Use this bit in my ER11 1/4" collet?

[dbb-the-bruce]

I'm just not sure about this....
Is the flat on this stubby 1/4" end mill going to mess up my ER11 collet?
There is a small amount of solid shaft between the flat and the flutes. I'm thinking that I should choke up on it such that the open end of the collet sees a full round shank.

The other / back end of the shank is about .4 and less that 2X the diameter. It seems like a bad idea to have only that in the collet.
Am I over thinking this?

 

[Ulma Doctor]

I have done exactly what you’re thinking.
As long as you close on an uninterrupted surface, it works.
I generally take lighter cuts when doing this

 

[Shotgun]

ER collets close along the entire length. I use them to hold screws when working on the heads. You can ignore the flat for this purpose.

 

[dbb-the-bruce]

Yeah, it's probably fine no matter where the flat falls. It just feels better to me to get the gap between the flutes and the flat just inside the collet face. ie. the uninterrupted circumference.

Screw threads would spread the contact/no-contact evenly around the whole collet, so yeah I would not expect them to be an issue at all.

Thanks for the help, mostly I just wanted to make sure I wasn't going to screw up my collet. I'm using this in my small desktop CNC and it's working great facing - much faster than using an 1/8" mill. Adding the Fogbuster also helped a lot.