rec.crafts.metalworking
measuring play in quill+spindle of milling machines & drills

Ned & Jon - thanks for the data and the insight regarding the flexure of the
head & stand or body of the tool. The numbers both of you mention are
reasuring.
A gap is left, however. Have either of you made measurements along
the lines I described? Possibly more significant would be mounting an
indicator on the table touching the spindle and then applying a measured
force between the spindle & the table. Both left & right and then again
in & out would be best and indicate what could be expected tolerence wise.

Hul

On Sat, 12 Jul 2008 22:55:02 +0000 (UTC), Hul Tytus
wrote:

rec.crafts.metalworking
measuring play in quill+spindle of milling machines & drills

Ned & Jon - thanks for the data and the insight regarding the flexure of the
head & stand or body of the tool. The numbers both of you mention are
reasuring.
A gap is left, however. Have either of you made measurements along
the lines I described? Possibly more significant would be mounting an
indicator on the table touching the spindle and then applying a measured
force between the spindle & the table. Both left & right and then again
in & out would be best and indicate what could be expected tolerence wise.

I've never done that with a measured force and don't see that it would
be useful unless you wanted to compare the stiffness of two machines.
It would tell you very little about the accuracy you could expect from
a mill, or the condition of the quill and spindle, except perhaps in
the case where one or the other was really trashed. In any case, the
methods that Jon and I described will yield much more information.

I do disagree with Jon about the amount of play that tolerable in a
mill spindle, anything more than zero is too much, but other than that
I think we're on the same page.

--
Ned Simmons

Hul,
Zero is good. If you see anything else, you would hear it as well.
Steve


"Hul Tytus" wrote in message
...
rec.crafts.metalworking
measuring play in quill+spindle of milling machines & drills

Ned & Jon - thanks for the data and the insight regarding the flexure of
the
head & stand or body of the tool. The numbers both of you mention are
reasuring.
A gap is left, however. Have either of you made measurements along
the lines I described? Possibly more significant would be mounting an
indicator on the table touching the spindle and then applying a measured
force between the spindle & the table. Both left & right and then again
in & out would be best and indicate what could be expected tolerence wise.

Hul

Hul Tytus wrote:
rec.crafts.metalworking
measuring play in quill+spindle of milling machines & drills

Ned & Jon - thanks for the data and the insight regarding the flexure of the
head & stand or body of the tool. The numbers both of you mention are
reasuring.
A gap is left, however. Have either of you made measurements along
the lines I described? Possibly more significant would be mounting an
indicator on the table touching the spindle and then applying a measured
force between the spindle & the table. Both left & right and then again
in & out would be best and indicate what could be expected tolerence wise.
Well, the measurement on my Bridgeport is not much different, if
you include the turret - ram - head knuckle - head stackup.
Maybe .0015 - .002" with a 50 Lb load applied both ways. I have
a home-made hack-job of a jury-rig to mount a J-head on a
machine originally made for an M-head. It is totally inadequate
for the weight and tool extension possible with the J-head,
but I am using it anyway.

I applied force manually pushing against the floor, not touching
the machine table, as that is yet another stack-up of movable
parts, and probably a lot looser that the spindle/quill, if you
include the leadscrew backlash.

Jon