Why can't S3D do this properly? Or can it?

[smeagollum]

S3D is a very fine slicer, but it has some quirks and annoyances, and this one is particularly irritating. Instead of many words, here's a picture:

This is just a simple plate where there are some pegs protruding upwards. The issue is that S3D insists on breaking up the top layer with holes where these pegs are, instead of just creating a solid foundation with unbroken top layers on which the pegs are printed. The way S3D does this makes the peg weaker, and the top layer finish less nice, since it doesn't lay down continuous layers.

In addition to this, it also takes slightly more time to print, since this behavior makes for more travel moves. It just isn't a good way of doing it, and even though I use S3D for everything, I tested this same STL in one of the free slicers, and that one did this the proper way with solid top layers and then the pegs.

Is there some way to fix this in S3D that I haven't thought of?

[brian442]

This is a simple example, but imagine a 50mm wide cube sitting on top of a larger 100mm wide cube. During printing, when you get to the top of the 100mm wide cube, it would be very wasteful to print the entire top layer as completely solid, since you already have infill to support the 50mm cube that will sit on top. So it prints solid fill where it is needed (i.e. anyplace near the outside of the model), but it uses regular infill for the interior of the part.

However, if you want it to use solid fill for the entire layer, you can still do that. Just setup a second process using the variable settings wizard and then adjust the settings as needed (i.e. either change infill to 100% or do something like setting it to print a solid diaphragm every 1 layer on the Infill tab, I think either of those would make it totally solid).

[smeagollum]

I agree that it would be wasteful in the example with the cubes, but I think the user should be able to choose. It could also have been an option to have a setting for an area where S3D should use solid layers instead of holes. This could be similar to the area setting for bridges, and for small areas (below the set area), S3D would fill with solid layers instead of breaking it up. This would also work a lot better for more complex prints, where you might have smaller protruding structures at many different heights during the print.

I tried the splitting and setting a diaphragm every 1 layers, but it still creates the hole first. Here's a picture (with a simpler STL, splitted process at 5 mm):

If I print just the lower process the top layers will be smooth, but including the second process causes the holes to be created, so the second process affects the first process. If they had been printed separately, (i.e the first process' top layers were printed all the way), then it would have worked.

I've attached the sample STL (10 mm total height, peg starts at 5 mm), perhaps you could show me how to set it up properly to avoid the hole under the peg?

[horst.w]

I find out an only one solution for this, a column standing inside a cube.

The 1st picture, clockwise,

left = 2 objects, column standing inside the cube, 1 stl; the column is handled inside the cube as a hole (without infill)
middle = same but the 2 objects are added to one object, 1 stl
right = 2 objects, column is standing on the cube, 1 stl
below = same but 2 stl

H.

[horst.w]

The gap between 2 object of 0,10 - 0,2 mm is doing what you want, but I fear it is not as solid as you wish.

H.

[wirlybird]

How funny! I am working with almost the exact same thing as smeagollum! I have a smaller flat part that will have two pegs sticking up. The pegs are 5mm in diameter and are the attaching method so they need a little strength where they attach to the flat part.

Even though I understand Brian's explanation and it makes sense especially on larger things or maybe in general I have to say that on a smaller peg type application it is not a good way for the slicer to do it. It does create a very weak "joint' area.

It seems I read a post a while back about this that there was a way to work with this in the last version of S3D. Anyone remember this?

I'll look tonight when I get time and see. At least it is handy to be able to run different version of S3D!

[brian442]

I've attached the sample STL (10 mm total height, peg starts at 5 mm), perhaps you could show me how to set it up properly to avoid the hole under the peg?

Sure, here's how to do it:
1) Import your STL file
2) Go to Tools > Variable Settings Wizard, add split locations at both 4mm and 5mm. Click "Split Process" to finish the wizard and it will create 3 processes. The middle process is the top 1mm that occurs right below your peg.
3) Double-click on the middle process, go the Infill tab, and enable the solid diaphragm option. Set it to include that solid diaphragm every 1 layer (that will just make sure it's completely solid for that entire process)

That's it! When you slice, select all 3 processes and you'll see you have solid layers below the peg. I use this approach pretty frequently when I need to add custom mechanical ribs within my prints for strength. Thankfully S3D let's you customize this wherever you want, since there's no way to adjust settings like this in other programs I've used.

[wirlybird]

Thanks Brian. I'll give this a try also. My assumption is you are just creating a boundry layer a bit below and a bit above the area where the pegs join the flat surface.

Any reason for the third process if it is just printing the remaining part of the pegs and they could remain at 100% fill?

[smeagollum]

@horst.w: Splitting into multiple objects is of course a possibility, but it is a bit cumbersome.
@brian442: Thanks a bunch, that method works, even if it gives me even more solid layers under the peg. Fine-tuning the splitting positions can fix this, though (reducing the total height of the middle process by a tiny bit).

I still think the default behaviour is almost never what you really want (at least for small protrusions), so having a setting like I mentioned in one of the previous posts would have been great. The splitting method will become increasingly complicated if there are multiple locations at multiple heights where one needs to have better foundations for protrusions, so an automated setting for this would really have been beneficial.

To any S3D developers that might read this thread: Please consider adding such an automated setting, it would make S3D even better!

[horst.w]

@Brian,

very tricky!

@ smeagollum

Using the wizzard to cut the object into 3 areas as processes is the automatism you wish to have! Also to reach step by step when adding processes with their start and stop points. All other properties must be set by the users and must stay flexible for all their wants !
Only the attribution of the solid diaphragm every one layer is the fine trick to win a high caliper and I didn't thought at this possibility to make a solid zone between the end of the toplayers and the beginning of the peg.

regards
horst.w
GER