Brief pauses mid-line - blobs and zits

Vertex 3D Printer
1

Hello all,

My k8400 pauses momentarily at various points in long lines, which often results in a blob or zit. Any thoughts as why this might be the case?

Thanks,
Trevor

2

Dear Trevor,

it would be helpful if you can provide some more information about your environment.
First of all it would be nice to know if these pauses are just stops in printing of mechanical shifts.

Assuming that your mechanics are correct then it would be interesting how you provide the print data: by SC-card or USB.

I have found in the past that a line of small segments can generate a buffer underflow, which results in a broken flow.
Is this effect evident sine a specific time or from the very beginning? Or is this an anomaly for some specific designs? How fast do you request status information (M105) from your printer? This has the chance to disturb the flow too.

So with some proper feedback on theses questions it may be possible to get a step forward.
Kind regards
hoh61

3

Hey,
Thanks so much for the detailed reply.

It doesn’t appear to be a mechanical issue, as the print has no problem resuming after these hesitations.

It only appears in complex models - most are fine, but one of the pieces that shows this kind of artifact is 1.8 million lines. I’ve been using USB and am switching to SD to see if that helps.

Best,
Trevor

4

Just wondering what slicer software are you using?

5

Wrong_Way - I’m using Cura within Vertex Repetier.

hoh61 - thank you for suggesting printing from SD. I’m doing so now and the problem is completely resolved! Looks like USB will work for less-complex models, but for more complex ones buffering does occur and is causing the brief pauses.

Thanks everyone!

6

Hello Trevor,

so my suggestion was not that wrong. Because of my own observations and activities on the firmware I tried to improve the firmware to be fully interrupt driven. This may remove your effect too. So I would like to ask you a favor and try out my version with the most critical design you have. Maybe the limit is the transfer rate itself, maybe it is the internal processing in the firmware. For the latter I think you should see any difference.
I*m personally running this firmware on my printer, so basically it works ;-).
http://ddd.k8400.hoehnemann.net/Firmware/Firmware_MarlinHOH.html

7

Thank you for the link! I’m doing a lot of printing right now, so I’m not going to get into changing the firmware right now as the effect is gone, but I might look into it after the bulk of the job is done.