5 axis pivot length in post-processor

[chris]

I am trying to setup a post for a 5 axis Motionmaster router with a Fagor control.  The control does not have G48/tool center point compensation so the postprocessor has to deal with the distance from the 5th axis pivot center to the tool tip.  

In posts for other CAM software we have for this machine the distance is specified in the post as a fixed length to the spindle face (or similar) and the tool length in the library provides the rest of the length to the tool tip.  

I understand that there is a DMS 5 axis with similar geometry at Autodesk Pier 9 - so maybe somebody has this sorted.  Looking for any guidance on how to set up a head/head 5 axis post in Fusion.  Thanks!

[ArjanDijk]

Hi Chris,

This option is not in HSM Fusion, this is a limitation of the software. The only thing what you can do is calculate the values in the postprocessor.

Its explained here: 

http://forums.autodesk.com/t5/hsm-post-processor-forum/trying-edit-post-for-5axismaker/m-p/6625512/h...

[Laurens-3DTechDraw]

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@Arjancncmachineworks wrote:

Hi Chris,

This option is not in HSM Fusion, this is a limitation of the software. The only thing what you can do is calculate the values in the postprocessor.

Its explained here: 

http://forums.autodesk.com/t5/hsm-post-processor-forum/trying-edit-post-for-5axismaker/m-p/6625512/h...

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That's what he asked for in the post processor. That's what he has for his other CAM software's so there is no extra limitation in AutodeskHSM for him.

Because you give in set lengths in the post and can then pull the tool length you gave in in the library to get the whole length it should be offset by.

[gmrini]

I'm having the exact same issue. 

What post are you using to begin? Have you had any success with just 3+2 machining? The generic Fagor post in HSM doesn't quite seem to work for me. 3+2 alone would be really awesome though, and I don't think the tool tip calculation would be needed for this. 

Let me know! I'm going to look into modifying the generic fagor post to work. 

Thanks.

[Laurens-3DTechDraw]

The post that has this implemented is the Thermwood 5-axis: http://cam.autodesk.com/posts/?p=thermwood_5-axis

[gmrini]

I've dug through the thermwood post as well. Shouldn't it require you to enter the distance between the B-Axis pivot and the tool tip into the post processor to perform this calculation? It seems like it needs to know this info to spit out the correct coordinates when changing tool orientation. Otherwise the machine would have to do that calculation and ours can not. 

The shopbot 5 axis processor is the only one I could find that seems like its doing that. You are required to enter a gauge length (spindle face to pivot) and tool length. I'm having trouble melding together the shopbot processor with the Freedom patriot processor which works for my router in just 3 axis. 

Ah! Maybe I'm missing something. It's driving me crazy. 

Thanks for the response!

GMR

[gmrini]

I've worked on combining the thermwood post with the Freedom Fagor router post  (which works fine for 3-axis on the motionmaster with 8055 fagor controller)

It seems to be very close. It spits out real working code that runs on the machine and moves all 5 axes, however; it seems to be ignoring my headOffset and/or pivotDistance.

It will turn the heads but not offset them properly. When I change the pivot distance in the post processor it doesnt change the resulting code. Somewhere it is not using this value. I can't quite seem to figure it out. I've attached the post processor code I have so far. I would LOVE it if someone could take a look and let me know where I might be missing something. 

Really stoked to have it this far, just need a little tweaking I think to get us to the finish line! Thanks again for the comments and help. 

processor code attached. 

GMR

[chris]

You got further than I did!  I too would love to know how to get the pivotDistance to work and how to set it as a fixed value in the post and add a tool length from the library value of the programmed tool.  In theory this would be a distance from the pivot axis to the spindle nose + tool length, and this is exactly how my existing CAM works.  

I am not able to add anything now but I will look at you post when I have more time and try to grasp what is happening.  Thanks for sharing your efforts!

[chris]

I have been looking through the posts on Fusion and 5 axis trying to see if there is a solution to handling the 5 axis (B/C head style) kinematics in the post vs. in the control - for machines without TCP.  I still can't figure out where the gauge length (intersection of rotary axes to tool tip) would be dealt with in the post.  I know this is possible, but it is not clear how to do it.  Have there been any updates in the last year or so?

[Marek_Skotak]

Hi,

you can set it by this way. 

Create variable with you pivot distance. Distance from your intersection to a spindle (without tool)

var pivotDistance = toPreciseUnit(274, MM); //pivot distance 

In a Function On Section you will make a transformation of coordinate. Your tool in HSM tool library must have same lenght as on a machine. 

headOffset =  tool.bodyLength + pivotDistance; // control will compensate for tool length
    var displacement = currentSection.getGlobalInitialToolAxis();
    displacement.multiply(headOffset);
    displacement = Vector.diff(displacement, new Vector(0, 0, headOffset));  
    // temporary solution
    xOutput.offset = displacement.x;
    yOutput.offset = displacement.y;
    zOutput.offset = displacement.z;

Im also test it on machine that i make a 90 degree operation and check if my tool is on a correct place. 

Which machine you have? 

[bob.schultz]

You can find a detailed description on how to handle 5-axis heads on machines that do not support TCP in the Post Processor Training Guide, Section 7.3.  For a sample of the code, you can look at the 5axismaker post processor.