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backcheck regulation

  • 1.  backcheck regulation

    Registered Piano Technician
    Posted 08-29-2020 21:12
    What is the reason for the backcheck to hammer tail distance spec of a 2mm gap (when not in check)? I'm assuming it affects repetition but it also seems (to me) like careful bending of the backcheck wire would/could make up for it as well as the fact that the shape of the tail  can mean the difference between success and failure.

    What is sacrificed if the hammer tail rests 2mm below the top of the backcheck?

    Thanks for considering

    ------------------------------
    Eric Johnson [RPT]
    [Eric Johnson Pianos]
    [Westport] [CT]
    www.ericjohnsonpianos.com
    One year older and dumber.
    ------------------------------


  • 2.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 01:05
    Is this with the key at full dip?

    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------



  • 3.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 18:15
    Yes, key fully depressed and hammer at letoff

    ------------------------------
    Eric Johnson [RPT]
    [Eric Johnson Pianos]
    [Westport] [CT]
    www.ericjohnsonpianos.com
    One year older and dumber.
    ------------------------------



  • 4.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 02:10
    Eric,
    What I have read is the 2 mm gap is before bending (after installation.) Richard Davenport mentions a 1 mm gap, and I think this after bending (which may be equivalent.) An interesting question about what may be sacrificed by a longer tail, and though I don’t have an answer, I will ponder it. Thank you for the question.

    Joe Wiencek




  • 5.  RE: backcheck regulation

    Member
    Posted 08-30-2020 09:38
    I no longer pay any attention to these prescriptive parameters, as they are all based on assumptions of geometry, which may or may not...usually not...be present in the actual as-built action.  When I tried to apply these prescriptions, without understanding the full system geometry, for several years, I left a trail of lousy checking actions; an MO if you will..."lousy checking, Ialeggio must of been here". The geomtery's were simply not described by these parameters with any regularity, either between pianos or within a particular piano.

    They assume, or have to assume, a certain check distance, 5/8, 7/16, 3/8. They have to assume a certain key dip, .390, .40, .410, or more. They assume bore is correctly matched to string height across the compass ( an entirely fictitious assumption, unless custom bored well...and even then still fictitious). They assume the out-of-cavity position of the action/keyframe is actually producing the targeted dip per each key, when tested. They assume check height is correct for the check height chosen (another usually incorrectly targeted dimension, relative to the as-built conditions of a particular action). They assume string height is within certain parameters, usually pretty close to 7-3/4" or so.

    Once I started ignoring these instructions, my check installations, instead of being my achilles heal, improved significantly.

    Check happens, geometrically, at one point in the intersection of the involved arcs...that's one point in the universe. Thankfully, give in the system widens the range of effective check, a little, but not much. Where that point will occur, in a particular action or manufacturer's action will vary as per the geometry of that installation. All geometry's vary, even model to model for a particular manufacturer. That geometry also changes across the keyboard of an individual piano.

    This whole thing is quite present to me, as I work on a lot of Chickerings, and redesigns of Chickerings. What does that, or any prescription, do when faced with a 7" string height action, when the prescription is based on a 7-3/4" string height, or when dips are shy by modern standards.

    Instead, I take each and every action as a unique geometry or collection of geometries, and empirically ask the geometry where those arcs will intersect in that particular action. Its rot gut simple to lay out, and leaves all the prescriptions to confuse somebody else.

    Not sure Eric wanted to take this to layout procedures. I can post if there is interest. But I did want to convey how, to me, these prescriptions are wildly confusing to counter productive, and do not confer understanding of the system's geometrical requirements. By the way, even though I love what WNG is doing with their parts, their installation protocols are prescriptive as well. They make all the disembodied assumptions outlined above, and preclude an understanding of the geometry involved in the use of their particular design of the check and tailing tools. And they also change prescriptions from time to time, leaving one scratching one's one's head trying to reconcile previous prescriptions with the new improved prescriptions.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 6.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 13:54
    Hi Jim-
    For myself I would be very interested in how you determine where the arcs of the hammer tail and back check surface intersect. My understanding is it is this convergence of arcs that actually makes for good checking.
    Many thanks in advance!

    ------------------------------
    David Brown
    Garland TX
    ------------------------------



  • 7.  RE: backcheck regulation

    Member
    Posted 08-30-2020 15:13
    David, I shoot for a 27 mm tail with a 3" arc. The back check is 68~72° to the key. You have to take into account string height, hammer bore, blow distance.
    Action Ratio dictates how well it all works.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 8.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 17:47
    Jon,
    Do you measure the 3” from the back of the hammer molding? (Or the center?)

