My problem- new to Mach(of course), bought the home-fabbed table second-hand. Have actually used it to great success for my needs(polycarb sheet, simple 2D patterns). I know very little about Mach 3, apparently just enough to get by until now. More often recently the machine has begun to (1) just STOP at random whilst executing g-code (stop button flashing) (2) go off and do its own thing whilst executing g-code (3) go into a 'limp mode' where the ability to jog the tool head diminishes by more than half(no estop button flashing, no message)

Given the problem isn't exactly the same at each instance but similar in nature, I'm assuming that (1) the general Mach config and motor tuning is off(I performed no such procedures after getting the table, just using whatever settings the previous owner initiated) (2) the general plumbness of the table is off slightly off(home-fabbed out of steel, but very robustly built)

I have been using this table successfully with good accuracy and repeatability for a couple of months now. Just recently I have observed the nuts that center the rotating collar on the z-axis lead screw(not the Lovejoy things on the motor shafts but the collars around the lead screws) loosening due to vibration, with the corresponding screws and such that do the same for the x-axis loosening as well. I tighten them back and use a little locktite blue and go on. Usually I just jog the gantry back until reasonably close to the pillow blocks at the end, power off and use a framing square to make sure it's square-ish(x-axis has two leadscrews) and restart the program, reboot, or whatever and it works fine after that. I have a sneaking suspicion that the machine is binding on the x, y, or z. I think this coupled with incorrect mach setup and motor tuning and my general ignorance of things such as accel/decel, stepping, etc is causing my trouble. I'd like to kick this in the head and get to a real understanding of the machine but I find the Mach manual to not be a very good read.

specs:
Motors- SureStep 434oz/in x2 on the x, x1 on the y
           SureStep 276 oz/in on the z
Breakout board- Stepper3 S3BRK2R1
Drives- Gecko G203V x4
Leadscrews- X- Hilead 3/4 x .333 RH 84" OAL (x2)
                Y- Hilead 3/4 x .333 RH 60" OAL (x1)
                Z- Acme 1/2-8 RH x 24" OAL
DeWalt 2.25 horse router head
PC- Win XP home, Intel Celeron 2 GHz, 768MB RAM (nothing else is run on this machine, ONLY MACH- not even Internet Explorer & g-code generated on different PC) Mach 3 version R3.037 fully licensed

pics below, screenshots of tuning setup included






I included the a-axis screenshot even though I haven't the slightest idea what it does or what it could be for, since the table is only 3-axis. IF ANYONE has any help to offer I'd be very grateful, if any additional info is required for you to help me just let me know. Thank you very much.


             

Looks like the Y axis has the two motors, not X, with the A slaved to Y. You can check this in Config>Slave Axis.

You might want to change the step pulse and dir pulse for all the axis to 2.

When it randomly stops, is there an error message? Are there limit switches on the machine?

Can you clarify #3? What do you mean "ability to jog diminishes"? You can't jog? You can only jog at half speed? It only jogs sometimes?

When it goes off and does it's own thing, is it stalling, or running smoothly?

#3 only jogs half speed, and when it does its own thing it usually runs smoothly, but sometimes groans and stalls

The error messages have sometimes stated limit triggered(it does have limit switches), sometimes no message at all. However this morning the error stated 'radius to end of arc differs from radius to startline' (this is on a file that has previously executed properly)

When the axis does the slow jog thing do the DROs in Mach show it is slowing?
Same for when it goes off and as you say does its own thing, do the DROs show where it is or are they wrong?

Hood

To reply to Hood, all DROs show correct travel information in realtime. The machine however is doing its own thing.

Sounds like you have a hardware problem, check all your wiring and make sure noise is not an issue.
Hood

OK Hood, will do. I was thinking the same thing, seeing as the mechanical limit switches are basically wired with what looks like Radio Shack small guage speaker wire. I would assume these should be shielded wire runs. Am I correct?

Really all 5v signal wires should be shielded, limits, Step/Dir etc

Hood