Layer Adhesion - Overflow Comb

[Kermit65 0]

Hi There

I engineer, produce and sell 3D printed parts for aquarists and fish breeders. Check-out my website if you are interested: https://www.fishgimmicks.com. I am currently working on an overflow comb used by aquarists to separate compartments of a tank. The idea is that my customers can order tailor-made overflow combs in different sizes, different mesh and even have a slogan or their name printed on it.

As you can see from the pictures, the area where the solid part meets the mesh is not solid and is too easily falling apart. Any ideas how I can change the design to avoid the issue respectively the slicing parameters or settings of the printer?

Object is designed with OpenCAD. I sliced it flat using Cura with the following settings:

Layer thickness: 0.1mm

shell thickness= 1.6mm

infill=100%

speed=50mm/s

I printed with ProFill PLA at 210 Degree Celsius.

You help or ideas are much appreciated!

Regards

Andreas

Edited November 16, 2015 by Guest

[gr5 2,265]

I can see that cura is putting a shell around the outside of the bottom piece. This means Cura thinks these are 2 different pieces.

OpenCAD or openSCAD?

Anyway you need to make this into one piece somehow - delete all the walls that seperate the lower part from the upper part. This is a CAD issue.

Alternatively you could try "fix horrible A" or "fix horrible B" in expert settings - look at it in slice view and make sure Cura is not putting a shell pass (red line) separating the lower portion from the upper portin.

[Kermit65 0]

Thank you very much for your response.

I checked in Cura and the object does not consist of multiple parts. After increasing the infill overlap to 20% print got better, but still weak between the bottom part and the upper part. What is a good recommended value for the infill overlap?

Regards

Andreas

[Labern 775]

What is the width of the combs?

If you nozzle is 0.4mm and the width of the comb is 1mm then you may have a problem. You can see that the combs are not joined together and not joined to the base. I wouldn't have thought it would effect the joining to the base but there might be some issue there.

If you don't have the Olsson block to select the correct nozzle which is a multiple of the comb width then you can Either change the model so it is, or manipulate the nozzle size a bit in cura. A 0.4mm nozzle can be set to 0.3 or 0.5 in cura and still work just fine, but better yet. Get an Olsson block.

[gr5 2,265]

I agree. I was wrong. It's all one part. I can see that especially the red path in the photo.

15% overlap should be plenty.

If this was a UMO I would immediately suspect your belts are loose - look at the X and Y belts anyway. ALL 6 BELTS! Not just the 4 long belts but the 2 short ones also.

But more likely this is not a backlash issue but instead an underextrusion issue. Try lowering the speed and increasing the nozzle temp. At that temp of 210C your bottom layer thickness of .3mm is too much for the extruder. Slow the printer down to 20mm/sec for that bottom layer and then you can go back to 50mm/sec for the rest. Also I hope your bed is at 60C - this will help with flow on the bottom layer.

You might need to also adjust your leveling - the bottom layer traces should be flattened somewhat like a pancake and not round like string. DO NOT run the leveling procedure as you are already almost perfect - just twist the 3 knobs the same amount if the bottom traces are flat enough.

[Kermit65 0]

Thank you for your great input. Btw I use the Olssen Block (Great!) with the 0.4mm nozzle and the Alternate UM2 Feeder from iRobertl (Superb!).

How can I change nozzle size and per-layer-speed in Cura?

Regards

Andreas

[gr5 2,265]

I don't recommend going with a smaller nozzle. It turns out your .4mm is a good size for this part. It's in the second tab, "advanced" but doesn't do anything if you don't also make the shell width a multiple of the new nozzle size.

Instead you could just up the flow rate to 130%. you can play with that *while* it's printing to see the effect. Note that because the bottom layer is 3X thicker than the other layers the affect will be different on the bottom layer versus the other layers.

You can set the bottom layer speed different but I would just slow it down in the TUNE menu from the prniter itself and watch for a difference. While you are debugging these things. Just set feedrate or speed or whatever it's called to about 30% and see if it helps (there is a delay of about 20 line segments). Then try other speeds and watch carefully. Maybe take notes. Same thing goes for adjusting the 3 leveling screws or adjusting flow rate.