Random "Growths" from the bed

[Pridanc 4]

OK folks, 

I've yet to do anything with this print, but am about to.  Having just finished adding a hole to the part in CAD before creating the .stl file used and opened to slice up in CURA 5.8.0

Understand, I've done this same thing for the first model that was without the hole, and that slice had no "growths" seen at the base.  

 

I can see no reason for these growths so am dumbfounded.   I'm here to ask "why are these put here?"  And once we've figured that out (OK, one of you), how do I get the slicer to leave this out?  I tried sweat talking the screen but got nothing so any help would be appreciated. I might try putting support blockers there but um...why? I'm reaching of course so I'll be quiet now.

 

Anyway, below is a close up of the base, and I've included the .3mf file. 

Whl Fair JWM proportion with hole.gcode.3mf

[Slashee_the_Cow 410]

They're support. Easy to tell if you set Color scheme to "Line Type" 🙂 

As for why they're printing there... Support > Support Horizontal Expansion. Set that to 0mm and boom:

Although do you even need support on at all? Thanks to the minimum X/Y distance those bits aren't even touching the model:

And other than maaaaaaaaybe that bottom front where it curves up nothing is overhanging at a particularly egregious angle - so I would just turn support off, start the print, and whistle to myself while I'm watching to make sure the first layers go down well. I would do that, if I could whistle. Since I can't I'd probably do the same thing except listen to the soundtrack for the Moulin Rouge musical instead of the whistling.

[GregValiant 1,342]

The "Support Overhang Angle" in the project is only 15° as well.  With that at a reasonable 55° support doesn't generate.

 

What this does need is the "Limit XY Accel and Jerk" post processor.  It makes adjustments to the Acceleration and Jerk settings as the model gets taller.  This model is tall with limited contact with the base.  Violent "Y" movements can shake the print loose from the bed.

I'd go this way and make a gradual adjust in the "Y" Accel from 1000 to around 350 over a hundred layers or so.

 

Edited August 22 by GregValiant

[Pridanc 4]

OK TY gents.  Not exactly sure how I managed to tweak supports to 15 as I'm not sure where I've ever used that. Oh well.

But we all have to agree that the slicer must be on a bender as there is nothing on the model to support at all accept near the curve of the fin sitting on the bed.  It's almost as if the slicer goes "well maaaybe we should start a tree trunk here as a just in case somewhere along the way we might have to actually use one"  :-)

 

And the your tip on using the "Limit X-Y accel/jerk" is very appreciated. Another lesson in options that without your mentions, would never have me using. 

 

Anyway, TY'all VM as I was stumped. 

 

And please mark this as "Solved" so feel free to close it up.

 

 All the best, PDC

[Slashee_the_Cow 410]

12 minutes ago, Pridanc said:

And please mark this as "Solved" so feel free to close it up.

I'm not supposed to use my assistant mod powers to mark my own posts as solutions, but I think I can make an exception in this case.

 

13 minutes ago, Pridanc said:

But we all have to agree that the slicer must be on a bender as there is nothing on the model to support at all accept near the curve of the fin sitting on the bed.

The whole base of the... whatever it is has a slight curve coming up from the bottom:

But Cura shows you in Prepare mode where it thinks the model needs support by colouring it red:

It changes with the Support Overhang Angle setting. That screenshot above is at 15° - as you can see it thinks the whole base needs some support around it... and it has generated a bit:

This is what it looks like if I set it to 55° (what I usually use):

 

In your case it was only generating a couple of bits - on the corners - because those were the only areas where it could generate any support without coming closer than the Support X/Y Distance setting. As for why they were going up when only the base was marked as needing support?

I'm guessing it was just being nice and thinking "well if I'm taking up this much space on the baseplate, I might as well come as close to supporting this wall as I'm allowed to".

[Pridanc 4]

Thanks for the education which of course is way beyond my pay grade but so appreciated.  And if the model isn't sitting flat on the build plate I'm not sure what to say as I tell CURA to put that end of the model on the plate. CURA stands it up vertically (as I've asked it to do)  from a laying position. From there, this blind old guy has no clue if it is, or is not, flat.  Regardless, not complaining, but thanking you for pointing this out.

 

And BTW, this is a small model of the body for our Bonneville land speed record motorcycle. Each of these models ends up in our small wind tunnel to give us shaping direction before we decide to say OK, lets present this to folks who take $$ to run the profile.  The picture below shows a model mounted up in the tunnel . The thing we love about printing is that we can easily make any desired form changes in CAD, slice in CURA, print again ,and run it in the wind tunnel for answers. This cuts way down on time etc. TY CURA!

 

Stay well, PDC

[Slashee_the_Cow 410]

31 minutes ago, Pridanc said:

And BTW, this is a small model of the body for our Bonneville land speed record motorcycle. Each of these models ends up in our small wind tunnel to give us shaping direction before we decide to say OK, lets present this to folks who take $$ to run the profile.  The picture below shows a model mounted up in the tunnel . The thing we love about printing is that we can easily make any desired form changes in CAD, slice in CURA, print again ,and run it in the wind tunnel for answers. This cuts way down on time etc. TY CURA!

Well now that I know what it is, it looks pretty cool for what it is 🙂 3D printing isn't called "rapid prototyping" for nothing.

[GregValiant 1,342]

"The best scale for a prototype is 1:1" - Unknown