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adriangillitt (Marine/Ocean)
26 Jun 03 11:04
We have 3 cnc machines now, 2 which are relatively new and one which is very very old. Its a matchmaker 750 CNC milling machine. We have it linked via serial to a computer which we feed the g code to.

We are having some problems getting a post processor to work with mastercam. We have a generic postprocessor from a matchmaker 850 series milling machine, but undoubtedly they are inherently different.

We are having problems with it understanding polar coordinates this is an example of a simple circle toolpath generated by mastercam using the postprovessor.

N100 G4 * O000026-06-03 *
N102 G4 *CIRCLE1 *
N104 G4 * TOOL 1 UNDEFINED   *
N106 G40 T1 M3 S1000 ( ) 3 ( )
N108 G0 X30. Y12.
N110 Z-50.
N112 G1 X18. F500.
N114 G3 X6. Y0. J-12.
N116 X94. I44.
N118 X6. I-44.
N120 X18. Y-12. I12.
N122 G1 X30.
N124 Z-60.
N126 G4 M91
N128 G4 M90

It does not understand the coordinate system. Does anyone know what i need to tell the postprocessor to output in terms of polar coordinates.

Even better would anyone know where i might be able to get a postprocessor for this machine?

Thank you all in advance.
Helpful Member!  adriangillitt (Marine/Ocean)
27 Jun 03 7:46
Can anyone answer this question please!
rhodie (Industrial)
27 Jun 03 8:56
Well, I'm not tremendously experienced with CNC, but since you asked...

* Looking at your program, I don't see any M30 code to end the program.  This may (or may not) be a problem.  

* Polar coordinates aren't a given capability of every machine, but it sounds like you've used them on your machine before.  I can only suggest looking at the reserved G-code values of G54, G55, G56, G57, G58, G59, or maybe G59.1, G59.2, & G59.3.  (These are your coordinate system selection modal codes.)

* I've used MasterCAM before, and I can't say that I like it much.  Seems that you have to do a lot of code hacking even after the post-processor to swag things into operation.  

* I asked my local CNC guru, and he said that he couldn't find a post processor for a "matchmaker 750" out of his library of several thousand.

* Do you have a null modem cable hooked up between your computer and CNC machine?

Like I said, I don't know much of anything about CNC much beyond my own machines, but I hope I can help.  If nothing else, maybe I busted a few new ideas loose for you.
adriangillitt (Marine/Ocean)
27 Jun 03 9:34
Thanks you for your reply.
I do have an end code G4 M2 etc, but had to add it at the end manually.

The machine is a Matchmaker 750, but it is controlled by a numericon 850 if that helps, maybe you have one of those in the library?

We do have an RS-232 cable hooked up to the thing.

It does not use the above polar coordinates, but does use V coordinates and also uses I,J,K with a radious function.

Maybe that helps a little more!
twinny (Aerospace)
27 Jun 03 16:08
maybe the code is too rough.
I is the circle centre x axis
J is circle centre Y axis
N114 does not quote I value the machine may need this value quoted.
Is there a setting in the post to force out all values, best to always output them all?
If you substitute the I & J with R (quoting the correct radius does it work?)
Be careful with R for radii > 180 degrees some controls then need to use I & J

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