Tine measurement chart

[O.Lahoz]

Hello guys, glad to see again after many years without visiting this unique forum.
(again, excuse my bad english!  )

I am in the process of sanding the ends of the rods (tines) due to their bad cut in the factory and inconsistent length.
Sanding will be 1-2 mm for a perfect shape of the rod end's.
Due to the change in length, I plan to place each restored tine in the next position.
I have the Tine Cutting Measurement Chart from Rhodes manual but I have a dilemma:

This chart includes a vertical line connecting the horizontal lengths. This line has a thickness of +/- 1 mm.

Do I have to include the thickness of the vertical line to get the right length?

Any help will be much appreciated. Thank you very much!

[David Aubke]

According to the diagram, specifically the dimension mark at the top labeled "TINE CUTTING MEASUREMENT AREA", the vertical black bar is to be included in the measurement. So you'd align the edge of the tine block with the outer (left) side of the vertical line.

[voltergeist]

Don't bother with the pictorial chart. 

Regarding tine lengths, here's a notated chart with decimal inch conversions.  This makes it quick and easy to use a digital caliper to measure out tine lengths.  Getting the lengths right helps achieve consistent tone across the board, and proper response from the high register.  When I overhaul a harp, I measure all the tines.  If they're short, but not too short, I generally let them be.  If they're long, I grind them down to spec.  All tines should have their ends ground flat.  This is very important for good tone and should not be overlooked.

A cheap (good enough) digital caliper can be found for around $20 or so at a hardware or home improvement store. 

[O.Lahoz]

Thanks David,

Some major inconsistencies between the Manual Chart and the voltergeist chart made ​​me wonder about this.

[O.Lahoz]

Thanks Voltergeist,

I've seen your chart but some lengths make me doubt a little.
In your chart the rods #48-49-50 have the same length(?). The same applies to #65-66-67. Also, #33 is longer than the #32...
This differs from the Rhodes Manual Chart and I 'm confused.

Decisions, decisions...!!! 

[David Aubke]

Some major inconsistencies between the Manual Chart and the voltergeist chart made ​​me wonder about this.

Glancing over that chart, I'd say 64ths of an inch do not provide enough resolution since some neighboring tines are marked for the same length. The visual chart also shows several neighbors that are to be cut to the same length. I'm personally skeptical that a 64th of an inch here or there can make any kind of discernible difference in the tone. But if we're getting down to it, how can it be appropriate that two tines should be the same length?

[O.Lahoz]

"I'm personally skeptical that a 64th of an inch here or there can make any kind of discernible difference in the tone"

Strongly agree about the tone but the length is critical in higher notes and 1/64" can mean a range of several semitones making it difficult to pitch.

"But if we're getting down to it, how can it be appropriate that two tines should be the same length?"

I think the same as the tone bar are all different.

[voltergeist]

The point is that it's easier and more accurate to use the numerical chart and a caliper than to use that hokey pictorial. 

The chart is straight out of the manual.  All I did was make the conversion to mils.  I don't claim there are no errors in the service manual chart.  Though, it could be that the two runs of three with the same length are not errors but simplifications done for ease-of-production reasons.  #33 appears to be a legitimate error in the manual.

Yes, 1/64 is not a big deal and is not enough to make a discernible difference in tone.  Often enough tines are 1/8" or more out of spec, which is definitely getting into discernible territory, especially for short tines or if a heavier spring is required.  Actually, on the short tines 1/64" could be the difference between a note that rings well and a problem note that drives you crazy. 

#67 is my error - it should be 1.015 mils
#66 looks like it should be 1 1/32, or 1.031 mils
#49 looks like it should be 1 41/64, or 1.641 mils
#48 looks like it should be 1 44/64, or 1.688 mils
#34 looks like it should be 2 31/64, or 2.484 mils
#33 looks like it should be 2 35/64, or 2.547 mils

[voltergeist]

If a person is overhauling a harp and going through note by note, why not just bring them all into spec?  O.Lahoz' plan is actually very good, though I haven't done it that way myself.  Move tines up one and grind them all to spec.  That costs one tine and guarantees there will be no too-short tines.   Whatever other problems may occur, you know it's not due to out of spec tine length, and you've set yourself up for the best possible tonal consistency.

I should probably add that if someone is just cutting the tines and not grinding them flat, there's no point to worry about precision in length, they'd probably have bad (or at least sub-optimum) and inconsistent tone simply by virtue of the jagged tine ends. 

Attention to detail adds up to a great piano.  Lack of attention to detail adds up to a not-so-great piano.

[laberge]

A quick question on measuring, does this include the tine block, or everything after the tine starts?

[voltergeist]

A quick question on measuring, does this include the tine block, or everything after the tine starts?

It does not include the tine block. 

For those not familiar with calipers, one side is used for outside measurements (say, measuring the diameter of a bolt), and the other side is used for inside measurements (like for measuring the inside diameter of a nut). 

I use the side for inside measurements and put one jaw against the tine block.  Basically just set the caliper to the desired length, lock it down with the tightening screw, put the one jaw against the tine block, and make a mark at the location of the other jaw.  Then I cut the tine a bit long.  Then measure, grind, measure, grind, until the length is correct.  I prefer a fine grit wheel for grinding tines, but a standard grinding wheel is fine. 

[O.Lahoz]

Thanks for the new lengths corrections, voltergeist. Make sense.

ALL my tines are jagged and the sound is definitely not clean when I play chords.