Rhodes | Escapement and Variance in Tone Bar Height

[juniornoodle]

When setting escapement on my piano, I'm noticing that if I set a number of adjacent notes to the same height that the tone bars vary in height a fair amount. Is this normal and acceptable?

I also noticed that some of the hammers sit at slightly different levels when they are at rest, which may have some impact on the above.

Additionally, are there any thoughts about best strategy for varying escapement across different sections of the piano. The manual as well as a number of other resources note that it makes sense to transition from the larger recommended escapement distances at the low end down to lower escapement distances at the high end, but I haven't seen tips about where (what keys) to begin these transitions, whether they should be more sudden or more gradual, etc. Is this completely dictated by personal preference and trial/error? Any tips to make this a faster process for me would be excellent!

[Ben Bove]

First off, what vintage of piano is this?  Early pianos with half wood / half plastic hammers set global escapement via the shims between the harp ends and the harp support blocks, or the all-plastic hammer models have global escapement set via increasing height levels of the hammer tips via the 5 different hardnesses of hammer tips.

Totally normal for tonebars to be at different heights.  A lot of variables in play in making the best tone - the pickup perfectly level, the tine perfectly in tone block, and the tone bar perfectly bent.  It never happens like that.

Usually, it's good to roughly have the hammers resting at the same height, but slight differences are not too concerning.  It's really making sure their escapement is good so that a small distance between the tip and tine doesn't cause double striking, or too far of a distance doesn't cause soft notes to not play.

[juniornoodle]

It's a 1978 stage piano seventy three so it's got all plastic hammers.  And graduated hammer tips.

So the manual describes setting escapement at three different ranges across the 5 different types of hammer tips, which lead me to believe that I would need to manually transition escapement measurement across the entire keyboard. Is that not true? Or are you saying that if I set all the tone bars to the same height the escapement will transition the way the manual describes automatically?

If this isn't making sense, maybe I should take a step back and ask, how do you set escapement across the entire piano from scratch? What's the step by step method?

Thanks!

[David Aubke]

I've always thought that ideally, the escapement would increase from treble to bass at a rate directly proportional to the length of the tines. If I'm not mistaken, the main thing we're trying to accomplish is keeping the hammer tip clear of the vibrating tine. And I have to believe the tine's arc increases proportionally to its length.

Unfortunately, calculating these numbers involves math skills I haven't possessed since my junior year of highschool.
Who remembers how to plot a logarithmic curve?

[pnoboy]

I have a '78 stage piano, and IMO, Fender did a poor job with sizing the graduated tips.  Here's the problem--the tips increase slowly in  height over the key compass, but the tine motion decreases very quickly as one goes from bass to treble.  Do this experiment--get your flashlight and strike the lowest note while watching the tine's movement where the hammer strikes it.  It moves quite a bit.  Now strike a note one octave higher.  Already the tine movement is much less.  One octave higher than that and it's moving so little you can pretty much ignore it. 

What I found with my piano is that there was no adjustment that allowed me to get proper escapement toward the middle of the piano.  So, I did something drastic.  I put in a set of Vintage Vibe's angled tips, which are not graduated.  I left in the original fender tips for the lowest octave (they had almost no grooving), and then transitioned to the VV tips.  I had already removed  the composition harp spacers, and put in new ones such that the escapement on the low end required a 5/16" tonebar setting (1/16" closer than the nominal 3/8"), and needed the nominal 3/8" spacing at the treble end.  At the transition between the graduated and angled tips, at the bass end, I increased the tonebar height to about 7/16" (1/16" higher than the nominal 3/8") and then not too much farther up the keyboard, was able to bring all the tonebars to the nominal height.  The piano played much better after this.

David may be correct that the escapement should increase according to the length of the tine.  That would mean that escapement could be reduced by 1/2 for every octave up the keyboard from the bass end.  Of course, this ratio may not be exactly correct.

I'd like to mention that when I removed the composite spacers that sat between the harp and the aluminum extrusions, I replaced them with plexiglas (acrylic).  It's much better, IMO.  The composite material was very soft and damaged easily.  It also looked lousy, I think.  The acrylic is harder and smoother.  I glued the acrylic spacers on with silicone adhesive (not caulk, adhesive).  This adhesive, like silicone caulking, dries rubbery, and the spacers can easily be removed by wedging a thin putty knife between the acrylic and the aluminum and just zipping them off.  If you really wanted to get fancy, you could get acrylic in various colors, but I just used the clear stuff you can get in Home Depot.

[rhodesjuzz]

I have a '78 stage piano, and IMO, Fender did a poor job with sizing the graduated tips.  Here's the problem--the tips increase slowly in  height over the key compass, but the tine motion decreases very quickly as one goes from bass to treble.  Do this experiment--get your flashlight and strike the lowest note while watching the tine's movement where the hammer strikes it.  It moves quite a bit.  Now strike a note one octave higher.  Already the tine movement is much less.  One octave higher than that and it's moving so little you can pretty much ignore it. 

