Messages

1821

G-Code, CAD, and CAM discussions / Re: G54-G59 Work offsets

« on: December 14, 2007, 06:12:35 AM »

That about sums it up.

G54 is set every time the fixture is set up because the fixture may be in a different place on the machine.

G52's are hard coded into the program as the parts on the fixture should/will be in the same place every time relative to the G54.

Graham.

1822

SmoothStepper USB / Re: Beta Testing Reports

« on: December 13, 2007, 09:13:31 AM »

Just got mine today, I will be playing nice tonight.

Graham.

1823

G-Code, CAD, and CAM discussions / Re: G54-G59 Work offsets

« on: December 13, 2007, 08:39:01 AM »

Hi Chris,

If you have a jig with 6 identical parts located on it, you do not want to have to set 6 lots of offsets.

G54 to G59 are global fixture offsets, that is, you can set each one up with a different fixture datum then when you use that fixture again you have to set all six datums again.  We do not want to do that we want to set one datum and all the other parts are in known locations so we can use 1 global and any number of local datums in this case 6.

To program each location on the fixture you use G52, this is a local datum that is relative to the fixture offset in use.

So, we set the fixture datum using G54, then in our program we have G52's that represent the positions of the individual parts on the fixture, these are hard coded into the program as they never change.

This program would drill the 2 holes in each part in the diagram below. Every time we would use this fixture we would set G54 X0 Y0 at the bottom left side and the Z on top of the job and the program sets all the local datums as it needs them.

Before anybody tells me :-

If I wanted to make things even better I could use incremental or absolute subs or macros to make the program even smaller, but lets start simple.

%
(USE FIXTURE OFFSET G54)

G21 G40
T1 M6
G54 G00 G90 G43 X0 Y0 Z25. H1 S750 M3 (MOVE TO FIXTURE DATUM)
(FIXTURE LOCATION 1)
G52 X20. Y20.                                        (SET FIRST LOCAL DATUM)
G00 X-5. Y0                                          (MOVE TO FIRST HOLE)
G81 Z-10. R1. F125.                                 (DRILL FIRST HOLE)
X5.                                                       (DRILL SECOND HOLE)
G80                                                        (CANCEL DRILLING)
G52 X0 Y0                                               (CANCEL LOCAL DATUM)

(FIXTURE LOCATION 2)
G52 X50. Y20.
G00 X-5. Y0
G81 Z-10. R1. F125.
X5.
G80
G52 X0 Y0

(FIXTURE LOCATION 3)
G52 X80. Y20.
G00 X-5. Y0
G81 Z-10. R1. F125.
X5.
G80
G52 X0 Y0

(FIXTURE LOCATION 4)
G52 X80. Y50.
G00 X5. Y0
G81 Z-10. R1. F125.
X-5.
G80
G52 X0 Y0

(FIXTURE LOCATION 5)
G52 X50. Y50.
G00 X5. Y0
G81 Z-10. R1. F125.
X-5.
G80
G52 X0 Y0

(FIXTURE LOCATION 6)
G52 X20. Y50.
G00 X5. Y0
G81 Z-10. R1. F125.
X-5.
G80
G52 X0 Y0
M5
M30
%

I hope this makes things a bit clearer.

Graham.

1824

G-Code, CAD, and CAM discussions / Re: G54-G59 Work offsets

« on: December 12, 2007, 10:26:54 AM »

G52 X0 Y0 Z0 A0 B0 C0

Cancels any G52 local offset you have set.

If you do not cancel them you will get accumulations of offset and things like go to tool change go to the wrong place. You do NOT want that.

Graham.

1825

G-Code, CAD, and CAM discussions / Re: G54-G59 Work offsets

« on: December 12, 2007, 10:00:17 AM »

OK, like this.

G00 G43 G40.1 G17 G80 G50 G90
G20
(Deep Drill )
G54 (set fixture offset before any moves)
M6 T1
G43 H1
M03 S800

G00 X0.6250 Y-0.7500
Z.2655
G73 Z-0.4595 R0.0 Q0.05 F2.0
X4.8150 Y-0.75
G80

G52 X-5.(SECOND PART)
G00 X0.6250 Y-0.7500
G73 Z-0.4595 R0.0 Q0.05 F2.0
X4.8150 Y-0.75
G80
G52 X0 (you must always cancel)
G00 Z1. M9
M5
M30

Graham.

1826

G-Code, CAD, and CAM discussions / Re: G54-G59 Work offsets

« on: December 12, 2007, 06:52:21 AM »

Hi Chris,

G54 to 59 are machine datums, you use them to set fixture xyz zero points.  To do multiple parts on a fixture you use local datums G52 :-

G00 G43 G40.1 G17 G80 G50 G90
G20
(Deep Drill )
G54 (set fixture offset before any moves)
M6 T1
G43 H1
M03 S800
G00 Z0.2655
X0.6250 Y-0.7500
G73 Z-0.4595 R0.0 Q0.05 F2.0
G80
G00 Z0.2655
G52 X-5. (set local datum offset)
X4.8150 Y-0.7500
G73 Z-0.4595 R0.0 Q0.05 F2.0
G80
G52 X0 (you must always cancel)
G00 Z0.2655
G00 Z1
M5 M9
M30

Graham.

1827

General Mach Discussion / Re: choppy circles?

« on: December 10, 2007, 06:15:47 PM »

Your problem is Corel, it treats circles as splines, everybody seems to have the same problem with it.  The only way round it is to drop Corel DXF file into something like Bob-Cad or Alphacam, they can convert it.

Graham.

1828

G-Code, CAD, and CAM discussions / Re: Stitching G-Code Together

« on: December 09, 2007, 02:26:35 PM »

Yes,

stick all your subs in the subs folder inside Mach3, then you can call them from the main program using there file name.

e.g.

M98 (sub1.tap)
M98 (sub2.tap)
Etc.
M30

Graham.

1829

General Mach Discussion / Re: Contol of 4th Axis

« on: December 05, 2007, 06:34:15 PM »

like this

G00 G90 X0 Y-20. A0 Z25.
Z0
G01 Y20. F10.
G00 Y-20.
A10. (ROTATE 10 DEGREES)
G01 Y20.

Graham.

1830

G-Code, CAD, and CAM discussions / Re: Visualmill 5.0 code for peck drilling

« on: December 05, 2007, 06:20:18 PM »

G83 *********.xx Yyy.yy Zzz.zz Q.250 F20.

Q is peck depth.

Graham.