Vertical Banding

[jimustanguitar]

So Glenn has his horizontal banding... I've got vertical banding. Trying a new glossier filament really makes it stand out. 




The SeeMe guys had a nice long discussion about it last year: forum.seemecnc.com/viewtopic.php?f=54&t=4203&
And the conclusion was that all CNC machines do it because of how stepper motors step. Machines that aren't built out of iron tend to transfer those vibrations into the work. More steps, higher processing power (enabling more segments per move), etc seemed to help slightly. 

Another thread blames this on out of balance cooling fans. forum.seemecnc.com/viewtopic.php?f=35&t=5538&p=41200&
I'm not sure that I buy that one, but it sounds like it helped a few people. 


What's odd to me is that the cartesian guys say it's happening to them too. Anybody here noticed it on a square machine? 

[ZionPhil]

Start messing around with your speed multiplier and see if it makes a difference.

[BeeAmaker]

I agree with Phil. I haven;'t taken the time to run test yet but something Graber said at one of the meetings got me thinking. Before I rebuilt my machine I was printing at around 50 to 55 on my speed. After I rebuilt I slowed it down to 30 and 35, got better prints but that's when the bands appeared.

I talked a little bit to Brian and we are thinking that because of the math certain speeds might have odd results. Kind of like driving on an unbalanced tire. 60mph might be fine but 61mph shakes the heck out of your car. But like I said, I haven't run any test yet.

[jimustanguitar]

Change my sliced speed, or change my multiplier on the same GCode?

Interesting idea. I'll try to test them both!

[ZionPhil]

Easiest thing to do is turn dial up on the Rambo under the speed section.

[jimustanguitar]

Sliced at 40mm/s. The 4 stripes are 100%, 150, 200, and 250 - so that turns into 40, 60, 80, and 100 mm/s.

One thing that I noticed as I ran the print was that my hot-end wasn't keeping up, so I'll have to re-tune my PID's to print faster and faster. I think that's part of why it's a more matte finish the further right you go. 

[BeeAmaker]

You may need to be hotter the faster you print and you will reach a point that you just can't force that much plastic threw a .3 or .5mm nozzle.

[bvandiepenbos]

I have found that adjusting speed at LCD does not have same results as changing your sliced speed.
Probably best to test this by adjusting speeds of slice and leave LCD at 100% for all.

[jimustanguitar]

Here's a printrbot discussion on the same thing.

www.printrbottalk.com/forum/viewtopic.php?f=15&t=5721

[jimustanguitar]

So what if this banding is the result of pulsed extrusion? The extruder does one 1 move per line of GCode, with a lot of little tiny pauses between each instruction... Could it be that simple?

Maybe changing the microstepping on the extruder or switching to 0.9 degree motors on the extruder would show a change in this behavior?