Guidelines for setting backchecks

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Withindale
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Guidelines for setting backchecks

Post by Withindale » 05 Dec 2012, 13:36

I need to regulate a 107 year old grand piano that was restored 3 - 5 years ago. Unaccountably the action had become "graunchy" to the point of being unplayable.

As a first pass I have set the let off close to the strings, increased the blow distance from less than 40 mm to about 45 mm and adjusted the drop on some sample keys. There has been a big improvement and, before doing the whole job properly, I would welcome any advice on setting the backchecks.

My previous experience is with an upright and, in contrast to Reblitz's rule of setting the back checks exactly 16 mm from the strings, I found the touch was much better when they were considerably closer.

In a response to a question about dip and back checks on my upright, Barrie mentioned that "Alfred Brendel liked a 9mm dip and the checking as close as possible".

Are there any guidelines, approaches or tips to setting the checks somewhere between Reblitz's and Brendel's extremes, or is it just a question of trial and error?

Also where on the back check leather should the curved tail of the head come to rest after hard and soft blows?

Many thanks.

Ian

PS One note I found, relating to a Steinway B, With the key depressed and the hammer against the string there should be approximately 1/16" between the end of the tail and the top of the check. This will give you 7/16th's tail in the check at 1/2 inch check from the string. General starting point.

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Re: Guidelines for setting backchecks

Post by Barrie Heaton » 05 Dec 2012, 17:35

Depends on the make S&S, Bluthner ect like you to bring the backchecks as closes as you can to the hammer tail, without snagging on them on the upstroke, so depending on the leathers checking can be very close. The likes of Yamaha and Kawai they like a measurement all depends on Model but a rule of thumb 16mm is OK However, on an older piano with worn parts measurements are only a guideline its the feel that matters.

You may have to make the Drop 5mm, 4mm and 3mm to help with checking if you have the set off (let off )at 3 2 1 with it being an older piano if you have the depth of touch (dip) set at 9.5mm

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Re: Guidelines for setting backchecks

Post by Withindale » 05 Dec 2012, 18:11

Many thanks, Barrie, that's precisely what I need to know.

The piano is an Ibach so I assume it's in your Bluthner etc. category. The depth of touch is just under 10mm, maybe 9.5mm, I'll check. 0.25mm made a big difference to the upright so I have some idea of what to look for.

I'll play with a few sample notes at the weekend and see what feels best.

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Re: Guidelines for setting backchecks

Post by Colin Nicholson » 05 Dec 2012, 23:14

I've got all the spec for Ibach if you need any measurements, but I think they are for new or restored pianos? The key dip for all grands is 10mm, back check distance is 13mm, drop 2mm. Blow distance = 45mm. Also just check the 'white' key height - should be 66mm from keyframe to top of key, and the sharps 11mm above the white keys. Thats for the grands F II (5'11"), F III (7'1") and F IV (7'9")

Hope that helps....

oh, and set-off (according to the book) is 3mm in the bass, and 2mm in the middle & top treble.

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Re: Guidelines for setting backchecks

Post by Withindale » 06 Dec 2012, 01:05

Many thanks, Colin, most helpful, those numbers will keep me on the right track.

The height of the white keys height is about 67 mm (with plastic replacement tops) and the key dip is about 10 mm ,

Everything else was way out; it's already evident that putting things back to where they should be will largely solve the problem.

Ian

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Re: Guidelines for setting backchecks

Post by Colin Nicholson » 06 Dec 2012, 07:42

As a general rule of thumb, if a "full-on restoration" - then I'll replace the back check leathers, backing felt (if fitted) and front rail baize washers due to uneven wear. Then most important, make sure your rep springs are working fine before you set the hammer height - so the rollers are resting on the rep levers, and not the jacks (even if over-tensioned at this stage). Then, set your hammer blow & key dip first - the rest should fall into place fine.... then finely adjust the rep spring tension later so the hammers give a little 'kick' after a decent blow . To get your checking spot-on, and to ensure your back checks are in a straight line, the odd very thin paper washer may be needed under the front rail baize washers during "drumming off" the back checks.

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Re: Guidelines for setting backchecks

Post by Withindale » 11 Dec 2012, 13:54

Thank you again Colin for your helpful advice.

I've just seen this on the Hurstwood Farm site:
Grand actions have changed little since the mid nineteenth century and are based on inspired work by the French entrepreneur and piano genius Erard. They are astonishly robust and versatile so that in the hands of a skilled technician can provide almost any feel or response an artist may demand. Their weakness is that these actions all require great skill to regulate them to perfection. These days few instruments are set and maintained in ideal condition because that takes great time and care which most modern technicians seem unwilling or unable to apply.

To do the job properly I'd better level the keys first so it's clear I'm in for a lot of fun over the holidays.

Ian

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Re: Guidelines for setting backchecks

Post by vernon » 11 Dec 2012, 21:02

I assume you are regulating the action out of the piano and on the bench.
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Re: Guidelines for setting backchecks

Post by Withindale » 11 Dec 2012, 22:02

Yes indeed, Sir.

Shortly after posting I came across a note by a Piano Technician in New York about spending 17 hours regulating a Steinway C and still needing to go back for some finishing touches on rep springs and dampers.

Among the things he mentioned, I need to level keys, check dip, level strings, align hammers, adjust rep lever height, blow, letoff, and drop as well as rep springs and dampers.

Hadn't expected to do any of that, given that the restorer had sold the piano to the previous owner less than three years ago, but what is par for the course?

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Re: Guidelines for setting backchecks

Post by D.J.Smith » 12 Dec 2012, 10:39

Have fun Withindale!

