Print Error on Fillets

Hey all,

I noticed my Taz 4 having issues printing the bottom of fillets and circular parts. For example if I have a cube and all the edges are filleted the fillets on the bottom edge that would touch the glass will look like crap but the fillets on top will look great. I seem to have the issue with support material turned on or off.

I have included some pictures. The three circular objects were supposed to be round, the one in the middle is the original injection molded piece. Guess I should mention that I printed these two pieces laying down as they are shown in the photo. Granted the Photo is showing upside down for some reason.
This one is the bottom that has messed up the fillet, while the top looks good. I apologize for bad picture quality, this black plastic is hard to photograph.
Bad Corner, against the glass

Good Corner, top surface

Small part fillets are one of the few areas where a Fan is a useful addition for ABS plastic. Under SLic3r its the “auto cooling for small parts” option, same cooling fan you would use for PLA. There is a fan installation guide in the Ohai kit stuff.

You also might try bumping your extrusion temperature up or down a bit. Down would possibly make the plastic droop less, but lower your layer adhesion. Up would possibly increase the droop, but it might make it better by allowing that layer to bond easier with the preceding layer.

You also may want to download some of the bridging test print objects and calibrate until those print great. It’s basically the same cause.

Piecret, Thanks for the reply.

I realized that I missed some important information.
Material: Black ABS
Fan: Not running through the whole print
Bed Temp: 76
Extuder Temp: 235
Running Cura for Lulzbot with the Lulzbot profile for Fine Abs (adjusted for nozzle change)

So you are thinking that I should up the extruder temp to 240 and reprint? and then down to 230 to see if it makes a difference?

I can post the gcode for the part if you want to see it.

Thanks for your help.

I would try both 240 and 230 and see if either of those help out. I’d be happy to take a look at the STL if you like.

Here is my gcode and STL with he part laying on its side.
Now I realize that I can stand this part on end and print it standing up and the fillet issue goes away, but I feel you are trading the strength of the part by printing it standing. With the pin placed in shear I’m afraid it will break at one of the print layers. If its printed horizontal it makes it a little stronger I think. Discussing for another day.
sideways.gcode (785 KB)
sideways.stl (987 KB)

From the Gcode, your infill is probably set too low to successfully print that part. Try something closer to %80-90%. Thats also a very small part to try and 3d print. You have to have a super well dialed in printer to get really good quality out of something like that. From the way the Gode is set now, you should have major voids inside the part. If you don’t you might also be overextruding relitive to what your settings are at.

You are correct on the part strength and direction issue. Longer strands of plastic are usually going to be stronger. Adhesion also plays a major role in strength too. Getting closer to 240 makes for a stronger ABS part usually, but also gets you closer to the failure point of the nozzle liner on a buddashnozzle.

Good catch on the infill I quickly made a demo part for you. I had printed this part earlier in the week with several variations on the position. I knew laying it on the side would cause the issue I was asking about so I just dropped a single instance of the part in Cura and saved it. When I printed them earlier I had 100% infill. I just printed one at 230 and the 240 temp is finishing up. Even with the 25% density the part printed but I still see the same issue. I’ll take some more pics once the 240 temp piece finishes comparing the two.

I don’t think I’m over extruding. I dialed in my esteps a few months ago and have been able to get some of these electrical connectors printed with out any issue that have a 0.25mm thick wall. (Granted its measuring out a 0.65mm but that’s the bed side so it has a little bit of an elephants foot)

Ok that makes sense. The only reason I mentioned overextrusion was if those parts had been printed with that low of an infi, they didn’t look it heh.

I’m thinking your best bet is going to be adding a cooling fan. It’s going to be useless for printing anything else in ABS, but for a small part like that it might be the only way to get a crisp line on that fillet. You might also try increasing your belt tension a little. hte parts look good and well in round, etc. but at that small of a scale, even a little belt slop might let the nozzle wobble enough.

I’m just a little concerned about running with the fan. I’ve had nothing but issues with the fan and my prints. Whenever I run the fan my parts always warp and crack. Maybe I’m running to much fan speed and cooling it to much.

Can you make some recommendations on fan setup?

Well the Temp change didn’t seem to affect to much.

It looks to me that the supports failed which caused the print error. I can see where it started building them on the first few layers and then stopped.

Thanks for the suggestion for the fan. IT made a huge difference.

Any thoughts on getting that last little bit perfect?

I have drawn in the axis of how the print was oriented when printing. Y is going Left to Right and X is going in and out.
Just feeling the belts the Y axis feels the tightest.
Printed with CURA lulzbot with a cool time of 20sec and the fan enabled.

The bottom section looks like it is probably curling upwards at the edge perimiter of the part just a tiny bit on each layer. You might try increasing the temperature a little with the cooling fan active to see if you get a bit better contact. You may also want to slice the layers much thinner, which will increase print time alot, but improve final quality.

You might also experement with position on the bed. Rotate it 90 degrees and see if that makes a difference. At that small a scale you may be getting air currents from the controller box on the one side. Also try moving it towards the right edge of the bed and see if that has an effect.

Edit: another thing to try is print 2 of them at once so the part has longer to cool between layers.

By increasing the time between layers won’t that make the part weaker?

If I am using a fan can I exceed the 240 extruder temp?

Layer height was 0.16mm

It shouldnt. And you will need a different hotel to exceed 240. Try a .01mm layer height.

Finally able to get back on this.

Piercet, did you really mean a 0.01mm layer height? or just a 0.1 since I was at 0.16mm?