I have been ruuning some test programs threw my new Tormach . Ever now and again I get a pop up window that says " Preperational Postioning " . It seems to happen at a tool change line such as " N490 T16 M6" . When this happens you have two choices 1) ok 2 ) cancel . If you ok it Z will go to the top limit switch and stop everything. If you cancel it program starts running without going to tool change postion and the spindle will not start , nor can you turn it on from Mach3 . Any ideas ?
> machine has been refrenced
> tool change postion using G28
Last edited by hall6ppc; 08-28-2011 at 10:36 PM.
How was the code generated. For example TurboCadCam puts a home command in at every tool change which will send the z axis to the limit switch. I've never seen "Prepreational Postioning " what ever that means, is your spelling correct. I just edit the offending code. Others may disagree but I think most CAM programs will, from time to time, produce code that needs to be edited. You have to learn what the commands mean and check the code at the start of the file to confirm it is going to do what you expect.
Actually the message says "Preperation positioning", ie preparation misspelt.
This occurs, as dbrija says, when Run from Here has been selected. The message is asking if it is OK to move the tool from the programed position of the last movement line above the line selected as "from here". When you OK it, the tool will be moved in a straight line from its current positino to the position displayed in the message window.
Since I assume you didn't select Run from here, then it seems you have a software problem. So do the usual steps until it is fixed; such as:
Power off everything and restart.
Run another Gcode program with tool changes.
Use M998 instead of G28.
Check latest Mach3 version loaded.
Pray to the God of Computers (perhaps do this first).
I ran some more programs and cleared out all of the G28 tool change positions and just let Z go to G28 Z0. during tool change . Had no more problems after that .
IF is possibly the key word in that sentence. Is yours - set up correctly?
Preparational positioning probably means it going to the tool change Z position, if you choose yes and don't have one it will got to the top and hit the limit switch. If you choose no it will assume you don't want to make a tool change and just carry on. Makes sense to me anyway.
Check your SafeZ position. You may have it set higher than your Z limit switch.
Mach3 2010 Screenset
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
did you set your tool change location?
Take a look at the G code Line 490 is were the trouble was .
Thanks for the help !
Last edited by hall6ppc; 08-28-2011 at 05:32 PM.
N490 G28 Z 0.0
N500 T6 M6
Z axis goes to home position (just off of switch) and all seems to work well . I have tried just posting just G28 and setting the tool change position to say G28 Z -2.0 , x0.0 y 0.0 . When I do this I get all kinda crazy things . Like Z going all the way to the limit switch and a A axis out put during tool change that moves the table very slowly. I don't even have a 4th axis on my machine . Crazy I know!