Bumpy Benchy

I have had my Tevo Tarantula for quite a few years now. It was running a version of repetier. Finally I got fed up with manual bed levelling and decide to try out BL Touch. For that I switched over to Marlin firmware because this fine person has created a fork of Marlin with Easy Config parameters in configuration.h that allow you to setup BL Touch easily among other things, and sure enough it was very easy to set it up. I was so happy to get the Auto Bed Level working.

Here is the link to his fork:
[github.com]

However I am having one issue. My benchy is not printing well. It is very bumpy. I have tried several things including different slicers, different versions of Octoprint, different ways to slice it,old gcode file that used to print great in Repetier before BL Touch install, nothing seems to make any difference. It stays bumpy.

The only suspect now I have is Marlin firmware. After looking at it closely I see that the bumps are created by the small stalls during print. It looks like either the printer is exhausting the buffer and waiting for more from Octoprint (I doubt it), or something else is interrupting and it is going out and processing it while leaving the nozzle at one place (more likely) causing a bump due to melting and oozing of filament.

I am attaching picture to show what I mean.

Hopefully one of you experts out there can help me out. The print looks very ugly and low quality.

I also tried increasing the BUFSIZE to increase the serial buffer to 16 from 4, but that didn't help either.

Just an update. I tried printing with SD card, and it prints without stalls/stutter. I tried printing straight from Cura and it again printed without stall/stutter. Looks like it is the combination of Octoprint and Marlin firmware that is causing it. Octoprint was working just fine with Repetier.

Looks like over extrusion I would try to reduce the filament flow to 95% using the LCD

This can be done using the LCD after the model has been selected.

Click > Tune > Flow : change to 95%

Edited 1 time(s). Last edit at 12/28/2020 09:16AM by Roberts_Clif.

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Computer Programmer / Electronics Technician

Thanks for the reply. I have already tried this as well, forgot to mention. I reduced it down to 90% flow rate, as well as reduced the steps/mm of extruder from 100 to 90, but that did not make any difference.

It is not over extrusion. The bumps are caused by the stalls which I can hear and see clearly. The nozzle momentarily stalls which causes the print to melt at that point, and may be some oozing is happening too, causing a bump at that point. This just keeps on happening particularly at the front curvature of the boat

Upgrading from Raspberry Pi 2 to Raspberry Pi 3 fixed the problem.

Quote
shah123
Upgrading from Raspberry Pi 2 to Raspberry Pi 3 fixed the problem.

Have always wondered about this, using OctoPrint I 3D Printed a large piece of my MPCNC the Burley while recording using OctoLapse.
When printed with SD the Burley model came out Perfect, When I Printed the next one while recording the Burley came out kind of fuzzy.

I have never purchased a Raspberry 3 or 4 to test my theory thou knew that the Raspberry 4 would be fast enough to correct the fuzzy skin.

Now just need to purchase a pair.

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Computer Programmer / Electronics Technician

Yeah, you should try upgrading to Raspberry Pi 3 or 4. Do you have Marlin? Apparently Raspberry Pi 2 doesn't have enough horse power to handle Marlin. It was fine with Repetier 1.0.3 at least, not sure how it is handling the latest Repetier either.

It has a little less power than needed when used with Octolapse timed videos any way.



I have been telling everyone which was printed with Octolapse and which was printed with SD card though you should be able to tell..

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Computer Programmer / Electronics Technician

Yeah, it is obvious. The left one is with Octalapse. Even with repetier firmware if I had the tab with video stream in Octoprint open, the printer used to start stuttering. So I used to move out of the tab immediately and printing would become normal. Basically anything compute intensive caused Raspberry Pi 2 to cause stutter. With Marlin firmware it is constant stutter regardless of whether video is streaming or not. Upgrading to Pi 3 and it can handle everything even video streaming while printing without stutter.

Thank You!

Was planning to go with the Rasberry Pi 4 2GB but hate the fact that you can only purchase one at a time, And do not know how long I have to wait before ordering another.

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Computer Programmer / Electronics Technician