Having Trouble Rotating Hand Written G-Code w/ PCNC 1100 - Page 2

# Thread: Having Trouble Rotating Hand Written G-Code w/ PCNC 1100

1. ## Re: Having Trouble Rotating Hand Written G-Code w/ PCNC 1100

Originally Posted by jwatte
Those numbers are where the spindle was located when you zeroed the axes. E g, "zeroing an axis" really means "put the negative value of the absolute position of the spindle, into the work coordinate system offset."
So, if the absolute value is X=2.5, Y=-1, Z=6, and you "zero axis" on all three axes, the G54 coordinate system will be X=-2.5, Y=1, Z=-6.
The DRO values you see for where the spindle is, are calculated as "the absolute position of the spindle (relative to the home of each axis) PLUS the current work coordinate system offset."
So, absolution position X=2.5, plus G54 offset X=-2.5, means that the DRO reads 0.

(Actually, hmm, I'm not at the machine right now, and I'm not sure if the absolute position is copied into G54 and the G54 offset subtracted; or whether the negative of the absolute position is copied into G54 and the G54 offset added -- it's the same result in the end, but if you edit G54 directly, obviously the sign matters :-)
With the physical machine, if you are in the g54 offset and you zero the machine, g54 offsets are adjusted accordingly. I had to re-zero the z axis for a tool change, and would have to manually update g55 and g56.

My question was more about the virtual pathpilot... A fresh install of PathPilot 1.x has a work offset table that is all zeroed out. On virtual, it is not.

Anyway to follow up, I was able to machine my parts. It was painful as I had problems with the controller; it would freeze on the Tormach logo. Pressing ESC showed an error which said to run fsck manually, but I couldn't figure out a way to drop to grub or a shell. Not sure what happened as the machine worked a few months ago. I ran to Walmart and bought a hard drive, but had the same error after a fresh install, so I grabbed another old PC that I luckily had not yet thrown out. That one did boot, but if I left it idle the interface would freeze (though the mouse cursor still worked). Luckily it did not freeze while the program was running. I did have to re-zero the Z once as mentioned above, and luckily PathPilot can resume where it left off after restarting (unlike Mach3), which is good because I think I ended up having eight freezes (gotta move quick).

Thanks all for the advice on the offsets... it made my life a lot easier; I'd never messed around with that table and it was super helpful for efficiently using my stock. I tweaked my g-code to streamline and have a list of other improvements I can now focus on instead of mucking around with my plywood fixtures...

2. ## Re: Having Trouble Rotating Hand Written G-Code w/ PCNC 1100

Originally Posted by deadlykitten
so far, i always believed that someone who is building a g-code over 'years' has machining background hmm, whatever
Well, I have an engineering degree vs this topic where nobody ever sat me down and explained how it works. The business just ramped up faster than I expected and I was spending too much money outsourcing short runs of relatively simple parts; Tormach was able to make a machine appear in my driveway in two weeks and I slapped a basic software pipeline and g-code together over Christmas... and it worked for five years. If I milled three parts in one evening, I was happy, but now I have to churn out eight in the same amount of time.

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