How to Use a New FFF at a Specified Layer

[Marshall]

Hi Guys,

My last print almost went well except a small error at the tip, so yet another question now comes up. (Using Makergear M2, MG BLK ABS 1.75mm)

My parts are typically printing great, all the way until the extruder has to work on very small layers tapering to a point, that is. I haven't actually had a part with this type of feature come up until now. In my last thread, for example I was printing a replica rifle round. The bullet is fine, except the last 3-4mm at the tip, it looks like a swirly ice-cream cone. Photo is below. I am using 0.160mm layer height which is "my standard" for fine detail.

I'm thinking that I need to set the travel speed higher where this localized heating begins happening, since it is staying in the same area too long it would appear, and melting the detail away. I was thinking at layer #245, right below where this problem begins, change to an FFF setting with 2 or 3x the printing speed to finish the part.

Also, check out the photo of my layer start points. The retract and extra start distance. I had bumped retract up to 3.00mm. I believe the retract is causing this dent along that line. Would 2.20mm retract be more appropriate a setting, or could this have to do with extra restart distance more so? Attached FFF.

Suggestions?

Part rendering:


Finished tip:


Retract and Extra Restart Distance line (set at 3.00mm and 0.05mm, also the retract lift is set at 0.10mm):

[scobo]

You need to slow the speed down to allow small/thin parts to cool between each layer.
Take a look at the cooling tab in settings, you should be able to configure that to do this for you.
I would also recommend a layer fan.
Re the dent, not sure about that one. My retract is set to 2mm

[jimc]

it doesnt even matter how much you slow this print down you will never print that bullet to a sharp tip like that by itself. the layer needs cooling time. this will need to be printed with something else. either print 10-15 bullets at a time or when you are printing something else in that same filament then toss the bullet on the bed with it.

[MikeO]

And you can save lots of testing time by dragging down the rifle round underneath the print bed so only some of the exposed bullet area is above the surface, then S3D will just print that part of your file. It's a BIG time-saver in situations like this!

[Marshall]

And you can save lots of testing time by dragging down the rifle round underneath the print bed so only some of the exposed bullet area is above the surface, then S3D will just print that part of your file. It's a BIG time-saver in situations like this!

YES! I learned this when I needed to "chop" a locked part.

But, you guys are telling me the print needs to be really slow there. OK. Well then what I proposed would be the correct idea, right? Print the rest of the part at 1 value, then set to a new FFF at layer X. How could you make the software grab or use two FFFs for the same model and just set a layer #? It's as simple as a temperature control, you would think. Simply render the model as if it were two, with the layer number being the model split point.

[jimc]

you can do a multi process print but in the cooling tab just adjust the option that says reduce speed for layers less than "x" sec. so any layer below x seconds will be reduced by x" %. on something like this though that wont be enough. the hot nozzle sitting there on that tip is going to work against you. you have got to print this with something else on the plate.

[Marshall]

It just seems like I'm pointing out a major issue in 3D printing that could be solved through software, not extra parts and filament.

For example. Any single part with a point is going to have an issue when one is needed. So why not create a software fix? Let's talk about this very exact part. I want to print the "case" of the rifle round using one setting. Software should easily be able to "convert" to vase-mode, or single-perimeter spiral mode at any given point when such a structure occurs. So why not allow single-outline corkscrew mode when reaching the "bullet"?

It seems to me with all the stuff the software can do and calculate, implementing a feature that solves the problem of small points on a part should be easy to modify it to do at layer X, and this could have major advantages for S3D. All S3D would really have to do would be look at the part from layer X+, and so long as it sees a part above that line which can use corkscrew mode, it should pass the rendering test, thus allowing it to work,

It sounds like S3D could have a big feature advantage if it could implement simply this process alone. Anyone else agree?

[JoeJ]

I'm not sure I agree that you want to use vase mode for that section alone, but I guess you could if you wanted...

Either way, S3D already has everything you need to do this. Read here: https://www.simplify3d.com/support/tuto ... f-a-model/

[KC_703]

I think Jimc is right. Just need to let the layer cool, otherwise the hot tip will just pull the molten material up.

Try:
- adding a new process for the last 5mm with the fan full blast, make outline underspeed a very low percentage
- Use the "Speed Overrides" on the cooling tab
- Use the "Fan overrides" on the cooling tab
- Try the "Prime Pillar" - 2-3mm minimizes filament waste
- Print multiple bullets