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Need help creating builtin support

Posted: January 3rd, 2017, 1:58 pm
by reibuehl
Hi all,

I have created a part that - at least with Cura - seems to be unprintable without adding builtin support :(

The attached STL would need support "Everywhere" in Cura, but since I need to insert two M5 hex nuts at Z=24mm, I can't use that type of support because it would fill the hole for the hex nuts. Is there a trick to get around this without buying Simplify3D...? :)

Best regards,
Reiner

Re: Need help creating builtin support

Posted: January 3rd, 2017, 2:18 pm
by LePaul
Maybe one of the S3D guys can re-do your model in S3D tweaks :)

Re: Need help creating builtin support

Posted: January 3rd, 2017, 2:56 pm
by reibuehl
As far as I can see, it would need support up to 16.8mm where the rectangular opening closes. Everything above should print fine without support. But I assume there is no "support-until-z-value" plugin for Cura, or?

Re: Need help creating builtin support

Posted: January 3rd, 2017, 3:17 pm
by LePaul
Unless your material is really really good at bridging! I took a peek at the model in Cura, it's that center section you're trying to support without the rest that goes to the top?

Re: Need help creating builtin support

Posted: January 3rd, 2017, 3:39 pm
by reibuehl
Yes, the 12.7x12.7mm rectangular cavity in there is what I would like to support. The holes going up from the bottom to the spaces for the hex nuts cut through that rectangular space.

Re: Need help creating builtin support

Posted: January 3rd, 2017, 3:40 pm
by Neotko
There's an option new on 2.4 to temove supports on areas by using an object and assigning a Per Object option to that object. I haven't use it but is there

Re: Need help creating builtin support

Posted: January 3rd, 2017, 3:44 pm
by reibuehl
I am not sure I understand...

Re: Need help creating builtin support

Posted: January 3rd, 2017, 3:57 pm
by LePaul
2.4 Beta Cura. They found a bad problem with it and removed it from the site.

Re: Need help creating builtin support

Posted: January 3rd, 2017, 4:13 pm
by Neotko
LePaul wrote:2.4 Beta Cura. They found a bad problem with it and removed it from the site.
Didn't knew that. Well beta is beta. I saw the option listed on the changelog, using objects to create negative areas where supports don't exist. So you could draw a box on the area that you don't want to get supports.

Re: Need help creating builtin support

Posted: January 3rd, 2017, 7:24 pm
by LePaul
Here's what Nallath posted

It was moved ofline as we found a pretty nasty bug with support meshes. These could in some cases result in g-code with no Z values (eg; all layers printed on z0), which can do pretty massive damage to the machine.

We already have a fix, so it should be up again today. Sorry about this!

Re: Need help creating builtin support

Posted: January 3rd, 2017, 7:46 pm
by Neotko
Back to topic. Other than waiting from r cura 2.4 I would just design my own supports.

Re: Need help creating builtin support

Posted: January 4th, 2017, 2:03 am
by Xeno
How would you even get those hex bolts inside the print ?
laying the model down while printing you could pause at height and add the bolts (and would probably stick through the build plate ?)
printing upright would cause the print head to bump into the hex heads if you add them during the print.

if you print the right speed and temp, you might get away with bridging the gap without support, but might impact layer adhesion and the strength of the part.

I sometimes print a filler block that I can put inside a gap for another object, pause at height and put the block in (with tape on the top,
because it is a loose block and has some screw holes, I can take it out without much problem, just don't make the block too tight fit :)

Re: Need help creating builtin support

Posted: January 4th, 2017, 2:50 am
by reibuehl
Neotko wrote:Back to topic. Other than waiting from r cura 2.4 I would just design my own supports.
That was my initial idea, but since I do not have experience with this, I was hoping for some advice from people here that have done that before successfully. I would be interested in how to dimension these supports, e.g. how thick do they need to be so that the slicer will not "optimize" them away, how much gap do I need to the actual part so that they break away easily, and such.

I noticed that structures that are just as wide as the nozzle diameter seem to disappear during slicing.

Re: Need help creating builtin support

Posted: January 4th, 2017, 2:58 am
by reibuehl
Xeno wrote:How would you even get those hex bolts inside the print ?
It is nuts, not bolts, so I just need to pause at Z, drop them in and continue the print.
Xeno wrote:I sometimes print a filler block that I can put inside a gap for another object, pause at height and put the block in (with tape on the top,
because it is a loose block and has some screw holes, I can take it out without much problem, just don't make the block too tight fit :)
That is a great idea! If I can't get the built-in support to work, I will try printing a filler piece and wrap it in kapton tape.