I remember hearing once that sifrey Tanach had to have a required minimum number of lines when written on a klaf and that this requirement is often not followed by those writing "parshas ketores" and Megillas Ester. Is there a source that discusses the minimum number of lines required for a Megilla or any other sefer Tanach when written on a klaf?
R Reuvain Mendlowitz in his book Inside stam (pp. 268ff) writes regarding Megillat Esther
- Many Rishonim are of the opinion that a Megillat Esther is the same as a sefer Torah in all respects. This includes the number of lines - customarily 42 and many older, pre-war megillot were 42 lines
- Other Rishonim however feel that there is no need to be particular about the number of lines. And in recent years most megillot sold are either 21 or 28 lines. Although there is nothing wrong with such megillot even according to those call for 42 lines, there is no halachic basis for those numbers
- The one other requirement is that 11 lines seem the minimum to write the 10 sons of Haman and the line preceding them on the same page.
Because of the halacha that the height of the written area be greater than the height of the upper and lower margin combined, the smallest halachically acceptable megilla should be 15.1cm high. R Mendlowitz goes into detail in this calculation and the various halachic opinions that lead to it.
Regarding sifrei neviim more generally he writes (p. 265) that there are no sources indicating a preference as to overall height or the number of lines per column.