Overhang Warping Issues

[davealdon 0]

Hello! I’m a new user of the Ultimaker 2+ Connect, and I’ve noticed that overhangs have been causing a lot of problems. I’ve tried to read about some solutions to overhang issues, such as altering the fan speed, or slowing down the print, on sites like this, but I’m not sure what else to try, or if I’m doing this wrong.

 

I’m trying to use this as a good test to know if overhangs aren’t warping anymore:

https://www.thingiverse.com/thing:4690959

 

My result with default temps (210 nozzle, 60 bed), with the filament that comes with the printer out of the box, (I cancelled the print mid-way once I saw the warping), is attached. This is with 25% infill, and .15 resolution. It will produce one good point, and then all the rest warp upwards.

 

My fan speeds are default, 100%, and I’ve tried print speeds of 60 and 40, with no visible difference. I have the air filter kit, so the printer is fully enclosed. I also attached the benchmark ship to show more obvious overhang problems.

 

Is there something more I can try? Thank you so much!

[geert_2 558]

Such steep overhangs curling up is normal. In my experience, printing cool and in thick layers helps a little bit, but does not eliminate it. More than half of the extruded sausage is printed in the air and has no support to stick to. So it sags when extruded, and then it curls up when cooling...

[davealdon 0]

I've done this screw with a Monoprice Voxel on default settings, and it's flawless, which is why I was interested in what could be causing it this time with the 2+ connect.

 

Slowing the print down to 20mm helped eliminate it as much as I could, which I wish wasn't the only solution, as it turns any simple model with an overhang into a half day print. Thank you though.

[gr5 2,234]

Or you can ignore those up-curls.  I call them "raised edges".  They happen a lot on overhangs but if you ignore them they mostly fix themselves when the nozzle pushes them back down.  Although the print head can hit the part pretty hard so you may want to use pva/water solution to get the part to stick extra well.

 

They look ugly half way through the print but tend to straighten out if you look away.

 

I'm not sure.  Those might be just too much.

 

PLA shrinks in the first dozen milliseconds after it leaves the nozzle and it sticks to itself like snot.  So you get a tight liquid rubber band being placed onto the lower layer and it pulls inwards (this is also why vertical holes always come out too small).

 

So this liquid rubber band action also lifts up the edges of overhangs like this.  There's not a lot you can do about it other than reduce the overhang amount.

 

[davealdon 0]

Yeah those don’t go away, they’re warping far too much to correct themselves.

 

Since slowing it down by around 75% helps, I wonder if printing multiple models at the same time would work at a more normal speed, to give it time to cool properly as it goes across to work on the other model? Things to try I suppose.

[geert_2 558]

Printing multiple models improves cooling, but increases the risk of the curled-up parts being hit hard when the nozzles comes back from the other object. It depends on the geometry of the models.

 

This testmodel was supposed to become a bridge, or table. The inverted triangles are only for support, and need to be removed after printing.

 

 

It got knocked over due to the edges curling up quite a lot, about 1.5mm, and the nozzle hitting really hard:

 

Close-up:

 

Now with redesigned supports, and a bigger footplate.

 

Inverted stairs gave less curling-up than inverted triangles, in my tests. This was just a test model to try-out the concept of free hanging supports, instead of traditional supports going all the way down to the bottom.

 

[Framar 38]

Try to print witht the air manger opened, it should improves cooling efficiency.

The Benchy looks horrible in the overhang areas...

[davealdon 0]

Yeah I'll try with different air manager settings, thank you.

 

Supports aren't really an option with screw threads.