Banding at regular intervals?

[mitchfx]

My most recent print on my Dremel (aka Flashforge Dreamer) exhibits some very prominent banding at almost exactly 7mm intervals which began about 25% up into a 5" tall print. It is much more noticeable on one side which happens to be the one nearest the end of each layer path. I had printed the same model the previous day at slightly faster speeds and didn't get these artifacts. The slower outer shell speed did reduce the ringing I was seeing in the previous print but now I have these bands which are even more annoying. Here's a photo of what I'm seeing.

Any ideas on what causes this? I've printed over 30 models on this printer and never seen this issue before now. One thing that is strange is how each band has a little raised "belt" that also seems fairly regular.

[jimmybuckets]

Could be the way you are feeding your filament. Could be a loose extruder as well.

[DarthRevan]

You may want to tune your hotend.

if you measure and mark the ends of 50mm of filament does extruding 50mm bring you exactly to that mark on the filament?

[mitchfx]

My filament is feeding from above using a wall mounted Hatchbox spool holder, rotated so filament is coming over TOP. This isn't my photo but an example of a very setup.



I used to have it feeding in through the side of the enclosure through one of the opening where I removed one of the side vent panels. I was concerned about that configuration possibly producing too much resistance so I switched to my current setup (which was suggested to my by Nick at Push Plastics who also has a Dreamer). I really need to buy some cradle style holders with ball bearings and put those on a custom shelf above.

if you measure and mark the ends of 50mm of filament does extruding 50mm bring you exactly to that mark on the filament?

How does one go about doing a controlled extrusion of exactly 50mm of filament?

Thanks,
Mitch

[jimmybuckets]

You can use the 100mm feed in the control panel. I don't think that's your problem though. Probably something mechanical.

[mitchfx]

You can use the 100mm feed in the control panel. I don't think that's your problem though. Probably something mechanical.

Ah, yeah...gotta move it over next to my computer to try this tonight. I've been printing stand-alone via SD card.

What's interesting is the prints both before (same model) and after (different model) the one pictured don't exhibit the banding issue. However the problem print was the only one I used 30% outline underspeed. The others used 50%. My base speed is 60mm/sec.

[KC_703]

Any chance you have a solid infill layer setup at specific intervals?

[mitchfx]

Any chance you have a solid infill layer setup at specific intervals?

No, not intentionally but that is an interesting theory. I will double check my factory file when I get home.

[jimmybuckets]

I would see if your extruder is on tight.

[jimc]

unless you see it in the gcode preview which i doubt then its most certainly a mechanical issue somewhere.