First Layer survace

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tomka
Posts: 2
Joined: Wed Feb 14, 2018 7:42 am

First Layer survace

Postby tomka » Wed Feb 14, 2018 8:05 am

Hi all,
i have a Raise 2N since 2 month and i´m printing parts for using in machines.
Everything is good so far but i have one problem with the quality of the first layer.
I print with raft to get the model better off the plate.
At the first layer from the model you can see the single lines. they are not melting together and it looks very bad.
After the first line everything is perfekt and the surface is good. That happens with eyery print.

Layer hight: 0,1
First layer Hight: 0.25
First layer speed: 30 (i tried 15 / 20 / .. but the same)
First layer Flowrate: 100%

Does anyone know what i´m doing wrong?
20180214_082624.jpg
20180214_082636.jpg

Jetguy
Posts: 2697
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: First Layer survace

Postby Jetguy » Thu Feb 15, 2018 2:40 pm

I print with raft to get the model better off the plate.
At the first layer from the model you can see the single lines. they are not melting together and it looks very bad.
After the first line everything is perfekt and the surface is good. That happens with eyery print


You pretty much answer your own question. You print with raft. In order for raft to not stick to the print as a break free surface, the settings to start the print after the raft leave a slight gap in Z height. The idea being that the extruded hot noodle of plastic from the nozzle is round and then because of the Z height start point above the raft the nozzle is drooling that noodle and not smashing it oval into the surface. That means adjacent threads of infill lines to not smash and bond together side by side as what is seen when you properly adjust first layer gap and print with no raft.

Again, this is a fundamental issue of using RAFT. In order to later be able to remove the raft, there is an intentional gap for the first layer of the actual object. That means the first layer of the object bottom is not ideal. That's the tradeoff of using raft. If you go into the slicer setting and begin changing or removing that gap, you will then NOT be able to remove the raft as your layer has squished and bonded into it.

In a nutshell, if you want a better bottom, don't use raft and properly level and adjust the bed first layer for proper adhesion.

Jetguy
Posts: 2697
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: First Layer survace

Postby Jetguy » Thu Feb 15, 2018 2:55 pm

To further help you, here is a good article on the general topic of first layer and print adhesion.
It explains the different options (and yes, Ideamaker does have all 3 options, Raft, Skirt, or Brim).
There are pros and cons to each choice and understanding that (example: the cons and limitations of what a raft does with first layer of the print object) is key to your success.
Ideally, you use Brim to solve adhesion before using raft as a last resort. All that said, bed leveling and first layer Z gap matter no matter what you use and is a skill you need to master. Using the supplied 0.2mm gauge is the first step in leveling/Z-gap, not the last and final step. You adjust based on printing test results by observing first layer patterns and width of the extrusion as put onto the surface of the build plate to fine tune. https://www.youtube.com/watch?v=o9L7f0zx1WQ

https://rigid.ink/blogs/news/3d-printed-raft-brim-skirt
Some of the cons of using Rafts are that in some slicer settings, they can be hard to remove (some more flexible materials can be harder to ‘pop’ away) and that the bottom won’t be that super smooth, glass like surface you’ll get when printing straight onto the bed surface.

tomka
Posts: 2
Joined: Wed Feb 14, 2018 7:42 am

Re: First Layer survace

Postby tomka » Wed Feb 21, 2018 11:04 am

Hi Jetguy
of course you are completely right.

Thank´s for your informations.

User avatar
jetdillo
Posts: 131
Joined: Mon Jun 12, 2017 5:10 am

Re: First Layer survace

Postby jetdillo » Thu Feb 22, 2018 1:48 am

I'm having trouble with my 2nd-nth layers. The first layer looks great and so does the rest of the model. The second through fifth or so look really scraggly but nothing else does, including the top. This results in a "scruffy" looking bottom part of my part but the rest of it appears unaffected. I've tried adjusting the speed of the bottom fill operation and also the flow rate from 94% to 102% and also slowed my bottom layer speed down to 40mm/sec. I'm printing 5 bottom layers and 6 top layers. I have retraction enabled w/ a Z-hop of 0.06mm.

This is with Hatchbox PLA, which likes a lower temperature of 200-205(vs. 215-230 for some others) and a buildplate temp of 60. The "scruffy" effect seems to scale with the size of the part. Small calibration cubes show some of this effect, but it's more pronounced like in picture below.

20180123_220628_HDR#1.jpg


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