Wednesday, November 30, 2011

Mach3 RepRap stuttering and STL file quality

It's been a while..

Changing the extrusion nozzle from 0.5mm to 0.35mm had induced a rapid stuttering while printing.  This is usually a good indication that the queue depth isn't getting a chance to build up and languishes around 0 records deep.  A look at the diagnostics screen confirmed this.

When and how Mach3 starts building up the motion queue isn't very clear.  System resources aren't an issue, no more than 30% processor utilization and 512+ MB RAM available.  This is all conjecture but, Mach3 shouldn't be having a problem crunching numbers, or there is something bottle necking the process within the program.

Adjusted the base frequency from 100kHz to 65kHz, no improvement.

Turned off CV mode, stuttering still present and prints looked worse.

The stuttering always started during a radius-ed motion and would stop shortly after it reached a section of long linear moves.  The STL file was Skeinforge'ed using the 0.5mm nozzle diameter and compared to the 0.35 and the 0.5mm code was 1/10th the file size.  Upon further investigation the 0.35mm code generated many many more little vectors for the circular motions.

If Mach3 can't process the data, and it can't be limited in Skeinforge, then the only option to address it is in the STL generation.  Changing anything from a circle to a polygon in SW isn't an option. References are lost or non existent and it really impedes work flow.

Do the usual Save as.... .STL but this time clicked the advanced button and changed the resolution from fine to course via the radio buttons.  Skein the new STL and the file size has been significantly reduced.  Good sign.  Let Mach3 do it's thing and things start buzzing along with queue depth hovering between 1000 and 800.  The coarse STL output made no appreciable difference in the circular motions and resolved the stuttering.  Overall improvement on print quality.