whats happening with threading

[keithmech]

I have just upgraded to the newest level *********xx.20.
Everything seems to work fine but when I tried to thread using the wizard
I get un reliable movement on the z axis.Thread starts-goes in fist cut
does not retract on x comes back addes cut on x and cuts fine for random
number of passes then randomly starts to feed in on or out the x durring the cut
obviously with disasterous results.Is this me or the wizard?

[RICH]

keithmech,
Is there any chance that your steppers are loosing holding torque, skipping?

I assume you used the threading wizard that is in Turn. While in the wizard, did you click the settings box, which gives you another screen and put an X clearence value in ?

RICH

[keithmech]

I knew about the clearance setting.I also pulled off the motor and checked the encoder
coupling, long shot as this is only showing up when threading.I seem to have lots of torque
and this will happen when cutting air.I'll try and hand code a thread and see what happens.

[Hood]

Has threading worked for you before?
Have a look in config menu and then plugins and enable the Turn Diags one, it may help find out where your problem lies.
Hood

[neptune]

I'm seeing the same problem in R3.042.020. Most of the passes are cutting correctly, but randomly the occasional pass will cut at a rapid feed, thereby destroying the pitch or the x axis will move (usually positive) as if cutting a tapered thread.

Peter

[Hood]

Have you enabled the plugin so that you can see if it picks up some problems?
Hood

[neptune]

I have enabled the plugin. I am experimenting with screwcutting in mach 3. Normal turning has been working fine over the past six months or so, but I have not yet cut a successful thread. I know I have a problem with automatic speed. I have seen others report similar problems in that the spindle speed changes during rapid moves, but the solutions given have not been successful in my case. If I try screwcutting with pwm spindle control, I get the message "scripter compile error in: spindle speed. mis"

I have therefore been doing my screwcutting tests with manual speed control and I have a nice steady feedback from the indexer and no error messages. The only problem is that roughly 2 passes out of 30 either cut at a rapid feed or with a taper on the X axis. The taper is usually positive, so it doesn't affect anything, it just doesn' cut. I tried approx 30 threads this evening, 4 of them were fine. The others were destroyed by the rogue cut at rapid feedrate.

Peter

[keithmech]

I have enabled the plugin.but no difference.
This is random only on the first pass is the error there all the time
the tool moves the correct pitch but fails to retract in the x axis.
the next pass maybe ok as the next several ,then a random
taper or + or- move of the x axis as the thread is cutting
regular turning works fine.I tried to load the servo motors by
taking a .250" doc on the radius 700 rpm and 10 ipm feed
nice chip but it still worked ok.while threading I cut the doc down to .01
and no good.

[keithmech]

what should I see on the diagnostic screen for the plugin?
My results seem random from one sample to the next.

[Hood]

To be honest I am not sure as I have never had problems with threading so have never used the diagnostics. Best bet is to post the info in the diagnostics and I will ask Art to have a look.
Hood