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Author Topic: Intermediate positions in linear movement during adaptive toolpath  (Read 98 times)

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Greetings,

 
I'm a beginner and I'm working on a DIY machine running on mach3.

I posted a similar thread on a Fusion 360 forum to solve the problem on the CAM side but I'm almost sure that this problem can be solved also through mach3 settings, maybe CV settings.

 
I was testing an end mill with an adaptive toolpath and I noticed that in some points there was a sort of micro-stalling (like a lost step in the stepper motor) in the linear motion and I thought it was a stiffness problem. After running the contour toolpath for finishing, which ended up having a width of cut comparable to the roughing pass due to my concern about stiffness, I noticed that this stalling was absent. I looked at the toolpath and noticed that in the adaptive strategy in single axis movement there were intermediate positioning command. Basically suppose I'm in A in order to go to D the adaptive toolpath commands to go to B and then to C and finally to D; contour instead simply commands to go to D (which  is equivalent in the example).

 
I'm confident that the micro-stalling in the machine is not related to stiffness but that the machine stalls when it reaches this intermediate position and then it starts again after few milliseconds. Like if there is a deceleration before reaching point B.

I can't post the video here so this is the link with the post on autodesk forum where you can see the video     https://forums.autodesk.com/t5/fusion-360-support/intermediate-positions-in-linear-movement-during-adaptive/td-p/10172952

In the video you can see the stalling event with no load. The code is from another run but for example lines 81, 82 and 83 seem useless to me.

Is there something I can check?



Thanks. Sorry for any English problem.
Stefano Prato.

Offline Graham Waterworth

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Re: Intermediate positions in linear movement during adaptive toolpath
« Reply #1 on: March 21, 2021, 11:09:05 PM »
Fusion 360 is known for outputting 10000 lines of code when 10 will do, I would use 2D profile and see what happens.
Without engineers the world stops
Re: Intermediate positions in linear movement during adaptive toolpath
« Reply #2 on: March 22, 2021, 08:16:16 AM »
Adaptive is much faster then other strategies.
Also I'm now thinking that maybe I have stalling between every line of gcode, like other few people in the forums, and that I noticed it only thanks to those intermediate lines in linear movement. I'm asking support on smoothstepper side. The other people with this problem seem to haven't found a solution.
I will also try some tweaking on the CV settings but it wasn't positive for other users. 

Offline Graham Waterworth

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Re: Intermediate positions in linear movement during adaptive toolpath
« Reply #3 on: March 22, 2021, 06:15:46 PM »
59K of code to go around a rectangle is embarrassing to say the least and ridiculous for an adaptive strategy.

10 lines per pass is all that is needed and a change of feed rate for the corners so get rid of the crap g-code and everything will run smooth as silk.

There is nothing in your part to make adaptive.

Use a standard 2D contour with a step over and see what a difference it makes.
Without engineers the world stops
Re: Intermediate positions in linear movement during adaptive toolpath
« Reply #4 on: March 22, 2021, 06:33:56 PM »
I actually made this test with the 2D contour and the machining was slower. Also the way it handles the corners is less optimized or maybe I'm not optimizing it well; basically when it approach the corner in the first stepover the load on the tool can be much higher then in the rest of the machining and to get rid of this I need to add more stepovers where, except for the moment where it approach the corners, the tool is cutting air. I can thing of solutions with a sketch geometry placed to round the corner and then a contour around the stock without the sharp corners. I'm a beginner so I'm 100% sure there are many other solution possibly inside the 2d Contourn tab itself.

About the main problem. I optimized Windows settings according to the suggestions on the smoothstepper (my board) webpage. Today I used an adaptive toolpath and I had no problems.
More testing is needed.

Thanks for the help.