Hi fns,
yes I think it´s a flow related problem, but air flow related. Which settings are you useing for the fan? As you said without fan the structure is strong, but the edges are ugly, with fan on (100%?) the objects are brittle. So the truth lies in the middle. I think the cooling is so strong that the layers do not stick together very well. They do not melt into each other.
Did you try to print with only 50% fan speed or less? In the expert settings in Cura you will find a menu for Cooling, perhaps try 40% as fan speed min and 50% as fan speed max. I haven´t tried ABS yet, but for printing PLA with 200°C this works very good.
Hope this helps,
Philip
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After fixing some errors with my heated bed, I finally installed the cross flow fan and tested it. The setup is improvised but works for first tests.
First impression: The cross flow fan is great. I made some great prints with it. I totally like it, but my setup and settings leave room for more.
I printed out some 20mm cubes, the surface was perfect on all sides. Very fine print.
I printed out an eggcup in a round design with a slight overhang. Came out great. Best eggcup I did so far and I did a lot of them in the past.
The next test object was the maker faire robot. The one they used as test object in the latest 3D printer review of MAKE magazin. http://www.thingiverse.com/thing:40212
At the beginning the first one looked great. The legs are perfect, but when printing the first overhang, things got so so... The overhang facing the fan was very good and the ones on the side also. But the one on the backside was bad. It looked buckled.
Next try, I turned the robot 90 degrees on the build platform, with its face faceing the fan. Much better. Both arms looked very good, but the overhang on the backside, its "ass" was still buckled. This seems to be because of the lee of the model itself. The backside does not get cooled as good as the front and the sides.
All previous prints I did were with 20% fan speed. So next thing I increased the fan speed to the recommended 50%. The backside was a little better, but not yet perfect. Unfortunatedly at this speed the fan gets much louder, even a lot louder than the stepper motors.
Conclusion:
- Works good, but is still in process.
- Print quality depends on models and is also dependent on their orientation to the fan.
- Overhangs on the "backside" of models look a little messy.
Next things to do:
- Optimize the position and alignment of the fan, macbe add a duct which forms a small slit.
- Find a way to run the fan at very low RPM <30% for noise reduction, but with high print quality.
- Eliminate the problem with bad overhangs in the lee.
I got some ideas for fixing all this. Let´s see how they work.
I will add pictures tomorrow.
Markus, any news on your cross flow fan?
Regards,
Philip
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