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Losing extruder calls for machining project
#1
Hi,
I have set up a machining project for 3D printing using the recommended Slic3r software. When I am using relative E-values for the extruder instead of absolute values, RoboDK loses a lot of Extruder calls. Maybe that's due to rounding errors. Anyway I do not think RoboDK is supposed to behave this way.
The error of one single skipped Extruder call is of course neglectable but it accumulates throughout the program.
I attached the RoboDK files for relative and absolute E-values and additionally the first part of the equivalent g-code (also prepared with Slic3r) as text file (the g-code file is not allowed as attachment and the complete txt-file would be too large).
Please have a look into that, especially the programs and tell me how you think about it.


Attached Files
.rdk   Print_absolute_E-value.rdk (Size: 12.43 MB / Downloads: 62)
.rdk   Print_relative_E-value.rdk (Size: 11.37 MB / Downloads: 52)
.txt   Box_small_rel_E.txt (Size: 54.88 KB / Downloads: 58)
Best regards
David
#2
Hi David, 

At the moment, we are not supporting relative extruder calls. 
But it's something that we fixed and it will be supported in our next release in a week or so. 

We believe that absolute extruder calls are a better tool than relative ones. Therefore we recommend you that option (if you disagree on this point, please share your thoughts on the topic).

Have a great day. 
Jeremy
#3
Hey Jeremy,
generally speaking absolute E-values definitely make more sense since the extruder is normally treated as third axis.
My struggle with that more or less has its origin in a poor system design which I took over from a previous project.
Long story short, I need to translate the E-values to a number of steps for a stepper motor.
With relative values I could do that straight like:
E-value * steps/mm = number of steps
With absolute values I have to take into account the previous E-value. Don't get me wrong, that is merely two lines more code. I just tried both options and thought that this data loss was undesirable. That is why I reported it.
Thanks for the clarification!
Best regards
David
#4
Hi David,

We are pretty much on the same page then.

So my final answer is :
You can save two lines of code in a week
or
You can program it now and keep going with your project.

Hahaha.

Have a good day.
Jeremy
  




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