What I found with my piano is that there was no adjustment that allowed me to get proper escapement toward the middle of the piano.  So, I did something drastic.  I put in a set of Vintage Vibe's angled tips, which are not graduated.  I left in the original fender tips for the lowest octave (they had almost no grooving), and then transitioned to the VV tips.  I had already removed  the composition harp spacers, and put in new ones such that the escapement on the low end required a 5/16" tonebar setting (1/16" closer than the nominal 3/8"), and needed the nominal 3/8" spacing at the treble end.  At the transition between the graduated and angled tips, at the bass end, I increased the tonebar height to about 7/16" (1/16" higher than the nominal 3/8") and then not too much farther up the keyboard, was able to bring all the tonebars to the nominal height.  The piano played much better after this.

David may be correct that the escapement should increase according to the length of the tine.  That would mean that escapement could be reduced by 1/2 for every octave up the keyboard from the bass end.  Of course, this ratio may not be exactly correct.

I'd like to mention that when I removed the composite spacers that sat between the harp and the aluminum extrusions, I replaced them with plexiglas (acrylic).  It's much better, IMO.  The composite material was very soft and damaged easily.  It also looked lousy, I think.  The acrylic is harder and smoother.  I glued the acrylic spacers on with silicone adhesive (not caulk, adhesive).  This adhesive, like silicone caulking, dries rubbery, and the spacers can easily be removed by wedging a thin putty knife between the acrylic and the aluminum and just zipping them off.  If you really wanted to get fancy, you could get acrylic in various colors, but I just used the clear stuff you can get in Home Depot.

It seems like VV changed the height of the graduated tips. Yellow, white and woodcore are of the same height and they provide the custom hand wrapped tips instead of the cheaper Molded Wood Core Hammer Tips. So no quality issues here, Vintage Vibe did a great job with these new wood core tips! Yes, it changed the escapement, but with only a dozen keys I had to change that. This results in almost the same setup as pnoboy has.

The tips sound good, but I kept the red and green tips in because they look and sound as new. The only thing I'm trying to find out is the optimal transition point from yellow to white tips. VV has this point from C#5 (46) tot D5 (47). In my piano this transition takes place from A5 tot A#5. The new VV yellow tips are too soft imho from F5 to A5 so I put the old tips back in. I ordered a few extra white tips to find out where the optimal smoothest point is.

I am wondering where you guys change from yellow to white. It is in the high traffic area so it's quite important

--Roy

[Ben Bove]

Interesting points above.  The graduated tips were definitely an attempt to minimize labor and technician expertise in setting the escapement.  By designing the parts to do the job, and assembler only had to slap the same composite shims on the harp support blocks, and slap the hammer tips on the hammers - job done, the piano sort of sets its own escapement by design.  This would honestly ensure a better output of quality assembled pianos, because it helps eliminate human error.  The only downfall to this of course is that hammer tips aren't graduated in 73 or 88 different heights... the first hammer tip and last hammer tip in a series play differently, particularly in the bass and mid-range areas where escapement causes the biggest problems.  Ideally, all hammertips should be of the same height, and the harp, being a flat planed object, is raised or lowered from the harp blocks being the extreme left and right points.

If you're mixing original hammer tips with new ones, the thought to consider is that old, original tips will be hardened over the ages due to oxidation, and will give a harder attack sound than newly produced hammer tips.  A test on this would be to shave the very top of an original hammer tip - the attack will be less, as a fresh rubber surface is exposed.  So on your piano in particular, the transition point may be different than an all-new tip piano.  I would definitely test the transition point by ear specifically on your piano then, to hear when there's the best audible change.  Via headphones would be the best gauge

[rhodesjuzz]

Interesting points above.  The graduated tips were definitely an attempt to minimize labor and technician expertise in setting the escapement.  By designing the parts to do the job, and assembler only had to slap the same composite shims on the harp support blocks, and slap the hammer tips on the hammers - job done, the piano sort of sets its own escapement by design.  This would honestly ensure a better output of quality assembled pianos, because it helps eliminate human error.  The only downfall to this of course is that hammer tips aren't graduated in 73 or 88 different heights... the first hammer tip and last hammer tip in a series play differently, particularly in the bass and mid-range areas where escapement causes the biggest problems.  Ideally, all hammertips should be of the same height, and the harp, being a flat planed object, is raised or lowered from the harp blocks being the extreme left and right points.

If you're mixing original hammer tips with new ones, the thought to consider is that old, original tips will be hardened over the ages due to oxidation, and will give a harder attack sound than newly produced hammer tips.  A test on this would be to shave the very top of an original hammer tip - the attack will be less, as a fresh rubber surface is exposed.  So on your piano in particular, the transition point may be different than an all-new tip piano.  I would definitely test the transition point by ear specifically on your piano then, to hear when there's the best audible change.  Via headphones would be the best gauge

Thank you Ben! The 4 tips I put back in are older and maybe hardened (harder than the new yellow tips) through the years although they show no wear and tear. Good tip to use a headphone, that  way you cannot hear the attacking sound of the harder tips