Stuttering causing tiny blobs on parts

[Kill K]

I just started using S3D about 2 weeks ago and I have a Kossel Mini that is running a Rumba board with DVR 8825's. The drivers are properly tuned and I have had great prints before running slicers other than S3D. I am seeing vary tiny blobs on the outside of my parts since i started slicing with S3D. I have printed the same model with MatterControl and with S3D using settings that are as similar as i can get them and the MC print comes out with a much better finish.

After watching the printer vary carefully I found that that the Hot End was stuttering vary sightly (almost couldn't see it happen but could hear it) and leaving a tiny blob on the finish of my parts. These blobs cause a rough finish that looks awful. I have inspected the gcode its self and first found that S3D was sending Z Height and Feedrate command with each line of movement. I turned on "Sticky" Parameters in the Gcode options and this helped some but did not get rid of the stuttering. I also have compaired it to the gcode that the MatterControl output and found that S3D programs for much smaller movements.

I'm not sure what else i can do to correct or mitigate this.

Please Help

[ikaplinsky]

Hi Kill K!

I also have Delta machine and also faced such blobs issue


I have some question to you:

What kind of extruder drive do you use: bowden, right ? What is the teflon tube length? (would like to compare with mine)
What type of material do you use (plastic) ?
Have you seen S3D Print Quality Troubleshooting Guide: https://www.simplify3d.com/support/prin ... s-and-zits

How do you think your blobs happens on the begin of the line or on the end of the line ? From your message I guess on the end (not so clear for me) learn "wipe nozzle" this case.

Regards,
Igor.

[Kill K]

Igor,

The extruder type is a Bowden and the Teflon tube is approximately 350 mm long. I am using AIO PLA (that I have had good results with before). I have seen the Troubleshooting guide and found no answer to my issue. The blobs are not happening at the beginning or end of the layer but throughout.

I believe that with S3D and the way it slices it puts out twice as many points (over other slicers) for the movement of the hotend trying to make the best curve possible. This causes the 8bit processor to have to make many more calculations for movement than if the points were farther apart. Making all those calculations causes the mini pauses which in turn causes the blobs. These blobs only appear on curved surface and not on any straight ones.

It appears that I’m hitting the 8bit wall as it were. I think I will upgrade to a 32bit board, such as a Duet or Smoothie board.

Hope this helps

[ikaplinsky]

Hm, it is interesting, I also noticed that S3D generate a lot of lines. I don't know for sure, my hypothesis that it related with STL detailing (resolution) - probably other slicers can simplify a model or interpolate or group lines for simplification.. (again - I don't know for sure)
Just for check, if it possible - try to reduce STL resolution (number of polygons) of the source model. From SolidWorks I can choose resolution (detailing) before save to STL, and Meshmixer can do such simplification on source STL.
It is also pity that slicers do not generate ARC g-codes (G2/G3) like CNC

I'm using MAKERBASE SBASE board (clone of Smoothieboard) it has 32bit ARM CPU

Regards,
Igor.

[Kill K]

Ill have to try to lower the amount of polys on the STL and see what happens. Im not sure that this will help but its worth a shot.

I also think that it is a shame that it wont output G02/G03 code as this would reduce the amount of points and allow for smoother movements. The problem with this line of thinking is that and STL is nothing but polygons NO curved lines. The solid model that you make in Solidworks/any other software has curved surfaces but once the solid model has been converted to STL it becomes nothing but straight lines (polygons).

I still thing that my issue is the 8bit ATmega 2560 Rumba Board. you said that you have a MAKERBASE SBASE board (clone of Smoothieboard). Which board are you using? Are you happy with it? Would you recommend i purchase the same or differant model?

Thanks for the Help
Chris

[ikaplinsky]

Hi Chris,

Rumba board is good, from my point the benefit of this board that it has 6 stepper drivers onboard and you could use Diamond extruder with no additional hardware upgrade (like stepper driver expansion board)

Say, are you using Marlin or Repetier firmware ?
According to information from this page: http://reprap.org/wiki/G-code#G2_.26_G3 ... d_Arc_Move
Marlin doesn't have Arc support for Delta machines and Repetier has.

Previously I've used Atmega 2560 + Ramps 1.4.
Now Makerbase SBase (http://www.instructables.com/id/Configu ... er-Basics/)

Talking about firmware:
I'm moving to Smoothie (ware) because (Marlin(RichCatell)/Repetier) has no reliable calibration algorithm implemented and I have a flat issue
Now I use Smoothieware from 626Pilot and enjoy Smoothie in general and setup and calibration.

I would suggest you do not hurry with board change. Try another slicer first.
I'm interested in IceSL, investigating it currently

Regards,
Igor.