Minnimum Spinlde Speed

Hi

I'm a Linuxnc newbie but after a few weeks of learning I now have my CNC lathe working pretty well with gmoccapy and Nativecam and I've started making some bits. Having used Mach3 for over 10 years it is a bit of a culture shock but I think I am becoming a Linuxcnc convert


One issue I have is that my lathe minimum speed isn't great and while it will run down to 100rpm, it doesn't have much torgue below 300rpm, So when I try and use CSS I find that the commanded speed is too slow.


Is there a way I could put a statement in the HAL file that says if commanded speed is less than 300rpm set spindle speed to 300rpm else set commanded speed to spindle speed.

Thanks in advance for the help.

linuxcnc doesn't have a built in way to set a minimum speed.
You would have to craft some HAL components to do this.
Can you elaborate on your spindle control hardware.
And posting your config file would help too.

Chris M

Thanks for the replies. I've got a 1/2hp DC motor which is the original on the lathe. While there is a minimum setting on the drive I found it is rather unreliable - it seems to vary upto 100rpm from day to day. However the commanded speed is always seems to good from 300rpm upwards.


Thanks for the guide on lincurve - I will have a go at the weekend and see how I get on.

Cheers

Dave

Right, i've had a go, but think I may not be linking the right HAL pins together.

I had an initial issue with the addf but realised that was a missing - between the servo and thread.

Below is my spindle section - i've split it into original and new section for lincurve. In the original section you can see that I have commented out two lines(in blue) - that's because I got errors about pins being connected more than once. The orange lines are where i have added the connection to lincurve which i think is wrong but not sure where i should connect it to.

With the code below the spindle just runs at a constant 500rpm and I cannot vary the spindle speed.

Any advice/help would be much appreciated

Thanks

Dave

#ORIGINAL WORKING SPINDLE
#net spindle-cmd-rpm => pwmgen.0.value
net spindle-on <= motion.spindle-on => pwmgen.0.enable
net spindle-pwm <= pwmgen.0.pwm
setp pwmgen.0.pwm-freq 50.0
setp pwmgen.0.scale 2600 #2333.33333333
setp pwmgen.0.offset -0.03 #-0.0285714285714
setp pwmgen.0.dither-pwm true
net spindle-cmd-rpm <= motion.spindle-speed-out
net spindle-cmd-rpm-abs <= motion.spindle-speed-out-abs
net spindle-cmd-rps <= motion.spindle-speed-out-rps
#net spindle-cmd-rps-abs <= motion.spindle-speed-out-rps-abs
net spindle-at-speed => motion.spindle-at-speed
net spindle-cw <= motion.spindle-forward

setp encoder.0.position-scale 48.000000
setp encoder.0.counter-mode 1
net spindle-position encoder.0.position => motion.spindle-revs
net spindle-velocity-feedback-rps encoder.0.velocity => motion.spindle-speed-in
net spindle-index-enable encoder.0.index-enable <=> motion.spindle-index-enable
net spindle-phase-a encoder.0.phase-A
net spindle-phase-b encoder.0.phase-B
net spindle-index encoder.0.phase-Z
#ORIGINAL WORKING SPINDLE ENDS HERE

addf lincurve.0 servo-thread
setp lincurve.0.x-val-00 0
setp lincurve.0.y-val-00 0
setp lincurve.0.x-val-01 5
setp lincurve.0.y-val-01 300
setp lincurve.0.x-val-02 300
setp lincurve.0.y-val-02 300
setp lincurve.0.x-val-03 2600
setp lincurve.0.y-val-03 2600

net spindle-raw motion.spindle-speed-out-rps-abs => lincurve.0.in
net spindle-clipped lincurve.0.out => pwmgen.0.value

Just tried modifying to use RPM but i ketp getting the debug window saying RPM not assigned. Removed the spindle raw at start and Linuxcnc now opens and I can run the spindle but the speed does not change.

I've attached my hal and ini files below.

Thanks

Dave

Thanks Andy

I am slowly starting to understand the HAL but as there is quite a bit to it, it is taking some time to get into the detail. I think the thing that threw me was the direction of the arrows which for some reason I thought defined an input or an output - reading the HAL manual I can see that is not the case - my error.

With regard to the debugging, is there any easy way to copy from the debug window?

I've updated the code now and it is doing exactly what I want. There is a slight issue as I am using spindle at speed, so that doesn't quite work right when the commanded speed is below 300rpm with constant surface speed but I will have a play and see what I can do.

Thanks for your help.

Dave