I've just completed the same task on a 6 foot 6 Barless. Starting from scratch with key-frame bedding it took me 3 full days.

I found key levelling and damper adjustment the most time-consuming.

The piano is transformed, well worth the effort. No doubt yours will be too, so go to it.

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Re: Guidelines for setting backchecks

Post by Barrie Heaton » 12 Dec 2012, 21:11

Withindale wrote: These days few instruments are set and maintained in ideal condition because that takes great time and care which most modern technicians seem unwilling or unable to apply. [/i]


Ian
There are technicians who can't because of lack of training. The ones that can, Its not that we are unwilling to do the job, clients are unwilling to pay. Lets face it most of us Tune pianos to make a profit. so you choose the most profitable

Reg and voicing = Shed full of tools and materials, backache, Housemaid's knee, bad tea and a cheque at the end of the job.

A Reg and voicing on say a grand that has come form Poland is equal to 20 Tunings. Tuning pianos = 4 tools at the most, No Housemaid's knee, No backache, some bad tea, lots of cash and cheque and you are home before 4 pm on most days


Yet some! still like the challenge so we reg and voice for the love of it in real terms of a balance sheet.


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Re: Guidelines for setting backchecks

Post by Withindale » 16 Dec 2012, 12:10

Barrie Heaton wrote: ... backache, Housemaid's knee, bad tea ...
A quick question about key dip, let off and aftertouch.

Sparked off by Roger Jolly's suggestion to set let off by backing off from where the hammer blocks (Complete Grand Regulation, PTG, 2004), it struck me I could do a quick initial regulation by setting let off with the action in the piano and then take it out to adjust hammer blow and drop. So far so good.

The complication is that key dip at the pin is about 9.5 mm rather than the standard 10 mm Colin mentioned. With this dip and close let off the result is minimal aftertouch.

I can live with that for the time being but is there any good technical reason to increase let off and thereby aftertouch?

Note: better to leave key dip for now as key bushings need attention as well as keys levelling.

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Re: Guidelines for setting backchecks

Post by Barrie Heaton » 16 Dec 2012, 14:26

You need to do the Blow first - When you alter the blow you alter the set off

You can use the block method on Set off (let off ) its the way most Blind tuners do it

The trick to good regulating is to go round and round getting it better each time

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Re: Guidelines for setting backchecks

Post by vernon » 16 Dec 2012, 19:31

Don't forget,before starting grand reg,bend all the dampers back out of the way so they don't give you false responses.
5 minute job to reg them at the end with checkbende rand and old fashioned germans
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Re: Guidelines for setting backchecks

Post by Withindale » 16 Dec 2012, 20:08

Barrie Heaton wrote:The trick to good regulating is to go round and round getting it better each time
Words of wisdom, Barrie. After a few readjustments, the piano is now fully playable and what needs to be done in the next round will soon become clear, no doubt.
vernon wrote:Don't forget,before starting grand reg,bend all the dampers back out of the way so they don't give you false responses.
I now know exactly what you mean, Vernon, three in the bass.

Sincere thanks to you all.

Ian

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Re: Guidelines for setting backchecks - Feedback

Post by Withindale » 02 Jan 2013, 19:29

D.J.Smith wrote:Have fun Withindale!

I've just completed the same task on a 6 foot 6 Barless. Starting from scratch with key-frame bedding it took me 3 full days.

I found key levelling and damper adjustment the most time-consuming.

The piano is transformed, well worth the effort. No doubt yours will be too, so go to it.
Yes, the piano is transformed. Took me longer than three days on and off though, going round and round the learning curve, and the (not too bad) dampers are still to do. I thought I was getting there when I found myself tweaking for pppp.

The biggest bang for my buck in terms of time came from setting the strings to liven up the treble and, to my complete surprise, from slightly tightening three or four frame brace screws which did absolute wonders for the sustain.

I'm afraid Colin's drumming off the back checks will have to wait until I rebush the keys. Meanwhile I've cheated with some folded paper shims in the worst of the knocking mortices.

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Re: Guidelines for setting backchecks

Post by rxd » 04 Jan 2013, 08:43

vernon wrote:Don't forget,before starting grand reg,bend all the dampers back out of the way so they don't give you false responses.
5 minute job to reg them at the end with checkbende rand and old fashioned germans
Care to expand on that, Vernon, it's not making sense to me, especially when I can save all that by simply stepping on the sustain pedal with my old fashioned plates.

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Re: Guidelines for setting backchecks

Post by vernon » 04 Jan 2013, 15:16

I'm talking about when the action is on the regulating bench.
As you know one of the last jobs in regulating is aligning the checks.
So one of my first jobs is to bend them well clear so the cannot influence the subsequent adjustments.
A check just touching a hammer or a check touching the next hammer-- all these things can send you up a blind alley or early dementia as you find adjustments to other components are'nt responding
So-- bend them out of the way.
Same with uprights,after you've confirmed that the slap rail isn't too close or the setoff rail is in the right place and indeed is tight and not sliding back and forth as the note is played.
Many a technician would still be with us now if he'd attended to the basics
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Re: Guidelines for setting backchecks

Post by rxd » 04 Jan 2013, 17:24

Ahhh, back checks, not dampers. That makes more sense.

It says dampers on my screen. Must be my spellchecker. Always blame the spellchecker.

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Re: Guidelines for setting backchecks

Post by vernon » 04 Jan 2013, 19:13

yes checks not dampers. It's not your spell checker. Must be that blasted Glenfiddich.
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