View Full Version : Ghost in the Machine

02-09-2006, 12:30 AM
Folks -

Okay, next problem. I had a file set up to cut some knobs out for woodworking jigs - turned out to be WAY more of a PITA than I had envisioned....

Anyway, I finished the file and had it set to run in the upper right corner (diagonally opposite of 0,0,0) of a sheet of MDF I was using for some other projects - an area about 2'x2'. I had the spindle at 95/4/3 for a bit change, did that and ran z zero without any trouble.

I loaded the sbp file to run and the spindle ran at a slight skew on X from 95/3 to about 88/2.5 and ran the bit to Z -.5 making a hell of a racket. It did this from where it was on the table, not starting from XY zero, as was in the file. NOWHERE in my spb file did I have a command for any sort of cut like that. I've never dove for the stop switch as fast as I did - didn't know I still HAD those fast-twitch muscles, except for my facial tics...

I quit the routine, pulled the spindle back up to a safe Z height, closed and reloaded SB, and did an "aircut" setting zero z about .75 above the table. No problems at all, it ran just fine.

What's the deal? Now I am somewhat snakebit on this - the bit was pretty badly burned up in just that short run.

I'm running SB on a laptop that's about 2 years old, with plenty of speed and memory - it's faster and remembers more than I do, but as time goes by that means less and less.

Any thoughts?

John Moorhead

02-09-2006, 08:03 AM
John, welcome to the land of mystical z-dives (http://www.talkshopbot.com/forum/messages/26/9719.html).