Thin walls

[mmcginnis9272]

I have been using the Cura engine within Repetier Host for about 6 months before I decided to purchase Simplify3D. I have had issues with Cura not generating thin walls. Simplify3D seems worse. For instance, the attached file of a Pirate ship.

pirateship.stl

(1.1 MiB) Downloaded 587 times

With a .4mm nozzle, I can get the sails to print with a magnification reduction as low as 67%. Simplify will not print the sails at any magnification lower than 81%. Anything lower than the stated percentages in each program cause the ship's sails to disappear. is there any way to get Simplify 3D to at least perform as well as Cura, if not better?

pirateship.stl

(1.1 MiB) Downloaded 587 times

[MichaelHerron]

I have been using the Cura engine within Repetier Host for about 6 months before I decided to purchase Simplify3D. I have had issues with Cura not generating thin walls. Simplify3D seems worse. For instance, the attached file of a Pirate ship.

pirateship.stl

With a .4mm nozzle, I can get the sails to print with a magnification reduction as low as 67%. Simplify will not print the sails at any magnification lower than 81%. Anything lower than the stated percentages in each program cause the ship's sails to disappear. is there any way to get Simplify 3D to at least perform as well as Cura, if not better?

pirateship.stl

This isn't a bug, but it is frustrating. The problem is that simplify doesn't try to print features that are thinner than the extrusion width. You can try to reduce your extrusion width, but this is generally tied to your nozzle width. Reducing it may have nasty side effects, but you'll just have to play with it to see if its livable.

[Rebekah_harper]

There is a post about that suggests lowering the nozzle width can be done. This does require a max 1.5mm layer height.

If cura prints this then the width would no longer be what the part parameter is.

You can trust S3D though

[dkightley]

Thin walls is a subject I always have to take into account when designing the sort of things I want to print. Here's an example I have successfully printed using a 0.4mm nozzle with 0.05 layer thickness:

Note the size compared to the UK £1 coin! btw This is T Gauge scale model railways!

Here's an illustration of the thin wall effect....sliced as printed above:

Note that I've had to make the wall thickness 2.5 times the extrusion width to get the indented detail. And I've had to make sure I leave room to get a single extrusion in in between the indentations.

I'll soon be trying a 0.2mm nozzle, which should give a bit more "elbow room" where thin walls are concerned. Here's the equivalent simulation:

[tenaja]

If cura prints this then the width would no longer be what the part parameter is.

You can trust S3D though

Omitting small model features should be an optional software feature, and should at least produce a notification. If you do not have the luxury of editing the part, or swapping your nozzle, then S3D is not trustworthy if you cannot force it to print the part.

[jimc]

i wouldnt go that far. there are limitations with every type of manufacturing. 3d printing is no different. parts or objects of every kind need to be designed with respect to how they are going to be made. a 3d printer has a size limitation and to expect every stl file to load into s3d and just slice and print no matter what should not be expected. s3d should stick with and be accurate to the model its printing. if you cant print it then get a smaller nozzle for your printer which is capable of printing your part. on the other side of the fence i could see that for items like little sculptures etc that have tiny features and accuracy doesnt matter then give the people what they want and just print something even if its not correct.

[tenaja]

...there are limitations with every type of manufacturing. 3d printing is no different.

True, but in this specific example, the weakness is in the software, not the tool.

In milling, I cannot realistically cut a .002" slot 1/2" deep. I can, however, tell my CAM software I own a .002" cutter, and force it to make the cut even though I put my smallest cutter in the machine, and it happens to be much larger than .002".

In the same way, we should have the option to have gcode generated that utilizes whatever smallest nozzle we have for thin walls. Again, this is a limitation of the software, not the hardware.

As it is, the software fails to print 100% of the time when it comes to thin walls, with no option for anything else. A simple checkbox, or even better, a textbox for entering decimal values, would allow the operator to choose the tolerance, rather than blind failure.

[dkightley]

There's obviously two schools of thought here.....

Firstly, there the "engineers" point of view. If it going to print, then it going to be true to dimensions and tolerances. A wall is thin for a reason!

And secondly, there's the "artists" point of view. I want it to print whatever it can, as long as it looks good. Dimensional errors are not that critical.

I can't fault either point of view, however here come the crux of the matter. Which point of view reflects how the developers of S3D want the software to work? A compromise would be for there to be a flag to switch between the two ways of printing as suggested above, but for there to be some alarm or warning to indicate if the "thin wall" print rule has been compromised.

Personally, I'm happy with the way the software works for thin walls.......probably because I'm an engineer.

[tenaja]

Personally, I'm happy with the way the software works for thin walls.......probably because I'm an engineer.

I am also an engineer--which is why I would never suggest it over-print without setting that flag--but I also realize that a) most people here aren't, and b) most of the files on the 3d download sites were not drawn by an engineer. The ship above is a perfect example; somebody drew it, it sliced with Cura (or whatever), but S3d could not print the design intent, which is far more important than any one dimension. An engineer knows when he's inherited a design that requires tweaking to be manufacturable, but as I said, the operator has to have control over the software, and blind changes made by the s/w--either thickening the rib or removing it-- are bad.

[jd_3d]

I think another thing to keep in mind here is S3D also cannot do a single pass (i.e., single perimeter) on thin walls. For instance, if you have a 0.4mm nozzle/extrusion width and slice a 0.4mm wide wall, S3D will create 2 perimeters for that wall (basically an inside one and an outside one). This effectively makes the wall way thicker than it is in the STL. They really need to enhance this so it can do a single pass on thin walls.

Once they fix that, then there could be a check box that says "Allow adjustment of extrusion width down to 50% of nozzle size to support thin walled areas". The 50% would be user-changeable and would allow the user full-control over how thin of a pass they want to allow.