Can't print small concentric cylinders

[BlackJack 0]

Hi all,

So happy to be here with you guys. I can't manage to solve the issue presented in the pictures attached. It seems that in the parts surrounding screw holes with axis parallel to the Z one it makes some mess... Sometimes it neither extrudes, like in the case of the mosfet holder.

Those are my settings with a BQ Red PLA with a 0.4 mm Nozzle:

 

Layer Height: 0.2mm

Initial Layer Height: 0.3mm

Line Width: 0.45mm

Initial Layer Line Width: 120%

 

Wall line count: 3

Top layers: 3

Bottom Layers: 3

 

Infill Density: 70%

Infill Pattern: Grid

Gradual Infill Steps: 0

 

Printing Temperature: 210°C

Build Plate Temperature: 60°C

Diameter: 1.73mm

Flow: 72% (Calculated with thin wall test on a 20x20 Cube)

Enable Retraction: Yes

 

Print Speed: 45mm/s

Travel Speed: 70mm/s

 

Enable Print Cooling: Yes

 

Generate Support: Yes

Support Placement: Touching Build Plate

 

Build Plate Adhesion Type: Brim

Brim Line Count: 4

 

Print Sequence: All at once.

 

Any of you already had this problem? Did you managed to solve it?

What can I do?

 

Never had this problem using Slic3r, but I like using Cura because of its settings.

 

Thank you all guys.

 

[gr5 2,224]

Line width 0.45 on a .4 nozzle is not a good idea.  This is probably most of the problem.  Maybe.  Except then you have flow at 72%.  I have 5 printers and have been printing for years and never needed to set flow lower than 100%.  Even when printing tiny fonts.  So something is messed up where you think you need flow at 72%.

 

I would try 0.35 instead of 0.45.  

Set flow back to 100% - it should work - maybe you need to calibrate your extruder (move it 100mm and measure with ruler to see if it actually moves 128mm like your 72% flow seems to indicate).

 

You have infill at 70mm/sec and at 70% infill.  I assume the 70 is to save time.  MUCH better to save time by dropping infill to 30%.  Infill doesn't strengthen the part as much as adding extra walls/shells.  The strength improvement between 30% versus 70% is probably too small to measure.  Probably about 1% weaker so the tiniest vibration will make the difference in if the part flexes too much or breaks too easily.  So try 20% to 30% infill and lower the speed to your shell speed (45) to get good parts before creeping the infill speed back up towards 70 again.  Every time you speed up for the infill you will get underextrusion for a few cm and every time you slow down you will get overextrusion hurting the quality.

 

Anyway that's it - I think the true issue is the 0.45 line width.  I hope it's that simple.  Or the 0.45 line width combined with 0.2 layer height and 70mm/sec which when multiplied together you get a flow volume of 6 mm^3/sec which I've done on all my UM printers but that's really pushing the capability of most feeders.  Slowing down to 45mm/sec (or thinner layer height) would help a lot.

 

If you are printing tons of these and trying to save time look into the gradual infill feature which saves time and experiment a lot with speed and temperature (you can print much faster at higher temps but quality goes down).

 

Oh - and seriously consider a 0.6mm nozzle - prints twice as fast and corners are only slightly rounder - most dimensions are going to be spot on.