Why a MT3 collet holder?

[358scott]

I have been considering a MT3-ER32 collet holder and collets. I have been on line and it looks like most collets have considerably more runout than the spindle. Why would I buy one when I can dial in a 4 Jaw to the spindle runout?
Scott

 

[Ulma Doctor]

speed of operations
A collet works in less than a second, dialing in a 4j could take several minutes

 

[pontiac428]

Collets are fast, and I don't know how to chuck a 1/4" diameter part in a 4-jaw.

TIR on collets is a funny thing. Technique in tightening has a lot to do with it, at least with imported stuff. I use ER32 a lot, and found that bearing nuts are a big help.

 

[projectnut]

Most inexpensive collets have a run out of .0002" to .0006". While a standard 3 jaw scroll chuck usually has .001" to .003" run out. If doing work that requires +/- .005" or less run out the collet is more accurate than the scroll chuck and less time consuming than the independent 4 jaw. If you're willing to spend $80.00 or more a collet you can get Hardinge Precision collets with less than .00005" run out. In most cases they wouldn't be worth the money since spindle run out is usually around .0003"

 

[NCjeeper]

Fit it in your lathe tail stock to grip taps.

 

[markba633csi]

Another thing to consider: If you were going to mount collets to your lathe spindle, it would be more useful to get a collet chuck that allows long
stock to pass thru the spindle, rather than a MT shank to ER chuck. Less wasteful of material when making multiple parts

 

[DavidR8]

Not sure if you have a mill but I have seen folks use a square ER32 collet block in a 4-jaw.
Not a speedy setup but if don’t need it often it can work well.