mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Heavy Lines Banding - Correspond to Detail and Supports?

Tue Jul 21, 2015 5:22 pm

I am using a Dremel re-branded Dreamer with Simplify 3d. After working well for a while it has recently developed a variety of issues, one of them being heavy lines that occur and various heights. What is interesting is on the latest part I have prominent lines in the EXACT SAME HEIGHT for two runs in a row. Printing at 0.10mm layer height, same as always. Same printer and spool of filament gave me beautiful prints of similar size and detail just a couple of weeks ago. I will need to double check for extruder temp variation. Room is not nearby any vents or fans.

What is interesting is how the pair of models using two different brands of PLA in my orig post show lines at the exact same spots. I would assume this might rule out filament diameter variation. Also if you look closely at this latest print you can see the first 30mm or so is very clean and the lines start to appear when it reaches more detailed areas of the model and more height.

Here are some interesting photos comparing two prints, one with supports and one without (I manually reduced overhangs in zbrush for the no supports version). What caught my eye is that the print without supports has far fewer layer line issues and the lines that appear in the print with supports often correspond to shifts or changes in the support pillars. Also of interest is the few lines that do appear in the non-support print correspond to sharp detail in the outer surface of the model. For example the heaviest one near the base lines up exactly to my signature engraved in the back but it wraps all the way around the perimeter.
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mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Re: Heavy Lines Banding - Correspond to Detail and Supports?

Tue Jul 21, 2015 5:25 pm

More pics...
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image.jpg (30.6 KiB) Viewed 2813 times

aesdaile
Posts: 2
Joined: Wed Jul 01, 2015 12:34 am

Re: Heavy Lines Banding - Correspond to Detail and Supports?

Thu Jul 23, 2015 11:43 pm

I'm have noticed the same thing on my prints, but I think the reason isn't really related to the software.

I think it's the hardware - the print gantry - resonating. My printer is a FlashForge Creator Pro, and I see the same lines, which look like sinusoidal vibrations wherever I use supports. I think it occurs after the rapid back-and-forth motion the printer takes while printing the supports causing the the entire gantry to shake.

The other possible cause is that the nozzle slightly 'clips' the support which just bumps it enough to get the same resonance.

I've been reading up on how to solve it - it's not easy as there are LOTS of causes and effects all interacting here.

Things I am looking at trying:
Slower printing
Writing pauses into the GCODE after the supports to wait for gantry to settle
Print off-axis (skew objects on build plate) so that both axes are moving instead of only a single one

I'm not too keen on diving into the hardware-based fixes just yet as there is only so much money in my bank account for such things!

mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Re: Heavy Lines Banding - Correspond to Detail and Supports?

Fri Jul 24, 2015 7:03 pm

Aesdaile,

Your theories are probably right on target. What I'm not sure about are the defined horizontal lines that extent all the way around the perimeter which even happen with no supports but at a height that corresponds to a small detail on the back side (my initials). These are very straight and seem different than the usual ringing or vibrational artifacts which look more like waves or moire.

I'm already printing very slow (15-20mm/s) so not sure I can go much lower without my prints taking days :)

KC_703
Posts: 238
Joined: Tue Aug 26, 2014 5:23 pm

Re: Heavy Lines Banding - Correspond to Detail and Supports?

Fri Jul 24, 2015 9:58 pm

Check that all the belts and screws on the toolhead are tight... as with all things, vibrations loosens things.

Joules
Posts: 9
Joined: Wed Jul 01, 2015 3:34 pm

Re: Heavy Lines Banding - Correspond to Detail and Supports?

Sat Jul 25, 2015 5:55 am

I wonder what these would look like printed on a delta machine. In theory this is where they excel having all three arms driven at all times. A delta also has its motion forces running in Z rather than a gantry bot's X,Y.

Holy1
Posts: 21
Joined: Mon Jul 28, 2014 12:01 pm

Re: Heavy Lines Banding - Correspond to Detail and Supports?

Sat Jul 25, 2015 9:59 pm

A delta will do it too. I have both a delta and Cartesian . The delta can have a whole host of problems.

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