ER 40 VS. 5-C

[ozzie34231]

Hi All,
I'm all excited about getting my new lathe and one of the first things I'll want to do is make a collet closer.
I have a collection of about 70 5-C collets and that was my first choice, a nice d1-4 unit with a real draw bar!
But then I was reading a post where someone was saying that when milling, ER collets hold a tool more accurately than a dedicated size R-8 mill holder, (at least a cheap one), and that if one has metric tools there is no reason for special holders because a set of ER's can hold a continuum of sizes.
So maybe I should use ER's in my lathe head?
Also I got to thinking that my ER 40 set has a longer holding surface than the 5-C's. And one last thought is that the ER's are self releasing, or at least easy releasing.
In reality, I'll probably build both, but I think I'll do the ER first, making "tommy bar" holes in both the body and nut rather than the normal wrench system, which always seems to me a bit clumsy.
So, I'm looking for comments and thoughts. Are there advantages to the traditional 5-C's over the ER's?

Ozzie

[Kiwi]

My understanding is that 5C is pulled from the rear of the collet, where ER40 is compressed from the front.

[HuFlungDung]

5C are handier for lathe work. One reason is that they release more easily with a lever-operated drawtube.

5C also have internal threads at the back end, which makes attaching work stops much easier.

The ER is a good strong-holding collet but its probably overkill unless you will seldom do any collet work of a mass production flavour.

Don't forget that other types of collets are available for 5C like step and clutch collets and internal expanding collets. Also, hex and square shapes are available as well as easy to machine emergency collets for special jobs.

[ozzie34231]

Yes, good thoughts!
Part of my 5C collection is a set of squares.
Since I'll be making the chucks I'll incorporate an internal thread in the ER chuck for a stop system.
I'm a hobbiest so a lever drawtube is not a consideration, too expensive, too hard to make.

I'm also thinking I want to be able to lock my spindle. A CNC lathe can be used as a short run sort of shaper to cut internal keyways.
Any ideas on the best design for a lock?

Thanks,
Ozzie