CURA 3.4.1 Profile definition problem? (SOLVED)

I have both CURA and Simplify3D and go back and forth between them depending upon my projects. I recently completed a new delta machine of my own design and have run into a problem.

My Simplify3D profile works just fine, but I tried to create a profile in CURA that mimics these settings and it is a miserable failure. This is the first time I have had absolute failure in this process, but it is also the first time that I have tried to mimic profiles between the two programs too. I have attached a picture of the two results, the left is S3D, the right is my customized CURA 3.4.1 profile.

This problem is obvious. But not the cause...

Clearly I am under-extruding in CURA, filament grinding makes me think that I am under temperature as well, but I am not. It could be CURA is trying to push filament too fast, but why? Both programs are set to the same speeds (so far as I can tell) and same temperatures. I am missing some nuance.

Is my "micromanagement" of the CURA settings the cause of this? I don't use the CURA stock settings ever since I typically use delta printers, and eSun PLA, for instance, likes 225C, not 200C (stock CURA PLA settings). What settings have I obviously run afoul of?

Edited 1 time(s). Last edit at 08/30/2018 04:32PM by dlc60.

Update:

No idea about acceleration and jerk. It is nothing that I have ever fiddled with in CURA before and I'll need to read up on just what it does.

Yes, the filament is 1.75mm in both S3D and CURA settings.

HOWEVER

I found something that is starting me on the way to a fix. This printer has a VERY effective part fan ducting system. I dropped the starting fan speed in CURA to 40%, with a maximum of 60%. This eliminated the filament starvation, but I still had some rough spots in the beginning. I then SLOWED the first layer down to about 6mm/s and this cleared up the initial roughness at the plate.

The attached print is of the beloved "Benchy" calibration print. We start out well, end out well and go whack in the middle. So, that is a puzzle. I am running an S3D Benchy on this printer to see if the problem may be mechanical (one of the linear rails has a rattle to it that I don't like).



FYI,

DLC



can you attach your current cura pofile, so can have a butchers.

Quote
obewan
can you attach your current cura pofile, so can have a butchers.

Where do I find the CURA profiles on a Windows box? I am sure I can find them if I search, but if you already know...

Thanks,
DLC

In cura, open settings/profile/manage profiles select your profile and export too file.

Quote
obewan
In cura, open settings/profile/manage profiles select your profile and export too file.

Thanks! I didn't know that step.

DLC

The solution appears to be obvious now.
As I noted above, when I turned down the part fan, I got better media flow and it stopped under-extruding. But I am getting a rough spot in the middle of the print. I just did a Simplify3D print of the same part, filament, settings and speeds as CURA (as much as I can match these). That print was also messed up in the exact same place.
SO...
It looks like the fan is my issue in CURA. It also looks like I have a mechanical stutter in my linear rails, or something else in the drive train of my delta. I don't think that the issue lies with my "Itty Bitty Belted" extruder since the problem occurs at a specific time in the print that is clearly based upon height. Maybe something is binding up, or a "flat spot" in my GT2 belts or pulleys. I will do a complete tear-down and check all those parts. I have had issues with these rails before - It may be time to get another set if I can't clean them out to fix them (or whichever one it is).

Thanks for your help everyone,
DLC

Edited 1 time(s). Last edit at 08/30/2018 04:31PM by dlc60.

Are you using steel core belts? How big are the pulleys?

I have seen people report weird behavior when the steel cables inside the belt break due to excessive flexing on too small pulleys. The belt is then free to stretch and cause all sorts of odd print defects.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
Are you using steel core belts? How big are the pulleys?

I have seen people report weird behavior when the steel cables inside the belt break due to excessive flexing on too small pulleys. The belt is then free to stretch and cause all sorts of odd print defects.

I had a kit come with those belts - Bletch! They ran rough, I replaced them with the typical ones. I am schooled to those things and how they can't be used with our small printers.
I am working through my mechanics and have rebuilt one linear bearing. I hear pretty bad noises from one more bearing that I will rebuild. My print got 50% better with the first bearing rebuild, I am hoping that the second one will fix the system up.

Thanks,
DLC

Quote
dlc60

Quote
the_digital_dentist
Are you using steel core belts? How big are the pulleys?

I have seen people report weird behavior when the steel cables inside the belt break due to excessive flexing on too small pulleys. The belt is then free to stretch and cause all sorts of odd print defects.

I had a kit come with those belts - Bletch! They ran rough, I replaced them with the typical ones. I am schooled to those things and how they can't be used with our small printers.
I am working through my mechanics and have rebuilt one linear bearing. I hear pretty bad noises from one more bearing that I will rebuild. My print got 50% better with the first bearing rebuild, I am hoping that the second one will fix the system up.

Thanks,
DLC

Well, I rebuilt my troublesome linear rail bearings. Same problem. Replaced my belts Same problem. I actually FOUND problems with both of these, but replacing them has not gotten my mechanical problem solved. The same junk happens in the same place of the print every time, no variation, no change in behavior after each thing that I replaced or repaired.
It can't be the steppers, the problem would manifest everywhere.
It can't be the sprockets, same thing as above.
Electronics seems a non-starter since the system "recovers" to finish the print perfectly. Leaving only the bad part in the middle of the print.
This delta worked great when I had the E3Dv6 3mm hotend in it. I recently pulled that and replaced it with a 1.75mm E3Dv6 (and new bowden tube). I am using the same extruder, except for the feeder which is not for 1.75mm instead of the larger filament. Not one other thing changed. I tweaked the marlin firmware for the 3mm head, and use the same settings, except for the extruder, which needed a slight tweak.
So, pretty much everything is the same. But this problem.

So, if anyone has other ideas, I am all ears. I am going to try a slower print speed to experiment with accel and jerk options...

EDIT: I am moving this to its own thread.

thanks,
DLC

Edited 1 time(s). Last edit at 09/02/2018 08:42AM by dlc60.