Need Help!- NL2500 using sub spindle as a tailstock

[MazakMack]

We have a Mor Seiki NL2500 with a sub spindle.I am looking for help on how to use the sub spindle(it has a chuck on it)to hold a live center, and how do you hold pressure against the part if you can hold a live center.I am looking for ways that others have used them.

[underthetire]

Careful how much pressure, but you can mount a dead center in a collet and sync the spindles. watch the load meter and dial it in.

[muddobber76]

I have done this different ways with mixed results. The best application I have found is to use a spring loaded live center. They are a little pricey. I think the last one we purchased from Royal was about $800. Make sure to check the rpm rating. A spring loaded center is best cause it will allow for deviation in length of your part.
The other option is to chuck up a piece of steel and turn a center. Make sure the material you use for the center is harder than the work you are turning. Apply some high temp/pressure grease to the center land. Dial in the sub to the exact point you have contact and then move in another two thou. Now the critical part is all spindle commands must be synchronised or else you will gall up the part and center.

[fordav11]

I once had a spring-loaded center.
It's now Resting In Peace. Or I should say Resting In Pieces

Unfortunately our rough stock bar has random variation in length
and it blew up on the first part that was too long where the
center drill broke during fully-automatic unattended operation.

You can do it a much smarter way and make the machine
think by using the Workpiece Pushing Function.
A regular live center works well.

i.e.

G00 B..... (rapid near part)
G01 G38 B..... Q..... (B = end point, Q = tolerance)
(the rest of the program here....)

This G code is Mori-specific and Model-specific.
Check your Mori manual for the details of your Workpiece Pushing Function

[MazakMack]

On this job, it will already have a center drill in one end and the part will be manually load into the main spindle, clamped, and then have the sub spindle manually moved into contact w/the part.How do you know how much pressure you are putting against the part and is there any concern with the sub spindle (B axis)moving?
Because I have a chuck on the sub spindle, what are options for holding a live center?

[fordav11]

the sub spindle is designed to move like any other axis but once you stop it then it will not move until you tell it to move.
you make it sound unusual but believe it or not it's called a sub spindle because there is a chuck on it
why move it manually when you can program it and let the machine do the work....

if you can only hold on a small amount of material you'll probably have to pre-drill it otherwise its best to do it in the machine so it runs true. You'll have trouble lining up the center hole when the center comes in otherwise. if you drill it in the machine you can keep going...... center drill, rapid center in and pressure it onto the part, start turning.

the pressure is pre-set for the Workpiece Pushing Function (I don't know which parameter but its Mori-specific)
the pressure is the same as a transfer push so it will be fine as-is unless you are taking very heavy roughing cuts.

to hold a center buy a straight sleeve to morse taper adapter like what is used to hold a morse taper drill in the turret. the OD of the sleeve will likely be 50mm/2" and the inside bore will be a morse taper.

Put the center in the sleeve and clamp it in the chuck like you would with any piece of round bar.

if you really want to do it manually just clamp the center into the chuck, move the center in manually (B axis movement) while watching the B axis load meter. I usually load it up to around 40%-50% for roughing. When you are pressured up unclamp then clamp the left chuck then re-pressure the part so you know it is pushing your bar back into the chuck jaws.
Then just start turning like normal, you can ignore the 2nd spindle completely.

[MazakMack]

These parts are long shafts,17 inches long and am only holding on by .400
After I manually move sub spindle into contact with centered part with 40-50% pressure...How do I lock spindle from moving?(I have a live center in chuck)Do I MDI M268 spindle brake?...or M245 C-Axis connection?Will machine run auto in main spindle while sub is locked that way?
Thanks for the help!!

[fordav11]

I would probably just enable the C axis connection and make sure you are not in a sync mode. it should work. or spindle brake if that doesn't work. either one should be ok as far as doing it's job to prevent the 2nd spindle from rotating.
You may not need to lock the 2nd spindle but if you get tiny lines on the part (due to 2nd spindle and live center spinning together) and the 2nd chuck locking doesn't work or you don't want to lock the spindle just use a dead center and leave the 2nd spindle live and free.
You can add the G/M codes to the top of the program you don't need to do the locking manually.

[MazakMack]

I was able to use the sub as a tailstock by turning a dead center (held in the chuck).I had to use M35 and synchronize spindles as just letting the 2nd spindle spin free, it alarmed out.I did preload the sub to about 60% on the load meter but think it would work better with a spring loaded center for this part....They are all the same length and have to be loaded manually.
Thanks for all the help!!

[russmatt]

I am doing the same thing. i used a dead center and synced the spindles and used the workpiece pusher. i was wondering how you adjust the pressure on the pusher. i would like to apply a little more pressure to the part. our tolerances are very tight. thanks