do you put a comma after the last name and before Jr.?

In American usage, The New Emily Post's Etiquette (1975) does as does the MLA Handbook for Writers of Research Papers, 5th Ed. (1999) because the junior furnishes parenthetical information just as M. D. and Ph. D. do.

Elizabeth L. Post elaborates, "A man with the same name as his father uses 'Jr.' after his name as long as his father is alive. He may drop the 'Jr.' after his father's death, or if he prefers, he may retain it in order not to be confused with his late father. This also helps to differentiate between his wife and his mother if the latter is still living and does not wish to be known as 'Mrs. Jones, Sr.' When a man is named after his father who is a 'Jr.,' he is called '3rd.' A man named after his grandfather, uncle, or cousin is called '2nd.' . . . Some family names are carried on through three or four generations. There is John (Sr.), John Jr., and Johns III, IV, and V (p. 25).

MLA gives an example of the use of a comma before Jr. in the following sentence: "Martin Luther King, Jr., was born on January 15, 1929, and died on April 4, 1968 (p. 55).

Comma Before Jr

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RE:

do you put a comma after the last name and before Jr.?

I Don't.

John Doe Jr.

or

Doe,John Jr.

Being a Jr. Can be a pain! I like it to be as simple as it can be, when it can be. On my DL it is comma (,)Jr. But, i don't fill it out that way on paperwork! I guess it is a preference thing

I agree with Evelyn S's answer. It would be with a comma, then Jr.

Write like: Bowlingball Jr.,Pin

You can. Not necessary.