ER collet chuck

Hi,

I just finished making a milling spindle with an ER 20 collet nose. In the construction articles I've seen in MEW it's been written to make the distance from the extraction groove to the spindle nose 3mm. Having made the spindle nose on my spindle too short I made the distance to the groove 5mm so I wouldn't bore through the bottom of the taper. Is that 5mm distance going to cause any holding problems?

Thanks,

Mark

Since it will, theoretically, allow you to press the collet further into the female taper, it ought to increase holding power.

In practice, it may not have any great effect other than decreasing the thread engagement of the nut by a little over one turn. (2mm travel on a 1.5mm pitch thread).

If you are that worried, why not turn back the front face by 2mm, or am I missing something?

Howard

Hi,

If I turn the front face back it will expose the extraction groove even more. I guess I'm not that worried;when I tighten the nut by hand it seems to hold fine. It's more like I was just wondering is it another case of " I did everything else perfectly except this one little thing and it ruined the whole part".

Thanks,

Mark

I think the issue is that the collet is protuding by 2mm too much, not going 2mm too far in.

Should not make any real problem, perhaps it will be slightly less accurate, secure, or easy to tighten, but not much, you've only lost about 10% (?) of the supporting length.

Neil