Messages

1

G-Code, CAD, and CAM discussions / Re: G52 Rapid Positioning Problem

« on: May 25, 2008, 09:48:11 AM »

Cool, thanks for passing it on, most of the time it is easy to change around the order but in some situations it has been difficult, and it is always good practice to have that safety Z move first in case I start a program from somewhere in the middle when it isn't already at a safe height.

Stewart

2

G-Code, CAD, and CAM discussions / Re: G52 Rapid Positioning Problem

« on: May 24, 2008, 08:57:30 PM »

If you stick the code in Mach3 and look at the tool path, then remove that one line in the subroutine (G00 Z.125) then you'll see the difference that it makes.  Attached are some screen grabs to show whats going on.  Removing that one rapid Z command makes it work correctly.

3

G-Code, CAD, and CAM discussions / Re: G52 Rapid Positioning Problem

« on: May 24, 2008, 08:49:37 PM »

Well I tried that, thanks for the tip, but it didn't make any difference.  In the manual, section 10.5.5 it says that a line that starts with a % is treated as a comment and not interpreted.  Perhaps that isn't true.

Thanks,
   Stewart

4

G-Code, CAD, and CAM discussions / G52 Rapid Positioning Problem

« on: May 24, 2008, 04:51:56 PM »

Hello,  I've got a problem that maybe someone can shed some light on.  Sometimes after issuing a G52 offset for X and Y, if I don't immediately issue a X or Y command, the next rapid position acts as if it were in Incrimental and not Absolute positioning mode.  I'm in Absolute.

If you plug the following code into Mach3 then you'll see that it rapid positions way to the right, and then back before entering the subroutine the first time.  However, if you remove the line in the subroutine "G00 Z.125 % Remove this line" then it acts fine.  I always like to have that safe z positioning in there, just in case I forgot somewhere else.  This has been a problem for a while, if anyone knows a fix for it then please let me know.  Perhaps I need to change some settings.

Thanks,
   Stewart

G90
G52 x0 y0

% Contour Outside
F10
G00 X6.75 Y-.020
G00 Z-.125
G01 X7 Y0
G03 X7.5 Y.5 R.5
G01 Y4
G03 X7 Y4.5 R.5
G01 X6.75 Y4.520
G00 Z.125

%Countersink holes

G52 X7 Y.75
M98 P100

G52 X7 Y1.75
M98 P100

G52 X7 Y2.75
M98 P100

G52 X7 Y3.75
M98 P100

G52 X0 Y0

M02  % end program


O100 % SUBROUTINE bore hole .630 diameter, .375" deep
  G00 Z.125 % Remove this line
  G00 X0 Y0
  G00 Z-.125
  F3 G01 Z-.25
  F6
  G02 X.057 Y0 R.0285
  G02 X.057 Y0 I0 J0
  G02 X0 Y0 R.0285
  F3 G01 Z-.375
  F6
  G02 X.065 Y0 R.0325
  G02 X.065 Y0 I0 J0
  G02 X0 Y0 R.0325
  G00 Z.125
M99

M0

5

General Mach Discussion / Re: gcode to mill half ball with cnc mill

« on: December 10, 2007, 07:10:08 PM »

One more note.  This code (the good parts anyway) are all thanks to sterling.  If anyone else finds it useful they should let him know.

6

General Mach Discussion / Re: gcode to mill half ball with cnc mill

« on: December 10, 2007, 07:06:50 PM »

Got it done, thanks for help!  Here is the part... [img http://www.kickasscamera.com/cad/100mmballadapter.jpg]http://[/img]  You may see a line on there that shouldn't be, its from a slightly off roughing pass from a previous attempt, not from this code.

It is an adapter plate for a 100mm bowl tripod, the curve of the part fits into a matching bowl so you can adjust its level easy.  My g code is kind of messy, but i'll post it here anyway in case someone ever searches for something similar.

Thanks.


#1080=.125  (safe z height)
#1081=2     (plung feedrate)
#1082=15    (feedrate)
#1060=.795  (z correction from top of ball to cropped starting point)

#1001=.25   (ballmill radius)

#1000=2.125  (hemisphere radius ROUGH pass)
#1050=1.9685 (hemisphere radius FINiSH pass)

#1002=20 (number of steps ROUGH pass)
#1052=80 (number of steps FINiSH pass)

#1070= 11 (number of ROUGH steps to skip)
#1071= 44 (number of FINiSH steps to skip)

#1005=0 (centre X)
#1006=0 (centre Y)

% end of user entered variables

#1000=[#1000 + #1001] (total)
#1003=[90.0 / #1002]
#1004=[#1003]
#1053=[0 - #1050 - #1001] (the z offset)

G00 Z[#1080]
M98 P1 L[#1070]         (run program)
M98 P2 L[#1002 - #1070] (run program)

G00 Z[#1080]

#1000=[#1050]
#1002=[#1052]

#1000=[#1000 + #1001] (total)
#1003=[90.0 / #1002]
#1004=[#1003]
#1053=[0 - #1000] (the z offset)

M98 P1 L[#1071]         (run program)
M98 P2 L[#1002 - #1071] (run program)
G00 Z[#1080]
M30

O1
  #1008=[#1000 * sin[#1004]]
  #1009=[#1008 / tan[#1004]]
  #1004=[#1004+#1003]
M99

O2
  #1008=[#1000 * sin[#1004]]
  #1009=[#1008 / tan[#1004]]
  g00 X[#1005 + #1008] Y#1006
  F[#1081]
  G01 Z[#1009 + #1053 +#1060]
  F[#1082]
  g03 I#1005 J#1006
  #1004=[#1004+#1003]
M99
M0

7

General Mach Discussion / Re: gcode to mill half ball with cnc mill

« on: December 10, 2007, 12:16:00 PM »

Yes, the mill isn't the perfect machine for making round cuts, but there are a lot of other cuts involved that require the mill and the time to chuck up the part in the lathe, setup the tools, and manually turn it isn't worth it in this particular case.  I've milled round cones before with great results, with a 1/2" ball endmill I was really surprised in the quality of the taper, after a light bead blasting you'd never know it wasn't a lathe.  I just haven't done a hemisphere before, it seems the quality should be the same results as a cone, but with sin and cos introduced.  I don't have a motorized rotary table.

I'll let you know the results when i'm done, still working on the code with much help from Stirling, i'm curious too.

8

General Mach Discussion / Re: gcode to mill half ball with cnc mill

« on: December 10, 2007, 12:05:38 PM »

Cool.  I had taken that line out since it didn't seem right, thanks for the fix!  I also  changed G01 Z[#1009] to G01 Z[#1009 - #1000] so that it starts at the surface of the material and mills down (negatively).  This is my first venture into any gcode scripting, thanks for helping and opening my eyes to this stuff.  Now i'm trying to figure out how to make the program jump to the start z point so I don't waste cycles milling air the first half of the hemisphere.

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General Mach Discussion / Re: gcode to mill half ball with cnc mill

« on: December 10, 2007, 11:03:29 AM »

I don't know if you'll make the wizard or not (I definately could use it), but if you do in this application my half ball is only the lower part of the ball, so it will look like a half ball with the top lopped off, so it wouldn't need to start from the top.

thanks again.

stewart

10

General Mach Discussion / Re: gcode to mill half ball with cnc mill

« on: December 10, 2007, 10:58:25 AM »

Thanks!  I'll try the code and let you know.  My half ball is 100mm in diameter, although i'm working in inches so it is 3.937", if it was smaller chucking the material in the spindle might have worked.