View Full Version : Spindle won't stop spinning at program end or "Stop" engaged.

Thu 20 December 2018, 16:23
Hello, I've got a new issue with our 2.2kw spindle and huangyang vfd. This hasn't happened with daily use until yesterday, but it hasn't stopped since. When the program ends or I hit "stop" the spindle used to stop, but now it shows 0rpm in Mach3 but the vfd shows around 1,000rpm and the spindle is still spinning. Has this happened to anyone or does anyone have ideas about how to fix it?

Mon 24 December 2018, 09:08
Are you using voltage control ( 0 - 10V ? ) for the spindle speed?

What hardware is connected to generate the speed control? I bet the output is no longer going all the way to zero, but instead floating at half a volt or so. It may be that it has always floated it bit, but over time went up a touch, or the VFD got more sensitive. That goes double if this is a PWM signal using an RC circuit to generate your voltage.

If this is the case, you may be missing a pulldown resistor, or have a changed value.

I'd measure the speed input terminal to ground at the VFD and see if it is actually getting to zero. Depending on the hardware, I might try something like a 100k resistor between those two terminals to force things down - but you'll need to recheck your speed calibrations for other settings then.

Wed 26 December 2018, 11:26
Brad #10, thanks for being the most likely to reply to my wacky and imcomplete questions, I'm gonna reply to all your suggestions now. We are using a Huangyang VFD with a 2.2kw water cooled spindle. The issue is intermittent, which is fun, but I don't think I've changed the value. The vfd should be showing accurate RPM which is reading 7,000ish RPM's at start, which is showing as 6000rpm in Mach3. When it doesn't keep spinning, the rpm's are reading at 6000rpm on the vfd and 6000rpm in mach3. I'm not sure where the extra 1000rpm comes from, but the resistor might be a thing.

Wed 26 December 2018, 18:00
How are you starting and stopping the spindle at the VFD? Normally you'd have a relay connected to the FWD terminal on the VFD.

Wed 26 December 2018, 20:48
Ger, I suspected the vfd is in forward mode all the time, and the spindle only stopped when the speed was all the way down. Which is what went imperfect.

I have a personal bias against the HY VFDs - one explosion ( minor, but annoying ) will do that. I do not trust them to be even close to spec. Compensate for my bias if you wish.

7K at start on VFD vs 6k on Mach3 sounds exactly like a close, but not dead on voltage control; it's also within a reasonable range of accuracy.

I think you're saying that at 6k/6k there is a separate signal that is taking the VFD out of forward mode, as per Ger's question. If that's the case, then we're looking for either why that signal is wrong, or why the VFD isn't responding.

All of those point to getting some measurements during a failure - when things are supposed to be off, but the spindle is moving. It would be great to know the multimeter readings of: Ground to speed input ( either the 10V in or 5V in, whichever is active ), and Ground to FWD.

If FWD is off or the speed input is grounded, you have a bad VFD. If not, then you have a funky control. We can then progress from there.

(I can't really be the most likely to respond to weird situations. Maybe just first)

Wed 26 December 2018, 20:56
The HY inputs are programmable, so if the FWD terminal was bad, you **should** be able to disable it, and use a different one. My HY came with a non working FWD terminal, so I reprogrammed the REV to be Forward Start, and used that instead.

Really need to know what he's using to control the thing to give any accurate answers.