challen regulation

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cormac kenny
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challen regulation

Post by cormac kenny » 28 Mar 2013, 05:40

hi
i have just purchased a beautiful challen baby grand ~1931

it was a total bargain, plays better than almost any non-steinway-perfect-concert-hall piano i have played before, an absolute dream piano! for me at least.
however its an old piano, and has a couple of small issues which i cant find answers for in the reblitz book or online. i also called a tech but i think he turned out to be a bit of a cowboy, had no answer to any of the problems i found in the piano.
i have been starting to learn about regulation and would love some advice from other enthusiasts!

the biggest issue is that the sustain pedal, when released, sort of slaps off the strings and makes sort of white noise accross every string. this only happens when you keep the weight of your foot on the pedal, if i lift my foot entirely there is no problem.
i have adjusted the pedal so that there is about 1/4 inch of lost motion but the problem persists. it feels like the pedal presses down too easily before starting to lift the dampers, and should have more even resistance before and after the dampers start to move.
it seems like this should be an obvious problem to resolve for someone who knows what theyre doing!
anyone have any advice?
thanks a lot!
i will post pictures if i get responses on this thread and hopefully continue the project of perfecting this beautiful instrument
there are a few more issues that i will get to but i dont want to create a massive post

(i am new to post on this forum but have been reading it for the last 2 months when considering what to look for in a second hand piano, thanks everyone!)

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Colin Nicholson
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Re: challen regulation

Post by Colin Nicholson » 31 Mar 2013, 02:38

Very common for old grands. There is no individual remedy for this - replace damper felt. backing cloth, and replace strings, and repin the whole damper assembly.... not a job for a novice or "flick through the pages DIYer"

(added Sunday) .... old dampers often have dry, brittle and 'crusted' felt as it is exposed to the elements. Due to various strings vibrating in sympathy with each other, its impossible to pin-point a specific damper. Lost motion in your pedal has got nothing to do with the actual sound production made by the strings & dampers.

I reckon - a piano aged over 80 years old.... needs a refurb.

Another problem that might occur.... check to see if the coil spring is missing, between the sustain pedal trap & underside of piano.... if this spring is missing, there will be little resistance. The spring is about 5-7cm in length, and often sits in a bushed hole.
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cormac kenny
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Re: challen regulation

Post by cormac kenny » 01 Apr 2013, 12:43

ah brilliant! yes its the coil spring i think theres a hole but no spring in it can i just use any spring that size or is there a specific tension piano spring?
other than that the dampers work really well
thanks a million colin!

by the way does anyone know a good tech in dublin? the guy i got didnt seem to know what he was doing he had no suggestions for a few problems..

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Colin Nicholson
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Re: challen regulation

Post by Colin Nicholson » 01 Apr 2013, 17:03

There are usually 2 coil springs on grands for the sustain pedal workings.
1. Coil spring between the rocker trap mech & underside 'bulkhead' (as mentioned)
2. Coil spring between the rear of keybed & damper rail (with action removed, its right at the back, on the right hand side near the bulkhead.

The bulkhead is the area where the back of the wrest plank & soundboard meet underneath - the damper bodies & damper blocks & grub screws located (where the damper wires are screwed into). Check that this long rail also has a spring?

You will need to get the right spring for it, so you dont damage the rail flanges & their housings. I'm not sure of the length of the spring, but here is a rough guide:-

Thickness of spring = 2.4mm
Diameter = 16mm (the bushed hole will be a guide & poss. slightly larger)
Length? = approx 50-70mm

The spring must also be tapered flat at each end.
You'll have to remove the pedal lyre to fit the spring, then offer the rocker back into position.

It could have been lost during removal?

Sorry, dont know a tuner in Dublin area - Barrie might know when he sees this.

Hope that helps

Hope that helps
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Colin Nicholson Dip. Mus. CMIT CLCM PTLLS
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cormac kenny
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Re: challen regulation

Post by cormac kenny » 01 Apr 2013, 17:06

the hole appears to be off to the side of the pedal trap, so it must have been a wierd shape, but i was able to improvise with a spring from an old drumkit, problem solved! feels soo much better
thanks again colin

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athomik
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Re: challen regulation

Post by athomik » 01 Apr 2013, 17:14

Conor Farren might be able to give you a name to contact. He's an electronics engineer who has worked on Disklaviers, so he may know a few tuners/technicians.:

Conor Farren Electronic Organ Repairing (Dublin 1)

9B Abbey st Lr 1 Co. Dublin
D1 Dublin 1 (Dublin city)
(01)8747909

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Colin Nicholson
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Re: challen regulation

Post by Colin Nicholson » 01 Apr 2013, 18:51

(See diagram below)
Your local tuner may have a spare pedal spring, however these are usually shorter than upright piano springs. The other spring may be the same length as the one missing.

An engineer (if you know one) should be able to make one giving the right spec. Most springs have the same diameter/width & pitch for all pianos.

Here is an example of 2 identical springs I ordered recently to be made by hand on a machine..... but these springs are too long for a grand piano!
Make sure they are made from brass (not mild steel), and always quote the diameter/ pitch of the spring for compression reasons..... >>>
BechSpringSpec.JPG
Sample pedal spring
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Colin Nicholson Dip. Mus. CMIT CLCM PTLLS
Piano tuning & repairs. Full UK restoration service
http://www.aatuners.com
Tuition ~ Accompaniment ~ Weddings
http://www.pianotime1964.com
Member of The Guild of Master Craftsmen

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