In which we learn more about how to fix problematic letters in tefillin parchment

In which we learn that the letters of the tefillin have to be "written and not "etched out" - when we can correct lettering affected by excess ink

In which we learn about asking a child to help determine the whether "broken" letters are still correctly formed.

In which we learn how advances in technology have changed the thickness of parchment selected for use in tefillin plus, more on holes in the parchment that might affect lettering.

In which we learn the correct intent needed to create the tefillin parchment and whether machines can make it. We also look at the source of parchment and parchment with a small hole in it. 

In which we learn that you can use any colour ink for writing tefillin (as long as it is black). Each letter must be separate and well formed.

In which we learn why we don't wear tefillin on Shabbos and Yom Tov, and what about Chol HaMoed? We also turn to the discussion of the writing of the tefillin parchments.

In which we learn the correct time for putting on tefillin and why technically there are cases at nighttime when one can wear tefillin.