[dighsx]

I’m running the 3 axis Xylotex with the 270oz motors (got the kit from them with the 24v power supply) with Mach 3. I've started having an odd thing happen to my cnc machine, if I run a big job about 30 minutes into it my motors seem to lock up. They make a knocking sound and just sit there. If I stop the job and then try and jog an axis at first it seems like nothing is happening but if you just hold down the key you can hear the motor starting to move, the longer you hold the key down the quicker the motor starts to move. But when I say move I mean like .001 per second. The other odd bit is if I close Mach 3 and start it back up everything works normal.

At first I thought it might an over heating issue so I changed it so the fan it’s actually on top of the heat sinks. Then I thought it’s a software problem so I fired Mach 2 back up and the same thing still happens. The next step was I swapped out the computer and it still does the same thing. I’ve also tried running a few different big jobs and it locks up on them too.

I hadn’t changed anything and everything was working fine, this just sprang up. So anyone got any ideas what’s going on?

Just a note: when this happens nothing feels hot. The heat sinks are pretty much cool, the power supply is just warm and the motors are warm like they normally are.

Thanks

[joecnc2006]

did you check you power supply and capaciter?

joe

[dighsx]

I just checked the voltage on the power supply and it stays the same the whole time, 26.6. When you say capaciter do you mean the vref pots? I've got to unhook the motors to check that right?

[ger21]

Sure sounds like overheating.

[dighsx]

It sure seems like overheating to me too but what I don't get is why closing Mach 3 down and opening it back up makes it work again? My last test I took the board out of the case and just had the fan resting on the heat sinks and it still did it. I'm not sure how else to cool it down. I don't have a fan on my power supply, should I? That too isn't in the case.

[ger21]

It sure seems like overheating to me too but what I don't get is why closing Mach 3 down and opening it back up makes it work again?

Missed that in your first post. That makes it sound Mach related. But then you've tried different PC's? How fast are the PC's? Have you run the driver test on them? Other than the PC, how about a loose wire somewhere?

[dighsx]

The first machine it started doing it on is a PIII 700, I ran Mach 2 on this machine. On the driver test I'd get 23000 - 24000. The machine I've got hooked up now is a P4 2ghz. I've run both Mach 2 and Mach 3 and get the same problem. And on the driver test I get 24000+.

I know this might sound stupid but it can't be something gcode related can it?

I'm going to try rigging up some more fans on everything and see if that helps.

Pretty strange thou isn't it. Thanks for the help.

[fkaCarel]

The datasheet mentions a thermal shutdown cycle. This cycle is off course very happy with restarts, trying to jog etc. The nice thing of electronics is off course that this thermal shutdown can be set to trigger with no load, sitting outside in Siberia. If it sets in, you will see almost no torque at the motor. You can also try with lower Amp settings and see if it jumps in later.

Carel

[dighsx]

Well thought I'd give an update and a bit of good news. I turned down the Vref on each axis just a hair and that seemed to do the trick. I rain the machine for 6 hours steady today.

What I don't get is it was working for almost a year and then started acting up.

Thanks everyone for your help tracking this down.

[fkaCarel]

Summer is coming, so you reach a fixed thermal limit earlier.

Carel

[dighsx]

That explains it better then anything I can think of? It has been pretty warm the last few days (25C) And I did have the air conditioning on yesterday.... Well I guess I better keep my house extra cold this summer. What temp do you think would be good? Maybe 7 or 8C? My wife’s going not going to buy that.

If you can't tell I like it cold and not hot. Anything above 2 is getting too warm for me.

Thanks again for the help.

[fkaCarel]

You should evaluate if this is a workaround or not. Electronics should work safe till 75C. So maybe the boardsetting is erronuous. A stepper driver should'nt interfere with a marriage.

Carel

[dighsx]

Well back to square one, it locked up again today. After it did it I thought I'd try slowing it down and seeing I was pushing it to fast. But it locked up on that too. It also missed some steps on my second test. This is getting pretty frustrating.

Any ideas on what to try now?

[ger21]

Check the power supply voltage when you lose steps?

[dighsx]

I've checked it before starting a job, during, when it locks up and after it resets and it stays about the same (26.6) now I haven't checked at the moment it was losing steps. That might be hard to do. It took 2 hours of running before it locked up this last time.

[fkaCarel]

I suspect your stepper driver board. You had your machine running. You have ruled the PC out by swapping. All the stepper motors are affected. Which means the center of attention goes to the driver board. There can be damage on the PCB level or the chip level, which shows with a slight temperature increase. I think you should buy another board. You can try the hair-dryer method for warming up the board, keep a reasonable distance. With this failure shows earlier. The lock-up can also mean that the translation from step signals to state-signals (meaning which coils should be activated now) is stopped. This at the logic (5V, 3.3V) level of the card. Oscilloscope and schematics required. I'm sorry for you.

Carel

[dighsx]

It sure seems like the stepper board to me too. I gave it the hair dryer test this morning and it passed. I moved the cooling fan off the board and blew the dryer on it for 10 minutes and it kept working. I felt the board and it was a lot warmer than I've ever felt it. Then I gave the power supply 5 minutes on the dryer and everything is still running fine. I've got it running now at 3 times the speed I normally run at to see if I can make it fail that way.

The part I can't figure out is this: yesterday it failed, so I stopped Mach 2 from sending instructions and turned off the power to the stepper board. Then this morning I came back to the computer which still had Mach 2 running right were I had stopped it yesterday. I turned on the power to the steppers. Now what would you think would happen? I'd think that I'd be able to jog the steppers because if the board had overheated by not it'd be ok. But what happens is you can't do anything until you close Mach2 and bring it back up. Then things work normal. I'm sure there's some logical reason so for this involving the stepper board sending Mach2 some data that sends it into space, but that sure seems odd to me.

My next question is, let say it's the board (which is sure seems like it is) do I get a new Xylotex board or is this the time I get something different? And if so what? I think I'll contact Xylotex and see if they have any ideas. But the problem now is I don't trust my setup.

Speaking of which it just locked up. 13 minutes after the dryer test (23 minutes total run time) This is the quickest I was able to get it to lock up and I assume that it’s due to the fact I was driving it three times as a fast.

Thanks again for all your time and help.

[fkaCarel]

The restart thing can happen like this: the printer port is driven with all the pulse and directional signals. So there is a combination of 1's (5V) and 0's (0V) on the port. A restart or reset will drive all the signals in a known state, probably all 0's. From my experience of broken electronics you can have inputs, breaking down to excessive loads. So a broken down board can be input combination sensitive. I would'nt panic to another brand. These things happen, they know it too.

Carel

[dighsx]

I sent Xylotex an email asking for help and included a link to this thread. So we'll see what they have to say.

Thanks again.

[dighsx]

Thought I post a quick update. I contacted Xylotex on Sunday and 2 hours later I got a message from Jeff asking for some of my settings. I was more then a little impressed that I got such quick support on a Sunday. He then asked if I could send him a picture of my setup. He wanted to see how I was cooling it and to make sure I had enough ventilation. My board is sitting out on a top of a cardboard box (in fact it's the box it came in) Jeff suggested I raise the board off the box as to get some airflow under it. I’m now 2 jobs into testing with the raised board and so far everything seems to running fine. In fact I think it runs faster but that could be just in my head.

So cross your fingers for me that everything stays nice and cool and running smoothly.

Thanks again for the help.