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how to switch a Mazak QTN Nexus 200 ms lathe from ID clamping to OD clamping?


Sep 20, 2022

I am trying to work out how to switch my Mazak QTN Nexus MS from ID clamping to OD clamping. My machine is a 2004 model and runs Mazatrol 640T

After pressing the machine key and then the chuck soft key there are the soft key options for chuck one and chuck 2 INT and EXT. If I push EXT soft key it blinks in and out of reverse display (blinks in and out of highlighted pink). I guess I am missing something because when I push the foot pedal it comes up with an alarm. I think the alarm is in regards to opening the chuck jaws while the spindle is rotating (which it was not). I can get the alarm details tomorrow if they are needed.

A reply in a previous thread on this site in regards to a QTN Nexus machine suggested ''to press the options key and then press the OD/ID chucking key and it will flash and then push the pedal to activate and and it should work'' I havn't noticed an options button with an OD/ID clamping option on my machine as yet. Maybe I need to have a better look

A bloke in a you tube video says you need to change Parameter R49 for the machine to accept the change. I think his lathe was running on Mazatrol 640T but his R49 parameter was different to what I have. Maybe its because his machine has tail stock.

Any help would be appreciated. Thanks
Chuck confirmation proxies arent adjusted properly for EXT chucking.
make R49.0 zero and see if you can use timer confirmation for switchover.
Thanks for your replies Scruffy and Noname.

No I didn't realize I needed to describe the jaws before I could get the spindle to spin in manual mode. I'll do that and see how it goes. If that doesn't fix it I'll follow your advice Noname.

I've removed the Autoblok collet chuck that came with the lathe and fitted a 3 jaw MMK chuck for the first time so I'm learning
You shouldn't need to change any parameters to go from ext to int chucking. I'd be interested in the error. It should work as you described, select int or ext- the choice blinks pink, use foot switch and changes to solid pink. That's what's supposed to happen. Are you in manual mode when doing this? 640 control?
G'day Bob
Thanks for your reply.

I am getting alarm 329 ''chucking selection prohibited'' when I push the foot pedal to open or close the chuck after selecting CHK - EXT.

Its happening when the lathe is in manual mode e.g its not running a program and the memory button is not selected. If that's what you mean.

Its Mazatrol 640T

I entered the number of jaws and grip diameter on the setup page.

I'll enter the chuck jaw details on the chuck jaw screen later today when I get a chance to see if that changes anything.

Here is the link to a video https://photos.app.goo.gl/od9YGP2GwzaaubBx9


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that is one of those funny MAZAKs alarms where PLC has L memory bits and sometime they go nuts. Do you know how to open LADDER and search for F bit ( alarm?)
It will be nice if you could open it and find F129 bit and take a picture and upload it here. It is gonna be something to do with M4012 bit, CHANGE CHUCKING OKEY ( see attachment ). That is where PLC checks if machine is in MANUAL and SPINDLE at ZERO SPEED.

more I look at it , more I believe it has something to do with proxy switches.


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In regards to searching for F129 I'm probably doing something wrong Scruffy as it comes up with Program not found when I enter F129 in the input bar and hit enter? I don't know much about the PLC ladder but I will see if I can find some info on the net.


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Not really. You are doing it right. I have PLC version for QTN with 640T and it doesnt have F129 alarm. Meanwhile QTN-2 with Matrix control has alarm F129.

So if your PLC doesnt have F129 bit? Who generates F129 ( Alarm 329) ?

Was there any software upgrade? PLC upgrade? IS there anything else wrong with the machine?
I purchased the machine second hand so I am not sure if there was any upgrades to the PLC or software. I am guessing the best way to find out is to contact the dealer? If it means anything it did come with two ROM options cards. One must be the original and one is a later card. It looks like 20 cylindrical interpolation, 26 EIA Helical Interpolation,27 EIA Coordinate rotation,34 EIA Helical tap and 35 sub Sp 1/1000 deg positioning was added at a later date. I still have the problem with mazatrol shutting down which you were helping me sort out (you have a performed an illegal operation and mazatrol will shut down) until the NC unit warms up


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can you recreate alarm 329 and take a picture of ALARM screen, ALARM history page.
it does look like someone added few more options and modified the software.

does you machine have sub spindle with proper C axis?
I should have checked the Proxi switches as you suggested first Noname777. Sorry for not looking into that one straight up. Now that I have adjusted the proxi switches, EXT chuck soft key option is solid pink and I have alarm 218 ''chucking type not selected. So it looks like progress has been made.

