Adjusting the operating force on the treble keyboard

[colinm]

Many of you do it yourselfers will know that you can adjust the force required to press down the treble keys on some keyboards, and it is generally reckoned to be in the range 2 to 5 ounces or 50 to 125 grams.

This is probably measured at the tip of the black key, but where do you measure it on the white key ? At the white key tip,or level with the black key tip ?

And what weight do you personally prefer ?
.



Sent from my iPad using Tapatalk

 

[debra]

I have not yet done such measurements (yet another tool to buy...), but I reckon you measure where a player typically positions the fingers. So on the white keys that is maybe about half an inch to an inch away from the tip of the black keys.
So far I have never had a problem with very unbalanced weight, but I have noticed it on newer Chinese brands. They have not yet figured out that you either need different springs for black and white keys or you need to have separate rods for the white and black keys...
For me the weight is fine when it feels light to the touch yet you can feel a note without accidentally pressing it. (I play CBA and need to feel the textured C and F notes without pressing down on them.) The pressure that is needed is determined more by the force the pallets need to stay closed when you push to close the bellows than with the comfort of the player.

 

[colinm]

I have not yet done such measurements (yet another tool to buy...), but I reckon you measure where a player typically positions the fingers. So on the white keys that is maybe about half an inch to an inch away from the tip of the black keys.
So far I have never had a problem with very unbalanced weight, but I have noticed it on newer Chinese brands. They have not yet figured out that you either need different springs for black and white keys or you need to have separate rods for the white and black keys...
For me the weight is fine when it feels light to the touch yet you can feel a note without accidentally pressing it. (I play CBA and need to feel the textured C and F notes without pressing down on them.) The pressure that is needed is determined more by the force the pallets need to stay closed when you push to close the bellows than with the comfort of the player.

Thanks Paul, I agree with your thoughts, Accordion revival shows how to make a gauge, I would have liked someone who has experience of making these adjustments to confirm their figures
Cm


Sent from my iPad using Tapatalk

 

[TomBR]

...... Accordion revival shows how to make a gauge, I would have liked someone who has experience of making these adjustments to confirm their figures
Cm

I wasnt able to find the Accordion Revival gauge. I made mine from the clear tube of a BIC Crystal pen, a piece of aluminium rod that fitted easily through it, a little rubber cap that I found that fitted the aluminium rod for the testing end and some fine piano wire wound into a coil spring. Its not to hand, but I think I painted a ring on the rod as the reading point, stuck a strip of label on the pen tube, then calibrated it by pressing on a digital kitchen scale and marking off the measurements on the paper strip. If all that makes sense!

An alternative would be something on the steelyard principle - ie a small strip of wood, the beam with a point below it at the measuring end and a free hinged handle at the other end, plus a sliding weight on the beam. (Sliding but attached and with a bit of friction.) Rest the measuring point on the key while holding the beam horizontal at the other hinged end and slide the weight along until the accordion key just dips. Again, calibration marks could be made on the beam using an accurate scale. The advantage of this is you can set the thing up for a given weight and see which keys are lighter and heavier.

Ultra simple alternative. A small bolt or nail and you load it with washers to a given weight, then just rest it on the key!

 

[colinm]

Tom, your gauge is the same as the one described in Accordion revival, and i calibrated mine against the kitchen scales, not very accurate but good enough.

I tried the washers and pound coins etc and it was a bit messy.

I would be interested to know what figures you ended up with and if you measured it where Paul suggested


Sent from my iPad using Tapatalk

 

[Geoff de Limousin]

If you search on-line for a " gram force gauge" , or similar wording you should come up with a hand held dial gauge which has a metal arm about 4-5cm long . These are ideal for measuring key pressure. I bought mine from a flea market stall specialising in old tools. I added a small lump of cork to the end of the metal arm, so it does not scratch the keys. One needs to find a guage that will cover the range O- 150 grams.

I have just measured my CBAs and the new one needs 100g to start the keys moving. Another accordéon that I feel has keys set up too light measures 50g . On my concertinas I like a button pressure of between 60 and 70 g.

Plenty of these on Ebay.

 

[colinm]

ok, I have purchased a gauge, I think I am going to aim for 75g to 100g
cm

 

[colinm]

If you search on-line for a gram force gauge , or similar wording you should come up with a hand held dial gauge which has a metal arm about 4-5cm long . These are ideal for measuring key pressure. I bought mine from a flea market stall specialising in old tools. I added a small lump of cork to the end of the metal arm, so it does not scratch the keys. One needs to find a guage that will cover the range O- 150 grams.

I have just measured my CBAs and the new one needs 100g to start the keys moving. Another accordéon that I feel has keys set up too light measures 50g . On my concertinas I like a button pressure of between 60 and 70 g.

Plenty of these on Ebay.

