Haas VM2 positional error

[Bearyo]

A few weeks ago when I was setting up a job with 4th axis (HRT 210 a axis) for my vertical mill (Haas VM2) I experienced positional errors. When zeroing G54 the display would update to the right coordinates but the machine "wouldn't realise it". This happened several times for both y and z. After several restarts the machine would eventually go to the right coordinates. A few days went by and the machine sat powered off. I ran a few test cuts and everything seemed to be in order. The next day when I was about to start making the parts I realized that my G54 Z offset was had moved ~150 mm in negative direction even though the machine coordinate for the offset remained the same. After several restarts the machine would read the right coordinates and I was able to start milling the parts.

I haven't really had any more issues with the Z offset until yesterday when the machine crashed into the part and fixture. After about 20 finished parts the machine crashed in the middle of the program resulting in a scrapped part, tool and hydraulic holder.

 

[DMF_TomB]

a program might not reread G54 so you have to watch restarts. and or add extra G54 to program so it rereads G54 or make sure its using G54
.
pressing reset button you often loose tool comp and your work offset might change for example from G55 to G54 on pressing reset button
.
in program you can change G54, common with a probing op to change or set the G54 and if program uses G92 you can loose your zero return position especially if doing restart and the G54 shift or a G92 is done 2 times

 

[G00 Proto]

a program might not reread G54 so you have to watch restarts. and or add extra G54 to program so it rereads G54 or make sure its using G54
.
pressing reset button you often loose tool comp and your work offset might change for example from G55 to G54 on pressing reset button
.
in program you can change G54, common with a probing op to change or set the G54 and if program uses G92 you can loose your zero return position especially if doing restart and the G54 shift or a G92 is done 2 times

That would be the first place to look, especially on a Haas. For some reason, when I update older programs in Cam and re-post, there is an occasional G92 thrown in seemingly randomly. This will hose up all of your work offsets and cause all kinds of fuckery. This is one piece of code I haven't used in a couple decades, but if you get one in the program, it seems to be modal and will not just mess up the program, it will make it so when you set new offsets they will be way off as well. A couple restarts and some swearing generally fixes it. At some point, I should delve into the post and settings to figure out the causes and effects, but I'm just hoping the issue eventually goes away by it self... kind of like herpes.

 

[coyoinu]

that sounds like something is wrong, you should talk to your haas dealer about that. if something like that happens again, IMMEDIATELY get an error report from the machine by hitting shift-f3. That saves a little zip file with diagnostic information for the dealer.

there was a problem a while back during zero return, the work offset position would be shifted a few thou due to the way the encoder z pulse was being read, but the error was very small. that's since been fixed, plus it wouldn't be a problem on the VM machine, which i believe has linear scales.