isometric vs isometrical

isometric is a noun but isometrical is not a noun.

Word	Noun	Adjective	Verb	Adverb
isometric	Yes	Yes	No	No
isometrical	No	Yes	No	No

As adjectives, isometric and isometrical are synonyms defined as:

isometric (noun)	isometrical (noun)
a line connecting isometric points

isometric (adjective)	isometrical (adjective)
of or involving muscular contraction in which tension increases while length remains constant	having equal dimensions or measurements
related by an isometry
of a crystal system characterized by three equal axes at right angles
having equal dimensions or measurements