Jump to content
Ultimaker Community of 3D Printing Experts
lars86

Sparse Infill with Stronger Members

Recommended Posts

Hi guys,

I'm wondering if a different style of sparse infill exists in a slicer. I believe that KISSLicer simply does every other line for 50% infill, every third line for 33%, every 4th for 25% etc; and just over extrudes to "interpolate" for values that fall in between.

I'm not sure how Cura handles it.

What I think would be very useful is an option like this:

infill.jpg.4a814889d3d0d25bde2fa3a6e09af831.jpg

You could specify the thickness of the members 't' like a shell thickness (increments of nozzle width), and the spacing between members 'S', independently.

The single pass infill normally used is only so strong, but I feel that this would allow for very strong internal ribbing when tuned well for a given part. Does this exist?

infill.jpg.4a814889d3d0d25bde2fa3a6e09af831.jpg

Share this post


Link to post
Share on other sites

Not sure I understand why you would want this? Lets say in a certain area you now make 20 infill lines of 0.4 you think 10 lines of 0.8 with double the gap in between would be stronger? In general a lower gap in between also helps with easy closing of top layer f.e.

For sure it's good to have options, in the picture below you see the infill options of simplify3D. As far  as I can see you can't set the thickness like you want, but you can over extrude the infill to create thicker infill.

InfillSimplify3D.thumb.jpg.c48c18f631f2c569dd6050214d3eb6c3.jpg

InfillSimplify3D.thumb.jpg.c48c18f631f2c569dd6050214d3eb6c3.jpg

Edited by Guest

Share this post


Link to post
Share on other sites
Lets say in a certain area you now make 20 infill lines of 0.4 you think 10 lines of 0.8 with double the gap in between would be stronger?

 

I do.

It's not something I've tested, but call it an engineer's hunch. I think that the cumulative strength of a thicker rib, can be higher than individual strands added up.

Share this post


Link to post
Share on other sites

Infill strength

I find this a very interesting subject: It is a fact that a solid steel rod bends more easily, than the same diameter steel rod with an axial hole in it (depends on wall thickness, which can not be "zero")! Saves weight.

It is because the core of the bar acts as a leverage for the bending action.

After a solid bar is bent, it is still almost as strong as before (depends a little on the type of steel/material).

When the hollow steel bends, it collapses more, and loses a lot of its stiffness.

After the hollow structure is bent, its designed strength is completely lost and no useful calculation is possible.

Share this post


Link to post
Share on other sites

With the new infill technique coming up for the next CuraEngine release, there is a new infill method that makes triangles rather than squares. Lars' idea still holds, but it's something to keep in mind because that makes it a bit more complicated.

I think the idea holds some merit, from what I know of static physics. With the same infill density, it could be stronger against certain types of force, specifically a force that is spread out throughout the surface of the object. This is because two beams stuck together will be more resistant to shear and (by extension) bending, while still having the same resistance to compression individually. Of course, the larger gaps will make the centre of these gaps weaker, so it will be weaker against sharp, piercing forces.

This sort of thing requires a lot of testing, because I predict that the thicker ribs could be visible on the outside if the shell is thin, and the bigger gaps could lead to more 'rounding errors' due to the coarser discretisation of the infill (e.g. a small part could get 0% infill because it happens to fall completely within a gap). There is also the matter of exposing too many parameters to the user, though the next Cura release will streamline that somewhat better too.

Share this post


Link to post
Share on other sites
Infill strength

I find this a very interesting subject: It is a fact that a solid steel rod bends more easily, than the same diameter steel rod with an axial hole in it (depends on wall thickness, which can not be "zero")! Saves weight.

It is because the core of the bar acts as a leverage for the bending action.

After a solid bar is bent, it is still almost as strong as before (depends a little on the type of steel/material).

When the hollow steel bends, it collapses more, and loses a lot of its  stiffness.

After the hollow structure is bent, its designed strength is completely lost and no useful calculation is possible.

Swordriff, you are close, but a little off.

For the same diameter bar, solid is both stiffer and stronger than a hollow bar.

For the same weight bar, a hollow will be stiffer than solid because the mass is distributed into areas where the material properties can stiffen the bar. For a given angular deflection, a greater material displacement is required, the further you get from the centerline. So, material very near center doesn't resist bending efficiently.

Share this post


Link to post
Share on other sites
With the new infill technique coming up for the next CuraEngine release, there is a new infill method that makes triangles rather than squares. Lars' idea still holds, but it's something to keep in mind because that makes it a bit more complicated.

I think the idea holds some merit, from what I know of static physics. With the same infill density, it could be stronger against certain types of force, specifically a force that is spread out throughout the surface of the object. This is because two beams stuck together will be more resistant to shear and (by extension) bending, while still having the same resistance to compression individually. Of course, the larger gaps will make the centre of these gaps weaker, so it will be weaker against sharp, piercing forces.

This sort of thing requires a lot of testing, because I predict that the thicker ribs could be visible on the outside if the shell is thin, and the bigger gaps could lead to more 'rounding errors' due to the coarser discretisation of the infill (e.g. a small part could get 0% infill because it happens to fall completely within a gap). There is also the matter of exposing too many parameters to the user, though the next Cura release will streamline that somewhat better too.

You bring up some good points.

It would definitely be an advanced method, where the user would be responsible for sizing the pattern appropriately.

Maybe there could be a checkbox that allowed any cavity equal to or smaller than the grid spacing, to be filled solid.

I like the triangular infill pattern idea, and can't wait to try it out.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Announcements

  • Our picks

    • Architect Design Contest | Vehicles.
      We're open for entries! - Design and submit your 3D designs of architectural entourage - vehicles - for a chance to win a large filament pack. Presenting an idea, an architectural design or something as big as an urban project isn't easy. A scaled model can really help to get your idea across.
        • Like
      • 14 replies
    • What The DfAM?
      I'm Steve Cox, an experienced engineer familiar with 3D printing. I wanted to share some DfAM guidelines with this community to help and make stronger parts.
      I'm also an Autodesk Certified Instructor for Fusion 360, so many of the images in ...
        • Thanks
        • Like
      • 17 replies
×

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!