At any rate, the lift and cut issue is very complex. What I don’t understand is that the gemara says misparayim k’ein taar is ok on the beard. What are the potential problems with lift and cut, and shavers in general?
1) Very close
2) Very sharp
3) Lift and Cut supposedly may cut at skin level
1) As we know, the screen prevents blades in a normal shaver from getting directly at the skin. Therefore it is not mashchis according to the view of Rashi and many poskim, that as long as there is any distance to the root, it is OK.
2) The gemara does not give any shiur on how sharp a scissors can be. It should have said that if one sharpens the scissors too much, it is assur. But it does not. It says scissors are OK.
3) Lift and Cut supposedly pulls hair out of skin, and then cuts. Aftre it drops back, it is supposedly below skin level. Even if we accept the manufacturer’s hype which is probably not true to begin with, let us examine. Does the gemara say that if one pulls the hair out very hard, and cuts with a scissors that it is assur. (Bameh devorim amurim shelo mashach bsaar, aval mashach bsaar asur afilu bisparayim k’ein taar.) Since the gemara does not say this, it implies that I can pull hair as hard as I want, and still cut with scissors.)
The Rabbi Blumenkrantz book has a paragraph which I completely don’t understand regarding the action of a shaver. The gemara says that one should cut with a scissors so that the upper blade moves, while the lower blade is stationary. If he moves the lower blade, then it is equivalent to a razor making direct contact with skin. Rabbi Blumenkrantz seems to say that the upper part of a shaver is the screen, while the lower is the moving blades. However, clearly this does not seem to be the case. The part against the skin is always called the lower, while the part away from the skin is the upper. Since the screen is stationary, while the blades move, it is exactly analogous to a permitted scissors.
So PY does not understand the distinction between lift and cut and all others. Having read the sources on KosherShavers.Com it is not clear that it is asur. He says Reb Moshe was very reluctant to be matir. What does that mean? Was he matir or not?