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Author Topic: Mach 4 3d Profiling. Slow and tedious with varying CV options.  (Read 517 times)

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Mach 4 3d Profiling. Slow and tedious with varying CV options.
« on: November 07, 2020, 01:54:24 PM »
I have used EMC2 for years and just tried Mach 4 on a light duty commercial setup that's geared up for Mach 4 only that was professionally built + configured. It's a stepper based system, Smooth Stepper board, i7 computer, and I stress tested the machine (Prime 95, etc) for hours with no issues.

My work almost always uses 10x stepover with 3 mm or 1.5mm ballmills and I cannot have significant deviation from the actual toolpath.

Regardless of which CV wizard I use or how I tweak the settings Mach 4 isn't very smooth or fast compared to the old software I generally use.

Is the trajectory planner not very ideal with many G1 moves found in raster finishing strategies?

I know this is a complex question (how the resolution is set in CAM, how CV is setup, how Mach 4 interprets the move in CV move depending on settings, etc) but compared to EMC2 or other trajectory planners is there some lacking in this particular department?

Thank you for any advice--I know CV is a complex part of Mach 4 and would like to make this work but also want to understand if this is the right package for my specific needs.



Offline smurph

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Re: Mach 4 3d Profiling. Slow and tedious with varying CV options.
« Reply #1 on: November 14, 2020, 01:57:26 AM »
First off, the CV wizard is really intended to control CV based off of angles.  It is mainly only needed for 2.5D work on machines that are about as rigid as a wet noodle and the programmer is too lazy for program realistic speeds for it.  :)  If you are doing 3D work or very granular G code, then you probably do not need the CV wizard at all.  Blow the CV section out of the Machine.ini of the profile or create another profile and don't run the CV wizard. 

Next, CV is really a misnomer, IMHO.  It is really VB (Velocity Blending).  Thus CV is wholly dependent on your motor acceleration parameters.   The higher the acceleration parameters you can use, the better CV will hold to the actual path.  So run your accel parameters up until the steppers start screaming and losing steps and then back it down.  It may just have really soft acceleration parameters even though it was professionally configured. 

And also check your look ahead buffer.  Pop it up to 200 or so from the default 20 and see if that helps. 

For me, my 3D profiling stuff is silky smooth.  But I'm using a Mach4/Galil with analog DC servos that have torque that allows for insane acceleration parameters.  And it absolutely chews through very granular G code. 

Steve