Overhang help 'Chins' dont print well on parts

[Cutlass]

I often find that the "Chin" of whatever model I am printing tents to come out stringy and blobby.

I have had this happen on other models as well, and I am wondering which setting I should try to change. I suspect it is related to print speed and temperature, but I am not sure the best way to test this. I sliced this using Cura, though I have not tried this model using Slic3r yet.

The material is Prototype Supply PLA.

I really want to get this fixed since I am going to print the Big Thick Gyro Cube for my brother using this filament, and it will use half a spool, so I don't really want to have this issue on it.

Thanks in advance.

[Captain Starfish]

Try different slicers,see how you go. Or add support structures maybe.

[gestalt73]

Overhangs are tricky, because you're basically expecting the printer to print on air.

Realistically, I've been able to print overhanging features like that as long as the angle is less than 40 degrees or so from vertical. more than that, and, and you'll need to add supports. It looks like your model should be able to print without supports.

There are a number of things you could try, but probably the best suggestion is to print your perimeter loops from the inside out, whatever that setting is for your slicer of choice.

Also, I've found that using a part cooling fan helps overhangs, by allowing it to cool fast enough to not droop, or at least to droop less.

If you post the part file or url, it seems small enough that I can give it a shot to see how I do with the print.

[Cutlass]

The model was a small Low Poly Bulbasaur from Thingiverse Using Cura it took about 50 minutes to print, most of my pla prints have come out better on Cura than Slic3r because of stringing. I dont know if Cura lets you change the direction of perimeter loop printing, I know where the setting is in Slic3r but I am not sure on Cura.

I think I will try this print using Slic3r and see what happens.

Also for cooling I have the stock ones that come with the V2, so the Peek and Layer fan and their shrouds only.

[gestalt73]

Everyone has their favorite slicer. the really good printer guys use several, depending on the model.

I fought with Slic3r for months before trying out KISSlicer, and haven't looked back since.

The model is definitely printable without supports. I'll throw it on the printer right now, and see what happens.

[gestalt73]

Ok, the part turned out rather well.

Here are the settings that I used:
- 0.2mm layer height
- 2 perimeters, 25% infill
- 20mm/s perimeter, 30mm/s solid infill, 40mm/s sparse infill
- 230c temps (ABS only)
- part fan on 33% (ABS)

The overhangs rendered perfectly. This part was designed to print.

If I were doing this for a client, I'd probably slow the print speed down to 15/20/30, but overall it turned out ok as is.

[img]https://i.imgur.com/72YZc62.jpg[/img]

[Polygonhell]

Overhangs are usually all about cooling, print as cold as you can, if printing PLA, get a lot of air blowing over the part to cool it.

[Cutlass]

Thanks Gestalt for taking the time/filament to print that out in order to help me. I will try and replicate the results you got tomorrow (I am traveling today).

Out of curiosity, your print speed on perimeters is much lower than mine, I usually use about 40mm/s, do you normally print that slowly or is that the speed you use for things with overhangs.

also, have you ever gotten Kiss to have good bridging, AFAIK there is zero support for bridging.

[gestalt73]

For small parts, or parts with fine detail, I'll slow the print down to 10-20 mm/s, depending on the model.

As far as KISSlicer and bridging, I've only tried it a limited number of times, but it seems to bridge just fine.

Haven't tried anything really crazy, but no problems so far.

[Cutlass]

Thanks for the help printing this. I finally got to reprint and it cane out great. I hope this good printing continues onto the larger print I am going to do next.