Originally Posted by Cheetah
welcome to the world of toly.
the purpose of the 'beta angle' in a serve is leverage. not spin.
I think it may be an error in communication. For like 9 out of 10 "forehand at contact" pictures on google, the forearm and racquet are (essentially) parallel to the ground, which means there is (essentially) no beta angle between x and y. At the same time, 9 out of 10 of the same pictures have the forearm and racquet making a 45-90 degree angle, which is a 45-90 degree beta angle between x and z.
Now, Nadal and Novak both use the hammer grip and they still fit the description above, so I think that adds to my argument. I am curious to know if the hammer grip adds any benefit in terms of the x and z axes. This is what I think may be possible - I may understand an argument that an increase in topspin is coming from how the hammer grip effects parts of the back and forward swing, since I do feel a difference with them when tinkering with the hammer grip (I would just need to be shown how/why). Or an argument that since the hammer grip naturally starts more perpendicular to your arm, that may give more room for error (since the forearm and racquet are perpendicular at contact anyway), but again, all grip combos tend to make contact about the same on a standard shot.