So I'm using Mach for half the morning no problem. Then out of the blue it decides that close enough is good enough

i.e. instead of moving X, Y and Z to EXACTLY where the part file tells it to, it goes to within a few (random) hundredths instead.
 
Please see the attached piccy and compare lines 70 and 80 to the DROs.

Anybody got any ideas?

WARNING: Rant alert....

Why do I seem to spend more time trying to get Mach working these days than making chips?

Rant over 

Did you hit the E stop before the machine was finished moving so you could look at the displays?
     DaveA.

Hi DAlgie -  cute...

That would be a no.

Seems to me that after reading some of the posts by Darrel Merrel.. the tuning of the drives to the motors makes all the difference in the world with how tight the machine stays on tolerances. you can see some of his posts here . http://www.machsupport.com/forum/index.php?action=profile;u=6676;sa=showPosts

are you using a Galil?

Hi FastFieros - thanks for your response.

I think I've discovered what the problem is. As an Englishman I have my default units set to... erm, well metric of course!!!!. My RhinoCAM POST also puts a G21 in the prolog of my tap files so I'm definitely in metric (mm). What seems to have happened is that Mach at some point decided to reset my native units to imperial - sorry, English  . After resetting the native units back as they were - i.e. to mm - all seems well and accurate again.

You've got a fair discrepancy between the last line of code and the DROs   

Greg

hehe - Reminds me of the Mars probe that crashed because some calculations were Metric and others in English (http://www.spaceref.com/news/viewnews.html?id=115)
I've made the same mistake, a "few thou" off here and there.  Made me nuts -- that's because I mixed code from two different posts.
I wrote some script to check for conversion codes.