    Joe Wiencek




  • 9.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-31-2020 11:38
    Thanks for that, Jon. How do you locate where the back check wire enters the key?  Straight or angled?

    ------------------------------
    David Brown
    Garland TX
    ------------------------------



  • 10.  RE: backcheck regulation

    Member
    Posted 08-30-2020 15:15
    <My understanding is it is this convergence of arcs that actually makes for good checking.

    This is absolutely correct, but not necessarily that easy to pull off, unless you ask the action itself where they converge.  I'll put a description together...it is rather simple...I'll do it later.

    ------------------------------
    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------



  • 11.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-31-2020 11:36
    Thank you Jim. I have often thought about how I could mock up dividers to actually locate this in space. I am sure your method will be simpler!

    D

    ------------------------------
    David Brown
    Garland TX
    ------------------------------



  • 12.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 09:23
    Older and dumber aside, your question poses a series of vageries that resist simple answers.  Given the significant range of tail / check configurations (profiles) and physical characteristics (surface texture-resilience, not to mention wire stiffnesses, I would imagine that 2mm is a conceptual distance, though your last question is further confusing (potentially) in posing the reverse condition (2mm below instead of 2mm above).   Is there a co-related assumption regarding the height (proximity to string) of checking?
    Assuming that (as per Ed McM's question) the measurement is at full dip, that there is no rubbing issue at forte, that there is no issue of hammer shoulder (especially in larger bass hammers) hitting tops of bchks returning to rest position, and the tail impact is not too abrupt, the question would remain as to which of the wippen functions (keeping hammer elevated or propelling key back to rest position) is more critical to repetition.  In the case of Steinway style butterfly springs, a strong setting with high checking could bounce back and restrike string in soft playing.  A weaker setting  would slow both the jack return as well as downward momentum of key.




    ------------------------------
    David Skolnik [RPT]
    Hastings-on-Hudson NY
    917-589-2625
    ------------------------------



  • 13.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-01-2020 11:21
    The basic goal is you want as high checking as possible without the tail of the hammer catching on the way up or the shoulder of the hammer contacting the back check when at rest.  High checking allows you to set the rep spring with more tension (not the other way around).  The hammer being thrown into the string happens with a combination of too great a checking distance combined with too high a tension.  So with high checking you get better repetition due to the ability to set the tension of the rep spring higher.  The 2mm rule is a guideline to achieve that.  The 3" arc that Jon mentions is so that the sharp edge of the tail doesn't contact the back check.  Instead the hammer should check on the curved arc of the tail.  Catching on the bottom edge of the hammer tail will cut into the leather and eventually form a shelf that prevents proper checking.  The angle of the back check should be such that when the hammer is in check and you press down on the hammer, pushing it further into check, you encounter increasing resistance.  You shouldn't be able to push the hammer all the way through checking as that means you will have inconsistent check height depending on the force of the blow.  As Jon mentioned that's usually best accomplished with the check set between 68 and 72 degrees.  Neither should you be unable to push the hammer deeper into check as that will result in what's called "hard checking": the catching of the hammer will be too abrupt and you'll feel it in your finger.   Back checks with stiffer wire (such as Renner) will tend to have a smaller angle to work properly in that respect than back checks with more flexible wire (such as Tokiwa).  More flexible wire allows you to set more angle to the backcheck without resulting in hard checking and that increased angle with more flexible wire will give you more consistent checking distance.

    For backcheck location on the key this diagram shows a jig for determining location (originally posted by David Brown back in 2018 by Richard Davenport).  The wire location jig is easy to make.



    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 14.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 10:33
    Hi Eric :o)

    Are you asking about the hammer tail being lower than the top of the backcheck at letoff?

    Assuming that's the case, it runs the risk of the hammer catching on a hard blow. 2mm is a rule of thumb for maximizing repetition. I check this by playing one note repeatedly, the same speed as a trill. (Keep the action in the keybed to avoid skewed readings that only a table can provide 😂)

    You'll want to check the angle too, which you're probably already aware of. You can have the right height but the wrong angle will cause the hammer to check lower with each repetition. I check this by playing the note, and once the hammer checks, pushing down to see if it slides backwards down the backcheck. If so you have the wrong angle. The goal is for the space at the bottom of the backcheck to be narrower than the space at the top (in relation to the hammer tail.)

