Measure ER collet run out?

[DaveH]

Hi,
Is there a specified or specific way the measure the run out.

How far from the collet should I measure it? 5mm……..10mm …….50mm?

DaveH

[doubleboost]

Hi
Dave
The less runout you have the better after playing around with my homemade holder this is the result

Click the picture 

That is a metric clock less than .002mm at 3 inches  :bugeye:very happy
From what i have been told 1.5 thou is about the norm for a bought one
John

[DaveH]

Hi John,

Is 3" from the collet the sort of standard for all sizes.
Or does it change depending on the diameter.

DaveH

[doubleboost]

I would think the collet size would make no differance (the collets will be precision ground)
It will be the holder that is in need of fettling
3 inches from the collett is just the length of the tool i had handy
I am not sure what the speck is
John

[DaveH]

Hi,

This is what I've found out from different sources.

a) Measure it 4 x dia from the collet.
b) Measure it 1 x dia from the collet.
c) Measure it as close to the collet as posible.

Now (a) 4 x dia seems a long way to me. 12 dia ends up 48 mm from the collet. [ John did 3" ]
(b) seems sensible.
(c) seems to me the right place. (But I really don't know)

How do the manufactures measure it.

I would still like to keep it simple for the home workshop.

Anyone have any views or comment. I would like to hear.

 
DaveH