vertical lines on my prints

My prints are generally getting better.
Nice sharp edges. Holes nice and round.

But what causes these vertical lines and what can I do about it to smooth out the vertical surfaces?



I have gt2 belts and z screw steadies.

Thanks
Gordon

Safe to assume you have a direct drive [motor on the carriage] motor on linear rails [8mm?].
Direct drives have a lot* of weight for the speeds and accuracy they demand. They don't like to turn corners all that well and with all that weight on a bouncy suspension [linear rails really aren't suited for 3D printing unless oversize/mounted along the entire rail to something stiff] causes vibrations after each hard corner.
Typically you can turn acceleration down, most start at 9000m/s² but I've had to go down to 2500mm/s² on my badly designed Solidoodle 3.
Harder/costing but more effective solution is to go bowden.

---

Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Yeah - I had the same thing, but not so bad. It's definitely due to acceleration being too high. The head doesn't really "turn a corner" because the X and Y motions are realized with different mechanisms, but when the X or Y axis comes to a stop, there might be some shaking. It all depends on the mass of the carriage and the speed of acceleration. Slow it down and you should see improvements. Dont slow down speed - at least not right away. Slow down acceleration

Edited 1 time(s). Last edit at 09/16/2014 02:19PM by jbernardis.

Yes the motor is on the carriage.
I haven't touched acceleration yet.
I'll give that a go.
The angle and light make it very pronounced.
I've just noticed as I'm printing spares, that the nuts on the z axis screws have a bit of slop
in the hex profile as they slip into the x ends. This must create a lot of backlash.
I'm going to have a go packing it out or gluing them in place.

Gordon

These are my settings in marlin.
So I'll start on reducing the x and y values from 9000 first.
I'll use the thinwall test as its quick and the lines are pronounced.

#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 25} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000}
#define DEFAULT_ACCELERATION 3000
#define DEFAULT_RETRACT_ACCELERATION 3000

#define DEFAULT_XYJERK 20.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 5.0 // (mm/sec)

Tried changing acceleration absalutely no improvement.
The lines looked the same even down to 3000.
No variation in the frequency of lines at all.

I tried the thinwall test and guess what, no vertical lines,

Today I noticed that the lines matched pretty much the infill pattern as id printed something at 15% infill. Id been printing most things at 40 - 50% up till then. But the vertical lines matched the infill patern.
Most obvious around holes as the infill pattern changed to accomodate them. You can see this in the picture in my first post.

So I reduced the infill overlap in cura to 7.5% from 15% and it looked better.
Less pronounced lines.
I've got it at 5% now and I can't see them.
I think i may be over extruding a little as well so i may adjust that and keep an eye on the infill overlap in case i need to increase it a touch with decreasing the extrusion.

The print looks much better now.
Thanks for the help.

Gordon