I have a z-axis that’s starting to lose steps when plunging on topo map finishing passes. This in turn makes the tool start to slowly elevate off the material after a few passes. The miss-steps are accompanied by a “thud” and tend to happen on the same obstacle on the map.
My finishing pass spd&fds (50% plunge) have easily handled tougher transitions in the past so I’m apt to think one of the movey bits inside the z-axis isn’t doing it’s job.
Anyone familiar with this phenomenon so I know exactly what I’m after when I get under the hood?
In terms of physical issues, you can search the forum for Z brake issues.
If it’s repeatable on a specific part of the toolpath, though, that at least suggests a toolpath issue. One possibility for Mach4 is throughput. For that, you could try enabling or increasing the smoothing settings in CAM. This should increase tool path step size and reduce how fast the controller needs to process commands, especially if the passes are in an axis direction, as that makes it possible to express the toolpath in arc segments. Another option is to manually edit the feedrate in that part of the G-Code.
I ran the same finishing pass at 75% of the original rate with no issues so there’s that…
I’m familiar with the most common brake issues but this seems to be a new one and I’ll have to revisit that little gremlin.
I’ll have a crack at the smooth setting too.
Thanks for that Stephen.
I was having problems like that - strange z-axis behavior accompanied by a thud. Lowering the feed rate mostly solved the problem. My machine is a 5 year old Pro version running Mach 4 and NEMA 34 steppers. In my case the dedicated computer running Mach 4 was a 5 year old laptop that barely met spec. While I didn’t have this issue for the first several years of owning the system, it seemed to get worse as time went on. I attribute that to the computer ‘aging.’ Windows generally gets slower as more and more updates are added, the SSD reads and writes more, etc. My solution was to buy a new computer. I also replaced my ethernet cable with a CAT6 sheilded cable. My computer and cable now also meet spec. for CNC12, and I’m thinking of upgrading soon.
Not only is the obvious z-axis issue gone, but the machine generally seems to run much smoother. I think that even at the best of times my old laptop was barely pushing out G code fast enough.
- Garth
Phenomenal information Garth. Thank you for sharing.
Same machine setup here. My computer is a bit less outdated but valuable to know the cnc can outrun the g-code processing capabilities.
I’m slated for the CNC12 upgrade this week so running the same file will be a great reference point between the two platforms.
I’ve been haggling with z-height LOSS for nearly three months now, even with Avid’s tech support trying to troubleshoot. I replaced the laptop twice; make sure you get one with the base CPU frequency above 2.0 GHz, not the turbo frequency (which is always listed, not the other way around).
One toolpath always had a “thunk” when it jogged up and could reliably be measured with a 7/32" height loss. Other toolpaths had issues at random places.
After running the repeatable-failure toolpath at 25% feedrate successfully, I kept increasing the speed. Even at 97% or 99% feedrate in Mach4, the toolpath was successful. But bumping up 1% to 100% feedrate would repeat the z-height loss issue.
For other toolpaths, increasing the file tolerance solved most of the problems, as people have noted, plus running them at 99% feedrate.
I still have “loss of ESS connection” issues and complete Mach4 blowouts (like a blue-screen Windows death) to resolve, but z-height seems better.
Matt