2488
« on: August 13, 2006, 04:48:35 AM »
Hi Mike,
there is nothing wrong with using G92 as a datum point, that is what it is for, changing to G54 will not improve the accuracy of the homing switches. The main advantage of using G54-G59 is that you can change from one datum point to another in program.
e.g.
If you have two fixtures on your table you can have one datum at G54 and the second one on datum G55. The code would be something like this :-
G20 G40 G80 Etc
(STANDARD SETUP LINES)
G54 G00 G90 G43 X0 Y0 Z1. H1 (MOVE TO FIXTURE 1 AND DRILL A HOLE AT X0 Y0)
S1000 M3
Z.1
G01 Z-.25 F2.
G00 Z1.
G55 X0 Y1. Z1. (MOVE TO SECOND FIXTURE AND DRILL A HOLE AT X0 Y1.)
Z.1
G01 Z-.25 F2.
G00 Z1.
M30
To set the fixture datums you go to 'Operator' and 'Fixtures' off the window menu. You will see listed in the new window a list down the left hand side the top 6 are marked G54 to G59 all you have to do is set your X,Y,Z,A values into the corresponding row. These values are the same as the known position for your G92
Remove all G92 commands from your code including the X,Y,Z and A and just enter a G54 instead. This will then tell mach to use the G54 datums stored in the fixture list.
The advantage of this is that if you have more than one program that uses your indexer and the datum point for each program is the same then you don't have to worry about changing the G92's in each program. They will all use the same G54 setting in the fixture list.
I hope this helps.
Graham.
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