3d printed columns are printing really bad (Prusa i3 - not ultimaker)

[MOTIVECODEX 0]

Hello, I've made a custom 3d printer from scratch, based on the prusa i3. I managed to calibrate everything as far printed walls are looking nice. I have two major problems with my printer.

Problem 1

One is that columns are printed terrible. Some are printed decent, others are printed like some hamster chewed on it. They have spiral effects. I can't describe it in words so I'll upload some images;

I can't find lots of information about my problem, but Maker's Muse from Youtube had similar spiral artifacts on prints using Cura and Simpify3D.

I'd really like to fix this...

Problem 2

Another problem is that my extruder motor (bowden setup) is making clicking noise and skips. When I hear the skipping / clicking noise, I look at the gear on the motor and it stops turning and then continues to turn. It doesn't grind into the filament. This happens mostly only when printing the walls of the design when it prints faster than the infill.

- The screw holding the gear on the motor is tight and not moving

- The motor isn't even warm, let alone hot

- The driver isn't even warm, let alone hot (also using a fan on the board to keep it cold)

- Driver is the red pololu a4988, for the extruder the volt is set to 1.2v

Printer slicer

Cura 15.04.4

Print settings

- Layer height mm: 0.2

- Shell thickness mm: 1

- Enable retraction: speed 30mm/s, distance mm 2

- Bottom / top thickness mm: 1

- Fill density: 20

- Print speed mm/s: 25

- Travel speed mm/s: 60

- Bottom layer speed mm/s: 25

- Infill speed mm/s: 10

- Other speeds: same as print speed.

- Printing temp C: 260 (I only get good prints and sticking layers when printing at this temp. Any lower it gets worse

- Bed temp C: 110

- Platform adhesion type: raft

- Filament dia mm: 2.9 (fila is 3mm, but I measure 2.9 all across with a caliper)

- Flow: anywhere from 90 to 120

- Nozzle dia mm:  0.5

Printer setup

- Inductive sensors for bed leveling, auto bed level before every print

- Paper fits between nozzle and bed

- 12v 30A power supply

- Sanguinololu 1.3a

- red pololu a4988 (dvr8825 coming within a week)

- Printer covered in heat chamber

- Using ABS 3mm (which is 2.9mm)

- Latest marlin

- Nema 17 motors

Hope someone can help me out, the printer is making me nuts and I do not have 2k to spend on a nice Ultimaker 2 as a student.

Thanks!

Edited March 6, 2016 by Guest

[gr5 1,370]

ABS has a temperature/density relationship such that it is less viscous at higher temperatures (like honey) and more dense at lower temperatures (like toothpaste).

260C is quite hot and dangerous in the sense that you can bake ABS into a gummy substance that will clog your nozzle so don't leave the nozzle that hot unless you are printing.

You should get better layer adhesion if you print with no fans or if you enclose the printer and then you can go to lower temperatuers but this is not what you are complaining about so let's leave it there.

I dont' know what is causing the "spirals posts" issue other than it's clearly underextrusion and you can get that spiral shape because the filament barely sticking out of the tube gets drawn out by the layer below so you get just a drop but it spirals around as each layer above it comes out further aroudn the spiral. Anyway this is severe underextrusion (getting only 50% or 25% of the filament you need to come out). But why only on the posts? I don't know. something about when it retracts and moves over to the posts - it must be leaking a bit and then there isn't enough filament to continue? Maybe increase your retraction distance to 3mm? I'm not a prusa expert. Don't have one. Maybe increase your travel speed? Try 300mm/sec for travel (non printing) speed so it leaks less on the way over there? Maybe you didn't slice those posts solid enough?

Did you set cura nozzle width to 0.5mm? If not that might explain your issue but I doubt it.

I have no suggestions for problem #2. Aren't there prusa forums somewhere?