In article ,
Wayne wrote:
Hi all,
I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?
If the ones which you are talking about are the ones with a
steep taper between the 60 degree taper at the tip and the bearing
housing -- there are reasons to get it, and reasons to not get it.
Not get:
1) The longer tip puts more leverage on the tailstock ram,
possibly producing more offset under heavy turning loads.
2) Usually significantly more expensive.
To get:
1) The longer taper gives you more clearance for the toolpost
and toolholder, allowing you to work with smaller diameters at
the very end while keeping a shorter tool extension, so the
chance for chatter is reduced. I find this most useful when
threading at the end of a shaft, as that requires more reach
towards the center than the turning just prior to that does.
2) Probably better (and more) bearings, so it is more rigid within
itself.
3) Bragging rights? :-)
What's the difference between than an a normal live center?
1) Based mostly on what I have seen in the catalog pages, it will
have more rows of bearings, so it handles a load better.
(Whether the tailstock ram will do so remains to be seen.)
2) The longer taper, to get the bearing housing out of the way of
your work. More necessary with a tool turret in a CNC lathe,
but useful also with a big fat toolpost.
3) Maybe a difference in the shank. Some of them may have
cylindrical shanks instead of Morse taper shanks.
Note that the one which I have (with a MT-1 shank), made by
Royal, is an interesting style. The profile looks more like this:
/\
/ \ ---- 60 degrees
| | --- straight
| |
/ \ --- 60 degrees
/ \
/ \
/ \
| | -- straight
| |
| |
+-----| |-----+ --- everything from this line up rotates
| | ---- Morse taper within the limits of
|| ASCII graphics
||
This means that not only is it an extended taper for close turning, but
it also is a bull-nose taper for turning pipes and tubing.
If you get a CNC live center, you will probably also need at
least a bull-nose taper sometime, and an interchangeable point one can
be quite useful at times, too.
I hope that this helps,
DoN.
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