A different (?) spindle drive problem

[zephyr9900]

I've been having an intermittent spindle drive problem. After powering up and ref'ing the machine, Mach's onscreen spindle button sometimes does not turn on the spindle. When that happens, if I switch the spindle to manual and then blip the physical start button, the spindle contactor will sometimes softly click, sometimes strongly clunk without actually pulling in, and then after several trys will actually start the spindle. After that the hardware and software buttons work reliably as long as I have the machine powered up.

Is there such a thing as a sticky contactor? They seem to me to be a kind of heavy-duty relay, and I know relays can have sticky contacts. Are there any other problems contactors can have? I don't think it is a case of low voltage, because the other contactors always work reliably.

Thanks,

Randy

[BSims66173]

I am having the same problem. When my spindle doesn't start, I get a fault light. I can lockout the spindle, put it in manual, hit start and the spindle will turn a little. I guess the capacitors are discharging at that point. After that I can put it back in auto and it will run. I talked with Tormach and we went through the spindle calibration and that seemd to help some, but it did fault one time yesterday. I guess I will be looking at the spindle upgrade before long.

Barry

[HMB3000]

Have you check to conecting at the spindle motor....the wire are just crimped ...but they don't twist wires before crimping which can cause an intermitten type of promblem...If you have a bad conecting any where in the Spindle circut you could trip a fualt...I spent long time tracking down a short on my Z axis (see photo)...When I check the wires by pulling on them they felt good as in a solid conecting....But after the stepper motor stop working I found the wire discolored from heat at the crimp...That is what makes tracking an intermittent issue a pain as it could be anywhere...I don't know if this is your issue... but it will not hurt to check...After I pulled the motor I put a meter on it and there is no short in the motor it is still good...just a bad crimp job

[zephyr9900]

Originally Posted by BSims66173 I am having the same problem. When my spindle doesn't start, I get a fault light.

Originally Posted by HMB3000 Have you check to conecting at the spindle motor...

Thanks for the replies, but this isn't a problem in the VFD or motor. I've calibrated the spindle speed and deceleration and don't get faults when it is running.

The problem lies with the contactor C2. When the spindle doesn't start AC is not getting to the VFD's input. I have checked the contactor wire connections and they're all tight.

Randy

[HMB3000]

is the door safty switch part of the circut?....intermitten type of problem are almost always a wire conection...I hate looking for those issues...I thought all my wire conecting where tight and they where...but it was a bad crimp job so it was not getting a full consent conection...crap biult up on the conection inside of crimp and after a while it just shorted out untill I cleaned the conection and it was fine...just becuase a conection is tight does not mean it is a good conection

[zephyr9900]

Originally Posted by HMB3000 ...but it was a bad crimp job so it was not getting a full consent conection...

I can accept that. My own test for my crimps is to try to pull the wire out of the terminal. If my fingers slip on the wire without it coming out I figure it's a good crimp (I can always pull wires out with a pliers, even on a good ratchet tool crimp.) Short of snipping off all the terminals and replacing them myself, I'm not sure how to do a better crimping test...

Fortunately it is an intermittent problem, maybe one in 20 or 30 machine starts and after the spindle starts once it starts reliably after that.

The door switch is part of the circuit, and I've checked and rechecked that switch. I've never had a failure there.

Randy

[Al_The_Man]

Originally Posted by zephyr9900 Is there such a thing as a sticky contactor? They seem to me to be a kind of heavy-duty relay, and I know relays can have sticky contacts. Are there any other problems contactors can have? I don't think it is a case of low voltage, because the other contactors always work reliably.

It should be easy to trouble shoot by measuring the coil voltage, what does the contactor coil use voltage? AC DC?
If a AC contactor does not fully pick up, i.e. the armature sticks, the coil will either over heat or burn out.
If DC then it may not be fully engaging, again, I would trouble shoot using voltage measurements first.
If this is a new contactor, it is unlikely that you have burnt contacts, in a VFD type application, the contactor should pick up under relatively low load,
as the spindle motor command should occur after pick up.
Systematic trouble shooting by voltage readings should pin-point the problem.
Al.

[philbur]

I don’t have a solution but I can keep you company.

