I made a small gram weight jig and evened the springs so to be all the same. I put a lot of time into it and in the end, I decided they were too much trouble for the work I put into them.
Win some and loose some.
By the way, I have a new program and I do not have the spell check working yet.
William
When I was young too, I tried my best to make dampers springs perfect. I made a small gram weight jig and evened the springs so to be all the same. I put a lot of time into it and in the end, I decided they were too much trouble for the work I put into them.
Win some and loose some.
By the way, I have a new program and I do not have the spell check working yet.
William
Joseph Garrett
Mar 14, 2014, 10:04:07 PM3/14/14
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William,
IMO, the dampers should graduate from bottom to top, i.e. heavy to light. That is because each note has a different amount of energy to be absorbed.
Joe
IMO, the dampers should graduate from bottom to top, i.e. heavy to light. That is because each note has a different amount of energy to be absorbed.
Joe
Euphonious Thumpe
Mar 14, 2014, 11:11:26 PM3/14/14
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| Reduce tension by spacing the spring rail further out from the action brackets with punchings. Thumpe Sent from Yahoo Mail for iPad |
Sent:
Sat, Mar 15, 2014 2:04:07 AM
Euphonious Thumpe
Mar 14, 2014, 11:13:58 PM3/14/14
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| My goof --- duhhhhhh. I meant that some lightness can be gained by spacing out the HAMMER BUTT SPRING RAIL! (Duhhh...) |
Sent:
Sat, Mar 15, 2014 1:13:52 AM
Joseph Garrett
Mar 14, 2014, 11:28:06 PM3/14/14
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Thumpe(r),
We are talking about an Asian piano that does not have a hammer spring rail. AND, we are talking about DAMPERS, not hammers. So, that "fix" isn't valid.<G>
Best,
Joe
-----Original Message-----
From: Euphonious Thumpe
Sent: Mar 14, 2014 8:11 PM
To: "pian...@googlegroups.com"
Subject: RE: [pianotech] Damper Spring Tension
Reduce tension by spacing the spring rail further out from the action brackets with punchings.
Captain of the Tool Police Squares R I gpianoworks.com
Joseph Garrett
Mar 14, 2014, 11:29:05 PM3/14/14
to pian...@googlegroups.com
Not recommended, imo.
Joe
-----Original Message-----
From: Euphonious Thumpe
Sent: Mar 14, 2014 8:13 PM
To: "pian...@googlegroups.com"
Subject: Re: [pianotech] Damper Spring Tension
My goof --- duhhhhhh. I meant that some lightness can be gained by spacing out the HAMMER BUTT SPRING RAIL!
(Duhhh...)
Terry Farrell
Mar 15, 2014, 7:50:16 AM3/15/14
to pian...@googlegroups.com
That's my goal - heavy to light. When at the piano I eased several damper springs in the middle of the piano to see how much easing I could do before the dampers started to leak - and then I tightened those few up a little bit. So presumably they were adjusted to minimal spring tension for good damper operation with a little bit more for insurance. Then back at the shop I measured the unadjusted and optimized damper pressures and found that the originals were around 30 grams (as measured by the simplistic spring force measuring tool - it was also at the very end of its scale, so I don't know that the absolute value of 30 grams means much), and the optimized were right around 20 grams (as measured at the top of the damper felt - there wasn't anywhere else on the damper to measure from with the tool I have).
I only did one octave in the middle of the piano as an experiment. Assuming all the dampers work well adjusted as they are, I will then experiment with the bass dampers, etc. to see how much pressure is required to have them work properly - I presume they will require more than 20 grams of pressure. My guess is that I'll end up with three different target damper pressures - 20g for the tricord flats, more for the bicord wedges and even more for the monocord (what the heck do you call the shape of a monocord damper felt?).
Terry Farrell
I only did one octave in the middle of the piano as an experiment. Assuming all the dampers work well adjusted as they are, I will then experiment with the bass dampers, etc. to see how much pressure is required to have them work properly - I presume they will require more than 20 grams of pressure. My guess is that I'll end up with three different target damper pressures - 20g for the tricord flats, more for the bicord wedges and even more for the monocord (what the heck do you call the shape of a monocord damper felt?).
Terry Farrell
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