Just got an Elite Journeyman up and running with a PwnCNC 1.4 kw 80mm air cooled spindle.
It all appears to work, I’m making cuts but 2 things seem odd. The Masso correctly displays requested RPM and Direction but the actual RPM always shows 0.
Here is a screenshot where I’ve set the spindle to 10,000 with the MDI screen:
Also, with the spindle set to 10,000 the VFD readout is showing 165.5…which doesn’t make sense to me. Is this number correct, and if so what is it telling me?
Hey cvcolomb:
the rotational speed of the spindle is calculated this way:
SPINDLE_RPM = $VFD_FREQ × 2 × 60 / $SPINDLE_NUMBER_OF_POLES
e.g. 400 Hertz × 2 × 60 seconds / 2 poles = 24 000 rpm
this means with a spindle with two magnetic poles a VFD capable of 0–400 Hz can deliver 0–24 000 RPM spindle speed.
Note that most 24 000 RPM spindles with magnetic 2 poles have a minimum speed allowed by manufacturer of something between 8 000 and 6 000 RPM and running them slower can damage them, it would be good to set “Lower limit of frequency” inside the VFD to something between 133 and 100 Hz.
So if you want approx. 10 000 rpm, you would set the VFD to 165 Hz:
165 Hz * 2 * 60 seconds / 2 magnetic poles = 9 900 rpm
Note that the Masso G3 does not support transmitting the exact requested spindle speed to the VFD via Modbus, like the buildbotics controller, but controls spindle speed with an analog voltage control line instead. So speed is not always exact.
Don’t forget that the spindle will only start to run with the M3 or M4 command. S only sets the speed.
I don’t know how the Masso could sense the current spindle speed, to my knowledge, it is not capable of sensing the spindle speed. The buildbotics controller reads the speed from the VFD which reports it via Modbus over the serial communication line, which the Masso G3 lacks.
Pretty sure that Masso will only provide the actual speed if there is an encoder on the spindle to read the RPM, the 165.5 might be that the VFD is set to read Hz instead of RPM.
Pat
Man, I hate it when I’m the one who needs to RTFM.
Thanks for the math @Aiph5u , and the other replies pointing out the display can be changed. I’d rather not have to do calculations just to verify my spindle speed. Easy enough.
Still surprising that the Masso can’t display the current RPMs, but hardly the end of the world.
Cheers,
cc
Masso can display the RPM you just have to send the pulse signal to it which is the issue on the Spindles commonly used on these machines.
Pat
