Gcode IJK R XYZ

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Gcode IJK R XYZ

Postby Haik » Mon Apr 15, 2019 4:27 pm

In UCCNC will motion planner output (to drives) the same no matter if Gcode is IJK, R, or simple XYZ?
Or will motion planner output differently for each type of Gcode even if shape of feature is identical?

Thanks!
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Re: Gcode IJK R XYZ

Postby cncdrive » Mon Apr 15, 2019 5:43 pm

Sorry, but I do not understand the question, please explain it a bit more detailed what do you mean by same output to drives?!
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Re: Gcode IJK R XYZ

Postby Haik » Thu Apr 18, 2019 9:13 am

Example Gcode of 10-inch circle attached.
In the case of IJK and R no resolution is indicated since the shape is purely a vector and the data is a mere 5 or 6 lines of Gcode. Under this condition a motion planner would likely output pulses based on configuration of steps per inch.
But with XYZ Gcode the shape is a polyline that is hundreds of Gcode lines long. Does UCCNC's motion planner attempt to optimize polylines into a vector prior to generating the pulses sent to drives?
I realize my question is odd, I'm hoping to understand some performance characteristics.
Attachments
XYZ_example.txt
10 inch circle in XYZ Gcode
(12.22 KiB) Downloaded 21 times
R_example.txt
10 inch circle in R Gcode
(180 Bytes) Downloaded 22 times
IJK_example.txt
10 inch circle in IJK Gcode
(184 Bytes) Downloaded 22 times
Haik
 
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Re: Gcode IJK R XYZ

Postby cncdrive » Thu Apr 18, 2019 10:04 am

Yes, ofcourse it optimises the path, the polylines.
With IJK or R format there is no difference in regards the motion planning, but there can be precision differences, because there are cases when R gives less precise result, because it does not define the center point as precise as the IJK format. This error is mathematical and in most cases it is low enough to not cause any tolerance issues, I mean the error is usually smaller than the tolerance requirements of the workpiece, but IJK is always precise, because it exactly defines the center and the end points...
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Re: Gcode IJK R XYZ

Postby Haik » Fri Apr 19, 2019 5:13 pm

It's very good to learn the error potential of R(adius) Gcode VS IJK. Thank you for your informative reply... this will help in my efforts to have the quickest, smoothest machine possible.

I'm nearing the completion of the long process of upgrading my Thermwood industrial router with closed loop steppers (aka-Step servos). I've long researched the pros and cons of the few types of systems (3ph AC servo, DC Servo, Step Servo). I will posting of my upgrade and the process withing a couple of weeks (I hope). As a teaser I have settled on Step Servo system with 2500 ppr encoders on PacSci NEMA42 (4000 in-lbs) motors with a 80vdc supply. Center stage is the UC300ETH atop UB1/UD1-U interface products.

Thanks again!
Haik
 
Posts: 32
Joined: Fri Sep 08, 2017 6:01 pm


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