Machinery's Handbook 26th edition (2000)
New American Machinist's Handbook (1955, reprinted some time after 1983)
American Machinists' Handbook 3rd edition (1920)
All hardbound dead tree editions. I use them all.
American Machinist's Handbook, originally published in 1908, predates machinery's handbook by about 6 years and they competed for the first half of the 20th century. Written by Colvin and Stanly, though the 1955 edition was revised by someone else (Colvin was 88years old then). He retired in 1937 but apparently worked on two more editions and his memoir, 60 years with Men and Machines. He died before completing his history of the American machine tool industry. Fred Colvin had been original chief editor of Machinery magazine and then worked on American Machinist magazine. He was author of dozens of books (some repeat editions) with Frank A Stanley a coauthor on many. The 1908 and 1914 editions are available online; unfortunately, book scanners tend not to retain the original public domain status.
Machinery's 26th has some CNC stuff including g-code and CAT30/40/etc dimensions, newer alloys, newer cutting tools, welding symbols, etc. But still weak on R8, and lathe spindle noses. Has some structural shape sizes. The American 1955 has some lathe spindle nose data A1, A2, B1 B2, D1, L, as well as various tapers. No R8 though.
But aside from changes in metallurgy, the 1920's edition is still pretty good. Has some nice engravings. And now public domain. Standard machine screws sizes, for example, have been around since then though the preferred sizes have changed and many sizes and thread/size combinations have been eliminated (just as the original standard eliminated some of the existing size/thread combinations). Lathe tools back then were forged. Coolants were something you made up in the shop or a common substance. Involute gears used a 14-1/2 degree pressure angle then. Big glossary that was lost in the 1955 ed. Machinery's is about 3 times the page count vs the 1920 edition of American. BTW, for metallurgy, MIL-HDBK-5J has more info.
And the 1920 edition of American of course has historic value.
I also have a couple dozen volumes of Machinery's Reference Series, circa 1910 and one of Machinery's data sheets. These were 48 page booklets which offered as incentives (you could buy up to 10 at $0.25 each for each year of subscription/renewal to the magazine.