mystery self feeding

[keen]

Hi all!

I think this is a Mach 3 problem.......... I think......

Sometimes, later in the day, usually after jogging around, one of the axis, usually the z, decides to go on a self feeded journey!

Its not the programme - because sometimes it does it when nothing is loaded, It always self feeds at the set feed rate - and can be changed by changing the feed rate .

So I thought my M3 has got corrupted - but re installing did not work for long - the problem re emerged after a couple of days.

So I thought maybe computer - installed new computer with fresh m3 download - now again, it has re emerged. happily self feeding off into the sunset.

Another stange problem that may be a clue is that occasionaly when I say MDI from Z10 ...G0 Z 15 ...it will go to Z35. Did this on both computers and M3 downloads. If I close and reopen m3 the problem goes away......but only for a while.

Any help very welcome!

Still Keen

[LeeWay]

Are you using a wireless keyboard or mouse? If so, these can sometimes do some really odd things. I found out without any damage and then swapped to old fashioned hardwired stuff. No more odd movement troubles.

[ger21]

Does the Z axis DRO change when it moves on it's own? If Mach3 is causing it, the DRO will show the movement. If the DRO isn't changing, then it's probably noise in the step or direction lines.

[woffler]

i have a wandering x that i cant figure out i used all shielded cable was careful to keep motor leads away from limit wires .i found that tuning down the motor helped and some times dosent do it or not as bad .before you couldnt even do a set you get it were you wanted it and about a minute or so lateer it would move about .250 and mess everything up. you can try that and see if it helps or eleviates the problem you just kind of play with the setup of the motor tuning in config.

[ChrisLT]

I had somewhat similar problems until I bought an add-in parallel port card. It turned out the desktop PC's built-in parallel port was only outputting just over 3v. Add-in cards are more like 5v. I had been convinced my z axis card was faulty as substitution tests narrowed down the problem to that card. But I was wrong.
But the feeds, although random, were always in the direction of the last Z movement and their timing was random - like a Geiger counter.
Chris Lusby Taylor

[keen]

Does the Z axis DRO change when it moves on it's own? If Mach3 is causing it, the DRO will show the movement. If the DRO isn't changing, then it's probably noise in the step or direction lines.

Thanks for that - I am sure the DRO shows (I mean i think i would have noticed if it did not - I will look closely next time) the speed of feed is equal to the display feed - and can be increased or decreased during its self feed.

It only does it during jogging and never during running a program - luckily!

I have had another fault with an intermittant limit switch error - showing on only one computer (of my two supply computers) with repeated tests - so i replaced its mother board. then it began to do it on both computers!

So I replaced the P port cable - so far so good. - any clues there?

Still Keen

[LeeWay]

I take it that you aren't using wireless input?

[Gary55Ford]

how does your DRO get its counts? I run a bed mill with its encoders on the bed, a couple of times they have gotten dirty and it keeps on going trying to find right count

[ger21]

how does your DRO get its counts? I run a bed mill with its encoders on the bed, a couple of times they have gotten dirty and it keeps on going trying to find right count

We're talking about the software DRO's in Mach3 that display the commanded position.

[dan_the_welder]

Hi,

Make sure you do not have step and direction spindle enabled, and those pins also applied to your wandering axis.

Dan

[keen]

Are you using a wireless keyboard or mouse? If so, these can sometimes do some really odd things. I found out without any damage and then swapped to old fashioned hardwired stuff. No more odd movement troubles.

Hard wired Lee - Could be my P Port cable though - i've just replaced it - will soon see. Thanks

[keen]

how does your DRO get its counts? I run a bed mill with its encoders on the bed, a couple of times they have gotten dirty and it keeps on going trying to find right count

Thanks Gary - no Encoders - open loop system.