Problem with bending and adhesion

[RoLa 1]

Hi, 

We are using s5 printer and Ultimaker Nylon filament, we are new to 3d printing.

We struggle with parts that bends on edges under printing, see attachment.

What is the reason for that and how to avoid it?

I suppose adhesion problems, what is recommended to use to improve adhesion for nylon and glass bed?

 

THX

[gr5 2,266]

Some people call that "warping" but you are correct in that it is basically an adhesion problem.  The upper layers cool and contract and pull very strongly and that lifts the corners up off the bed.  The fix is adhesion.

 

So adhesion improvements are done with: brim or rounded corners, squish, heat, glues.  You can do some or all of the techniques.  I have much greater detail in this long but comprehensive video so I'll just give you a few bits of advice here.

https://www.youtube.com/watch?v=t58-WTxDy-k

 

squish - the S5 does autoleveling and does a good job with squish.  You could increase "initial layer flow" from 100% to 150% but I wouldn't bother.

 

corners - how sharp are the corners?  If sharp then all the force is on a single tiny point at the corner of your print.  Can you round them (change the CAD)?  If not maybe add some brim which is even better than rounding the corners at stopping lifted corners but somewhat annoying to remove.

 

heat - nylon is unusual in that it gets more and more flexible as it gets warmer up until around 120C where it melts. Flexibility helps spread the forces and keep corners from lifting (effectively the entire corner area of the print warps just ever so slightly and spreads the lifting forces to a larger area of the print).

 

So try heating the bed 10 or even 20C hotter than the default profile.  The only drawback is you have to wait another minute or so for the bed to heat up that much more.  Just keep the bed below 110C.  I think the default bed temp for nylon is usually 70C so try 85C.  Nylon is noticeably more flexible at 85 versus 70C and is less likely to warp up off the table.

 

glues - this is the most important thing.  You might want to invest in a few types of Magigoo (they have different types for different materials).  Personally I use Elmer's wood glue mixed with water (about 20 to 1) and paint that on the glass print bed, heat the bed to printing temp and wait for it to dry.  If you must use glue stick then also remove it with a wet tissue to make the glue stick layer very thin.  Less is more when it comes to these types of glues (more glue means less sticking to the bed).

 

My video shows me applying various types of bed adhesion, shows how I do leveling, explains the issues with diagrams and so on.  You should skip all the leveling details (squish) as that part the S5 does quite well.

[RoLa 1]

Thanks for help and sharing this.

I got Magigoo for PA and it helps, it's almost prefect. 

[TimonR 21]

@RoLa: @gr5 So with Ultimaker Nylon Magigoo PA works very well with the default profile (70C build plate temperature).

 

If you do still have a lot of warping, you can also lower the build plate temperature to 30-40C, this will stop the Nylon from crystallizing during printing ( = warping / bending what you describe). However, the Nylon part will get a bit more flexible this way (depending on your application this might actually be desired).

 

Ultimaker Nylon is PA6/66 by the way, and it melts at ~190C. 

[geert_2 558]

If there are specific problem areas, where only one corner or area lifts and the rest not, you could design a custom brim in the shape of "mickey-mouse ears" around that corner to keep it down. This could happen if that area has a steep overhang, causing a lot of upwards warping forces. But this does not seem the case for you, it seems more general.

 

If the standard brim would not work, because it is too thin and still warps, you could design your own custom brims in the CAD design, and make it a few layers thick, for example 0.5mm. This is still reasonably easy to cut off with a sharp knife or scalpel (surgical knife). I sometimes do that for very specific parts.

 

For example in the design below: the pink and orange parts have overhangs, and are custom supports to prevent the yellow top from sagging. They do need a custom brim, a bigger ground plate, otherwise they would fall over because of their tiny ground-area. Usually I make my custom brims about 0.5mm thick. The hollow cube also needs one, otherwise the walls tend to bend inwards and the cube tends to peel off. This is just a dummy cube, to move the print head away from the yellow part, so the yellow has more time to cool down and solidify, otherwise it gets deformed. The shape has to be accurate, because the blue part has to slide through the yellow part (where the pink and orange supports are now sitting). This is a small model, text caps height is 3.5mm, text legs are 0.5mm, so I can't use heavy tools. The rest of the models don't need brims, they print fine.