Leveller first try

[Bruce]

So after getting the autoleveller windows version running ok I had the autoleveller run my gcode as generated
by pcb-gcode. It generated the new g-code with probing and z movement corrections ok as far as
I can see but the file is somewhat obscure to me since I have no idea how the corrections are implimented.
I set up my pcb mill and started the gcode with levelling, since I start at the right side being a bottom etch
the machine moves the spindle all the way to the left side of the pcb but within bounds of the pcb outline.
Then it sat there with no z axis movement, I hit cycle start again then it started moving the z axis and taking
measurements. The first time it went along most of the path then near the last 2 tracks it was like not getting the
probe contact so would drive down that 1/16 of an inch. So I stopped it rechecked the probe contact using mach3
diag screen and it showed it was working. Reset everything and tried again, this time it made it all the way, probed
70 points then stopped for a tool change which I didn't have to do since I was using the engraving bit as the
contact. I hit cycle start again to continue and the spindle went to the first spot and the z axis went down BUT
didn't stop where it should have and went thru the pcb and into the table. The tip of the bit broke off but it still
cut ok just made a wider path which was fine for the pcb I was doing and didn't need to take multiple runs.
Like I said at the beginning I looked at the gcode that autoleveller generated but can't tell why the z axis went
that deep. I did restart the pcb engraving with out leveller corrections and it ran ok other than the engraving width
was wider since the bit tip was damaged (a Soigeneris bit I might add, it took a licking but kept on ticking).
I would be willing to upload or send the autolevelled gcode file so someone that is familiar with its coding
can tell me why the z axis did what it did.
Thanks,
Bruce

[daedelus]

I think we got our timings crossed but here is what I said on the Yahoo groups if you havent seen it already:

"Right at the start, you need to zero your Z axis to approximately 3/8" above the surface of the material, so this could be the cause of the other problems if you didnt do this. http://www.autoleveller.co.uk/autoleveller-guide/

Try to test on some scrap material and maybe some older tool bits first but let me know it the problem persists."

[KenH]

I saw the thread on yahoo.groups, but looked here to see if it was covered also.

I've had a similar issue with my setup - all versions of program. If a Gcode file is loaded (from most any source) and started, but for what ever reason the run is interrupted - then just hit the start again, very often the machine will suddenly go left on X axis and down on Z axis jamming tool bit into work surface. I've planned to mention this, but have not really got a solid feel for what times causes it, or what will make it happen every time.

To prevent this, if a program is interrupted (air cuts, decide to try different tool, etc), if the program is reloaded (maybe it even requires turning CNC off?) and starts again from opening file, the program works ok then.

I'm not sure what causes this to happen, and not exactly sure of the circumstances that cause it, I just wished to add that I've had a similar issue.

Ken H>

[daedelus]

Hi Ken,

Thanks for the workaround. That seems like a good rule, i.e.

If the program is interrupted for whatever reason and you need to restart the program, reload the file and/or switch off the machine and restart.

It might be a Mach3 problem since I don't remember this issue on LinuxCNC and I don't yet have a license for Mach.

Did you re-zero the Z before hitting start?

This is my best guess... During probing the Z height values are stored in variables from #500 and up and in the Mach3 gcode documentation it says something like the variables between #500 and #1000 are retained between restarts. Maybe these variables are locked and prevent further probing. This is just a guess at this stage but if I am right then it might just be a case of storing the probed values elsewhere.

I will have a look ASAP.

best,

[KenH]

James, I'm using LinuxCNC. To be honest, I don't remember if I re-zeroed Z or not. I'll play with this some more and see if I can come up with a consistent method of creating the issue. Just in case I do jam down and sideways, I'll use an old tool bit and my old spindle motor that has excessive TIR to prevent damage to the good stuff<:)

Ken H>

[daedelus]

Thanks Ken, I thought you were using Mach3 for some reason. Must have got you confused with someone else and I must be getting old

But yes, check the Z has been re-zeroed before any probing. otherwise it might assume Z zero is below the real material surface which might explain the issue here.