    I hope this helps! Take good care of yourself :o)

    ------------------------------
    Elizabeth Pearson
    Gaithersburg MD
    240-751-5900
    ------------------------------



  • 15.  RE: backcheck regulation

    Member
    Posted 08-30-2020 11:00
    Depending on the length of the tail, the back checks might be hitting the rear shoulder of the hammer.  Tail arc and b/c angle have to be considered in the equation.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 16.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 18:38
    Thanks everyone for your replies. I've seen this in a couple of places as a specification...have others of you as well or am I making this up?

    You appear to be confirming my hunch that this specification probably doesn't pay much role in repetition and is more to reduce  pre-checking  on a hard blow as Elizabeth says.

    ------------------------------
    Eric Johnson [RPT]
    [Eric Johnson Pianos]
    [Westport] [CT]
    www.ericjohnsonpianos.com
    One year older and dumber.
    ------------------------------



  • 17.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-30-2020 19:54
    Eric -
    Older and dumber aside, I'm not sure that anything was said that would either support or refute a correlation between the characteristics described and effective or exemplary repetition. Why jump to conclusions?  Do you have somewhere you have to be?

    ------------------------------
    David Skolnik [RPT]
    Hastings-on-Hudson NY
    917-589-2625
    ------------------------------



  • 18.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-31-2020 18:49
    No but life is appearing increasingly short...

    ------------------------------
    Eric Johnson [RPT]
    [Eric Johnson Pianos]
    [Westport] [CT]
    www.ericjohnsonpianos.com
    One year older and dumber.
    ------------------------------



  • 19.  RE: backcheck regulation

    Registered Piano Technician
    Posted 08-31-2020 18:50
    Is that a double negative?

    ------------------------------
    Eric Johnson [RPT]
    [Eric Johnson Pianos]
    [Westport] [CT]
    www.ericjohnsonpianos.com
    One year older and dumber.
    ------------------------------



  • 20.  RE: backcheck regulation

    Posted 08-31-2020 19:07
    Thank you Jon and Elizabeth for some important details
    From what I remember of a class from Roger Jolly.
    The back of the hammer molding from center pin scribes an arc radius 5 1/4 inches or so... depending on who made the piano.
    So the radius arc of the tail has to be less than the hammer shank radius.
    Not enough radius and the tip of the tail has problems clearing the check.
    Too much radius and there is less surface contact area on the check. Then roughing the tail becomes necessary and wear becomes a problem.
    2 3/4 to 3 inches is the middle of the road.
    Draw these radius on a piece of paper and add the 68* to 72* line of the back check at full dip. Use an old back check if you need more than a line for visual.
    Shank drawn at level is going to be assumed to be parallel to the key. Then you determine how to adjust the back check angle for the differing pianos.
    Obviously the angle of the check surface is different from the angle of the wire coming out of the key and this provides another radius to be drawn as you pull or push the check. The angle of the check changes in relation to the tail.
    I will be adjusting my new set of back checks this week as she has had time to play it in.
    Thank you for the tips.
    I ended up unscrewing the old checks with the back check remover and put the new ones on with the cordless drill in about an hour and a half.
    Easy, very easy.

    ------------------------------
    Keith Roberts
    owner
    Hathaway Pines CA
    209-770-4312
    ------------------------------



  • 21.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-01-2020 12:00

    Keith,

    You touched on a problem posted on Pianotec in the past; trouble adjusting check without checking on the upswing. As is see it, too much radius (5.25") creates a slow checking sequence. The pianist will have difficulty with fast repetition because the hammer will be traveling in a downward motion (because of slow checking) as the key is returning to rest for the subsequent stroke. Too little radius and the checking is so fast that it creates an undesirable kickback somewhat akin to what we've all experienced when the hammer tail bounces off the top of the backcheck. The unanswered question is: what is the Goldilocks radius and, additionally where is the ideal focal point to give us the ideal checking speed and allow proper checking adjustment, i.e. checking without upward checking. Most manufactures use a 1.5" radius arc, and most important, the focal point. If a 1.5" radius with a focal point placed on the hammer shank line you will encounter removing most the tail because the arc will have started too soon. To eliminate this problem the focal point is placed about 3/8" below (below defined as under the shank while at rest in the action) the shank line.

    Another way of looking at this; the back check has only a certain amount of travel within its motion. If the starting point and final checking point are too far apart you will have boxed yourself into a corner with certain keys stick arcs.



    ------------------------------
    Roger Gable
    Gable Piano
    Everett WA
    425-252-5000
    ------------------------------



  • 22.  RE: backcheck regulation

    Member
    Posted 09-01-2020 12:41
      |   view attached
    Here's a picture of two arcs. Slightly different profile but converge at the end of a 27 mm tail.

