A different (?) spindle drive problem

[saabaero]

You will find that the spindle motor contactor latches the first the spindle is turned on after starting the control software so there is a longer delay for the drive to power up that first time. After that all that is applied is a run and direction signal which starts the motor almost immediately. The drive stays powered up even if the spindle is stopped unless you open the spindle cover and unlatch the contactor.

I learned (almost the hard way) to start the motor at least once before running a program. Especially if the spindle is close to the workpiece as there is little time for it to come to speed.

You can actually have the cutter try to push trough the work without it spinning. Not a good thing!!!!

[zephyr9900]

Originally Posted by saabaero You will find that the spindle motor contactor latches the first the spindle is turned on after starting the control software so there is a longer delay for the drive to power up that first time.

I'm not sure I follow that, saabaero. The spindle contactor drops out every time the belt cover is opened for a toolchange, so every spindle start starts with a contactor pull-in. It is only the very first spindle start after entering PCNC/Mach that has the longer delay, in my experience. That is why I'm theorizing that it is some kind of software difference...

Originally Posted by saabaero The drive stays powered up even if the spindle is stopped unless you open the spindle cover and unlatch the contactor.

I'm not sure why I'd be stopping the spindle without a toolchange, but that statement is correct.

Randy

[HMB3000]

Originally Posted by zephyr9900 It is only the very first spindle start after entering PCNC/Mach that has the longer delay, in my experience. That is why I'm theorizing that it is some kind of software difference... I'm not sure why I'd be stopping the spindle without a toolchange, but that statement is correct.Randy

So your issue is not ramdom or intermitted...only on first start up after entering Mach 3...Do you have other programs that maybe opening on PC at the same time?...I put a thumb drive in one time when mach 3 was running and it opened up Mach did not like that

[zephyr9900]

Originally Posted by HMB3000 So your issue is not ramdom or intermitted...only on first start up after entering Mach 3...

Well, it is random and intermittent in the sense that it only happens once in every 20 or 30 starts of Mach... But yes, when it does happen it is always on the first spindle start after booting Mach. I said that early on.

Originally Posted by HMB3000 Do you have other programs that maybe opening on PC at the same time?

Oh, no. I have a stripped-down nlite'd XP installation (no Media Player, Internet Explorer, Outlook Express, MSN Explorer, Messenger, Automatic Update, Remote Desktop, etc.) and the only program I installed other than Mach is Professional File Editor, a simple text editor. No Acrobat Reader, nothing. I further prepared Windows with the older super-paranoid instructions from rev. B6 of the PCNC manual with many services disabled. I don't think there is a cleaner Windows installation around.

I take care to not plug or unplug the thumb drive while the machine is running a gcode and have not had any problems reading the thumb. I have Autoplay disabled so Explorer doesn't pop up every time I insert it.

I'm not using an external USB hub--all components (keyboard, mouse, shuttle, USB socket) run back to four ports on the motherboard with nice double-shielded Belkin extension cables.

It's a pretty clean installation electrically and software-wise. After 8 years of running TurboCNC in DOS I wanted something that was as clean as possible given the fact that it had to be running under Windows...

Randy

[Al_The_Man]

I think someone hit the nail of the head, why are you dropping the contactor out on the VFD?
Normally this will only occur on an e-stop.
Once your control power is active, the VFD should be controlled by contact closure to the Fwd Rev or Start relay.
Al.

[zephyr9900]

Originally Posted by Al_The_Man I think someone hit the nail of the head, why are you dropping the contactor out on the VFD?

As I wrote above

Between the control transformer and the contactor coil, there is a fuse, the estop switch, a spindle lockout keyswitch and a belt guard interlock.

There is a safety switch on the belt guard door that drops out the VFD contactor, so the spindle can't accidentally be started with the door open (which gives access to the spindle lock and the drawbar for tool changes, and the belt for pulley changes). The door can't be closed (and thus the VFD fired up) with the spindle lock engaged, which is another safety feature.

Several people have jumpered that safety switch, but Tormach strongly warns against that for safety/liability reasons.

But given that, the spindle reliably starts after every tool change. The non-start only ever happens on the first attempted spindle start after launching Mach, never on subsequent starts.

Randy

[zephyr9900]

I'm beginning to think my VFD is going flaky. I've been through the speed and braking calibrations twice now.

The speed regulation is not very tight. I can hear random fluctuations in the RPM (less than a semitone variation but it's there) at full speed.

The braking is also variable. Ironically the large tools (large drill chuck, flycutter) brake better than the small tools (endmill holders, small drill chuck).

With the large drill chuck installed, successive toolpaths will actively brake or just coast down. (I tend to run my drill cycles twice, first with the next smaller bit and then with the final bit.) When the spindle is not actively braked, I can open the cabinet door while it is coasting down and the drive has not faulted out.

I have the Minarik manual for the VFD, and it doesn't have any information on these symptoms. Unfortuately I don't have an ammeter so I can't check the torque limit setting.

But I think that the problem is inherent in the current VFD. When I can afford it, I'll buy the upgrade VFD, of which I've read only good reviews.

Thanks to you all for your comments and troubleshooting suggestions.

Randy