Import 5C Collet Chuck questions

[Jimsehr]

Considering a 5C collet Chuck over a Jacobs flex collet Chuck, mostly because the rarified J921 1-1/2" Jacobs collet is either a myth or lost to the ages.

Question, I know I will be pushing the limits of my Atlas 10" lathe but has anyone run a 5C collet Chuck with a step collet? Specifically, as large as 3"? If so, any concerns, pitfalls to look out for?

In my 70 years of machining I have used many many step collets. Mostly in production runs. As step collets are bored on the lathe that you make the part on
there shough be no trouble holding 3 inch Material. Anything bigger it is best to have a collet backing plate holder where the collet is closed with angle on the backing plate. See the ones Hardinge makes but the are pricy. And I have used inside 5c collets up to 6 inches see Rovi collets still pricy. But great for production work. On my Logan 11 inch lathes often used 4 in step collets to hold thin production runs. If you Google Hardinge look at their 5c holding tooling.