Cutting Nails on Chol Hamoed
Question
Answer
I am quoting what our teacher, the Gaon, Rabbi Avraham Fried, shlita, wrote in the Azmera Leshimcha bulletin:
According to the Shulchan Aruch, it is permitted to cut nails on Chol Hamoed, but according to the Rema, adults are prohibited from cutting nails on Chol Hamoed, both fingernails and toenails. [However, it is permitted to cut them with teeth or hands, and in case of need, one can start with a tool and continue with teeth or hands]. Children's nails are permitted to be cut even according to the Rema.
The rule of cutting nails on the eve of Shabbat during Chol Hamoed
[One who cut his nails on the eve of Sukkot or the eve of the Shabbat before Sukkot, in years when Sukkot falls on a Monday, can cut his nails on Chol Hamoed with a tool. If he did not cut his nails on the eve of Sukkot, it is permitted to cut on the eve of Shabbat Chol Hamoed only if he is accustomed to cutting every eve of Shabbat].
Source
Azmera Leshimcha 263