Threading on a CNC turning centre

[cnc-it]

Hi recently bought an Hitachi Seiki 4NE11 cnc lathe with 2 speed gear box.
Its not up and running yet but I hope to try threading on it ID and OD.

My only worry is that the inherant back lash in the gear drive and and the fact that it uses older type dc spindle and servo motors might affect the thread quality...?

I'm wondering how well matched the feed to spindle speed will be...has anybody had good results with this type of lathe...

It has Fanuc 6T and yellow cap dc sevos.

Thanks for any help guys.

John.

[Al_The_Man]

This control is capable of it, providing the mechanics are in shape, the spindle gear backlash is generally not a problem as the encoder should be driven off the final shaft, and this is what the Z axis gears off, the error you are probabally going to get is if there is appreciable backlash in the Z ball screw/drive system.
There is nothing wrong with DC spindle or DC servo's, in themselves, it is the mechanics that will be the hangup.
Al.

[cnc-it]

Thanks Al.

Your right the spindle encoder is driven off the final shaft..there is a small ammount of backlash on the z axis ball screw but its only tiny and no noticeable backlash in the x axis.

Sounds like the Fanuc 6 will do the job then, now it's time for a test run

John.

[gridley51]

We do a lot of threading,int and ext on a W&S Universal with 6T.The machine is over twenty five years old,has a 16" chuck and the turret will weigh at least 500kgs.Even behind a shoulder with limited approach we have no problems.

[cnc-it]

That sounds like a BIG machine Mark! Sounds like my Hitachi will do fine then, its about the same age and spec and looks like it will be fairly accurate .
John.