Geoff
I note you state the force to start the key moving, it does increase as the key goes down, and I think it is difficult to change this unless a new set of springs with a different rating is installed


Sent from my iPad using Tapatalk

 

[Geronimo]

I note you state the force to start the key moving, it does increase as the key goes down, and I think it is difficult to change this unless a new set of springs with a different rating is installed

A spring is a spring. It has linear response over its deformation, so if the basic shape is identical (and it does not buckle like a spring in an IBM Model M keyboard), the force will increase in the same manner as the key goes down. It will change less if you use a weaker spring to start with but with a larger starting deformation, yielding the same starting force. In that case, the additional percentage of deformation (and thus the additional force) will be lower. Think of clock spring as an extreme. Of course, fitting a weak spring requiring a strong deformation in its resting position may be a heck of a nuisance.

For the scissoring kind of spring, youd want a shorter but weaker spring so that its action (spring deformation angle per key travel) starts out larger but becomes smaller as the key goes down. Thats not quite buckling spring but a similar idea. Of course you dont want to do this too extreme or the key return will be sluggish.

 

[colinm]

Geronimo
Yes I understand that, I do not see the increase in pressure as a problem, its just if we are going to share figures on force required it would be good to take the reading just as the key starts to move.

I have had enough problems obtaining suitable springs, so I don,t want to start designing my own

 

[boxplayer4000]

Key Force.
Regarding key operating force discussion I would like to suggest that before any adjustment of springs is even considered that the condition of the palette felt/leather is checked. If the leather is compacted/dirty through age and use then any adjustment to springs will be waste of time.
After the palette felt/leathers are seen to be in good condition, the palette properly levelled and centralised then it will be possible to adjust the key pressure to a minimum level to stop the passage of air when the bellows are pressed hard.
In the limited occasions when being involved with key pressure adjustment I have used the the keys near the ends of the keyboard as a reference point in the hope that since they would likely have been used less than the other keys then this was more likely to have been the manufacturer’s adjustment.
For measuring this key force I’m sorry to say I have only used some coins or washers placed
on the end of the key.
Regarding springs all users will be aware that their manufacture is a highly specialised skill. They are all basically metal bars under torsion but have endless design parameters giving compression, tension or simple torsion features.
Despite the skills required in professional spring manufacture for those involved in everyday accordion maintenance I recommend in a ‘one-off’ or small number situation trying to fashion a spring on a simple jig from piano wire.

 

[colinm]

Thanks Boxman
Are all accordion scissor springs made from piano wire ? Is “piano wire “ a precise specification ?
Cm

 

[boxplayer4000]

colinm,
I only mention piano wire because it is available in a wide range of sizes and I find it very elastic and 'springy'. From memory the piano industry have their own wire size code which directly relates to diameter and SWG (Standard Wire Guage). The smaller diameter piano wire is closest to accordion keyboard spring sizes and the last time I looked it remains readily available in the U.K.

 

[Morne]

Despite the skills required in professional spring manufacture for those involved in everyday accordion maintenance I recommend in a ‘one-off’ or small number situation trying to fashion a spring on a simple jig from piano wire.

For anyone interested in doing that, see this video for a general idea:
Since accordion torsion springs have very few coils, you can do it by hand instead.

While not for the keyboard side, here is what I used for some simple bass button springs on a 12 bass instrument:
<ATTACHMENT filename=Spring Jig.jpg index=1>
<ATTACHMENT filename=Spring Winder.jpg index=0>

I make the 90 degree bend beforehand using pliers. Then I slip that short end between the two clipped nails at the top (in the same position as the finished spring). The wire then goes past the bottom nail. The brass tube goes over that nail and when you turn it the filed-out nib will coil the wire around the nail.

The diameter of the main nail determines the inside diameter of the spring. The tube needs to be wide enough to accommodate the diameter of the nail + 2x diameter of the wire.

I used 0.64mm wire (22 AWG or 0.025 inch).

My springs didnt require any other kinks or bends. Now obviously you dont want to do this with a professional instrument unless its really an emergency

 

[colinm]

Despite the skills required in professional spring manufacture for those involved in everyday accordion maintenance I recommend in a ‘one-off’ or small number situation trying to fashion a spring on a simple jig from piano wire.

For anyone interested in doing that, see this video for a general idea:
Since accordion torsion springs have very few coils, you can do it by hand instead.

While not for the keyboard side, here is what I used for some simple bass button springs on a 12 bass instrument:
<ATTACHMENT filename=Spring Jig.jpg index=1>[ATTACHMENT NOT FOUND]
<ATTACHMENT filename=Spring Winder.jpg index=0>[ATTACHMENT NOT FOUND]

I make the 90 degree bend beforehand using pliers. Then I slip that short end between the two clipped nails at the top (in the same position as the finished spring). The wire then goes past the bottom nail. The brass tube goes over that nail and when you turn it the filed-out nib will coil the wire around the nail.

The diameter of the main nail determines the inside diameter of the spring. The tube needs to be wide enough to accommodate the diameter of the nail + 2x diameter of the wire.

I used 0.64mm wire (22 AWG or 0.025 inch).

My springs didnt require any other kinks or bends. Now obviously you dont want to do this with a professional instrument unless its really an emergency[/quote]
Thanks all, yes its dead easy to get hold of the wire, I only need 5 springs so making them should be no problem


Sent from my iPad using Tapatalk