QT15 Stroke Limit

Hello all,

Now with the machine finally up and running, I got a job where I have to turn some 8.250 diameter stock. However, when I try to go out to that diameter, and I get to around 6.5 inches diameter readout on the control with my turning tool loaded and set correctly, It gives me a stroke limit alarm? Can this be bypassed in some way? In the manual it says this is set by parameter B1, but what can I change there if anything? I dont want to mess anything up! The max turning diameter for the machine was listed right at 10 inches if I remember correctly, So I am sure I can somehow cut that diameter... What do I need to do to cut these parts?

Thanks for any help!

Nick

B1 is a software stop. We have a QT15 with a T-2 control built in 1989 and can cut to a diameter of + 12 inches. Try inputting 120000 in B1. I believe that the machine has to be turned off and back on again in order for the controller to read the changed parameter.

My bad. On our QT15 we have 3750 at B1#1, and 256700 at B1#2. Try these, just record your present settings before changing so you can go back to them if you must.

To get the max turning diameter you may also need to shorten up your tool holders. We have a small QT-8 and a standard length tool holders are way too long to get anywhere near the max turning diameter without cutting a couple of inches off and chocking up on the tool close to the turret.

You can tweak the max turning dia only so much until you run into the urethane bump stop and / or the thrust bearing mount.

Also, make sure the previously unused portion of the X axis ways are free from dirt and grime before adjusting the B1 #1 parameter for more stroke.

The following process works on T-2 (T-3) controls. No clue if this works on other controls--newer or older. YSMV = Your stroke may vary.

Easiest way I have done this is to home machine normally and then power down machine while still at home position. Restart machine but do not home machine. At this point, X and Z axis will show 0. Set to 10X pulse generator and slowly crank X+ while a helper (remote USB camera might work great here) checks clearance between urethane bump stop and sliding X axis body. I left about 1/8" air gap between bump stop for my comfort.

At this point, read the value displayed on X axis. This is the diametrical distance the machine can move above the X home position, which is entered in value B1 with no decimal. For example, 2.420" would be entered as 24200. Enter the value now. Move machine toward the chuck (well away from X and Z home positions) with MPG and shut off machine. Restarting machine is required for machine to 'read' this parameter.

Restart machine and home out X and Z axes normally. Switch to X10 and move X+ slowly until machine gives you the X+ over travel alarm. If you do not set B1 correctly, you will get X axis overload as the machine bottoms out on urethane bump stop, so move slow to verify.

Enjoy the longer strokes.

Awesome, I just tried this today as I have been covered up busy on my Mill.....Now I have all kinds of extra stroke!!! Thanks everybody for your help!!! I only could get to about 9.25 inches diameter following Philabusters method, but I have the 16 tool turret, and the tools mount way out there even choked up as much as possible so I figure this is normal? The toolholder itself is about to hit the back wall of the lathe!!! lol....

Now Im on to my next question, Regaurding the sub spindle.... I have been able to sycronize it with the main using a m code at the beginning of the program, and move it using manual process..... but I have not been able to control the feedrate of the sub coming toward the main no matter what I try....seems to go rapid no matter what???? How can I slow this down to "sneak up on the correct coordinate?" can somebody send me a copy of a program that works correctly so I know what it should look like?? Also, I hit the tailstock teach in the run screen and now I have a barrier alarm every time I try to home the machine out...How do I get rid of It?

Thanks again everybody!!!
Nick