reducing chuck size / acceleration times

[deadlykitten]

hello guys & girls i am considering replacing my actual 10inch normal chuck with 8 normal or big bore


8 normal can take up to 2.65 MPA, and that is pretty close to 10 normal : 2.70 MPA
however, the 8 big bore can take up only 2.3 MPA and has only 3 screws on its frontal instead of 6
i wish to be able to keep actual cutting specs


i am doing this also to reduce inertia on the spindle


i had a setup that winds the chuck 1900cw > 1900ccw; this is syncro with turret movement and it does not always run smooth; sometimes is ok, othertimes is not


i asked for a less agresive acceleration, and i was told that this can be done somehow, but not from parameters


please, do you think that i am missing something ? kindly !

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[deadlykitten]

with the 10 i do not go over 2000 rpm

i think that the 8 may hit 2300 .. 2500 and have same feeling, so to say

[deadlykitten]

hello again about my discussions with the chuck suplier, i can tell that there may be some issues :

... Okuma dealer should have the drawing for the motor + pull bar + initial chuck, etc, thus the drawing for the lathe at delivery
... Chuck dealers also may have such drawings, but their variant may not be the same as the one from the Okuma dealer, even if the lathe is standard
... is good to be aware of such differences

however, even more, the flange between the spindle/motor and the chuck has a dimension_a
the dimension for it from the technical drawings is dimension_b
the dimensions for it from the Chuck dealer catalogue is dimension_c

in my case : dimension_a <> dimension_b <> dimension_c

such things may lead to a case where the barr that pulls the chuck is not well dimensioned

also, please be aware when buying chucks that are not screwed directly into the spindle, but indirectly, thus :
... flange is screwed on the spindle
... chuck is screwed on the flange + radial play is adjusted, because in this case, there is play between the flange OD and chuck ID
...... in this case, the chuck vendor may offer by default the narrowest flange, while there may be thicker flanges ... in such a case a narrow flange will lead to vibrations, and also has a chance to deform ( deformation is not visible ... i guess you know what i am talking about )

a narrow flange also is not suitable for heavy specs
thicker is better of course, not extraordinary thick kindly !