I've had (have) a similar problem, but only in direct manual or manual via the computer. The symptom is that when I try to start the spindle I get a "light" mechanical click and no start. Then after I do a bit of fiddling it gives a good solid "clunk" and off the spindle goes. I can't recall it happening under full computer control, it wouldn’t be something that would pass by unnoticed. Although that might just be luck. I've never tried very hard to traced the problem. Originally I though it might be something to do with my machine/computer start-up sequence or the door switch. Lather I thought it might be one of the VFD quirks. However it sounds like the light “click” is possibly a control solenoid, and the louder “clunk” is possibly a main power relay kick in, which if correct would make the culprit C2, I think?

It has happened maybe 5 or 6 times in two years. I know enough to know that chasing problems that you can't repeat on demand can be an exercise in futility, so I've let it ride for now.

Good Luck
Phil

Originally Posted by zephyr9900 I've been having an intermittent spindle drive problem. After powering up and ref'ing the machine, Mach's onscreen spindle button sometimes does not turn on the spindle. When that happens, if I switch the spindle to manual and then blip the physical start button, the spindle contactor will sometimes softly click, sometimes strongly clunk without actually pulling in, and then after several trys will actually start the spindle. After that the hardware and software buttons work reliably as long as I have the machine powered up. Is there such a thing as a sticky contactor? They seem to me to be a kind of heavy-duty relay, and I know relays can have sticky contacts. Are there any other problems contactors can have? I don't think it is a case of low voltage, because the other contactors always work reliably. Thanks, Randy

[HMB3000]

Originally Posted by zephyr9900 Fortunately it is an intermittent problem, maybe one in 20 or 30 machine starts and after the spindle starts once it starts reliably after that. Randy

some where you have a bad conection...if you had a short in the coil,motor or VFD it would be a constant issue...with a bad conection particals build up and then blow off at time of short....making a new conection untill next build up occurs causing another short...this type of intermittent problem fits the pattern of a bad conection somewhere

[benji2505]

zephyr,

what is the time between spindle start ups?

Does the spindle start fail on a restart after a shorter down period only?

In that case one of the electromechanical elements might not get enough voltage and/or current. Typical indicator is that there are no problems after a longer period of time, because the circuits have a longer time to build up the "juice". Could also be the difference between "clink" and "clock" or what ever you heard .

If this is the case then there might be some capacitors/induction elements on your motor/spindle control board history/bad/old.

A cold connection on one of the wires sounds unlikely to me but you always have the option to strenghten it with some solder into the existing connection

[HMB3000]

Originally Posted by benji2505 A cold connection on one of the wires sounds unlikely to me but you always have the option to strenghten it with some solder into the existing connection

The type of issue I had with my motor because of a bad crimp was not a cold connecting just a bad crimp job....My motor would only fail every once in a great while until the wire was burned enough to short out completely...When they crimp them at the factory all the do is put a cap on end of wires and crimp...The wires are not twisted together or solder at time of crimp...wires that carry current and crimped in this fashion can build up carbon particles between wires...when enough particles build up you have a short that then blows particles off of wire and connection is good until enough of the wires are burned. A bad crimp job will build up heat at connection...If you have a voltage issue you would have a consent issue not an intermitted issue...I don't know if this is you issue, but it does fit the pattern....as you said it only occurs every 20-30 spindle start-up....if you had low voltage it would be every start-up

[zephyr9900]

Originally Posted by Al_The_Man Systematic trouble shooting by voltage readings should pin-point the problem.

I'm sure that is true, Al. I'll put a datalogger on my wishlist. I think that's the only way I'd catch the glitch, given that I haven't ever been able to cause the problem on purpose.

From the Tormach wiring diagram, the control voltage is 120V. I did find the datasheet for the contactor and it confirms that too.

Between the control transformer and the contactor coil, there is a fuse, the estop switch, a spindle lockout keyswitch and a belt guard interlock. As far as I can tell, all those components give good continuity with the power disconnected. On the machine control board, I'm assuming that a solid-state relay energizes the contactor.

There is one maybe related clue which makes me think it might be some kind of software issue. The first time the machine is powered up and the spindle energized, there is a several seconds delay between the contactor pulling in and the spindle actually ramping up. On subsequent starts, the delay is less.

The glitch hasn't shown up since my initial posting, so for now all is well!

edit: Looking at the wiring diagram, even the manual spindle start switch is low-voltage, so that is just acutating the (I assume) SSR on the machine control board. Any difference in operation must be either in the wiring on that board, or the Mach software. Or so it seems to me...

Randy