Unecessary Support Structure

[Paul_01 0]

I was printing a somewhat complex  and tall (1:5 aspect ratio) part (ABS) with several locations of overhang inside and outside the model, and as a result had to print supports (PVA). I set the minimum overhang angle to 15 degrees, but when I printed it, the model was encased in supports along sheer sides that don't require supports. To further illustrate what the slicer is doing, I have another example: I had to print some small parts and a large part, so I lumped them all together on the build plate for a neat overnight print. I had supports on for the benefit of the large part, the small parts have 0 locations of overhang. Yet the sides of the small parts were surrounded by support material (this time Breakaway).

This is not only wasteful, but it also scars the sides of the part, why does the slicer construct these supports, and what settings could change this?

[Brulti 177]

You can find all the settings for the supports in the 'Support' menu. You'll have to play with the various distances, placement, extension and such to find out what works best for the parts that you are printing.

 

Also, if you want to avoid support in some parts when printing multiple parts at the same time, I'd suggest using the support blocker feature. You put that over the small parts and CURA won't bother generating supports for them.

[kmanstudios 1,120]

I am curious as to why you put the overhang degree setting to 15°. It usually defaults to 45°. Changing that to a low number increases the areas of support. This may not be needed.

 

Also, change the support horizontal expansion to something very small or even zero. This will greatly eliminate a lot of support on edges and such.

 

You can also go into 'per model settings' and set parts to just not have support at will. That is also where you will find the support blocker @Brulti mentioned.

[Paul_01 0]

Here are some pictures of the aforementioned problem. I'm currently running one of these prints (they take about a day) with 0 horizontal expansion, to see what that changes.

 

Different yet related question, what settings can I modify to reduce scarring? The PVA doesn't print very prettily, and often strings and displaces ABS from the surface with little burs, which when dissolved leave the print pockmarked (as seen in the pictures).

[kmanstudios 1,120]

PVA and ABS really do not play well together. I am amazed that you even got it to work at all. Have you tried the Breakaway material yet?

[Paul_01 0]

The part has complicated inner tubes, breakaway was tough enough to remove on simplistic supports. I've read that PVA works fine with Nylon, yet Nylon prints at an even greater temperature than ABS. When I place an enclosure around the printer to mitigate warping (of ABS) the PVA kinda just melted in irregular, stringy, blobs. Is it worth it to try switching to Nylon?

 

AD: ABS has been really hit or miss with warping, 2-3 days prints fine, 1-2 days of failed prints, rinse, repeat.

 

[kmanstudios 1,120]

I would definitely switch to nylon if having issues.

 

The temperature of the ABS is not the issue with printing in combination with PVA....it is just a material incompatibility and the warping will make it pull away.

 

I like nylon. Of course, I like the plague better than ABS...ANY of the plagues. ?

[Brulti 177]

Nylon + PVA in an enclosure works like a charm. I printed enough parts in Nylon to know it does. ?

[Paul_01 0]

I'm about ready to give up on ABS, too unpredictable, but Nylon has been giving me crap with hydrolysis, bubbles, and stringing (<my biggest issue) at the edges. I've baked the spool, and built a desiccant box for it, which helped the hydrolysis except at the beginning of prints (is there any way to make the prime blob bigger?).

As if to pile on the trouble of switching filaments, the printer keeps spitting out "Difference between relative heights of both print cores exceeds realistic values" error message at semi-regular intervals, despite having leveled the build plate manually. Active leveling is set to "Always" and as such runs before every print.

 

I might end up using some black PETG, looks like less maintenance than getting ABS to print nicely or Nylon to print recognizably.

 

[kmanstudios 1,120]

7 minutes ago, Paul_01 said:

the printer keeps spitting out "Difference between relative heights of both print cores exceeds realistic values" error message at semi-regular intervals, despite having leveled the build plate manually. Active leveling is set to "Always" and as such runs before every print.

This is usually because of some sort of schmutz on the nozzles. Clean the nozzles by heating them to about 150°C first. This softens the plastics involved without baking in the plastic at the same time.

 

It does not take much to throw it off. Also, there may be electrical noise.

 

I have that issue sometimes and I know I am getting some sort of interference on the machines (electrical) and think it is something that is going on on the floor above me.

 

If you are confident in your manual leveling, then use it. But even then, make sure the nozzles are spiffy clean.

[Brulti 177]

As @kmanstudios said: make sure that the nozzles are clean. I usually wipe them with a soft cloth when a printing is just finished, if I'm around the printer at that time, to remove all the little bits that can stick to them. You want the tip of the nozzles to be squeaky clean so it can reliably perform the leveling test.

 

It's very strange that your Nylon behaves like this. I use UM standard settings for Nylon and it works like a charm. I've always had a bit of stringing with Nylon, though it's also very dependent on the shape of the part being printed.

 

To print reliably, Nylon requires a brim or a raft for big pieces. No need for glue or for an enclosure, using an enclosure might cause troubles. I'm not too sure what other advices I could give you...

[Paul_01 0]

On ‎7‎/‎23‎/‎2018 at 6:17 AM, Brulti said:

It's very strange that your Nylon behaves like this. I use UM standard settings for Nylon and it works like a charm. I've always had a bit of stringing with Nylon, though it's also very dependent on the shape of the part being printed.

FYI I solved the stringing issue by using a Ooze Shield (3mm distance). super effective, now I get nice prints.

Unrelated further question, I have a right angle overhang on a print, and it insists on warping up (Nylon + PVA). It's not a serious problem by any means (and I'm probably wasting your time asking), but short of making the overhang angle acute in the CAD software, any filaments/printer settings you know of to change this?

 

 

Edited July 24, 2018 by Paul_01

[kmanstudios 1,120]

How are you keeping your heat in the buildplate area?

 

See if this article helps at all.

https://www.matterhackers.com/articles/printing-with-nylon

 

Edit: And, of course, I found this right after that....

https://ultimaker.com/en/resources/22233-how-to-print-with-ultimaker-nylon

Edited July 24, 2018 by kmanstudios