Frage X axis stops functioning mid-job

During several jobs while executing a roughing file (mach 2/3) my X axis motion stops in the middle of the job, but the job continues to execute and UCCNC shows the X axis commands moving on the digital tool path. When I stop the job and try to manually move the X axis there is no motion with a X axis command, however the X axis displacement shows active on UCCNC digital tool position display. The other axis Y and Z axis work fine when manually moved. Software restart of UCCNC does not regain the axis, but a power cycle to the Stepcraft does regain control of the X axis (and the entire machine functions fine for some amount of time). The same job has been attempted multiple times yet the X axis stops at different points in the job progress every time, so i don't suspect a problem with the tool path file or UCCNC. For some reason the stepper motor just stops accepting commands, or the stepcraft is not sending Y axis commands to the stepper motor. All axis seem smooth and operational at 100% feed.

I also have occasional problems with the z axis loosing steps during a job and not returning to the same "zero" point. It sounds some times like its binding, but with 100% speed in manual mode I can NOT find any binding and everything seems very smooth mechanically in all axis even with 100% feed and multiple axis moves.

Sounds very much like an intermittant fault in the controller board, something latching up in the X-axis path that only clears when you recycle the power.

Unfortunately I think you are probably going to have to replace the control board - that type of fault is notoriously hard to locate and rectify without specialist test equipment.

An intermittant joint is unlikely to recover as soon as power is recycled, so it is probably a fault in one of the IC's. If you have a test meter, check that the logic supply is really at 5V (+- 0.25V) - if that is out of spec it could possibly cause the symptoms you are seeing.

Peter is correct. Most likely is one of the IC's but very hard to self debug and test. We have seen one guy with random Y axis performance similar to what you describe. We replaced the UC100 and UCCNC setup and the problem remained exactly the same.

Then we replaced the control card and the problem went away. He now used the same UC100 PC and UCCNC and he has been working 100% ever since withouth these problems.

you need a replacement control board.

I just experienced a similar problem with the X axis on my Stepcraft 840. While carving a circle, it abrubtly started traveling back and forth along the Y axis in straight line back and forth, while UCCNC showed the tool still on the correct tool path. My X axis did not start working after power cycle

Toby,

Time to write to S Claus Esq. I fear - a new controller board seems to be called for.

Incidentally, how many powered up hours on your controller board? Even well designed modern electronics can and does fail, though the failures tend to be in the first few hundreds of hours (infant mortality) or after many tens or even hundreds of thousands of hours. This of course excludes accidental abuse!!

Peter.

Hi Peter,

It's my second day of having it. I've done a couple test cuts. The StepCraft logo of course, and a couple foam depron parts. (flawlessly I might add) That's it, and she stopped working in the middle of a job. In UCCNC I can jog it along the Z axis and the Y axis. When I try to jog it along the X axis, it doesn't move. It makes sound when the right jog arrow is pressed, no sound when left jog arrow is pressed. Thanks for the help.

Toby

Toby,

So it's recovered overnight - sounds as though you haven't a fried IC on the control board after all. Possibly a bad soldered joint that opens when the board heats up when in use and closes again when everything cools down.

Another alternative is a stepper winding doing the same, i.e going O/C once it warms up. If you are a dab hand with a test meter you could try measuring the motor coil resistances before and after the fault develops. If you do attempt this then make sure the control board is unpowered when you make the measurement. A good winding will only show a few ohms.

If your machine is only recently built, you might have a warranty claim - worth checking, I don't know the terms myself.

Peter