Messages

21

SmoothStepper USB / Re: Mach3/USB SmoothStepper will not control spindle speed

« on: April 23, 2015, 10:28:22 AM »

Are you trying use the spindle speed PID in Mach 3? If so turn it off and also delete any file in the Mach 3 folder/macro folder called 'linearity.dat'.

The SmoothStepper just generates pules, just like the parallel port. The only difference is that for a PWM spindle you can set the acceleration. The SmoothStepper and parallel port both adjust the output in a linear fashion, i.e. 50% speed output is a 50% duty cycle square wave output. Any non-linearity is the result of your speed controller/motor. The spindle speed PID Mach 3 is a function of the parallel port driver and it can help with non-linearity problems (sometimes it works OK and sometimes it does not). It does not work with an external device so if you have it turned on or have a linearity .dat file it will screw things up.

22

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 15, 2015, 02:23:24 PM »

I was chatting with Greg about this. The issue is that in Mach 3 that a Step/Direction spindle is sent to external devices as a jog command, when you hit 'Stop' Mach cancels the jog processor so all the sudden you have no S/D output to the spindle servo controller. The axis are also cut off suddenly.

What I might think of doing is customize the screen set with my own stop button. The stop button would do a feed hold, when the axis stop then do an M5, when the spindle stop then do a 'Stop'.

23

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 15, 2015, 12:19:39 PM »

What problems with the S/D spindle are you referring to? I have several customers who use S/D to Analog cards to control their spindle speed and that seems to work fine.

24

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 15, 2015, 11:55:54 AM »

Hood, a S/D spindle is treated just like an axis in that Mach 3 generates a pulse train just as for the other axis. When you press the 'Stop' button Mach 3 (parallel port driver) will immediately stop outputting pulses, in other words instant deceleration. I don't think this is desirable but it is how it works and with stepper motors you are sure to loose position if the machine is moving.

The SmoothStepper tries to emulate the parallel port driver so it to immediately stops outputting pulses. Using Feedhold is the only way to decelerate to a stop, then press the Spindle button to turn off the spindle safely, then you can hit Stop. The issue I was talking about before is that if the SmoothStepper tries to decelerate the axis (including S/D spindle) on its own, it has no idea of the correct path the machine should be following so the best it will be able to do is decelerate in a straight line (whereas Feedhold will stay on the correct path.)

Mach 4 is so much quicker at talking to the plug-ins that I think we'll see a lot better behavior in this type of scenario and we can make the Stop button to a feed hold, which will work properly with external devices, and then to a spindle off and then a Stop.

25

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 15, 2015, 07:27:59 AM »

Hood, the default behavior for Mach 3 is to stop all pulses when Stop is pressed. The ESS is simply doing what the parallel port driver has always done, not that it is a good thing to do. Think about it this way, what path should an axis decelerate in? The ESS has no idea, only Mach 3 knows the path that was programmed via GCode. The only thing the ESS could do is decelerate each axis in a straight line.

26

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 14, 2015, 04:20:50 PM »

I don't have a problem with the Estop as it sends a command directly to the Servo emergency stop input

That describes an enable line not an EStop. An EStop generally removes power immediately from all things that move. That means when you hit the EStop button the mains to the servo power supply should be cut. If you are relying on a logic input to the servo drive what do you do when the servo encoder dies and the servo runs away?

There are some types of machine that will let servo controlled axis coast for a few seconds in order to safely decelerate them and then cut power. Different regulating bodies will have different codes that cover this sort of thing.

27

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 14, 2015, 11:03:42 AM »

True, I did not think of that. Then the custom start button would need to fed hold and turn off the spindle. Still you will have the same undesirable action with EStop so a electromagnetic brake may be the only way to go.

28

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 14, 2015, 10:29:29 AM »

Make sure you are using the latest ESS plug-in and a Mach version higher than 3.043.058. There was an issue with how previous versions of Mach filled the motion buffer that could cause the 'ran out of data' problem.

If you want to avoid the possibility of a user hitting Stop and causing a problem then write your own macro for the Stop button, it could do a feed hold and wait till the machine stopped moving and then issue the stop. You will have a similar problem though if the user hits EStop so you might need a brake on the spindle to stop if safely in an emergency.

29

General Mach Discussion / Re: AC Servo Spindle and ESS

« on: April 14, 2015, 08:18:09 AM »

In Mach 3 when you hit 'Stop' the output immediately stops, you get no deceleration. I'm not saying that is desirable but that is how it works. If you hot 'Feed Hold' you get a nice deceleration to a stop. Always use 'Feed Hold' and once the machine has halted then hit 'Stop'.

30

SmoothStepper USB / Re: Mach3/USB SmoothStepper will not control spindle speed

« on: April 11, 2015, 05:36:31 PM »

Yes spindle control comes up a lot because it is fairly involved as you have the Mach3, SmoothStepper, BOB, PWM or S/D converter and your VFD/speed control. You have to figure out enough about all of them to wire things up and then to configure each one of them to work together. Programming a by itself itself can be very complex.

Now add in the fact that everyone has a different machine, which is wired differently, and it is not a matter of having a list of settings in a manual as the settings are unique to each machine.