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Spindle RPM and Threading Problem
« on: October 07, 2017, 09:05:39 AM »
Hello everyone, and sorry for my probably bad English.
I have some problems with Mach 3 Turn and more with the Threading Cycle to be specific.
I am retrofitting a Guildemeister NEF 480 Turn which used to run with some old Fanuc CNC that we couldn't start up so we decided to use Mach 3 because it is cheaper then a new CNC.
I've placed my old desktop PC inside with freshly installed Windows XP and Mach3 R3.043.066.
Removed the old Fanuc DC Drives and placed new one that run with step/dir signals.
I am using K845P optocoupler for the inputs so i can use the original 24V power supply.
The spindle is controlled by two contactors (one for M3 and other for M4) and there are two solenoids changing between two gears (N1 and N2 - slower and faster). It also has mechanical levers for different gears that you change before starting the mottor. I am activating the contactors manual (Mach has no control on them). The solenoids however are connected to outputs of Mach and when no one of them is active a brake is activated inside the gearbox. I assigned inputs for the contactors , so when i turn one of them either M3/M4 Mach 3 knows that the Spindle Motor is active, after this with Joystick Plugin i have buttons that trigger the solenoids and after one of them is activate Mach receives a M3/M4 command. Only the mottor is turning until a solenoid is activated, then the Spindle stars rotating. Something that i find strange is that if I type M3/M4 in MDI Line it instantly puts some RPM's in the DRO ( In this moment the Spindle is not spinning and the Index Signal is '0') . I've set the index debounce to 0 but even when it was higher it still counted the RPM's. Now when i type in the G76 thread cycle for example:
Code: [Select]
G76 X-1 Z-10 P1.25 H2 I29 C2 Mach moves the X and Z axes a little bit and stops whithout any message or anything and stays there forever. In the diagnostic screen of the Turn i could see a LED "Wait fot Trigger" wich turns on in the moment when i start the cycle and turns off almost immediately ( This should be the moment when the Spindle Index signal is arriving i guess? ) and then the LED "Currently Threading" lights up and that's it.

Now for counting the RPM's i am using a inductive sensor placed over a nut that is tightened on the back of the spindle (Picture Here) so the ratio is 1:1 as I've set it in Spindle Pulleys setting. So my questions are:
Why the cycle is not going?
Why when i type in M3/M4 it gets RPM reading when there is no one?

Thanks in advance.  :)
Re: Spindle RPM and Threading Problem
« Reply #1 on: October 07, 2017, 02:25:30 PM »
hi
the version of mach 3 you are using is no good for threading ,you will find threading works better with an older version of mach 3 , i use 062 & have never had a problem with threading
robert
Re: Spindle RPM and Threading Problem
« Reply #2 on: October 08, 2017, 01:09:05 AM »
Hi,
you've got a lot of things on the go, no wonder you're getting confused. Start with getting the spindle to run then worry about other stuff.

When you manually turn on either of the contactors does Mach see the input signals? You should see the LEDs for the inputs you've used on the
machine diagnostics page. When you MDI either an M3 or M4 are the solenoids coming on as they are meant to? Does the spindle start to
rotate and does it eventually come up to speed?

I think what's happening when you MDI an M3 or M4 the spindle speed DRO is reading the current S command, that is to say the speed that the spindle
should get to not its actual speed.

If you turn the spindle manually does the index signal show on the machine diagnostics page? Once you get the index to work and work out how to
get Mach to read the actual spindle speed THEN start thinking about threading....threading without all these other things working is a joke.

Craig
My wife left with my best friend...
     and I miss him!
Re: Spindle RPM and Threading Problem
« Reply #3 on: October 08, 2017, 07:34:51 AM »
The spindle motor is turned on by hand, and the solenoid is activate by Mach. The spindle runs after it is activated by the solenoid. And all the inputs are read correctly. When i turn on the contactor the input is read and after i push the joystick button for the solenoid it activates and sends a M3/M4 command to Mach. All LEDs are working, i can see the spindle index signal, the inputs and everything. Something that i'm not sure if it is correct is that i cannot see the index on every single rotation of the spindle. But i am not sure if the diagnostic leds are enough fast or something like that, because if it's missing pulses then why it counts the RPM correctly. There is no S command, cause i am sending only M3, mach has no control on the RPM.
Re: Spindle RPM and Threading Problem
« Reply #4 on: October 08, 2017, 11:32:38 AM »
hi
is the spindle speed you are getting very steady , something in the range of + or - 1 rpm  deviation if this ok then that is a part of the threading cycle
please find the type of program i use for doing thread programs for my machine
this program is for a M14 x 1mm pitch external thread , this is a hand coded program

G95
M6 T0505 (external threading tool 60 deg)
G0 X14.00 Z10.00
M3 S600
G76 X12.780 Z-6.80 Q1 P1.00 J0.010 L45 H0.300 I29 C0.250
G0 X40.00 Z50.00

all the best
robert
Re: Spindle RPM and Threading Problem
« Reply #5 on: October 08, 2017, 12:23:09 PM »
Hi saschko,
Mach may not have control of the speed and you or your program may not have specifically issued an Snnn command but there is a variable
inside Machs core that it will use whether you chose to update it or not.

Craig
My wife left with my best friend...
     and I miss him!
Re: Spindle RPM and Threading Problem
« Reply #6 on: October 08, 2017, 05:58:23 PM »
@ministeam: Yes the spindle speed is steady, it takes it probably a second until the spindle accerelates and once it reaches it's speed the DRO isn't floating arround, it stays constant.

@joeaverage:
When it will use this variable and for what? I think i am missing your point, shouldn't it synchonise the axes feed depending on the RPM that it counts from the Spindle Index input.
Re: Spindle RPM and Threading Problem
« Reply #7 on: October 08, 2017, 06:19:47 PM »
Hi,
Mach has a variable that it uses as its commanded speed, even if you don't set its still there.
Just as an experiment try setting S to some funny number, 15995, for instance. If this number
crops up on Machs screen then you will know whether its using the index and measuruing the
speed or just reporting the programmed speed. It can do both.

Craig
My wife left with my best friend...
     and I miss him!
Re: Spindle RPM and Threading Problem
« Reply #8 on: October 09, 2017, 01:38:44 AM »
Hi saschko,
Quote
shouldn't it synchonise the axes feed depending on the RPM that it counts from the Spindle Index input.
yes it should, but is it?
Isn't that the whole point of the post?

You need some way of confirming that Mach is ACTUALLY reading the spindle index. While it needs it to calculate its current speed it is in fact more
important than that, it synchronises the start of the thread when doing multiple cuts.

Do you have or can you borrow an oscilloscope? The picture showed what I called a proximity sensor. They are pretty lethargic, it may not be fast
enuf to send individual pulses. Do you have any specs for the sensor? I have seen some that are good to several hundred Hz, easily good enuf but others
that can only manage 10 Hz, and they wouldn't.

Craig
My wife left with my best friend...
     and I miss him!
Re: Spindle RPM and Threading Problem
« Reply #9 on: October 17, 2017, 12:10:09 PM »
I had doubt in the proximity sensor too, but i've checked that with the oscilloscope and it is working, i can't see every single pulse in Mach, but it should be there, because it measures the RPM correctly.
If i type "M3 S100" on the screen i can see a DRO with label 'S' wich aquires the value i entered. However in the STrue DRO  are the real RPM that Mach counts through the SpindleIndex Input. Still it doesn't thread, it is moving the axes, just a little bit and then nothing. I tried with the other version of Mach (062) but it's the same.