4 AXIS G93 PROBLEM

[ege.gener]

I have a VMC with divisor but unfortunately it doesn't support G93 commands. I couldn't find any Fanuc post processor without G93 commands. Therefore I found a solution by altering NC codes. I made 3 changes to code. First I  changed all "A" codes to "B" because my 4th axis is defined as B on my machine even it revolves around X axis. I think it is an installation or initial programming mistake by someone. Second I changed all G93 and G94 commands to G01. Third change is changing all variable feed values which caused by G93 to a fixed one (in this  case F600.). 

By doing these changes I managed my machine to run the code. It seems working fine. The part is not finished yet. I would like to know if there will be any negative effects of these changes in terms of dimensional accuracy or surface finish. 

Or can anybody suggests a 4-axis post processor wihout G93? Thanks in advance.

Ps: You can find the cam file, edited and unedited NC codes as atttachments.   

[boopathi.sivakumar · Accepted solution]

Hi @ege.gener 

I hope you can download the Fanuc with A axis post processor with the link here

https://cam.autodesk.com/hsmposts?p=fanuc_with_a-axis

You need to modify the post to turn off the inverse time feedrate type and change the prefix to B

Edit the post in any editor

look for this codes

  if (true) {
    var aAxis = createAxis({coordinate:0, table:true, axis:[(properties.makeAAxisOtherWay ? -1 : 1) * -1, 0, 0], cyclic:true, preference:1});
    machineConfiguration = new MachineConfiguration(aAxis);

    setMachineConfiguration(machineConfiguration);
    optimizeMachineAngles2(1); // map tip mode
  }

change the "coordinate:0" to "coordinate:1"  it should look like below it now it will post "B" instead of "A"

  if (true) {
    var aAxis = createAxis({coordinate:1, table:true, axis:[(properties.makeAAxisOtherWay ? -1 : 1) * -1, 0, 0], cyclic:true, preference:1});
    machineConfiguration = new MachineConfiguration(aAxis);

    setMachineConfiguration(machineConfiguration);
    optimizeMachineAngles2(1); // map tip mode
  }

and find for this place   var useInverseTimeFeed = true; // use 1/T feeds

And change this false

var useInverseTimeFeed = false; // use 1/T feeds

and Find for this "// combination FPM/DPM"  

 your code should like this

      dpmFeed = previousDPMFeed;
    }
  } else if (true) { // combination FPM/DPM
    var length = Math.sqrt(Math.pow(_moveLength.xyzLength, 2.0) + Math.pow((toDeg(_moveLength.abcLength) * dpmBPW), 2.0));
    dpmFeed = Math.min((length / moveTime), maxDPM);

 And change the true to false like below

      dpmFeed = previousDPMFeed;
    }
  } else if (false) { // combination FPM/DPM
    var length = Math.sqrt(Math.pow(_moveLength.xyzLength, 2.0) + Math.pow((toDeg(_moveLength.abcLength) * dpmBPW), 2.0));
    dpmFeed = Math.min((length / moveTime), maxDPM);

  Save and test the post and let me know the feedback

[ege.gener]

Thank you very much. I have downloaded and made the changes that you instructed. Resulting code looks fine. I haven't tried it yet in production parts, but I think it will do the job. 

[salesYNYP2]

Hello,

I have a fanuc 0i-Mf control and I have tried to fix this G93 problem by the method used in this thread.

This hasn't worked for me and it is now coming up with an alarm describing improper use of a minus symbol.

Please help I have been trying to get my 4th axis working for weeks!

Thanks

dan

[engineguy]

@salesYNYP2 

Give the attached PP a try, it is configured for an A axis rotating around the X axis so if you have your Model correctly orientated in your Setup then it should work OK, attached is the modified PP and an example program for you to play with, it Posts code OK here so run the simulation to see what it is doing. Hope this is of some help 🙂

[salesYNYP2]

Absolute legend, thanks for taking the time to help me with this issue. 

Worked a treat! Many Thanks!

[pmpratik999]

Hi

boopathi.sivakumar

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,

Thank you for sharing the link. However, I wasn’t able to download the Fanuc with A-axis post processor from it. Could you please check if the link is correct or provide an alternative way to access the file?

Looking forward to your response.

[a.laasW8M6T]

Hi

The Fanuc with a axis post is no longer available

Just use the normal Fanuc post with a Machine Definition:

https://help.autodesk.com/view/fusion360/ENU/?guid=MFG-MACHINE-DEFINITION

You don't need to use a machine model with a Machine Definition BTW

You can set the Feedrate method to DPM Combination which is the best option if you cant use G93

[pmpratik999]

Thanks for the quick reply, I set the DPM combination as you said but now the machine is not running the codes G68.2, G53.1 and G43.4 in the program, please give some suggestions.

[a.laasW8M6T]

Hi

You just need to turn off TCP

[pmpratik999]

Thank you very much.a.laasW8M6T

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