limit z axis for support material PVA UM3

[aoand 0]

Dear Community,

seems that the first post did not work. Again my question: In my model i would like to be able to limit the support material to a predefined height in z axis. e.g only 10mm from the bottom plate and then it should stop for obvious time saving reasons. In many cnc programs there is a chance to set a plane which prevents g code from being generated. Is there such a "banal" functionality that i unfortunately cannot find in cura 2.7.0?. I was already fiddling around with some of the experimental support settings. none of them seem to do just that. thanks in advance

ao

[gr5 2,224]

Short answer, "No. Sorry." Hopefully soon.

[aoand 0]

Hi gr5,

thanks for your quick response. Shame that such a functionality has not been implemented yet. would be super useful. I figured out later that this has been asked in 2013 already...https://ultimaker.com/en/community/4388-reducing-support-structure.

Anyway with the possibility of dual extrusion i am now trying a workaround by modelling my own support geometry using Tetgen, a volumetric tetrahedral mesh generator with adaptive density control in various bounding conditions. Meanwhile, i hope this can be useful to others too.

PS. its exciting to be part of this community now. cu around

[kmanstudios 1,120]

Another thing you can do with the model is to split it at the point you want support to stop and use 'per model settings' to define which model generates support or not. Then use '\Merge Models" to align them properly. I have done this and it works quite well.

Also, if you go to support settings and use the 'horizontal expansion' you can really reduce a lot of the support material used and how far up it goes. It is defaulted to 3mm, but I usually go with 0.25mm.

I am going to have to look at Tetgen though.,....that seems interesting.

[aoand 0]

Hello kmanstudios,

on my geometry here its less of a struggle to use the inbuilt generate support material algorithm as you suggest it. Slicing, settings per object and aligning it back again worked like a charm and reduced printing time drastically. thanks and thumbs up for the horizontal expansion tweak, nice!

[kmanstudios 1,120]

Hello kmanstudios,

on my geometry here its less of a struggle to use the inbuilt generate support material algorithm as you suggest it. Slicing, settings per object and aligning it back again worked like a charm and reduced printing time drastically. thanks and thumbs up for the horizontal expansion tweak, nice!

 

Yer quite welcome

[gr5 2,224]

Keep in mind that although pla sticks on top of pva, pva will not stick on top of pla. I know - it's strange. but true.

So the whole point of horizontal expansion is that for typical prints that need pva, this allows the pva on upper levels of your part to connect all the way down to the glass. If they only rest on pla then they tend to fail (come loose as strings all over your print bed).

So keep that in mind before reducing horizontal expansion for support material. Basically make sure that if you removed the pla the pva would all be connected still.

[kmanstudios 1,120]

Keep in mind that although pla sticks on top of pva, pva will not stick on top of pla.  I know - it's strange.  but true......

It has been working for me. For instance, this is a print that will be finished in 18 hours with tons of PVA on top of PLA in a lot of big and small places. It has to be super dry though.

[gr5 2,224]

Nice! Okay I guess sometimes it works - it seems to work for you. But for me it works only maybe half the time. And I was told that was the entire purpose for adding the "horizontal expansion for support" feature. So I'm not sure how you got this to work, kman.

I know tinkergnome (or maybe foehnsturm?) did some tests and found that if you squish the PVA extra hard into the layer below it will work. He had to hand edit the gcodes to over extrude 2x on a layer that was just above a PLA layer. That definitely worked well for him and I hope they add that as a cura feature some day.

[kmanstudios 1,120]

It was quite finicky a first before I got the things to really super dry out my filament. Tht is the only thing I can figure.

[gr5 2,224]

I'm wondering if you purposely level the second nozzle "wrong" you can get it to squish the pva into the pla harder enough so that this works nicely. On the other hand the second nozzle would have a tendency to scrape/scratch the pla on the layer below.

[kmanstudios 1,120]

I'm wondering if you purposely level the second nozzle "wrong" you can get it to squish the pva into the pla harder enough so that this works nicely.  On the other hand the second nozzle would have a tendency to scrape/scratch the pla on the layer below.

I am on a UM3E and I am not sure that individual leveling of the nozzles is possible.

[gr5 2,224]

It's not only possible you have done it many times I'm sure. You run the leveling wizard. It makes you go through this process - the first have you are supposed to have the nozzle 1mm from the glass. Then it goes to the back center and you level by spinning the electronic control wheel. Then you level the front 2 corners by spinning the leveling screws.

THEN it always has you level the second nozzle/core as well as the last step. At that point it is storing the z offset between the 2 different nozzles/cores. If you level the first nozzle with paper but skip the paper for the second nozzle then the z offset will have the second nozzle always a bit low and it will tend to crash into your model a bit but also squish that pva in better (asuming you put pva in second core).

There should be some happy medium between not hitting the part but still squishing the pva nicely.

Even better it would be good if when printing pva over pla Cura automatically over extrudes by maybe 50%.

[kmanstudios 1,120]

It's not only possible you have done it many times I'm sure.  You run the leveling wizard.  It makes you go through this process - the first have you are supposed to have the nozzle 1mm from the glass. Then it goes to the back center and you level by spinning the electronic control wheel.  Then you level the front 2 corners by spinning the leveling screws.

THEN it always has you level the second nozzle/core as well as the last step.  At that point it is storing the z offset between the 2 different nozzles/cores.  If you level the first nozzle with paper but skip the paper for the second nozzle then the z offset will have the second nozzle always a bit low and it will tend to crash into your model a bit but also squish that pva in better (asuming you put pva in second core).

There should be some happy medium between  not hitting the part but still squishing the pva nicely.

Even better it would be good if when printing pva over pla Cura automatically over extrudes by maybe 50%.

 

Huh....that is interesting to hear. I never would have thought of that. Thanks