High pitch vs low pitch on blades

[GusShnaps]

Different blades (only wood, without the rubbers on) make different sounds when they hit the ball. I'm curious to know why that happens. Some are low pitched and some are higher pitched. What does the sound mean? What does it show about the blade?

 

[Atas Newton]

Theoretically the higher the pitch the faster the blade. Harder blades don't want to deform as much as soft ones, so they vibrate faster.

 

[langel]

One of the many threads on this topic:

https://www.tabletennisdaily.com/fo...rmining-blade-speed-info&highlight=pitch+test

 

[Atas Newton]

One of the many threads on this topic:

https://www.tabletennisdaily.com/fo...rmining-blade-speed-info&highlight=pitch+test

damn, the 'thoughts on table tennis' blog is no longer available :-( Shame, it had some very nice detailed articles on small aspects of table tennis. But it's not quite on this topic, I think OP is more interested in the physics side of it.

 

[dominus7]

One of the many threads on this topic:

https://www.tabletennisdaily.com/fo...rmining-blade-speed-info&highlight=pitch+test

It doesn't exist the post....

Enviado desde mi Moto G (4) mediante Tapatalk

 

[GinjaNinja]

Different blades (only wood, without the rubbers on) make different sounds when they hit the ball. I'm curious to know why that happens. Some are low pitched and some are higher pitched. What does the sound mean? What does it show about the blade?

Generally the higher the pitch the faster the blade, however, this is not always the case. The factors that contribute to the pitch include the stiffness, how thick the blade is and the head size. I am also sure glue type and varnish affect the pitch too but can't back that up with hard evidence and the effect is probably only small. These factors are interlinked, for example a thicker blade tends to be stiffer. There are different threads on here which look at this in much more detail including how the frequency of a blade relates to a speed rating.

 

[langel]

There is a thread I just can't find, by a blade builder, with some experimental aproach and scientific bases.
The discussion and the observations in practice lead to some different conclusions and assumptions.
Generally it was agreed that there is SOME kind of corelation between the pitch and the blade speed, this corelation is stronger in the more simple structured blades, mostly allwood, and can be used to determine the speed class of different blades, but not exactly the speed dynamics and the max speed. The more sophiticated the blade structure is, the more uncertain the result of the pitch test will be. To describe fully the speed dynamics of a blade, you need to execute several tests with different ball acceleration values in the real world ball speed range. Besides that the single droped ball pitch test gives information for the slowest impact only, which is not very informative as at such touch the rubber is the much more important factor. With composite blades the story gets much more complicated.

 

[hipnotic]

That´s me.

Pitch is affected by the stiffness of the blade. Higher stiffness means higher pitch. Stiffness is dictated by many factors such as weight, composition, thickness, head size, etc... Out of these, weight is the most important when correlating pitch to speed. If the composition is the same, the one with higher pitch will be faster if the weight is the same. If the weight is not the same, the heavier one will produce lower pitch but will in fact be faster. That's because at higher speeds hardness is very important. So, there is a correlation between pitch and stiffness, but the correlation between stiffness and speed is not linear. The most evident cases are balsa and kiri core blades, that produce higher pitch than a different core blade counterpart, but will be much slower due to their lower weight (lower density->softer feel->lower speed at high impact), so they are usually paired with composites to get the best of both worlds (Lower weight, higher stiffness and hardness).

That being said, usually you can assume the speed of a blade based on the measured pitch with good confidence but direct comparisons have to be made with caution.