gcotterl wrote:
The bottom section of an already-installed tileboard panel has been
torn off and the resulting end is very ragged.

How can I cut the ragged end so it's square and even? (I want to
replace the missing section with a section of new tileboard).

(I don't have any power saws (i.e., circular-saw, jigsaws, etc)

The orange angle grinder (4.5") from harbor freight is $18 with the coupon
(or $20 on sale right now). A segmented diamond blade for said angle
grinder is fifteen bucks.

The problem is that cement backer board releases a lot of silicone dust when
it is cut by a power tool, so you would need to isolate the work area, wear
a respirator (safety goggles, hearing protection, old colthes) and clean up
***thoroughly***.

Jon