Support help

[toolman0114 0]

I am printing a part with ears that protrude to the side. My support only goes under the very bottom of the ears, how can i make the support extend further up the ear, under the entire curve, not just the flat bottom?

I'd like the support to go under the entire red area of the ear as shown in the pic. Cura is only putting it under the flat bottom area.

[fvrmr 73]

Hi @toolman0114 try adjusting the support overhang. At a value of 0 degrees all overhangs are supported. 90 degrees will not provide any support.

Let me know if you have more questions.

[toolman0114 0]

Thank you for the suggestion, it worked.

BUT.....under the ear after I remove the support the ear has a very rough finish, what should I adjust to help get a smoother finish??

[gr5 2,269]

That's the problem with support.  There's not much you can do where support touches your model however...

 

You can rotate these models.  Have you considered a different rotation?  You might be able to print with zero support in certain orientations.  Or if not then at least you can pick which side is uglier.

 

Or you can buy a printer with dual extrusion and use a different material for the support (like breakaway or PVA).

[toolman0114 0]

as a bolt passes thru the holes, i want the grain to go up/down when in place to prevent fracturing on the knit lines if they were vertical. The top when in place is the radius that shows on the left in the pic i posted.

 

Edited March 2, 2021 by toolman0114

[GregValiant 1,412]

"... I want the grain to go up/down..."

That does require horizontal orientation of the holes as you show in the image.  As gr5 advises, you are stuck with the "finish over supports" as the material can't "squish" onto the interface, and there is typically a gap between the interface and the first layer above as well.  At a Support Overhang Angle of about 55° to 60° the extrusions become self-supporting.  That negates the necessity for supports all along the "ears" and the finish will be acceptable where there are no supports.

If you were to rotate that part about the CL of the holes and put the flat feature on the bed there would be support required for the area above, but maybe it would be hidden in your assembly?  Dimensionally, surfaces over supports are not as good as we have come to expect so doing the ears as you show would be better than having the flats down.  That is especially true if you are trying to hold the dimension between the flat the the CL of the holes.

 

The material you use will make a difference.  Clamping force drops over time as the plastic cold-deforms from the pressure of the fasteners.  I usually use nylock nuts and try not to put much force on the part as they don't like that very much.

 

I typically use the "Grid" for support interface.  The "support interface density" and "support interface thickness" have an effect on the surface finish above.  A high density interface generally leaves a better surface above but is harder to remove cleanly, and your post-processing of the part may leave it's own tool marks.

[toolman0114 0]

If I print it with the flat on the bottom, and ears up, my concern would be having horizontal knit lines, which may allow the part to crack more easily if over tightened. I'm printing with PETG.