Jt Arbor Sizes...why So Many ?

[EmilioG]

Why are there so many different arbor sizes? I understand the JT taper size for each chuck socket taper but why are there so many arbor end sizes like 1/2" - 1 1/2"? Are the larger sizes better for accuracy or just for changing out quickly to the same size r8 collet?

 

[Bob Korves]

I have drill chucks with 1/4, 3/8, 1/2, 5/8, 3/4, and 1" straight arbors. Also a wide range of arbors on other common milling machine tools. Changing back and forth from spotting drill, to drill, to tap, and to end mill is quick as lightning! Now, I am just lucky to have so many sizes, purchased cheaply with lots of tools, but purposefully choosing one or two sizes, like perhaps 1/2" or 3/4" for all your arbors will make life a hell of a lot easier, even for the hobby machinist who is not often under the gun to get things done by yesterday. Fewer collet changes = more work accomplished.

 

[EmilioG]

I'm trying to put 1/2" arbors on most of my chucks, with two mt2's.
I now have 8 drill chucks, 6 Albrechts and two USA Jacobs. Need one more Jacobs, USA.
Thanks