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How to solve weak vertical structures

Posted: Tue Sep 02, 2014 2:38 am
by danieljb
Hello

Today I printed quite a large part, 10 hours worth and when I accidentally dropped it a small distance, the part snapped in 2 on a vertical pillar of cross section about 2cmx2cm. I couldnt believe it broke so easily but I know why. Here are some screenshots of the print preview and you can see what happened

Here is the part, normally
http://i.imgur.com/3L763H7.png

This is the layer just before the vertical column
http://i.imgur.com/GSZi0Xm.png

and here it is above it
http://i.imgur.com/kj6RWY6.png

As you can see, the transition from infil into wall is immediate, this resulted in a massively weak part where the infil became a shell.

Now in makerware, it does this
http://i.imgur.com/51cY99m.png

where it prints a solid sheet below the transition from infil into the vertical wall
http://i.imgur.com/DPaPiMK.png

Meaning the wall is connected to solid plastic.

This is FAR stronger. I want to know, is there any settings in simplify3D where I can fix this? If not, maybe one could be implemented. I find it quite critical.

Re: How to solve weak vertical structures

Posted: Tue Sep 02, 2014 1:25 pm
by 3Drasle
Hello danieljb

No there is no solution in Simplify at the moment, but do a search on "honeycomb" on this forum and you will see that it is a "feature request".

Re: How to solve weak vertical structures

Posted: Wed Sep 03, 2014 12:15 am
by BaronWilliams
Hi danieljb,

You could force Simplify3D to make a complete solid infill at the point you need that extra strength.

There are 3 ways to do this.

METHOD 1
One infill option that can do this is "Include Solid Diaphragm Every X Layers". With that option you need to know the exact layer to make the solid infill. It's not that useful for what you need, but it can work. I repeats the solid infill even X layers. So if you specify 10, then every 10 layers will be solid.

METHOD 2
Make 2 processes. Make process 1 start at the bottom and go up until the height you want the extra solid infill for strength. Make process 2 identical to process 1 but make it start at the exact height process 1 stops at.

You just need to go into "Advanced" settings tab and set the "Start printing at" and "Stop printing at" properties appropriately for your 2 processes.

For example, if a spot at 100 mm needs extra strength for the infill, make process 1 stop at exactly 100 mm. Make process 2 start at exactly 100 mm. Now, instead of using interior infill at the 100 mm point, this will cause exterior infill to be generated for the layers that meet at the 100 mm point in your print object.

Process 1 will end at the joining point creating "Top Soiid Layers". Process 2 starts with "Bottom Solid Layers". If you set "Top Solid Layers" to 1 and "Bottom Solid Layers" to 1 for both processes then this joining area will have 2 solid layers. If they were each set to 3 then this area would have 6 solids layers, etc. You could use other combinations as well.

METHOD 3
Like method 2 but this uses 3 layers.

Process 1 is your normal process and uses the infill you want. Process 2 has 100% solid infill. Process 3 is the same as process 1.

You make process 1 print until the height of that spot you want to strengthen.

You make process 2 print starting from the exact height process 1 left off at. You make it print until you have as much solid infill as you like, perhaps 10 mm? Any amount is fine.

You make process 3 print starting just where process 2 stops and print the rest of the object with normal settings.

The 3 process method is pretty simple. You just need to go into "Advanced" settings tab and set the "Start printing at" and "Stop printing at" properties appropriately for your 3 processes.

For example, if at 100 mm you need solid infill to be exactly 10 mm thick to make your print much stronger, but you don't care about the other portions of your print having solid infill, then you would make process 1 print with say 10% infill, and stop at 100 mm. You would make process 2 print with 100% infill and start at 100 mm and stop at 110 mm. You'd make process 3 start at 110 mm using 10% infill again.


Pretty cool tricks in all. These are things MakerWare can't do, and one of the reasons I love Simplify3D so much.

Here's an example of method 3. This is a cylinder (cut so you can see the interior) that is 100 mm high. From 50-55 mm I made it have 100% infill. The rest is 20% infill.
S3DSolidLayerExample.jpg
Example of using 3 different processes to make solid infill at a specified height.

Re: How to solve weak vertical structures

Posted: Fri Sep 12, 2014 10:35 am
by Dave
Layer bonding strength is also a factor. A hotter extruder temperature (or slower cooling fan) might give you stronger bonding between layers. I have also found that if printing in ABS, giving the part a generous rub with acetone makes it stronger. The acetone seeps between layers and causes them to dissolve and flow together, creating a stronger bond after the acetone has evaporated. There are now stronger plastic materials than PLA and ABS available in filament format suitable for 3D printing. For structural parts you need to carefully consider which orientation to print - a printed part is much weaker in the Z direction than the X or Y directions. Print a square column laying down and the same part standing up for example, and you will easily be able to snap the latter part in half, but not the former part. with some items it is better to print the item in two sections and later glue/bolt them together than printing in an orientation that will allow it to be printed as one piece but be structurally weaker.

Dave

Re: How to solve weak vertical structures

Posted: Sat Sep 13, 2014 4:35 pm
by jimmybuckets
Since S3d has such great support options you could also print with support if needed and have the layers printed in the strongest direction for your part AND do what others have said with a layer of solid infill.

Re: How to solve weak vertical structures

Posted: Mon Sep 15, 2014 11:28 pm
by KC_703
BaronWilliams wrote: METHOD 2
Make 2 processes. Make process 1 start at the bottom and go up until the height you want the extra solid infill for strength. Make process 2 identical to process 1 but make it start at the exact height process 1 stops at.

You just need to go into "Advanced" settings tab and set the "Start printing at" and "Stop printing at" properties appropriately for your 2 processes.

For example, if a spot at 100 mm needs extra strength for the infill, make process 1 stop at exactly 100 mm. Make process 2 start at exactly 100 mm. Now, instead of using interior infill at the 100 mm point, this will cause exterior infill to be generated for the layers that meet at the 100 mm point in your print object.

Process 1 will end at the joining point creating "Top Soiid Layers". Process 2 starts with "Bottom Solid Layers". If you set "Top Solid Layers" to 1 and "Bottom Solid Layers" to 1 for both processes then this joining area will have 2 solid layers. If they were each set to 3 then this area would have 6 solids layers, etc. You could use other combinations as well.
I'll have to try this... Didn't realize each process had a top and bottom. I thought it was relative to the project.

Alternatively, you could have a process which has a higher infill and extrusion temp spanning the layers which require more strength.