TPR "rubber" filament printing infill question

[montauk1989 0]

Hi, I need to make a small rubber part for an old car I'm working on.   It's just a boot to cover the back of the ignition switch.    I googled around and found an Atomstack 3d printer that prints using TPR filament.   It just seems a lot easier to use 3d printing than making rubber molds so I bought the Atomstack.  

 

I made a tests and finally got one that works well but I needed to modify the dimensions a bit.  I'm using 3DS Max for the modelling.     For some reason the preview doesn't show any infill on my latest two versions but it does show on the last test run I made.    I haven't bother to print that ones that aren't showing any infill because I know they'll collapse.  

 

Any suggestions?

Thanks

 

infill problems.3mf

[Verdeel 1]

Cura does not properly recognize some of the models, because they consist of several meshes and it does not know they are the same model. The one on the bottom right for instance, when I imported the model and used mesh fixer to split it into parts I get four parts. The outer shell, the inner shell and two "donuts". 

 

Cura does not place infill between the inner and outer shell because it does not see it as a single model. I don't have any recent experience with 3DS max but there should be a way to cut and combine the existing shapes\surfaces into a single mesh. 

[GregValiant 1,287]

Let's see if I understand this.

Your test model is the simpler one and shows support that is holding up the angled cone shaped area.  That cone is at a greater angle than your "Support Overhang Angle" setting while the other two models are below "Support Overhang Angle" and so the 2 fancier models don't require support.

The left lower model consists of a single wall 1mm thick.

The right lower model has double walls that are 1mm thick.  There is a gap between the walls that you need to take care of in the CAD program.

You might be able to work with this in Cura.

In Mesh Fixes enable the setting "Remove all Holes".

Set the "Top Bottom Thickness" to 0.

Set the Infill Density to 0

Set the Number of walls to 3 or 4 depending on how thick you think they should be.  The image below is with 3 walls and I turned support off because they don't really need any.

One of the rules of printing with TPU is GO SLOW.  That 3mf file has the print speed at 60 with the inner wall speed at 80.  That ain't happenin'.  I suggest you start at 15mm/sec for all speeds and see how a test goes.  You should be able to tune the print from the printer control panel and up the speed at intervals and see what works best.  I print TPU at 10mm/sec and I lubricate the filament with mineral spirits so it moves through the bowden tube easier.  I also set all the flow rates in Cura to 112% or I get under-extrusion. 

I see that your retraction distance is 1.5mm and that is normal for a Direct Drive printer.  If your printer is a bowden tube design the I suggest you turn retractions off.  The 3mf file are suggestions.  My printer isn't good at TPU but I manage to get custom gaskets out of it.  Old motorcycles need some love too.

 

 

 

GV_infillproblems.3mf

Edited January 1, 2022 by GregValiant

[montauk1989 0]

Thanks so much for the suggestions.  As you can tell, I'm totally new to this.   I'll make some changes and see how it goes.

Dave

 

[montauk1989 0]

I've got my part thank you!!!!!    It a boot for the back of an ignition switch.

 

Here's a photo with two early tries, the remnants of the original boot and the final version.

 

Happy new year!!!

 

Dave

 

[GregValiant 1,287]

Nice.  Now the magic smoke can't escape quite so easy.

 

Is that from a 1961 Land Rover?  There is a reason that Joseph Lucas was known as the "Prince of Darkness" ya know.  The "Lucas Electric Vacuum Cleaner" was the only product they made that didn't suck.

[montauk1989 0]

No, 1970 Jag e-type (xke).