Adding a function in Autodesk post processor class without using TCP

[Anonymous]

A 5 axis simultaneous tool path made on Fusion 360, post processed without TCP mode, is resulting in a jerky motion of the machine. But at the same time, with TCP mode ON, the tool path is smooth but the controller requires an in-built TCP mode to perform smoothly. And a lot of economic controllers in the market does not have this feature. 

I would like to request for the addition of a function to Autodesk Post Processor Class, so that any controller which does not have a TCP mode can be used to run 5-axis simultaneous G-code. 

A similar function, as below, could be added or the same can be updated to include an option for using controllers without TCP mode, so that the tool-path will not be jerky.

optimizeMachineAnglesByMachine ( MachineConfiguration machine, Integer tcp )

 0: Maintain tool tip position (TCPM).  In this function we have only 3 options

1. 1: Map tool tip position.
2. 2: Map tool tip position for machine axes in table only.

Kindly look into this issue.

Hoping to hear a positive response from your end.

Amit Kumar.

[ArjanDijk]

Hi @Anonymous

Controls that don't support TCP are mostly not really aimed at 5 axis simulatinous machining and don't always have the speed to prevent jerkyness. What kind of non TCP control are you using?

[Laurens-3DTechDraw]

@Anonymous

I'm pretty sure the jerkyness comes from the NON-TCP controller vs TCP Controller.

Not from the difference in code.

Codewise the only difference is that the coordinate system in the machine does or doesn't rotate with rotary movement.

So you should get the same points outputted just respective of a different coordinate system.

[Anonymous]

@Laurens-3DTechDraw So you should get the same points outputted just respective of a different coordinate system.


How to Do that, i tried enabling TCP true in post processor but coordinates i am getting is not jerky but without TCP its jerky and there is difference in coordinates also. i just want to reduce Non TCP jerk in my post processor

[Anonymous]

@ArjanDijk What kind of non TCP control are you using? 

I am using Mach4 Controller and when i input non TCP gcode in mach4 i am getting weird shapes , but with tcp mode toolpath is exact./

But there is only one problem with Non tcp is toolpath is jerky , for example in case of circle i am getting toolpath of polygon of different lines. that results in jerky motion.

[Laurens-3DTechDraw]

@Anonymous

It's pretty straight forward.

The Post processor get's coordinates from the CAM.

In TCP mode it gives them out with the coordinate system rotating with the rotary axis.

When NON-TCP, it outputs the coordinate the machine needs to go to in just it's axis value's.

The jerky motion you see might be caused by the post outputting feed/min where you are rotating your rotary axis also, which means it probably wants to go much faster than it is able to.

It's really not that the post does make the motion different for TCP and NON-TCP.

There could be settings in the post you set wrong for NON-TCP or on your control.

But the post doesn't do witchcraft on the TCP.

[Anonymous]

So calculations based on Inverse time feedrate is necessary to synchronize my (x,y,z) and (A ,C) axis together?
Also in fusion we have an option of feed optimization in 5 axis toolpath, can that be used to solve the problem?

[Laurens-3DTechDraw]

@Anonymous @Anonymous

I think Inverse time feed would be necessary for 5-axis simultaneous for non-tcp toolpaths.

[Anonymous]

I tried adding inverse time feedrate function, but my issue is still there, there is conversion happening from tool to part coordinate that is not smooth in fusion 360 post processor, i tried in hsmworks too, still same problem with more jerky motion.

[Laurens-3DTechDraw]

@Anonymous 

Can you upload the two NC-Files?

So the same program on in TCP one in NON-TCP.

[Anonymous]

@Laurens-3DTechDraw here are the files for TCP and Non TCP for hemisphere gcode 

TCP - https://drive.google.com/open?id=0B4s4URz-fp1jUWNZWHNMNnZBQ2s

Non-TCP - https://drive.google.com/open?id=0B4s4URz-fp1jNXVqWnRSMlZGTDQ

Please check above drive files.

[Laurens-3DTechDraw]

It seems something is wrong in the NON-TCP post processor.

Could you also upload that one?

[Anonymous]

@Laurens-3DTechDraw here is the link to the modified version of  pocketnc post processor that i have used, please look into that.

https://drive.google.com/open?id=0B4s4URz-fp1jU2hIdkJFeG4yc2M

[Laurens-3DTechDraw]

@Anonymous @Anonymous

Alright, I made an example part, posts and backplotted them.

Both TCP and NON-TCP look exactly the same.

Also they have the same amount of code.

So it's not the TCP vs NON-TCP that makes a change.

Find all the files here: https://drive.google.com/drive/folders/0Bxj6K_efj3l_R1BYR2pYekpaRzA?usp=sharing 

[Anonymous]

@Laurens-3DTechDraw I tried loading these gcodes onto my controller but it is showing different results.

the images are shared below.

whats changes do i have to make, to get the same result as the TCP based toolpath.

[Laurens-3DTechDraw]

@Anonymous

I believe one code should be run in G43.4 the other one shouldn't.

[Anonymous]

@Laurens-3DTechDraw

The G43.4 is used for TCP mode only, and i have a non TCP controller, so what should i do to run smoothly toolpath without using TCP or G43.4.

So which function i have to modify in post processor that i sent, for smooth non tcp toolpath

[Laurens-3DTechDraw]

If you have a non tcp control. The TCP file will look bad.

So the post processor in the folder I shared that is post.cps should work for you.

[Anonymous]

@Laurens-3DTechDraw i tried posting with both post processor you sent , but tcp file is looking good but wrong coordinate system because of my controller. But non tcp looks bad still motion is jerky. I am using mach4 version. So can you tell me is there any function modifications. To make that toolpath smoother without tcp. Yours post are giving same result as mine.

[Laurens-3DTechDraw]

@Anonymous

The code is correct.

The problem is in your controller.

Maybe you should contact them on how to solve this.

[Anonymous]

@Laurens-3DTechDraw
Then backplot is showing different in TCP and Non TCP. It should show same. If the problem is with my controller. Can you send backplot of the gcode files i sent you TCP and non TCP. So i can verify with my backplotter.