I wonder where I need to select the chucking type. I would have assumed the solid pink on soft key EXT chuck was the selection its after.

My machine has a sub spindle. I haven't used the sub spindle yet to find out if it has a proper c axis. When you say proper C axis do you mean if I can do interpolation milling and things like that on the sub spindle?

In regards to the alarm history the only recent alarms other than 329 alarm were air pressure low and emergency stop alarms. This is due to me shutting off the air supply to save the air compressor running all day and the emergency stop alarm was due to the lack of air pressure.
yea. Progress. Now alarm 218. Bit F18. PLC shows these funny L (battery backed up) bits again.
Sometimes you just have to force them to fix the problem.

Proper C axis is one you can index with 0.001 degree

try this to clear 218 alarm. I think some PLC versions have a back door to reset L bits, some you have to manually override in DIAGNOSTIC MONITOR:

I.Determining the open/close direction of the chuck
A.Step 1
1.Press the MACHINE key on the operation panel to display the machine menu on thescreen.

2.The chuck menu appears when the [CHUCK] menu key on the machine menu is pressed.

3.Select either the [CHUCK INT.] or [CHUCK EXT.] menu key, depending on the shape ofthe work, while pressing the MF1 key.
The menu key selected is highlighted. [CHUCK INT.] opens the chuck by the chuck closing operation [CHUCK EXT.] closes the check by the chuck closing operation


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Thanks for that info noname777. I didn't press the MF1 key at the same time I selected the EXT chucking although I did get a solid pink I better have another go.

In regards to the PLC ladder if I need to change anything I've got a lot to learn before I have some idea of what I'm doing but I'll try to school up on it.
Yes you are making progress!!

Are you in "milling mode"? I'm not sure if the 640T has that or not. That would prevent your selection and cause the error. I don't think anything is wrong, the 640M&T&MT (my machine) is very particular about when you choose things & the mode your in & head selection. I think it will bitch at you if your changing the Sub options but have the SP1 head selected by the rotary switch. Funny stuff like that you'll get sorted as you start to use it. I always seem to be looking for the switch I forgot or mode I missed... Setup switch on?

Go back to position screen, then try it again, take a picture of the screen, also take a picture of the lower switch panel.
Thanks for that Noname777. I pushed the MF1 key at the same time as selecting CHK EXT but alarm 218 is still showing. I have attached a picture of F18 in the PLC ladder if that helps.

Thanks for that info Bob-00. If I am understanding correctly Its not in milling mode. I think putting it into milling mode its a similar procedure as it is to connecting the main spindle e.g push C axis connect and MF1 together. Let me know if you think I am not understanding you correctly though.

I have attached a photo of the screen and full control panel. Here is a link to a video https://photos.app.goo.gl/TGFApU9z494QYu558

I have played around with swapping from head 1 and head 2, adjusted the proxi switches so they are closer to the specs in the maintenance manual.
I played around with the machine setup switch. The alarm didn't change.

On the setup page where it asks for jaw number I guess you enter the appropriate chuck jaw number that is filled out on the chuck jaw data page. This data includes out or inner jaws and jaw dimensions. In the attached photo of the setup page I have chosen Jaw number 2 which I assume is jaw number 2 on the chuck jaw data page. The alarm is still up after doing this.


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it doesnt. Search for F18 few more times till you see -( F18)- as output. You should see something similar to my previous post ( above).

Make ALARM active, dont press anything, go to LADDER monitor and keep searching for -(F18)- .

Once you post this picture, we will quickly reset this alarm.
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The attached image on the left looks similar to the ladder image in your previous post noname777. Is this what your after? I'm not sure how to make alarm active


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what type of chuck you are using now? POWER chuck or COLLET chuck on BOTH spindles?

your MAZAK has parameter R54 bit 6 setup as a collet CHUCK ( it is 1 ), not normal CHUCK.

That is why it alarms F218, you cannot change INT-EXT CHUCKING for collet chuck.

Set R54 bit 6 to zero
It had a collet chuck on the main spindle and now I have fitted a 3 jaw power chuck on the main spindle.

For some reason I can't find the R parameter list today. They were easy to find yesterday. The photo on the left is a what I can see today when I push the machine parameter key. The photo on the right was taken yesterday when I was looking at the R parameters.

Sorry I not familiar with bits yet. In regards to the attached photo on the RHS with the R parameter list do I change the number 1 circled in red at R54 on the left or the RHS? Thank you for being very patient and helpful


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