    When I order hammer from Ronsen, I request no coving.  Too many times, there is not enough wood to arc if the coving it too deep.  Plus the front of the molding below the shank is a good place to remove a few tenths of a gram.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 23.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-01-2020 16:45
    Thank you for drawing this out. If I understand correctly, to create the 3” arc, one would rotate the hammer tail at a point 3” down the centerline of the shank while shaping? And to create a 1.5” arc, one would rotate from 3/8” below the centerline of the shank (and 1.5” below the center of shank?)

    Based on Jon’s drawing I am not sure I see one arc as being more beneficial over the other for the same 27mm tail. I can see more ease in rotating the hammer tail from the center of the shank (using the bored hammer hole.) Figuring out how to rotate 3/8” below the shank gives my head a spin.

    Of all the converging arcs of two disparate bodies in the piano it seems the hammer tail and back check are the only ones I can conceive that have the same orientation (comparing the opposing arcs of capstan/wippen, knuckle/rep lever, knuckle/jack, key end/damper underlever, damper pedal/damper tray. Though the shift pedal presents an interesting perpendicular convergence.

    Joe Wiencek




  • 24.  RE: backcheck regulation

    Posted 09-02-2020 10:03
    Thanks Jon,,
    That's what happened to me. Ray put the cove on. All the other hammers of his have been uncoved because I got them from Dale Erwin and I put my own cove on. 
    How is the best way to resolve the situation?
    A bit more radius at the tip of the tail?and angle the check back just slightly?





  • 25.  RE: backcheck regulation

    Member
    Posted 09-02-2020 13:16
    The cove removes so little weight, it is not worth the effort. There is no tonal benefit to the cove. In the final weigh off, the front of the molding is a good place to reduce Strike Weight by a few tenths of a gram. I also ease the bottom outside edge of the arc so as not to have a sharp edge impacting on the b/c.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 26.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-02-2020 23:23
    Jon is singing my tune. I have been shaping tails like Jon's picture shows for thirty years. You do need to round the edges that contact the backcheck or it does cut.

    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------



  • 27.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 01:26

    I always ask Ray to cove hammers but request that the cove not be deeper than about 1/3 of the moulding depth. Never have a problem with making the adequate radius.  Makes it easier to identify front and back of the hammers.  

     



    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 28.  RE: backcheck regulation

    Member
    Posted 09-03-2020 06:32
    On a new set of hammers. I'll number each on the back lower portion that will be removed in the arc. (I discard the hammer that might have the underfelt half-way across the molding). The hammers are uncoved and untapered. After prefiling and weighing, I match to the shank SW to get a closer final SW. After installation, I'll trim off the shank protrusion with a band saw and rough cut the arc, trim the tails to length and arc the tail with the Spurlock jig before final weigh off.  Sanding the arc in this manner gives a nice finished edge to the shank and tail of the hammer, craftsmanship counts.

    I also order the overall molding length 3 mm longer than needed for the longest bore distance.  This way, I'm not left with a shortened tail caused by a longer custom bore as could be from a stock length, and still have a decent amount of material left for a clean removal.

    After the hammers are hung, I'll number each shank on the underside near the knuckle. This keeps them indexed for final removal from the rail and weigh off.

    Another thing I do is to place a ring of glue around the protruding shank after installation to allow it to wick into the joint.  On too many sets hung by others, you can see a gap at the back and even a rocking motion. (Newly hung BTW), photos avail.  I set the shanks vertically and place a glue ring around the shank. That will quickly wick in and I apply a second ring.  This is caused by the joint being glue-starved. The front edge of the molding scrapes the glue as the shank enters leaving little or no glue at the back of the molding. Ron Nossaman recommended to bevel the font of the hole prior to installation to allow the glue to wick in properly. This pays off and whenever I rehang a hammer, I bevel the front with a dedication tool in my hammer case (counter sink on a handle) and make certain the glue is pressed out the back of the shank (keeping my finger over the whole for pneumatic effect).

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 29.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 11:10
    Photo with Drawing overlay
    I have been thinking on the subject of tail shape and decided to annotate a photo with various dimension points.  Quickly I found out that using a line from the center of the checking seat to the hammer center does not work.  I had wondered if it was an option.
    Secondly while this seems to duplicate this original Yamaha hammer in the photo, I feel like a 3" radius is not quite aggressive enough.  Currently I use the shaping jig from WN&G which seems to work exceptionally well with either standard backchecks or the WN&G backchecks and from my drawing experiment looks closer to 2" radius green line,  but maybe not quite that aggressive.  Thirdly the breaking over of the lower edge not only reduces the the cutting wear of the leather, but also seems to benefit repetition speed.  Just my three cents worth!




