Corners collapsing on a thin feature

Hi Guys,

I wondered if I can pick your brains. I have installed a new extruder with 0.4mm nozzle to my printer. I am trying to print a single wall box out of ABS. I got to the point where it prints the box but the corners seem to collapse (you can see ont he photo that these are pretty much missing)

At the moment the settings are as follows
temp extruder: 245C first layer/ 235 thereafter
temp bed: 115 first layer/110 after
print speed 8mm/s firs layer/ 16mm/s for perimeters later
layer height 0.3mm

It almost looks like it is stopping and starting in the corner. Hope you can help here.

Kind regards

Pawel

4 things i can think of would be:

1. To low speed, so nozzle pressure get close to zero. Try tp up your speed. (I print 30mm/s first layer and 70mm/s for the rest on a Mendel90)
2. To much play (backlash) in your extruder gears, so you get a delay.
3. To high firmware acceleration, my xy acceleration is 1500 and 3000 for non printing moves. To high acceleration, can stretch you filament path when getting up to speed.
4. 0.3 layer height is a bit to much with a 0.4 nozzle (but that's only a bondig problem), try 0.25 or lower.

Hope it help you

Jesper

Edited 1 time(s). Last edit at 12/12/2013 02:50AM by Kenzu.

Many thanks Jesper,

I have actually lowered the speed significantly as Ithought that was the problem initially. Extruder gears worked well with different nozzle so I guess it is not the problem. I will play with the accelleration and will let you know whether that helped or not.

Many thanks

Pawel