Raft enhancements #6003
Raft enhancements #6003
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Fixed missing curly brace after improperly solved merge conflict.
Squashed commit of the following: commit a16674f Merge: a5972e6 28e5e41 Author: Vojtech Bubnik <bubnikv@gmail.com> Date: Wed Feb 10 08:56:21 2021 +0100 Merge branch 'rafting_extras_2' of https://github.com/nemart69/PrusaSlicer into nemart69-rafting_extras_2 commit 28e5e41 Author: nemart69 <78763471+nemart69@users.noreply.github.com> Date: Wed Feb 10 00:58:50 2021 +0100 Fix after merge with master Fixed missing curly brace after improperly solved merge conflict. commit 02b71f7 Merge: 08131f0 8fbafbe Author: nemart69 <78763471+nemart69@users.noreply.github.com> Date: Tue Feb 9 22:12:26 2021 +0100 Merge branch 'master' into rafting_extras_2 commit 08131f0 Author: nemart69 <78763471+nemart69@users.noreply.github.com> Date: Tue Feb 9 21:17:19 2021 +0100 Raft changes, GUI part commit 69aae4a Author: nemart69 <78763471+nemart69@users.noreply.github.com> Date: Tue Feb 9 21:15:33 2021 +0100 Raft changes, libslic3r part
of pull request Raft enhancements #6003: Enabling the bridging flow above raft to match the defaults of the old slicer.
Thanks. I have squash merged it into our repository into branch nemart69-raft. I am sure that separating the raft Z distance and disabling the bridging flow about the raft is a good thing. IMHO we need to split the raft / support parameters a bit more, for example the soluble / non-soluble is now part of the support parameters, we should likely extract it out of that support box. |
Uhm, for some bizarre reason, both issues are working now. It seems that Slicer for some reason decided to ignore all settings I've changed. Unexplained 0.1mm gap
When inspecting the layers, the raft layers are extruded at The next extrusion is the first layer, which happens at Calculation: Edit: Removed the info regarding fixed raft height - for some reason it works now. |
It seems that the confusion came from the "Bridge flow above raft" setting, which not only increases the flow but also increases the layer height, looks like the first layer is |
It is great to see some progress here. 👍 Yes, if "bridge flow" is turned on, it will result in 0.4 mm layer height (with 0.4 mm nozzle diameter) - this works exactly the same way in other (non-raft) cases. And regarding the height of raft layers - these are intentionally set to 0.75 * nozzle diameter (= 0.3 mm in your case), and the setting of First layer height has no influence on this - it is treated as first object layer height. |
I'm so glad that you wrote this 🥇, rafts were broken for me and I had to use Cura for everything with rafts.
It would be cool if there was a hint somewhere. I didn't knew that bridge flow actually affected the layer height.
That makes sense, but also a tooltip here would be nice! I'm currently printing some test benchys. My first test with 0.1mm did not come off the raft, but since the 0.2mm distance from Cura did work, I think it'll work once my 0.2mm distance benchy is printed. Will let you know! |
I agree, it must be documented properly, because there are multiple settings that come into play and things are not obvious unless you know the internals.
Regarding the Z-distance, there is always a trade-off between ease of removal of the raft vs the quality of the first object layer. I think the right value also depends on the material. In my experiments, I tried even Z = 0.07 mm with PLA and 0.1 to 0.12 mm with Polymax PC-Max (a polycarbonate blend). I can remember only one case when I was able to remove the raft easily without a tool (rather a blunt than a sharp knife because otherwise you risk some damage of your print). Personally I prefer a lower Z-distance and a bit more effort to remove the raft. I added some photos from my experiments to issue #3425. |
Yep, I was printing ABS so 0.1mm was too optimistic. ABS@0.2mm was okay-ish to remove and I feel this would be a sane default, as it's also the default Z distance for supports - I guess we should treat settings for PLA as sane as it's pretty much the default and gives probably the least amount of support requests. |
Merged into master with aee136c I have made some changes:
For my reference I am listing some of the issues related to this pull request: |
I'm not so sure about that. I'm trying to print ABS with a raft, and the issue is that without bridge flow, I either get one of two scenarios, depending on the air gap height:
I remember that when I used slic3r years ago printing ABS on a raft was no issue, and a plausible explanation would be that slic3r used bridge flow with an air gap, which could result in a "rounder" filament extrusion with less contact points - however I did not review the slic3r code from years ago as I can't pinpoint the exact time frame. Here's a graphical form directly from @nemart69's original PR. First with bridge flow, second without bridge flow.
The second one is more squished and makes it extremely hard to remove ABS from the raft below. I guess another solution would be to allow fan cooling for the first layer after the raft only, but I have yet to experiment with that. |
First of all, thank you for merging this PR!
This is OK from my point of view - I will not miss it, I left it there just for backward compatibility.
I cannot say much because I have not seen the new feature yet. If that allows a similar expansion then I am fine with it.
Based on my experiments, some shrinking of the first layer above the raft occurs and that was a possibility to compensate it. On the other hand I understand that the complexity of the slicer should be kept as low as possible... |
@Drachenkaetzchen: I tried to turn the fan cooling on for the first object layer and it helped a bit. I tested some additional materials: ABS+ / gray (although the one I have I consider a bit strange) and PETG / black and I can remove the raft (0.1 mm Z distance, standard flow) easily. With the first object layer cooling on - samples on the right side, I can remove the raft even without any tool, just with help of my nails.
My setup is MK3S, nozzle 0.4 mm, layer height 0.2 mm, standard temperatures for the materials, enclosure. |
Several users have been complaining about unsatisfactory raft support in PrusaSlicer.
This PR addresses some of the missing functionality, which is summarized in #3425 (section Expected behavior):
The first model layer printed at 1:1 nozzle size layer height is in my opinion way too high, and produces in almost all cases a random print in the middle of the air.
While the original implementation uses bridge flow (therefore the first object layer is printed too high), this fix adds a new configuration option "Bridge flow above raft" to select either bridge flow or normal flow for the first object layer above the raft.
The first layer height setting must specify that it's being applied to first raft layer and not first model layer above the raft in prints with a raft.
Perhaps the user should be allowed to customize the non-first raft layer height, otherwise it should be specified what it's going to be calculated at.
In this fix, the standard configuration option "First layer height" always specifies the first object / model layer height, no matter whether a raft is used or not. Note that the raft is currently printed with fixed layer height: 0.75 * nozzle diameter.
Super-mega feature request: allow the raft contact z distance to be different than the support contact z distance. This will in so many cases need to be vastly different! And the support option of the height range modifier feature was removed! I've found myself splicing together 2 gcodes several times to achieve both a functional raft with a negative contact z value [which is in and of itself something that was requested and is now available but we absolutely don't know why it's necessary and if so even more to the point, why are we printing so high up off the raft?] and supports that didn't actually physically conflict with the model but were in fact removable.
This fix introduces independent contact Z distance for raft (note: it is not fully independent: it is ignored if soluble interface is selected).
In addition, there are also two extra options:
Settings:
Resulting sliced layers (normal flow, bridge flow, normal flow + expanded bottom layer):
Configurable raft sizes:
Final comment - recommended settings to try (nozzle diameter 0.4):
This gives me significantly better results (with poly carbonate blends), compared with the original implementation. If the raft cannot be just peeled off from the model, some blunt knife is a good tool to help.