    ------------------------------
    Lonnie Young
    Registered Piano Technician
    Petal MS
    601-270-6844
    ------------------------------



  • 30.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 11:59

    Lonnie, your observations are correct in that manufacturers use a smaller arcing radius than the service industry seems to have migrated into. Many years ago, I was confronted with a repetition problem aired by an accomplished pianist. Upon examination of a Steinway "B" I found that all the regulation specifications were spot on, hammer weight within normal standards, and no excessive friction. But what I eventually discovered, after lengthy experimenting, was that the technician who replaced the hammers used the 5.25" radius and the shank center pin as a focal point to establish the arc. This caused the checking process to become so slow that the hammer was still in a downward stroke when he let up on the key to cycle another stroke. This led me to examine established manufacturers arcing specifications, and I found with Steinway, Yamaha, and Kawai the arc fell between 1 7/8" to 1.5", and I discovered that the arc center-point (focal point) never lied on the shank line. This led me to make my own arcing jig to duplicate the arc radius and focal point of these well established manufacturers.
    Later, I became puzzled with the claim by some technicians that a larger arc (3" or more) never created a checking problem regarding speed. My suspicion  is that the larger arc is not as much a problem with those who install "light" hammers.



    ------------------------------
    Roger Gable
    Gable Piano
    Everett WA
    425-252-5000
    ------------------------------



  • 31.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 12:04
    Thanks for sharing your advanced and insightful thinking about the relationship between backchecking and repetition, Roger!

    Alan

    ------------------------------
    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
    ------------------------------



  • 32.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 11:59
    I think what's clear is that the radius of the tail must work in conjunction with the angle of the backcheck.  The longer the radius the more vertical the backcheck position will need to be and vice versa.  If you cut a very small radius in the tail you will have to increase the angle of the backcheck to insure there is adequate tail contact.  As in all things there is a point of diminishing returns.

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 33.  RE: backcheck regulation

    Posted 09-03-2020 13:49
    Reducing the radius lessens the sq mm of surface contact with the backcheck and therefore less friction. The longer radius tail is the more aggressive as it increases the friction. When the check leather or esquine? slicks over, roughing the tail might be required to get the hammer to check on short radius tails. I don't like having to turn the tails into backcheck chewers.  





  • 34.  RE: backcheck regulation

    Member
    Posted 09-03-2020 16:46
    A shorter radius on the arc induces more impact into the b/c. I prefer a sweeping catch that a 3" radius produces than an abrupt 'knuckling-in".  Old, dried buckskin also causes an impact which is felt in the finger.

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 35.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 17:06
    Jon,
    Other than replacing the leather or the b/c, do you treat the hardened leather with anything to soften it?

    Joe Wiencek





  • 36.  RE: backcheck regulation

    Member
    Posted 09-03-2020 18:12
    No but I would scuff it with a coarse grit paper to aide checking if replacement is not an option. I've tried removing underfelt to give the cover a bit of slack but that does not do enough.  I worked on an old Bluthner and had it working very well but the impact of the hammer into the b/c was annoying. After trying all sorts of things, I replaced them. It made all the difference in the world. The action went from playing well to sublime. Without the impact, the key's motion became transparent. Sort of enticing you to play more...

    ------------------------------
    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
    ------------------------------



  • 37.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-03-2020 19:28

    I've just replaced b/c on a "rebuilt " A from 1893 with Tokiwa ecsaine b/c.  The "mistakes" too numerous to describe included action support cleats completely loose and unglued from the keyframe and super hardened back checks. A nice back check does really transform the feel of the action, I especially like the ecsaine over buck skin. 

    Joe Wiencek. 





  • 38.  RE: backcheck regulation

    Posted 09-03-2020 18:25
    I would imagine someone in this group has tried to clean the back checks. With real leather you could scrape and sand if it wasn't already worn through.





  • 39.  RE: backcheck regulation

    Registered Piano Technician
    Posted 09-04-2020 00:13
    A longer radius to the tail does require more precision in adjusting the angle of the backcheck face. But they grip so much better and my actions check reliably on pianissimo blows, which the standard radius and check cannot do.

    The relationship of the keystick angle at rest and at full dip in to the string plane and bore distance also have an important effect on being able to set checking close. The backcheck will have the greatest horizontal displacment if the keystick is level with the supposedly horizontal string plane at half dip. Most keysets are angled so at full dip they get to horizontal.

    ------------------------------
    Edward McMorrow
    Edmonds WA
    425-299-3431
    ------------------------------