Normal or screw up, on er40 collet chuck?

SubtleHustle

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So, just got around to opening a er40 collet chuck, that I picked up from shars, and I noticed that something looked "off", on the nut of the chuck. This I'd my first collet chuck, so I'm not sure if normal. I have not recieved my collets yet, so I'm not sure if it has an affect on them or not yet.
20190101_165319.jpg20190101_165313.jpg
Notice, in the second pic, that the inside top of the threaded nut appears to be considerably off center? Figured I'd bounce it off of you guys first, before I give shars a call. Anyone know if this is something that should be addressed, or if its completely normal?
 
That looks normal for ER collets. the collets lock in the nut so when you losen the nut it ejects the collet from the taper.
 
Han hoptical hillusion.
She's in the center. It is the thread that does it, the Hillusion ie.
Plus there is a ''ring" inside, that clips around the collet, it sort of FLOATS, also misleading.
Reckon, she'll be right.
 
The off-center ring in ER collet chucks is meant to be there by design.
This will make it look like the thread is off center too - but I'll bet its not.
Mount it in the Mill or the lathe with a collet and a good drill bit.
I'll bet its fine.
There is a 'trick' to mounting and unmounting collets. You use the off - center ring by off - centering the collet in the nut.
Kind of twisting it in and twisting it out.
Also once a tool is tightened in the collet - The 'release' is a two step process.
When you undo the nut the nut will release but the collet only releases when you further undo the nut, that's the off - center ring pulling the collet out.

Regards Malcolm
 
Always remeber you need to snap the ER collet into the nut before inserting the collet into the holder. Always insert your material/tooling after the collet is in the chuck.If the collet is not snapped into the nut first it will seat incorrectly. The ring in the nut is offset or may have a snap ring to allow the collet to snap in. There are also coated and bearing ER nuts that make tightening/loosening a bit easier, they also tend to reduce the TIR (i.e. more repeatable). I use one on my ER lathe chuck and I did notice an improvement.
 
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