Lost Steps?

[IAD]

Hello...

I'm using Mach 3 with a HobbyCNC 3-axis board, and I'm having trouble with arbitrary loss of steps...

This has happened several times now, usually on the Y or X axes... For instance, today I was milling polystyrene foam wings, at ~150 IPM... Light cuts, 0.005" per pass... I had cut a pair of wing beds and a wing, no problem... I go to cut the other wing, and it was about 50% finished when the X-axis suddenly lost ~1", and destroyed the part. I canceled the job, and returned the axes to home, and sure enough, the home point had moved by ~1" in the X-direction.

I checked the mechanical systems (it's a DIY mill, so sometimes things slip), but everything was in order. I was sitting right there, watching it run, so I know that it didn't stall on anything, either. Also, at 150 IPM, the steppers aren't being pushed too hard, the machine can jog (or rough-cut foam) at 350 IPM without skipping.

Any suggestions, at least as to where I should start trouble-shooting? Could this be caused by a dirty power supply? For what it's worth, I'm running a shopvac and the 'spindle' (a Hitachi router) off the same circuit as the computer and stepper controller, and I've been meaning to get a surge protector for about two months now...

~Luke

[Khalid]

check ur lead screw at the location for any wear/tear or dust...

[IAD]

Well, I'm running timing belts on everything except the Z-axis... However, they're clean and well-tensioned, and the bearings are running freely... It only occurs very sporadically, and I can never reproduce it, but it's quite annoying when it happens...

~Luke

[IAD]

Ooh, by the way, the computer I'm running MACH 3 on has a 1.8 GHz processor, with 256 MB of RAM, running XP. I guess the RAM is a bit under spec., eh?

~Luke

[Khalid]

Hmmm... When u run Mach3, avoid working on any other program. Stop internet, stop media player, every thing... except Mach3

[Juka]

Did you use FeedOverRide ?

Juka

[asd]

i am just starting to use my router running mach 3 and having the same problem would be pleased to find a cure

[IAD]

I used speed override a couple times, and it ended WAY off... 6"+ on the Y-axis. Now I leave it alone.

Thanks for the pointer on other programs. Would that include screen saver? Also, should I keep the computer from going into any sort of power-save mode?

~Luke

[ger21]

Thanks for the pointer on other programs. Would that include screen saver? Also, should I keep the computer from going into any sort of power-save mode?

~Luke

Yes, and yes. ANY other programs running can cause problems. Especially the ones that run in the background that you don't see.

[stirling]

you could also try lowering your acceleration settings.

[dukes57@295.ca]

Power suppy is a good start, dediaction for power supply may not ever fix problem, if you a lot of inductive loads in your shop this cause's spike's or fluctuations on all branch curcuits. segrigate to seperate curcuit's, try surge protection filtration second. I dont know what else... have fun.

[IAD]

Well, I switched to LinuxEMC, and that helped a lot. Then I disabled idle current reduction, which basically puts the controllers into sleep mode, if they haven't been moved within the past minute or so... (Coming out of sleep mode can take a fraction of a second, during which steps can be lost.) That seems to have helped, too.

Now I'm only having intermittent problems with the Z-axis, it's still skipping, sometimes as much as an inch. I can actually hear the motor go into 'runaway'; today I'm going to try loosening the bearings a hair, see if that helps.

~Luke